Yann Bulteau

Christine Lepetit

Corinne Lacaze-Dufaure

Topological Analysis of Hydroxyquinoline Derivatives lnteracting with Aluminum Cations or with an Al(l 11) Surface

Keywords:

The reactivity of hydroxyquinoline derivatives (native molecules (Hq) and modified species (HqX, X = Br, S0 3 H, or S0 3 )) is investigated either (i) with aluminum cations for the formation of chelates or (ii) with aluminum surfaces for their adsorption properties, in the framework of the dispersion corrected Density Functional Theory (DFT D). It is shown that the substituent X has no influence on the complexation to the aluminum cation of the deprotonated active form, i.e., the one exhibiting a phenolate moiety and referred to as q-for the native Hq and qX"-(n = 1 or 2) for its derivatives. The formation energies of the Al 43 and Al(qX) 3 complexes, taking values of -60.87 ± 3.10 eV in vacuum and -24.30 ± 0.29 eV in water, are indicative of a strong chelating affinity of the q-and qX"-( n = 1 or 8Hq molecule ' [m"'" an Al(b comp lei'J Aasorbed on an Al(lll) surface Al•NBCP p 0050 AP•.0.201 ,,c-1.or, 11/i;l � AI-N 9CP D 0.111,11

INTRODUCTION

It is well established that hydroxyquinoline species, i.e., the 8 hydroxyquinoline molecule (Hq), can be used for various applications such as metal cation detection and removal, 1 -3 organic light emitting diodes (OLEDs), 4 ,s and medicine. 6 These uses ail depend on the chelating ability of the Hq molecule, which is able to complex metal ions leading to higbly fluorescent chelates. The Hq molecule was also studied in the perspective ofbeing used as a corrosion inhibitor of aluminum, as the replacement of currently used chromates by environ mentally friendly alternatives is required. 7 -11 Various derivatives of the Hq molecule have been synthesized, with, for instance, substitution of an H atom by a sulfonic group at the para position of the phenyl ring (HqSH in Figure 1 andTable 1). It forms higbly soluble fl uorescent complexes, 3 ' 12 and it is used for metal ion detection in aqueous solutions. ln addition, electrochemistry studies have shown that this species is an aluminum corrosion accelerator. 11'13 Another Hq derivative, with Br atoms on the ortho and para sites of the phenol ring (HqBr in Figure 1 andTable 1), is known for its metal chelating properties. It could be used in the medical field such as other halogen Hq derivatives. 6 It has also been tested as a potential corrosion inhibitor of aluminum and showed only very little efficiency. 8 These applications require stabilization of the organo metallic species and thus strengthening of the interactions of the hydroxyquinoline derivatives (i) with metal ions in order to form chelates and (ii) with metallic surfaces to yield adsorbed Hq species. In the present work, the bonding with aluminum of native and modified Hq molecules, called derivatives (modification at X1 and X2 positions presented in Figure 1), is compared in order to rationalize further chemical modifications. Our first aim is to get insights into the chelating properties of the Hq derivatives. Moreover, to get information in relation to the inhibiting properties of the Hq derivatives, the interaction of the molecules with surfaces is investigated using first principle calculations. 14 It was demonstrated in previous works that the Hq molecule can form stable layers on the Al(111) surface, by direct adsorption of the molecules on the metallic surface [15][16][17] or by adsorption of Alq 3 complexes on Al(111). 17 As the bromo and sulfonic Hq modified species showed a weaker inhibiting efficiency than the native Hq, studies of the adsorption of these molecules on aluminum surfaces are required.

The understanding of electronic effects of the substituents on the reactivity of molecules can be addressed using quantum chemistry analysis tools. On the one hand, the simplest approach, called Quantitative Structure Properties Relationship (QSPR), is the deduction of the chemical reactivity of a molecule from descriptors such as the dipole moment and the energy of the frontier orbitals. 18 These descriptors can be calculated by quantum methods, and this approach can be a convenient method to sort a large amount of molecules in a short period of time. However, it has been shown to be of little use concerning complex reactions such as the one involved in corrosion inhibition. [START_REF] Taylor | A Multiphysics Perspective on Mechanistic Models for Chemical Corrosion Inhibitor Performance[END_REF] On the other hand, accurate analyses of the electronic structure of molecules, obtained by first principles methods, can be performed using topological analyses. For instance, the Quantum Theory of Atoms in Molecules (QTAIM) [START_REF] Bader | Atoms In Molecules[END_REF] refers to the topological analysis of the electron density partitioning the molecular space into non overlapping atomic basins and yielding atomic charges. The nature of chemical bonds may be characterized from various properties of the electron density at bond critical points. This analysis has been proved useful for the study of metal-ligand bonding. [START_REF] Bianchi | Experimental Electron Density Analysis of Mn2(CO)10: Metal-Metal and Metal-Ligand Bond Characterization[END_REF][START_REF] Cortes Guzman | Complementarity of QTAIM and MO theory in the study of bonding in donor-acceptor complexes[END_REF][START_REF] Boukallaba | Coordination complexes of 4 methylimidazole with ZnII and CuII in gas phase and in water: a DFT study[END_REF][START_REF] Lepetit | Topological analysis of the metal metal bond: a tutorial review[END_REF][START_REF] Lepetit | square pyramidal cationic PCP Ni(II) pincer complexes: ELF and QTAIM topological analyses of nickel triflate interactions[END_REF][START_REF] Aray | Topology of the Electron Density and Cohesive Energy of the Face Centered Cubic Transition Metals[END_REF][START_REF] Vega | AIM UC: An application for QTAIM analysis[END_REF][START_REF] Aray | Exploring the electron density localization in MoS2 nanoparticles using a localized electron detector: Unraveling the origin of the onedimensional metallic sites on MoS2 catalysts[END_REF] Another approach is the topological analysis of the Electron Localization Function (ELF). [START_REF] Becke | A simple measure of electron localization in atomic and molecular systems[END_REF][START_REF] Silvi | Classification of chemical bonds based on topological analysis of electron localization function[END_REF] It is a unique tool for chemical bonding analysis. It has been successfully used to characterize bonds in molecular [START_REF] Boukallaba | Coordination complexes of 4 methylimidazole with ZnII and CuII in gas phase and in water: a DFT study[END_REF][START_REF] Lepetit | Topological analysis of the metal metal bond: a tutorial review[END_REF][START_REF] Lepetit | square pyramidal cationic PCP Ni(II) pincer complexes: ELF and QTAIM topological analyses of nickel triflate interactions[END_REF][START_REF] Lepetit | ELF Analysis of Out of Plane Aromaticity and In Plane Homoaromaticity in Carbo[N]annulenes and[END_REF] or periodic extended systems. [START_REF] Savin | The Electron Localization Function[END_REF][START_REF] Loffreda | Structural Identification of Conjugated Molecules on Metal Surfaces by Means of Soft Vibrations[END_REF] In the first part of the present paper, a description of the models and methods used in the molecular or periodic calculations is given in the Computational Details section together with the principles of ELF and QTAIM topological analyses. The results from calculations and topological analyses of the Hq and HqX molecules and of their Al(qX) 3 complexes are then disclosed in a second part. In the last part, the periodic computations performed in order to evaluate the influence of the substitution in the Hq molecule on its adsorption properties on an Al(111) surface are described.

COMPUTATIONAL DETAILS

The hydroxyquinoline molecule studied (Hq) is often referred to as 8 hydroxyquinoline in the literature. The native Hq was studied, together with two derivatives (referred to as HqX in a generic way), namely the 5,7 dibromo 8 hydroxyquinoline molecule (HqBr) and the 8 hydroxyquinoline 5 sulfonic acid (HqSH) presented in Figure 1 and Table 1. Some of our previous studies had already shown that the deprotonation of the hydroxyl group of the Hq molecule leads to the most reactive species toward aluminum. 15,16 In the present computational work, we thus investigated the bonding of the deprotonated derivatives (i) with an aluminum atom leading to chelates (molecular computations) and (ii) as a standalone molecule adsorbed on an aluminum surface (periodic computations). The atom numbering for the deprotonated species used hereafter is presented in Figure 2. For clarity, only the C atoms are numbered (C1 to C9).

Molecular Calculations and Topological Analysis.

Calculations were first performed on the deprotonated molecules that are anions, i.e., q -, qBr -, and qSH -presented in Table 1, and on aluminum complexes, i.e., Alq 3 , Al(qBr) 3 , and Al(qSH) 3 . Concerning the HqSH molecule, the pK a of the (SO) 3 H/(SO) 3

-chemical group has a negative value, [START_REF] Bahers | Theoretical determination of the pKas of the 8 hydroxyquinoline 5 sulfonic acid: A DFT based approach[END_REF] and the sulfonic group of the molecule is deprotonated in aqueous solution. The qS 2 anion and the Al(qS) 3 3complex were thus studied in addition to the qSH -species. The generic notation of the anions is thus (qX) n-(n = 1 or 2) and Al(qX) 3 m-(m = 0 and 3) for the complexes. However, the charge on the complexes will be omitted hereafter for clarity. The complexes will be thus referred to as Al(qX) 3 .

2.1.1. DFT Computations. The structure of free deprotonated q - and qX n-(n = 1 or 2) anions and of their Alq 3 and Al(qX) 3 complexes was calculated in vacuum at the DFT D level. The geometries of the systems were fully optimized without symmetry constraints using conjugate gradient methods with the GAUSSIAN09 package. [START_REF] Frisch | Revision D.01[END_REF] The gradient corrected PBE functional [START_REF] Perdew | Generalized Gradient Approximation Made Simple[END_REF] was chosen together with the def2TZVP basis set [START_REF] Weigend | Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy[END_REF][START_REF] Weigend | Accurate Coulomb fitting basis sets for H to Rn[END_REF] and Grimme's dispersion corrections. [START_REF] Grimme | Semiempirical GGA type density functional constructed with a long range dispersion correction[END_REF][START_REF] Grimme | A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT D) for the 94 elements H Pu[END_REF] All the stationary points were characterized as minima by a vibrational analysis. The calculated total energies included zero point corrections.

The formation energies E form complex of the Alq 3 and Al(qX) 3 complexes were calculated in vacuum from the total energies E complex of the complex, E mol of the isolated q -and qX n-species, and E Al 3+ of the aluminum ion, respectively: (1)

The electronic structure of the most stable geometries was analyzed in terms of atomic charges and chemical bonding using ELF and QTAIM topological analyses.

2.1.2. Topological Analyses. Topological methods are based on the analysis of the gradient field of a local function within the dynamic field theory and provide a partition of the molecular space into nonoverlapping basins.

The topological analysis of the electron density ρ designed as the Quantum Theory of Atoms in Molecules (QTAIM) by Bader yields atomic basins and QTAIM atomic charges. [START_REF] Bader | Atoms In Molecules[END_REF] It allows defining bond paths and bond critical points (BCPs). The nature of the chemical bond is characterized from various properties of the electron density at the BCPs (ρ bcp ), especially the sign of the Laplacian of the electron density (∇ 2 ρ bcp ) and the values of the kinetic energy density (G bcp ), of the potential energy density (V bcp ), and of the energy density (H bcp ) = (G bcp ) + (V bcp ) following Macchi's classification. [START_REF] Macchi | Experimental Electron Density in a Transition Metal Dimer: Metal Metal and Metal Ligand Bonds[END_REF] A negative Laplacian of ρ at the BCP (∇ 2 ρ bcp < 0) corresponds to a local concentration of ρ indicating an electron sharing bond (i.e., covalent bond), while a positive Laplacian (∇ 2 ρ bcp > 0) corresponds to a local depletion of ρ, indicating a closed shell interaction (i.e., ionic bond). . [START_REF] Espinosa | From weak to strong interactions: A comprehensive analysis of the topological and energetic properties of the electron density distribution involving X HF Y systems[END_REF] The electron localization function (ELF) measures the excess of kinetic energy due to the Pauli repulsion. [START_REF] Becke | A simple measure of electron localization in atomic and molecular systems[END_REF][START_REF] Silvi | Classification of chemical bonds based on topological analysis of electron localization function[END_REF] ELF values are confined between 0 and 1. ELF tends to a value of 1 in those regions where the electron localization is high (atomic shells, chemical bonds, and single electron or lone pairs), whereas it tends toward small values at the boundaries between these regions. [START_REF] Poater | Theoretical Evaluation of Electron Delocalization in Aromatic Molecules by Means of Atoms in Molecules (AIM) and Electron Localization Function (ELF) Topological Approaches[END_REF][START_REF] Silvi | Electron density analysis[END_REF] The topological analysis of the ELF gradient field yields a partition of the molecular space into nonoverlapping basins of attractors, classified into core, valence bonding, and nonbonding basins. The attractors, namely local maxima of the ELF function, can be single points (general case), circles, or spheres depending on the symmetry. These basins are in one to one correspondence to the core, lone, or shared pairs of the Lewis model. A core basin contains a nucleus X (except a proton) and is designated as C(X). A valence basin lies between two or more core basins. Valence basins are further distinguished by their synaptic order, which is the number of core basins with which they share a common boundary. The monosynaptic basins denoted as V(X), correspond to lone pairs, whereas the di and polysynaptic ones are related to bi or multicentric bonds, denoted as V(X1, X2, X3, ...). The average population of the basin is obtained by integration of the one electron density over the basin volume. A statistical population analysis allows for considering the variance and the covariance of the basin populations, which are related to the electron delocalization. [START_REF] Silvi | How topological partitions of the electron distributions reveal delocalization[END_REF] The populations do not take integral values and are about twice the topologically defined Lewis bond orders for bonding valence basins. Electron Localization Function (ELF) [START_REF] Becke | A simple measure of electron localization in atomic and molecular systems[END_REF][START_REF] Silvi | Classification of chemical bonds based on topological analysis of electron localization function[END_REF] topological analyses were performed at the PBE D3/def2TZVP level of calculation, using the TopMoD package. [START_REF] Noury | Computational tools for the electron localization function topological analysis[END_REF] ELF maps were plotted using the Molekel program. 47 Quantum Theory of Atoms in Molecules (QTAIM) [START_REF] Bader | Atoms In Molecules[END_REF]48 analyses were performed at the PBE D3/def2TZVP level of calculation, using the AIMAll software. [START_REF] Keith | TK Gristmill Software[END_REF] 2.2. Periodic Calculations and Topological Analyses. Periodic calculations were performed to investigate the adsorption of the molecules on an Al(111) surface. The adsorption of the deprotonated q -and qX n-anions was not investigated, because charged species should be avoided in the framework of periodic calculations. Instead we studied the adsorption of the dehydrogenated molecules, i.e., q, qBr, qSH, and qS, that are radicals. This method is usually chosen to study the adsorption of molecules on metallic surfaces resulting in an adsorbed state almost independent of the initial molecule charge. [50][START_REF] Kokalj | The Effect of Surface Geometry of Copper on Dehydrogenation of Benzotriazole. Part II[END_REF][START_REF] Poberzňik | Insight into the Bonding of Silanols to Oxidized Aluminum Surfaces[END_REF] 2.2.1. DFT Computations. Periodic calculations were performed using the Vienna Ab Initio Simulation Package (VASP [START_REF] Kresse | Ab initio molecular dynamics for liquid metals[END_REF][START_REF] Kresse | Efficient iterative schemes for ab initio total energy calculations using a plane wave basis set[END_REF][START_REF] Kresse | Efficiency of ab initio total energy calculations for metals and semiconductors using a plane wave basis set[END_REF] ) with the PAW method. [START_REF] Blochl | Projector augmented wave method[END_REF][START_REF] Kresse | From ultrasoft pseudopotentials to the projector augmented wave method[END_REF] The PBE functional [START_REF] Perdew | Generalized Gradient Approximation Made Simple[END_REF][START_REF] Perdew | Generalized Gradient Approximation Made Simple[END_REF] was used for the exchange correlation term. Spin polarization was included. The addition of a dispersion (van der Waals) term to the DFT energy has shown to give more accurate results for organic molecules interacting with a metallic surface in terms of geometry and bonding energy. 15,16,[START_REF] Schiavo | Tuning dispersion correction in DFT D2 for metal molecule interactions: A tailored reparameteriza tion strategy for the adsorption of aromatic systems on Ag(111)[END_REF] To this end, we used the Grimme's D2 functional. [START_REF] Grimme | Semiempirical GGA type density functional constructed with a long range dispersion correction[END_REF] All calculations used a cutoff energy (E cut ) of 450 eV and a Methfessel Paxton (MP) smearing [START_REF] Methfessel | High precision sampling for Brillouin zone integration in metals[END_REF] with σ = 0.1 eV. The electronic convergence criterion was 10 -6 eV. For the geometry optimization, convergence was considered to be reached when the forces on each atom were less than 5 × 10 -3 eV•Å -1 .

Our aim was to investigate the adsorption properties and bonding of the qX molecules on the (111) aluminum surface. An asymmetric Al(111) slab of four layers and 30 atoms per layer (6 × 5 corresponding to a 17.12 × 14.27 Å 2 surface area) was used. The two top layers were free to relax, and the two bottom layers were fixed at their bulk positions. On the direction normal to the surface, the vacuum region, that is the distance between the top of the adsorbed species and the bottom of the periodic image of the slab, was larger than 15 Å. A Monkhorst-Pack grid 61 of 3 × 3 × 1 k points was chosen as to have the closest k points density along each dimension, and the convergence of the energy (variation of the energy of less than 0.002 eV) with respect to the number of k points was checked. Finally, dipole correction [START_REF] Neugebauer | Adsorbate substrate and adsorbate adsorbate interactions of Na and K adlayers on Al(111)[END_REF] to the potential and forces was used to minimize dipole-dipole interaction between image slabs. With the four layers slab and these calculating conditions, a surface energy of 1.19 J/m 2 was calculated, and it is in very good agreement with the experimental counterpart [START_REF] Tyson | Surface free energies of solid metals: Estimation from liquid surface tension measurements[END_REF] (1.14 J/m 2 ).

The dehydrogenated species were adsorbed on the Al(111) surface at a coverage of 4.62 × 10 -3 molecule Å -2 , the maximal surface coverage being 2.36 × 10 -2 molecule Å -2 with all the surface Al atoms covered. The initial positions were chosen to investigate different adsorption topologies and with O and N atoms of the molecules on top, bridge, and 3 fold sites on the Al(111) surface (Figure 3).

To get insights in the adsorption process, we calculated the following:

(i) the adsorption energy of the q and qX species on the Al(111) surface:

= - - + E E E E ads mol slab mol slab mol (2)
with E slab+mol the total energy of the system with q or qX adsorbed on the Al(111) surface. E slab and E mol are respectively the energy of the bare relaxed Al(111) slab and of the free q or qX molecules optimized in vacuum. (ii) the molecule deformation energy:

= - E E E deform mol SP mol mol
(3) with E ads mol and E mol respectively the total energy of the isolated molecule at the geometry after adsorption and of the free molecule optimized in vacuum. (iii) the substrate deformation energy:

= - E E E deform slab SP slab slab (4)
with E SP slab and E slab the total energy of the isolated slab at the geometry after adsorption and the total energy of the relaxed slab in vacuum. (iv) the interaction energy:

= - - + E E E E int slab/mol slab mol SP slab SP mol (5)
Figures were plotted using the VESTA code. 64,65 2.2.2. Topological Analyses. The QTAIM 20 atomic charge Q x was calculated from the Bader population analysis implemented by Henkelman et al. [START_REF] Tang | A grid based Bader analysis algorithm without lattice bias[END_REF] for all the atoms of the Al(111) slab and of the q and qX molecules before and after the adsorption process.

Further QTAIM analyses on the optimized geometries of surface adsorbed species were performed using the AIM UC program [START_REF] Vega | AIM UC: An application for QTAIM analysis[END_REF] and the Abramov's approximation. [START_REF] Abramov | On the Possibility of Kinetic Energy Density Evaluation from the Experimental Electron Density Distribution[END_REF] Abramov suggested to calculate the ki ne tic ene rg y dens ity at the BCP s from

G ( r c ) = π ρ ρ + ∇ ( ) () r r (3 ) ( ) ( ) c c

RESULTS AND DISCUSSION

In microelectronic applications, Alq 3 complexes are commonly used as amorphous thin films. When they are present in aqueous solution, they are also suspected to deposit on aluminum surfaces to protect them against corrosion. Similarly, in solution, deprotonated Hq species may also adsorb on the metallic surface to form a protective layer. The bonding of the molecules to aluminum cations or with surface Al atoms is thus of prime interest, and chemical modifications of blueHq could influence this bonding. Hereafter, the structure of the free q - and qX n-(n = 1 or 2) species and Alq 3 and Al(qX) 3 complexes in vacuum and the topological analysis of their electronic structure are first presented. Then, the adsorption of q and qX species on Al(111) is investigated and is followed by the determination of the nature and strength of the bonding at the molecule/metal interface.

3.1. Topological Analyses of the Free q -and qX n-(n = 1 or 2) Anions and Their Alq 3 and Al(qX) 3 Complexes.

The electronic structures of the q -and qX n-anions and their aluminum complexes, calculated at the PBE D3/def2TZVP level, were first studied using ELF and QTAIM analyses. The relevant topological descriptors are illustrated first hereafter for the parent q -anion and further discussed over the series of inhibitors, qBr -, qSH -, and qS 2 .

3.1.1. Free q -and qX n (n = 1 or 2) Species. The map of ELF attractors and their average population is displayed in Figure 4, Table 2, and Table S1 for q -. It is consistent with previous reports of ELF and QTAIM analyses of aromatic compounds among which are naphthalene derivatives [START_REF] Poater | Theoretical Evaluation of Electron Delocalization in Aromatic Molecules by Means of Atoms in Molecules (AIM) and Electron Localization Function (ELF) Topological Approaches[END_REF][START_REF] Fuster | Topological analysis of the electron localization function (ELF) applied to the electrophilic aromatic substitution[END_REF][START_REF] Fuster | Intramolecular Hydrogen Bonds: the QTAIM and ELF Characteristics[END_REF] and of QTAIM descriptors calculated for complexes of hydroxyquinoline with Mn III , Fe III , and Co III . [START_REF] Murgich | A Density Functional Theory Study of the Topology of the Charge Density of Complexes of 8 Hydroxyquinoline with Mn (III), Fe (III), and Co (III)[END_REF] In previous studies, 15,16 it was shown that surface Al atoms interact with the deprotonated inhibitor via the O atom of the phenolate moiety and/or the N atom of the pyridine ring. The focus was therefore set on the average population of the ELF monosynaptic V(O) and V(N) basins, that may be related to the lone pairs of the phenolate and amine ligands. According to the local symmetry of the planar q -anion, the O atom exhibits two inequivalent V(O) a and V(O) b ELF basins, while the N atom has only one V(N) basin (Table 2 and Figure 4). For the q -anion, the populations of V(O) a and V(O) b basins add to 5.64 e, thus close to 6 e, while the population of the disynaptic V(C4,O) basin related to the C4-O bond is close to 2 e, in agreement with the phenolate mesomeric form of Figure 4. The population of the V(N) basin is much larger (2.74 e) than the expected value of 2 e, and the population of the disynaptic basins V(C5,N) and V(C9,N) respectively 2.29 and 2.44 e is much lower than the 3 e value expected for an aromatic C-N bond, suggesting that the weight of the pyridine mesomeric form of Figure 4 is significant. All the above population values are however slightly dependent on the substituting group (Table 2), suggesting that the coordinating properties of the phenolate and pyridine ligands of the qX n-anions will not be dependent on the substituents introduced in X1 and X2 positions.

Similarly the QTAIM atomic charges of O, N, C5, and C9 are almost the same over the anions series, close to -1.1 e, -1.0 e, and -0.8 e (Table S2). This is consistent with the mesomeric form of Figure 4.

3.1.2. Alq 3 and Al(qX) 3 Complexes. The Alq 3 and Al(qS) 3 complexes have already been studied in the literature and can exist in two forms, the fac and mer isomers, differing in the arrangement of O and N atoms around the Al 3+ ion. The present study was restricted to the mer isomer (Figure 5), more stable by 138 meV (this work) and 135 meV 3 than the fac isomer for Alq 3 and Al(qS) 3 , respectively.

The metal-ligand bond distances of the Alq 3 complex of distorted octahedral symmetry are given in Table 3. The Al-O bond lengths of 1.863, 1.891, and 1.894 Å and Al-N bond lengths of 2.058, 2.101, and 2.045 Å are in accordance with previous BLYP, [START_REF] Curioni | 3: ab initio calculations of its structural and electronic properties in neutral and charged states[END_REF] GGA, [START_REF] Wang | Adsorption of tris(8 hydroxyquinoline)aluminum molecules on cobalt surfaces[END_REF] and PBE [START_REF] Yanagisawa | First principles theoretical study of Alq(3)/Al interfaces: Origin of the interfacial dipole[END_REF] calculations as well as with experimental measurements. [START_REF] Halls | Molecular Orbital Study of the First Excited State of the OLED Material Tris(8 hydroxyquinoline) aluminum(III)[END_REF][START_REF] Colle | The structure of the blue luminescent delta phase of tris(8 hydroxyquinoline)aluminium (iii) (Alq3)[END_REF] The Al-O bond lengths are comparable to the sum of ionic radii of Al and O, i.e., about 1.9 Å, suggesting the formation of three ionic bonds between Al 3+ and q -ions. Similar arrangements of the molecules are found in Al(qBr) 3 , Al(qSH) 3 , and Al(qS) 3 (Table 3), suggesting that the modification of the substituent on X1 and X2 positions and the deprotonation of the SO 3 H group has no influence on the final geometry of the aluminum complex.

The energies of formation of the Alq 3 and Al(qX) 3 complexes in vacuum are given in Table S3. The values are -60.87 ± 3.10 eV and indicate strong interactions between q - and qX n-anions, and the Al 3+ ion and are consistent with the ionic bonding as it will be shown below. The description of the electronic structure of the complexes was improved to get formation energies in aqueous solution, using Truhlar and co workers' SMD solvation model [START_REF] Marenich | Universal Solvation Model Based on Solute Electron Density and on a Continuum Model of the Solvent Defined by the Bulk Dielectric Constant and Atomic Surface Tensions[END_REF] by placing the solute in a cavity within the solvent reaction field. The energies of formation in water converge toward -24.30 ± 0.29 eV for all the complexes, suggesting again similar chelating properties for the q -and qX n-species.

The investigation of the bonding in Alq 3 complexes has been started in a previous work, 17 in the framework of periodic DFT computations. The study of the interactions between dehydrogenated q species and an Al atom was shown to be in favor of an iono covalent bonding, but accurate topological analysis was needed to support this conclusion and to quantify the covalent character of the bonding. In the present work, the ELF descriptors calculated for Alq 3 are displayed in Figure 6, Table 4, and Table S1. Only the population of V(O) and V(C4,O) basins of qX n-, thus the description of the phenolate moieties, is modified upon complexation to Al. Due to strong symmetry reduction, the V(O) basins exhibit very different populations, V(O) a = 2.31 e, V(O) b = 3.70 e, adding to a larger value (6 e) than for the unbonded q -anion (5.64 e), while the V(C4,O) basin populations have been concomitantly depleted from 1.94 e down to 1.64 e. The absence of a disynaptic attractor between Al and O or between Al and N is in favor of an ionic bonding between Al 3+ and the three q -anions. The negligible atomic contribution of Al to V(O) a or to V(N) basins (about 3%) and the very low covariance between C(Al) and V(O) and V(N) basins (cov(V(O) a , C(Al)) = -0.05 and cov(V(N), C(Al)) = -0.04) are indeed indicative of a very weak covalence degree of the Al-O and Al-N ionic bonds (Table 4).

The same ELF description holds for the other complexes of the series, i.e., Al(qBr) 3 , Al(qSH) 3 , and Al(qS) 3 complexes. In the case of Al(qBr) 3 , the populations of the V(C, Br) and V(Br) basins are also affected by the local symmetry reduction. The population of disynaptic V(C,Br) valence basins is depleted of about 0.13 e. Moreover, the number of monosynaptic V(Br) basins decreases from 3 in the free qBr -anion to 2 in the complex.

QTAIM analysis was performed on the four complexes. Selected QTAIM atomic charges are displayed in Table S2 and are very similar over the series. The QTAIM descriptors, i.e., ρ bcp , ∇ 2 ρ bcp , Although this work focuses on Hq derivatives for which both experimental and computational data are available, topological analysis of two additional Hq derivatives was performed in order to be able to browse the Hammett scale [START_REF] Hansch | A Survey of Hammett Substituent Constants and Resonance and Field Parameters[END_REF] from the more donating para substituent (p NH 2 , Hammett constant σ = -0.66) to the more withdrawing para substituent (p CN, σ = 0.66) going through the moderately withdrawing experimental substituents of this work, namely (p Br, σ = 0.23 and p SO 3 -, σ = 0.35). The corresponding data are presented in Table 4 and Table 5 and further supports that the substituent does not have any influence on the Al-O and Al-N bonds of the Alq 3 complexes thus on the complexation of the investigated Hq derivatives. The ELF and QTAIM descriptions of the interaction of qX n (n = 1 or 2) anions with aluminum within Al(qX) 3 complexes show no dependence on the ortho and para substituent of the phenol ring. The Al chelating properties are thus similar for the Hq derivatives studied. This is consistent with the calculated formation energies in aqueous solution that are the same within all the derivatives.

| | V G bcp bcp
3.2. Topological Analyses of the Charge Density of q and qX Species Adsorbed on Al(111). Studies of the interaction of q and qX with an Al(111) surface were then further performed. In contrast to the above Alq 3 and Al(qX) 3 complexes, the interaction with Al atoms is not restricted to the O or N atoms. The underlying hypothesis is then that the interaction of several atoms of qX with the Al surface atoms could change their properties, as anticipated from the variable efficiencies of the various HqX derivatives toward corrosion inhibition.

3.2.1. Energies and Geometries of the q and qX Species Adsorbed on Al(111). For each molecule, two adsorption modes were investigated, i.e., a tilted (qX tilt ) and a parallel (qX paral ) adsorption mode. The most stable geometries are presented in Figure 8. For the tilted adsorption mode, the molecules are bound to the surface only by their O and N atoms. The parallel adsorption mode corresponds to a geometry where the molecule is nearly parallel to the surface, with the formation of additional bonds between surface Al atoms and the molecule (mostly by a C atom of the phenol ring or an O atom of the SO 3 and SO 3 H groups). Adsorption, deformation, and interaction energies and charge (Q mol ) on the adsorbed molecules for each configuration are given in Table 6. For the free qS species, no stable geometry could be found. Thus, adsorption energy and deformation energy were not calculated. The lengths of the shortest bonds between the atoms of the molecules and surface Al atoms are given in Table 7. In the case of adsorption on a bridge site of the surface (Figure 3), two bonds are formed, and two bond lengths (d Al1-O and d Al2-O ) are given. For the tilted configurations, the tilt angle can be defined as the angle formed between the C5-C6 bond and its projection on the Al(111) surface. The tilt angle values are 64.9°, 40.6°, 52.1°, and 87.2°, respectively, for the q, qBr, qSH, and qS species. These variations of the tilt angle are due to the intensity of the interactions of the molecules with the Al surface that governs the adsorption geometry.

For the q molecule, the tilted mode is more stable than the parallel mode by 0.11 eV. For this tilted configuration, the adsorption energy is -3.59 eV, 17 8) upon adsorption. The interaction energy E int slab/mol corresponds to the energy associated with both chemical and van der Waals bonding between the molecule and the surface, without taking into account the value of the energy of deformation of the molecules and the slab. The interaction energy of the tilted mode is -4.57 eV. It again shows a strong interaction between the molecule and the Al(111) surface, and 14.4% of the interaction energy comes from van der Waals interactions (-0.66 eV). The adsorption energy of the parallel mode is -3.48 eV, 17 also indicating a strong interaction with the Al(111) surface. In that case, the molecule is strongly distorted upon adsorption with a deformation energy of 1.69 eV. This strong value corresponds to the deformation of the pyridine ring (see Figure 8 surface. The deformation energy of the slab is of 0.27 eV, showing a weakly deformed slab. The interaction energy E int slab/mol of the parallel mode is of -5.43 eV. The binding is thus stronger for the parallel mode than for the tilted mode because of the Al3-C7 bond, as well as by stronger van der Waals interactions (-1.26 eV and 23.2% of the interaction energy) in the parallel mode than in the tilted mode.

The strong interaction between the qX species and the Al(111) surface runs for all the molecules with adsorption energies values from -3.51 eV to -3.91 eV. In contrast to the adsorption of the q molecule, for which the most stable geometry on the Al(111) surface is the tilted one, the parallel adsorption mode is more stable than the tilted mode by 0.16, 0.21, and 1.82 eV for qBr, qSH, and qS, respectively. It is due to a stronger interaction with the surface Al atoms in the parallel mode for the qBr and qSH molecules (E int slab/mol = -5.78 eV and -6.29 eV) than for the q molecule (E int slab/mol = -5.43 eV) and high stabilizing van der Waals contribution to the interaction energy (25.9% and 22.1%, respectively). Moreover, the interaction of the Br2 atom on C3 with the Al(111) surface gives rise to a tilted mode less stable for qBr than the parallel geometry. For the qSH species, the adsorption geometry is close to the parallel one for qS, but only one O atom of the SO 3 H group is in interaction with atoms of the Al(111) surface (d Al-O2 = 2.059 Å). For the qS molecule, the parallel mode is the most stable configuration because the molecule is chemisorbed on the surface by the O atom (d Al1-O = 1.818 Å), the N atom (d Al1-N = 1.909 Å), and the C7 atom (d Al3-C7 = 2.202 Å) like for the parallel mode of the other qX molecules, as well as by two oxygen atoms of the SO 3 group (d Al-O2 = 1.930 Å and d Al-O3 = 1.935 Å). For the qS molecule, one conformation with the molecule adsorbed on the surface by the SO 3 group was also determined and is presented in Table S4.

The deformation energies of the slab and the molecules do not change drastically upon the series of inhibitors for the tilted mode. For the parallel mode, the deformation energy of the qSH molecule is stronger because of the additional bonding between the surface Al atoms and the sulfonic group. Thanks to its adsorption geometry, the qS species might have a similar high value for the deformation energy upon adsorption. The bond lengths in the molecules, in their free state and for the parallel adsorption mode (strongest deformations of the molecules upon adsorption), are presented in Table S5. The bond lengths are modified in the molecules upon adsorption on Al(111) showing a strong electronic reorganization. In the free q, qBr, and qSH species, the C-C bond length values in the pyridine ring range from 1.384 to 1.433 Å, and the C-N bond length values range from 1.332 to 1.344 Å. All these values are in favor of an aromatic character in the pyridine ring. 78 In the phenol ring, the C1-C2, C2-C3, C5-C6, and C6-C1 bond lengths show also electron delocalization on these C-C bonds, whereas the C3-C4 and C4-C5 bonds are larger (1.454-1.499 Å). The C-O distance is 1.239-1.249 Å, and it is characteristic of a phenoxy radical bond. 79 In the adsorbed species (parallel adsorption mode), the aromatic character of the phenol ring and the pyridine ring is modified. The phenol ring of the molecules is not very distorted and shows a more aromatic character (C-C distances between 1.384 and 1.426 Å; C-O distances between 1.335 and 1.346 Å, showing single bonds with a partial double bond character [START_REF] Demaison | Equilibrium CO bond lengths[END_REF] ) than in the free state. The pyridine ring is strongly distorted, and the aromatic character is strongly lowered in the cycle. The C6-C7 and C7-C8 distances could show a single bond between one Csp 2 and one Csp 3 atoms. [START_REF] Fox | Organische Chemie: Grundlagen Mechanis men, Bioorganische Anwendungen[END_REF] The C8-C9 bond length of 1.36 Å is in favor of a double bond. The C5-N and C9-N bonds are enlarged with bond lengths closer to single bonds with a partial double bond character.

In the periodic DFT approach, the type and the strength of the interactions between an adsorbate and a substrate are usually characterized by the evaluation of the electron transfer upon adsorption (Table 6) and the plotting of the electron density at the adsorbate/substrate interface (Figure 9). For the q species, the QTAIM charges calculated before and after adsorption show that the adsorbed molecules are negatively charged with a higher charge (in absolute value) for the parallel mode (-2.02 e) than for the tilted mode (-1.15 e). The charges are even bigger for the qX molecules, with charges ranging from -1.09 to -1.69 e for the tilted mode and -2.13 e to -3.03 e for the parallel geometry. These large values of the charges on the adsorbed species already suggest an ionic character of the bonds between anionic molecules and slightly cationic Al surface atoms. The electron density ρ presented in Figure 9 for the q and qS species on Al(111) could evidence also, by the presence of electrons at the molecule/metal interface, some covalent bonding between the N and O atoms and surface Al atoms (tilted adsorption mode), with in addition bonds between C atoms and surface Al atoms in the parallel geometry. For the qS species specially, the covalent bonding of the SO 3 group with surface Al atoms could also exist for the parallel adsorption mode. However, as stated by Gillespie, [START_REF] Gillespie | Electron Densities, Atomic Charges, and Ionic, Covalent,and Polar Bonds[END_REF] "there are no purely ionic bonds even in crystals, since the ions are not truly spherical and there is always a small amount of density shared between the atoms". A further investigation of the bonding at the molecule/metal interface was then performed using QTAIM descriptors to quantify the ionic and covalent nature of the interactions, and it is described below.

3.2.2. Topological Analyses of the Charge Density of the q/Al(111) and qX/Al(111) Systems. Selected values of the electron density ρ and Laplacian of the electron density ∇ 2 ρ at Al-O and Al-N bond critical points (BCPs) are presented in Table 8 and Tables S6 andS7, together with 8 account also for an ionic bonding with a small covalence degree.

CONCLUSION

In this work, we investigated the influence of the substitution of H atoms by Br atoms and the SO 3 -group on the reactivity of hydroxyquinoline species toward aluminum. We thus compared on the one hand the chelating properties of q -, qBr -, qSH -, and qS 2 anions toward Al 3+ cations, and on the other hand the adsorption properties of q, qBr, qSH, and qS species on an Al(111) surface.

Formation energies of Alq 3 and Al(qX) 3 complexes, with a value of -24.30 ± 0.29 eV in water, show a strong bonding affinity of q -and qX n-(n = 1 or 2) species to the aluminum cations. The small variation of the formation energies in water within the series of complexes evidence that the substitutions on the hydroxyquinoline species do not influence the coordinating properties of these molecules with aluminum cations for the formation of chelates. ELF and QTAIM topological analyses of these complexes showed that the bonding of the deprotonated molecules, i.e., q -, qBr -, qSH -, and qS 2 species, with the Al 3+ ion is ionic with a very weak covalence degree. The substitution of H atoms on the hydroxyquinoline species only modifies locally the electronic structures of the species, and it is consistent with the small variation of the formation energies of the complexes. It shows that all these chemically modified Hq species could be used without distinction in various applications where stable Al complexes are needed. Other properties of the Al(qX) complexes, i.e., their solubility in water that may be influenced by the chemical modifications on X1 and X2 positions, have to be studied. This will be the aim of further investigations.

Periodic calculations on the adsorption of qX species on an Al(111) surface give rise to different most stable geometries for the q and the modified qX species, i.e., qBr, qSH, and qS. All the species are strongly in interaction with the Al(111) surface, with values of the adsorption energy of -3.69 ± 0.21 eV for the most stable geometries. Thus the chemical modifications on the hydroxyquinoline molecule influence only slightly the adsorption energies. It was also shown that the different adsorption modes are driven by O , N and additional interactions of the substituents with the Al surface. The latter interactions modify the adsorption geometries of the species on Al(111). These different adsorption modes could lead to q and qX layers of different compacity, with thus different protecting efficiency, in particular against corrosion. Such studies are in progress combining in vacuum and in solvent computations.

The ELF and QTAIM descriptors of both models studied in this work are indicative of ionic bonding with a weak covalence degree, between the deprotonated Hq and HqX species and either the aluminum cation or the aluminum surface. The species are thus held together by the Coulombic interactions between the adsorbed species that are negatively charged and

Table S5

BVS calculation for the Mn metal ion S6

Figure S1

1 H NMR spectrum of H2L S6

Figure S2

FT-IR spectra of H2L, complex 1 and complex 4 S6

Figure S3-S4

PXRD pattern of complexes 1-6 S7

Figure S5

Asymmetric unit and core structure of complex 1 S7

Figure S6

Packing diagram of complex 1 S8

Table S6-S7

Bond distances and bond angles of complex 1 S8-10

Figure S7

Molecular structure of complex 2 S10

Table S8-S9

Bond distances and bond angles of complex 2 S10-12

Figure S8

Molecular structure of complex 3 S12

Table S10-S11

Bond distances and bond angles of complex 3 S12-14

Figure S9

Packing diagram of complex 4 S14

Figure S10

Asymmetric unit and core structure of complex 4 S14

Table S12-S13

Bond distances and bond angles of complex 4 S15-16

Figure S11

Molecular structure of complex 6 S16

Table S14-S15

Bond distances and bond angles of complex 6 S17-18

Figure S12

Magnetization vs. Field data for all complexes S19

Figure S13

AC susceptibility study for complexes 2, 3, 5 and 6 S20

Figure S14

Field dependent AC magnetic susceptibility data of 1 and 4 S20

Figure S17

Hysteresis loops for complex 1 and 4 S22

Figure S18

Easy-axes of the ground state for Dy atoms of 1 and 4 S22

Figure S19

DFT calculated spin densities of BS states in 1 and 4 S23

Figure S20

The fit of magnetic susceptibility of 1 with Poly_Aniso S23

Figure S21

The fit of magnetic susceptibility of 4 with Poly_Aniso S24 S3

Figure 1 .

 1 Figure 1. HqX species studied in this work. Substituents Xl and X2 of the phenyl ring are given in Table 1. The oxygen atom is shown in red, the nitrogen atom is shown in blue, carbon atoms are shown in brown, and hydrogen atoms are shown in white.

  by Bianchi et al.[START_REF] Bianchi | Experimental Electron Density Analysis of Mn2(CO)10: Metal-Metal and Metal-Ligand Bond Characterization[END_REF] to distinguish three bonding regimes: (i) ionic bonds with and (iii) an intermediate bonding regime including dative and metal-metal bonds (1 <

Figure 3 .

 3 Figure 3. Adsorption sites of the Al(111) surface: 3 fold, top, and bridge sites. Dark blue: surface atoms (layer S). Light blue: subsurface atoms (layers S 1 and S 2).

.

  The local potential energy density can be deduced from an equation derived from the local virial theorem:[START_REF] Bader | Atoms In Molecules[END_REF] ρ ∇ r c ) + V(r c ).

Figure 4 .

 4 Figure 4. ELF descriptors for the q -anion. Left: ELF map. Middle: map of ELF attractors (small brown spheres), displaying in red their average populations (in e) and selected QTAIM atomic charges in blue brackets (in e). The oxygen atom is shown in red, the nitrogen atom is shown in blue, carbon atoms are shown in green, and hydrogen atoms are shown in white. Right: phenolate mesomeric form. PBE D3/def2TZVP level of calculation.

  -O and Al-N bond critical points (BCPs) are also very similar over all the series of Al complexes (Figure7and Table5).The| | V G bcp bcp values slightly larger than 1 point toward the ionic bonding domain at the borderline with the intermediate bonding regime including dative bonding. The weak electron density values and the large positive Laplacian values are also in favor of ionic bonding. Small negative energy densities suggest however a very weak covalence degree as indicated by

Figure 5 .

 5 Figure 5. Mer isomer of the Alq 3 complex.

  description is consistent with the above ELF analysis.

Figure 6 .

 6 Figure6. ELF descriptors of the Alq 3 complex. Left: ELF map. Right: partial map of ELF attractors (small brown spheres) restricted to a q -moiety of Alq 3 , displaying in red their average populations (in e) and selected QTAIM atomic charges in blue brackets (in e). The aluminum atom is shown in magenta, the oxygen atom is shown in red, the nitrogen atom is shown in blue, carbon atoms are shown in green, and hydrogen atoms are shown in white. PBE D3/def2TZVP level of calculation.

a

  Descriptors are averaged over the three quasi equivalent bonds. ELF populations are given in e, cov(V(X),C(Al)) refers to the covariance between V(X) and C(Al) basins, and % Al is the QTAIM contribution of Al to V(O) or V(N) basins. PBE D3/def2TZVP level of calculation.

Figure 7 .

 7 Figure7. QTAIM molecular graph of Alq 3 restricted to a q -moiety of the complex (in au).

Figure 8 .

 8 Figure8. Tilted and parallel adsorption geometries for the q, qBr, qSH, and qS molecules. Dark blue: surface atoms (layer S). Light blue: subsurface atoms (layers S 1 and S 2). PBE D2 level of calculation.

  showing a strong adsorption of the molecule on the Al(111) surface. The molecule is bound to the surface by the O atom (bridge position on the Al(111) surface, d Al1-O = 1.909 Å and d Al-O = 2.034 Å) and the N atom (top position, d Al-N = 2.043 Å). This leads to a deformation of the molecule (E deform mol = 0.54 eV). The slab is also deformed (E def slab = 0.43 eV) as the Al atom bound to both the O and N atoms is pulled out of the surface (Δz Al2 = 0.652 Å in Figure

  ) as the C7 atom forms a bond with one Al surface atom (d Al3-C7 = 2.192 Å) in addition to the bonding of the molecule via the O atom (d Al1-O = 1.800 Å) and the N atom (d Al-N = 1.916 Å) in top positions on the Al(111)

  values of the selected QTAIM descriptors are very similar over the series. At all BCPs, the electron density ρ bcp values in Table8are weak in a range from 0.05 to 0.09 e. This suggests van der Waals interactions or ionic bonding between the molecules and the Al(111) surface. This is consistent with the large charges on the species observed and the strong contribution of dispersive forces to the interaction energy between the molecules and the aluminum surface. Large positive Laplacian of the electron density values is observed also in favor of ionic bonding. The QTAIM descriptors O and Al-N bond critical points (BCPs) are also very similar all over the series of qX/Al(111) systems. The than 1 (except for q tilt with a value of 0.985 for the Al2-O bond) point again toward the ionic bonding domain at the borderline with the intermediate bonding regime including dative bonding. Small negative energy densities suggest however a very weak covalence degree as indicated by the ρ H bcp bcp values. For the parallel adsorption geometries, the C7 atom of the molecules is also bound to the surface Al atom, and the values of the QTAIM descriptors in Table

Figure 9 .

 9 Figure 9. Electron density ρ for the q/Al(111) and qS/Al(111) systems. a 0 is the Bohr radius.

■

  ACKNOWLEDGMENTS This work was granted access to the HPC resources of CA LMIP supercomputing center under the allocation 2019 [pl2174]. It was also supported by the French Ministry of Higher Education and Research [Y.B., PhD grant]. C.L. D. would like to acknowledge N. Tarrat (CEMES, Toulouse) for helpful suggestions. Albrecht, M.; Fiege, M.; Osetska, O. 8 Hydro xy quinolines in metallosupramolecular chemistry. Ccord. Chem. Rev. 2008, 252, Barros, F. C. F.; Sousa, F. W.; Cavalcante, R M.; Carvalho, T.V.; Dias, F. S.; Qµeiroz, D. C.; Vasconcellos, L. C. G.; Nascirnento, R. F. Removal of Copper, Nickel and Zinc Ions from Aqueous Solution by Chitosan 8 Hydro xy quinoline Beads. Clean: Soi� Air, Water 2008, 36, , P. E.; Fonseca, S. M.; Burrows, H. D. NMR, DFT and luminescence studies of the complexation of Al(III) with 8 hydro xy quinoline 5 sulfunate. Daltcn Trans. 2012, 41, 12478-12489. ( 4) Tang, C. W.; VanSlyke, S. A Organic electroluminescent diodes. AppL Phys. Lett. 1987, 51, 913-915. (5) Shen, Z; Burrows, P. E.; Bulovié, V.; Forrest, S. R; Thompson, M. E. Three Color, Tunable, Organic Light Emitting Devices. Science 1997, 276, 2009-2011. ( 6) Prachayasittikul, V.; Prachayasittikul, S.; Ruchirawat, S.; Prachayasittikul, V. 8 Hydr oxy quinolines: a review of their metal chelating properties and medicinal applications. Drug Des, Dev. Ther. 2013, 7, 1157-1178. (7) Garrigues, L.; Pébère, N.; Dabosi, F. An investigation of the corrosion inhibition of pure aluminum in neutral and acidic chloride solutions. Electrochim. Acta 1996, 41, 1209-1215. (8) Lamaka, S.; Zheludkevich, M.; Yasakau, K.; Montemor, M.; Ferreira, M. High effective organic corrosion inhibitors for 2024 aluminium alloy. Electrochim Acta 2007, 52, 7231-7247. (9) Marcelin, S. ; Pébère, N. Synergistic effect between 8 hydro xy quinoline and benzotriazole for the corrosion protection of 2024 aluminium alloy: A local electrochemical irnpedance approach. Corros. Sei. 2015, 101, 66-74. (10) Soliman, H. Influence of 8 hydr oxy quinoline addition on the corrosion behavior of commercial Al and Al H0411 alloys in NaOH aqueous media. Ccrros. Sei. 2011, 53, 2994-3006. (11) Verma, C.; Quraishi, M.; Ebenso, E. Qµinoline and its derivatives as corrosion inhibitors: A review. Surf Interfaces 2020, 21, 100634-100646. (12) Fairman, B.; Medel, A S. Improved Determination of Aluminium Species in Waters Using FIA Separation/Fluorirnetric Detection Techniques. Int. J. Environ. AnaL Chem. 1993, 50, 161-171. (13) Li, S. M.; Zhang, H. R; Liu, J. H. Corrosion behavior of aluminum alloy 2024 T3 by 8 hydro xy quinoline and its derivative in 3.5% chloride solution. Trans. Nonferrous Met. Soc. China 2007, 17, 318-325. (14) Costa, D.; Marcus, P. Molecular Modeling of Corrosion Proc.esses: Scientific Develo pm ent and Engineering Applicati ons; John Wiley and Sons, Inc.: Hoboken, 2015; Chapter 5, Bonding Mechanism of 8 Hydro xy quinoline and Derivatives on the (111) Aluminum Surface. Phys. Chem Chem Phys. 2015, 17, 22243-22258. (16) Chiter, F.; Bonnet, M. L.; Lacaze Dufaure, C.; Tang, H.; Pébère, N. Corrosion protection of Al(lll) by 8 hydro xy quinoline: a comprehensive DFT study. Phys. Chem. Chem. Phys. 2018, 20, 21474-21486. (17) Bulteau, Y.; Tarrat, N.; Pébère, N.; Lacaze Dufaure, C. 8 Hydro xy quinoline complexes (Al 43 ) on Al( 111) :atomic scale structure, energetics and charge distribution. New J. Chem. 2020, 44, 15209-15222. (18) Obot, L; Macdonald, D.; Gasem, Z Density Functional Theory (DFT) as a powerful tool for designing new organic corrosion inhibitors. Part 1: An overview. Ccrros. Sei. 2015, 99, 1-30.

Figure S15 -

 S15 Figure S15-S16 Cole-Cole plots and Experimental χʹ plot of complex 1 and 4 S21

Figure S6 .

 S6 Figure S6. Crystal packing of 1 along crystallographic b axis

Figure S8 .

 S8 Figure S8. Molecular structure of Complex 3 with partial atomic numbering scheme. Solvent molecules are omitted for clarity.

Figure S9 .

 S9 Figure S9. (a) Crystal packing of 4 along crystallographic b axis. (b) Zigzag crystal packing of 4 along crystallographic c axis with solvent methanol in the void position.

Figure S10 .

 S10 Figure S10. (a) Asymmetric unit of complex 4 with partial atom numbering scheme (b) Core structure of complex 1 with intra-metallic bond distances with atom numbering scheme

Figure S12 .S20Figure S13 .

 S12S13 Figure S12. Magnetisation vs Field data for all complexes in the temperature range of 2 to 4 K and a field range of 0 to 7 T.

Figure S14 .S21Figure

 S14 Figure S14. Field dependent out-of-phase magnetic susceptibility study at 2 K conducted on a) Complex 1 and b) Complex 4. As shown in the data, application of a DC does not decrease relaxation.

Figure S16 .Figure S17 .Figure S18 .

 S16S17S18 Figure S16. a) Cole-Cole plots for complex 4; b) Experimental χMʹ() with HDC = 0 for complex 4; c) and d) are the experimental χMʹ() and χMʹT() data for the Ni2Mn2Dy2 complex.

Figure S20 .Figure S21 .

 S20S21 Figure S20. The comparison of the experimental and calculated T product of 1. The calculated data were computed with POLY_ANISO module using J(Ni1-Ni2) = +16.0 cm -1 , J(Dy1-Dy1 * ) = 0.74 cm -1 , J(Ni1-Dy1) = -0.87 cm -1 and J(Ni1-Dy1 * ) = J(Ni2-Dy1) = 1.40 cm -1 and scaling coefficient 0.89.

Table 1 .

 1 Native Hq and HqX Molecules and Deprotonated q -and qX n-Anions with Corresponding Groups at X1 and X2 Positions

	native	anion	X1	X2
	Hq	q -	H	H
	HqBr	qBr -	Br	Br
	HqSH	qSH -	SO 3 H	H
	HqS	qS 2	SO 3 -

H Figure 2. Atom numbering for the deprotonated species studied in this work. Substituents X1 and X2 of the phenyl ring are given in Table 1. The oxygen atom is shown in red, the nitrogen atom is shown in blue, carbon atoms are shown in brown, and hydrogen atoms are shown in white.

Table 2 .

 2 Population (in e) of Selected ELF Basins of the q - and qX n-Anions a

	valence basins	q -	qBr -	qSH -	qS 2
	V(O) a	2.88	2.83	2.82	2.92
	V(O) b	2.76	2.76	2.79	2.79
	V(C4,O)	1.94	2.00	2.02	1.88
	V(N)	2.74	2.72	2.73	2.76
	V(C5,N)	2.29	2.30	2.27	2.31
	V(C9,N)	2.44	2.44	2.45	2.43

a PBE D3/def2TZVP level of calculation.

Table 3 .

 3 Bond Lengths (in Å) in the Alq 3 and Al(qX) 3 Complexes a

		Alq 3	Al(qBr) 3	Al(qSH) 3	Al(qS) 3
	A
	d Al-O	1.863	1.860	1.867	1.871
	d Al-N	2.058	2.057	2.056	2.066
	B
	d Al-O	1.891	1.886	1.890	1.896
	d Al-N	2.101	2.100	2.088	2.100
	C
	d Al-O	1.894	1.888	1.892	1.899
	d Al-N	2.045	2.045	2.042	2.053
	a See A, B, and C moieties of the complexes in Figure 5. PBE D3/
	def2TZVP level of calculation.

Table 4 .

 4 Relevant ELF Descriptors of the Al-O and Al-N Bonds in Alq 3 and Al(qX) 3 Complexes a

	ELF descriptors	Alq 3	Al(qBr) 3	Al(qSH) 3	Al(qS) 3	Al(qCN) 3	Al(qNH 2 ) 3
	V(O) a	2.31	2.30	2.34	2.29	2.33	2.26
	% Al	3	3	3	3	3	3
	cov(V(O)a, C(Al))	0.05	0.05	0.05	0.05	0.05	0.05
	V(N)	2.78	2.80	2.80	2.80	2.79	2.77
	% Al

Table 5 .

 5 Relevant QTAIM Descriptors (in au a ) Related to the Al-O and Al-N Bonds in Alq 3 and Al(qX) 3 Complexes b

			Alq 3	Al(qBr) 3	Al(qSH) 3	Al(qS) 3	Al(qCN) 3	Al(qNH 2 ) 3
	BCP Al O
	ρ bcp	0.071	0.072	0.071	0.070	0.071	0.072
	∇ 2 ρ bcp	0.397	0.403	0.397	0.388	0.394	0.403
	| | V bcp G bcp	1.06	1.06	1.06	1.06	1.06	1.06
	H bcp
	ρ	bcp	0.09	0.08	0.08	0.09	0.09	0.09
	BCP Al N
	ρ bcp	0.053	0.053	0.054	0.053	0.054	0.052
	∇ 2 ρ bcp	0.223	0.223	0.227	0.219	0.226	0.219
	| | V bcp G bcp	1.09	1.09	1.09	1.09	1.09	1.09
	H bcp
	ρ	bcp	0.10	0.11	0.11	0.11	0.11	0.10

a ρ bcp in e/bohr 3 , V bcp , G bcp , and H bcp in hartree/bohr 3 . b Descriptors are averaged over the three equivalent bonds. PBE D3/def2TZVP level of calculation.

Table 6 .

 6 Relative Total Energies (the Reference Is the Total Energy of the Tilted Geometry of the q and qX Species), Adsorption Energies, Deformation Energies of the Molecule and of the Slab upon Adsorption, Interaction Energies between the Molecule and the Al(111) Surface and van der Waals Contribution (in eV), and Charge on the Adsorbed Molecule (in e) b

		q tilt	q paral	qBr tilt	qBr paral	qSH tilt	qSH paral	qS tilt	qS paral
	ΔE	0	0.11	0	0.16	0	0.21	0	1.82
	E ads mol	3.59 a	3.48 a	3.51	3.67	3.70	3.91
	E deform mol	0.54	1.69	0.35	1.84	0.51	2.04
	E deform slab	0.43	0.27	0.19	0.28	0.42	0.32
	E int slab/mol	4.57	5.43	4.04	5.78	4.63	6.29
	E int slab/mol (vdW)	0.66	1.26	0.96	1.50	0.74	1.39
	Q mol	1.15	2.02	1.09	2.13	1.25	2.26	1.69	3.03

a Reference 17. b PBE D2 level of calculation.

Table 7 .

 7 Shortest Distances between Surface Al Atoms and the Atoms of the Molecules (in Å) a

		q tilt	q paral	qBr tilt	qBr paral	qSH tilt	qSH paral	qS tilt	qS paral
	d Al1-O	1.909	1.800	1.818	1.809	1.916	1.814	1.892	1.818
	d Al2-O	2.034				2.057		1.977
	d Al2-N	2.043	1.916	2.085	1.920	2.038	1.919	2.002	1.909
	d Al3-C7		2.192		2.174		2.200		2.202
	d Al-O2						2.059		1.930
	d Al-O3								1.935

a PBE D2 level of calculation.

Table 8 .

 8 Relevant QTAIM Descriptors (in au a ) Related to the Al-O, Al-N, and Al-C7 Bonds in the q/Al(111) and qX/ Al(111) Systems b

			q tilt	q paral	qBr tilt	qBr paral	qSH tilt	qSH paral	qS tilt	qS paral
	BCP Al1 O
	ρ bcp	0.066	0.089	0.082	0.086	0.065	0.085	0.070	0.086
	∇ 2 ρ	0.336	0.526	0.530	0.550	0.327	0.533	0.353	0.537
	| | V bcp G bcp	1.032	1.050	1.001	1.019	1.034	1.020	1.050	1.022
	H bcp
	ρ	bcp	0.043	0.078	0.002	0.031	0.044	0.033	0.066	0.035
	BCP Al2 O
	ρ bcp	0.051				0.049		0.058
	∇ 2 ρ	0.253				0.213		0.295
	| | V bcp G bcp	0.985				1.016		1.007
	H bcp
	ρ	bcp	0.018				0.017		0.009
	BCP Al2 N
	ρ bcp	0.060	0.079	0.055	0.078	0.061	0.078	0.067	0.080
	∇ 2 ρ	0.256	0.377	0.205	0.373	0.248	0.381	0.270	0.391
	| | V bcp G bcp	1.073	1.097	1.097	1.094	1.093	1.088	1.118	1.092
	H bcp
	ρ	bcp	0.074	0.128	0.100	0.124	0.075	0.117	0.135	0.125
	BCP Al3 C7
	ρ bcp		0.057		0.058		0.056		0.055
	∇ 2 ρ		0.111		0.129		0.116		0.100
	| | V bcp G bcp		1.345		1.309		1.318		1.370
	H bcp
	ρ	bcp		0.259		0.248		0.243		0.266

a ρ bcp in e/bohr 3 , V bcp , G bcp , and H bcp in hartree/bohr 3 . b PBE D2 level of calculation.

the polarized,

cationic like, aluminum surface. This is consistent with the plots of the electron density showing several regions of shared electron density at the interface between the 0, N and several C or H atoms of the adsorbed molecule and the Al surface atoms, suggesting a weak covalent character. The latter graphical qualitative electron density anal ys is was here however refined with the quantitative descriptors of the topological analyses. ■ ASSOCIATED CONTENT e Supporting Information The Supporting Information is available free of ch arg e at https:/ /pubs.acs.o rg / doi/ 10.1021/ acs.inorgchem.0cO 1972. Table SI: population of ELF basins (in e) for free q and qX"-anions and for Alq 3 and Al( qX) 3 complexes (for latter systems, descriptors are averaged over three equivalent bonds); Table S2: QTAIM cha rg es (in e) for free q-and qX"-anions and for A1 43 and Al(qX) 3 complexes (for latter s ys tems, charges are averaged over three equivalent atoms); Table S3: complex formation energy E't.':f lrx in vacuum (in eV); Table S4: relative total energies (reference is total energy of tilted geometry for q and qX species), adsorption energies, deformation energies of molecule and of slab upon adsorption, interaction energies between mole cule and Al ( 111) surface and van der Waals contribution (in eV), ch arg e on adsorbed molecule (in e ); Table SS: bond lengths (in A) for free qX and qX species adsorbed on Al(lll) in parallel adsorption mode (qxparal); Table S6: QTAIM descriptors (in au) related to Al-CS, A-C9, Al-C3, Al-Brl, and Al-Br2 bonds between atoms of q and qX molecules and surface Al a toms in q/ Al ( 111) and qX/ Al(lll) systems; and Table S7: QTAIM descriptors (in au) related toAI-H(C9) andA-H(C3) bonds between atoms of q and qX molecules and surface Al atoms in q/ Al(lll) and qX/Al(lll) s ys tems (PDF) ■ AUTHOR INFORMATION Corresponding Author Corinne Lacaze Dufaure -CIRIMAT, Université de Toulouse, CNRS, 31030 Toulouse, Franc�; CD orcid.o rg / 0000 0003 3151 2685; Email: corinne.dufaure@) ensiacet.fr Authors Yann Bulteau -CIRlMAT, Université de Toulouse, CNRS, 31030 Toulouse, France Christine Lepetit -LCC CNRS, Université de Toulouse, CNRS, UPS, F 31077 Toulouse, France; � orcid.org/0000 0002 0008 9506 Complete contact information is available at: https:/ / pubs.acs.o rg / 10.1021 / acs.inorgchem.0cO 1972 Notes The authors declare no competing financial interest.

Table S1

 S1 Crystallographic data and structure refinement details of 1-6

	parameters	4	5	6
	Parameters Formula	1 C68H78Dy2Mn2N6Ni2O30	2 C68H78Tb2Mn2N6Ni2O30	3 C68H78Ho2Mn2N6Ni2O30
	Formula F.W. (g mol -1 )	C70H86Dy2N4Ni4O26 2011.66	C66H78Tb2N4Ni4O26 2004.48	C70H86Ho2N4Ni4O26 2016.49
	F.W.(g mol -1 ) crystal system	1959.26 monoclinic	1895.96 monoclinic	1964.12 monoclinic
	crystal system space group	triclinic P 21/n	triclinic P 21/n	triclinic P 21/n
	space group Crystal color	P1 ̅ Greenish brown	P1 ̅ Greenish brown	P1 ̅ Greenish brown
	Crystal color Crystal size/mm 3	Green 0.18×0.14×0.10	Green 0.21×0.12×0.08	Green 0.20×0.16×0.13
	Crystal size/mm 3 a/ Å	0.24×0.16×0.12 11.938(2)	0.22×0.14×0.12 11.954(5)	0.23×0.16×0.10 11.9904(8)
	a/ Å b/ Å	12.612(5) 24.563(5)	12.094(4) 24.543(7)	12.6388(17) 24.7140(16)
	b/ Å c/ Å	12.720(3) 13.784(3)	12.689(4) 13.797(4)	12.8502(16) 13.8321(9)
	c/ Å α/ deg	13.876(3) 90.00(3)	13.583(5) 90.00(2)	13.8998(17) 90.00
	α/ deg β/ deg	105.43(2) 111.96(3)	107.691(10) 112.06(2)	105.625(7) 112.164(2)
	β/ deg γ/ deg	114.02(3) 90.00(3)	110.472(10) 90.00(2)	113.161(7) 90.00
	γ/ deg V/ Å 3	100.40(2) 3748.6(15)	98.339(10) 3734.2(15)	100.582(8) 3796.0(4)
	V/ Å 3 Z	1851.5(11) 2	1785.2(11)	1888.9(4) 2
	Z limiting indices	1 -14 ≤ h ≤ 15	1	1 -14 ≤ h ≤ 14
	limiting indices	-15 ≤ h ≤ 15 -31 ≤ k ≤ 30	-14 ≤ h ≤ 14	-14 ≤ h ≤ 15 -29 ≤ k ≤ 29
		-15 ≤ k ≤ 15 -17 ≤ l ≤ 17	-15 ≤ k ≤ 15	-15 ≤ k ≤ 15 -16 ≤ l ≤ 16
	Dc/g cm -3	-17 ≤ l ≤ 17 1.782	-15 ≤ l ≤ 16	-16 ≤ l ≤ 16 1.764
	Dc/g cm -3 μ (mm -1 )	1.757 2.876	1.756	1.727 2.956
	μ (mm -1 ) F(000)	3.071 2012	3.070	3.127 2016
	F(000) T/K	986 150(2)	944	988 150(2)
	T/K Total reflections	150 47899	296	299 26196
	Total reflections R(int)	27488 0.0601	15733	18061 0.0766
	R(int) Unique reflections	0.0450 7874	0.0747	0.0804 6669
	Unique reflections Observed reflections	7581 6480	6838	6678 5600
	Observed reflections Parameters	6788 502	4280	4699 502
	Parameters R1; wR2 (I > 2σ(I))	486 0.0380, 0.0968	464	486 0.0495, 0.1523
	R1; wR2 (I > 2σ(I)) GOF (F 2 )	0.0266, 0.0669 1.046	0.0590, 0.1904	0.0714, 0.1966 1.114
	GOF (F 2 ) (e Å -3 ) Largest diff peak and hole	1.033 1.730, -0.706	1.035	1.053 1.686, -0.973
	Largest diff peak and hole (e Å -3 ) CCDC No.	1.068, -0.632 2005020	1.676, -1.503 -	4.371, -1.427 2005021
	CCDC No.	2005017	2005018	2005019
		S4

Table S6

 S6 Selected bond distances of 1

	O2 N1	Dy1 Ni1			O10 O2	84.25(9) 91.28(11)	O3 Ni2	Ni1 O8		O9 Dy1*	88.45(10) 99.43(9)
	O5* O3	Dy1 Ni1			O10 O7	107.36(8) 92.74(9)	N1 Ni2	Ni1 O8		O9 Dy1	98.89(10) 101.88(9)
	O2 N1	Dy1 Ni1			O7 O7	74.25(8) 169.51(10)	O2 Dy1	Ni1 O8		O9 Dy1*	88.88(9) 105.90(9)
	O5*	Dy1			O7	158.25(7)	O7	Ni1		O9	91.14(9)
	O10	Dy1			O7	75.52(8)	O3	Ni1		O6	99.75(9)
	O2	Dy1			O8*	160.27(8)	N1	Ni1		O6	92.61(10)
	O5*	Dy1			O8*	72.52(8)	O2	Ni1		O6	82.56(9)
	O10	Dy1			O8*	90.08(8)	O7	Ni1		O6	77.03(9)
	O7	Dy1			O8*	86.04(8)	O9	Ni1		O6	165.82(8)
	O2	Dy1			O8	99.12(8)	N2	Ni2		O5	90.57(10)
	O5*	Dy1			O8	100.42(8)	N2	Ni2		O6	89.23(10)
	O10	Dy1			O8	142.13(8)	O5	Ni2		O6	179.61(10)
	O7	Dy1			O8	69.36(8)	N2	Ni2		O7	102.29(10)
	O8	Dy1			O8*	74.10(9)	O5	Ni2		O7	95.48(9)
	Atom 1 O2	Atom 2 Dy1	O4*	Distance [Å] 72.37(8)	Atom 1 O6	Atom 2 Ni2	O7	Distance [Å] 84.23(9)
	Dy1 O5*	Dy1	O2		O4*	2.239(3) 63.55(8)	Ni1 N2	Ni2	O2	O11	2.018(2) 90.05(10)
	Dy1 O10	Dy1	O5*		O4*	2.294(2) 72.45(8)	Ni1 O5	Ni2	O7	O11	2.045(2) 91.59(10)
	Dy1 O7	Dy1	O10		O4*	2.316(2) 135.36(8)	Ni1 O6	Ni2	O9	O11	2.104(2) 88.75(9)
	Dy1 O8*	Dy1	O7		O4*	2.343(2) 123.78(8)	Ni1 O7	Ni2	O6	O11	2.307(2) 165.68(9)
	Dy1 O8	Dy1	O8*		O4*	2.357(2) 144.66(7)	Ni2 N2	Ni2	N2	O8	2.015(3) 172.83(10)
	Dy1 O2	Dy1	O8		O1	2.359(2) 64.43(8)	Ni2 O5	Ni2	O5	O8	2.022(2) 82.32(9)
	Dy1 O5*	Dy1	O4*		O1	2.571(2) 74.47(8)	Ni2 O6	Ni2	O6	O8	2.025(2) 97.88(9)
	Dy1 O10	Dy1	O1		O1	2.595(2) 137.26(8)	Ni2 O7	Ni2	O7	O8	2.027(2) 79.47(9)
	Ni1 O7	Dy1	O3		O1	1.983(2) 118.64(8)	Ni2 O11	Ni2	O11	O8	2.148(2) 89.19(9)
	Ni1 O8*	Dy1	N1		O1	1.997(3) 128.71(8)	Ni2 Ni2	O7	O8	Ni1	2.155(2) 101.92(10)
	Table S7 Selected bond angles of 1 O8 Dy1 O1 74.61(8)	Ni2	O7		Dy1	106.54(9)
	Atom 1 O4*	Atom 2 Dy1	Atom 3 O1	Bond 70.81(8)	Atom 1 Ni1	Atom 2 O7	Atom 3 Dy1	Bond 96.71(9)
	O3	Ni1			N1	Angles(°) 90.62(11)	Ni2	O6		Ni1	Angles(°) 93.59(9)
	O2 O3	Dy1 Ni1			O5* O2	127.21(8) 176.93(9)	O2 Ni1	Ni1 O2		O7 Dy1	85.80(9) 100.89(9)
						S9 S10

Figure S7. Molecular structure of Complex 2 with partial atomic numbering scheme. Solvent molecules are omitted for clarity.

Table S8

 S8 Selected bond distances of 2

	Table S9 Selected bond angles of 2 N1 Ni1 O9 97.5(3)	Ni2*	O7		Tb1	106.2(2)
	Atom 1 N1	Atom 2 Ni1	Atom 3 O6	Bond 93.3(3)	Atom 1 Ni2	Atom 2 O7	Atom 3 Ni1*	Bond 101.1(3)
	N1	Ni1			O7	Angles(°) 171.1(3)	Ni1	O7		Tb1	Angles(°) 96.9(2)
	O4 O9	Tb1 Ni1			O1 O6	70.1(2) 166.9(2)	O7 Ni1	Ni1 O2		O6 Tb1	78.0(2) 101.5(3)
	O10 O7	Tb1 Ni1			O4 O9	73.4(2) 90.9(2)	O3 Ni2	Ni1 O5		N1 Tb1	91.3(3) 106.5(3)
	O10	Tb1			O8	92.8(2)	O3	Ni1		O9	88.3(3)
	O10	Tb1			O8*	142.9(2)	O3	Ni1		O6	98.9(3)
	O10	Tb1			O7	75.6(2)	O3	Ni1		O7	91.9(2)
	O10	Tb1			O1	137.1(2)	O3	Ni1		O2	176.2(3)
	O8*	Tb1			O4	142.3(2)	O2	Ni1		N1	91.4(3)
	O8	Tb1			O4	124.8(2)	O2	Ni1		O9	88.7(3)
	O8	Tb1			O8*	74.3(2)	O2	Ni1		O6	83.7(2)
	O8*	Tb1			O1	72.8(2)	O2	Ni1		O7	85.8(2)
	O8	Tb1			O1	126.57(19)	O6	Ni2		O11	88.7(3)
	O7	Tb1			O4	135.54(19)	O6	Ni2		O8	98.8(2)
	O7	Tb1			O8*	69.3(2)	O6	Ni2		O7	84.1(2)
	O7	Tb1			O8	87.60(19)	O6	Ni2		O5	178.9(3)
	O7	Tb1			O1	117.4(2)	O7	Ni2		O11	165.1(3)
	Atom 1 O2	Atom 2 Tb1	O4	Distance [Å] 72.7(2)	Atom 1 O7	Atom 2 Ni2	O8	Distance [Å] 79.8(2)
	Tb1 O2	Tb1	O4		O10	2.544(6) 84.6(2)	Ni1 O7	Ni2	O3	O5	1.975(7) 96.3(2)
	O2	Tb1			O8*	96.5(2)	N2	Ni2		O11	91.6(3)
	Tb1 O2	Tb1	O8*		O8	2.338(6) 160.8(2)	Ni1 N2	Ni2	O2	O8	2.006(6) 171.9(3)
	Tb1 O2	Tb1	O8		O7	2.386(6) 73.3(2)	Ni1 N2	Ni2	O9	O6	2.079(6) 89.3(3)
	Tb1 O2	Tb1	O7		O1	2.360(6) 63.7(2)	Ni1 N2	Ni2	N1	O7	2.001(8) 101.3(3)
	Tb1 O2	Tb1	O1		O5	2.619(7) 127.5(2)	Ni2 N2	Ni2	O8	O5	2.151(6) 89.6(3)
	Tb1 O5	Tb1	O2		O4	2.243(6) 63.7(2)	Ni2 O5	Ni2	O6	O11	2.012(6) 91.1(3)
	Tb1 O5	Tb1	O5		O10	2.314(6) 108.3(2)	Ni2 O5	Ni2	O7	O8	2.009(6) 82.3(2)
	Tb1 O5	Tb1	O10		O8*	2.303(6) 100.3(2)	Ni2 Tb1	O8	N2	Tb1*	2.016(8) 105.7(2)
	Ni1 O5	Tb1	O6		O8	2.236(6) 71.4(2)	Ni2 Ni2	O8	O5	Tb1*	2.014(6) 102.4(2)
	Ni1 O5	Tb1	O7		O7	2.033(5) 158.7(2)	Ni2 Ni2	O8	O11	Tb1	2.148(7) 99.8(2)
	O5	Tb1			O1	74.6(2)	Ni2	O6		Ni1	94.4(3)
						S11 S12

Table S10

 S10 Selected bond distances of 3

	Table S11 Selected bond angles of 3 N1 Ni1 O9 98.2(4)	Ni2*	O7		Ho1	105.8(3)
	Atom 1 N1	Atom 2 Ni1	Atom 3 O6	Bond 93.0(4)	Atom 1 Ni2	Atom 2 O7	Atom 3 Ni1*	Bond 101.4(3)
	O4 N1	Ho1 Ni1			O1 O7	Angles(°) 71.0(3) 169.8(4)	O7 Ni1	Ni1 O7		O6 Ho1	Angles(°) 77.1(3) 96.5(3)
	O9	Ni1			O6	165.8(3)	Ni1	O2		Ho1	100.8(3)
	O10 O7	Ho1 Ni1			O4 O9	72.6(3) 91.3(3)	O3 Ni2	Ni1 O5		N1 Ho1	91.3(4) 106.1(3)
	O10	Ho1			O8	89.7(3)	O3	Ni1		O9	89.0(4)
	O10	Ho1			O8*	142.2(3)	O3	Ni1		O6	99.6(3)
	O10	Ho1			O7	75.4(3)	O3	Ni1		O7	92.4(3)
	O10	Ho1			O1	137.9(3)	O3	Ni1		O2	177.7(3)
	O8*	Ho1			O4	144.5(3)	O2	Ni1		N1	90.8(4)
	O8	Ho1			O4	124.3(3)	O2	Ni1		O9	89.7(3)
	O8	Ho1			O8*	73.6(3)	O2	Ni1		O6	81.3(3)
	O8*	Ho1			O1	74.3(3)	O2	Ni1		O7	85.7(3)
	O8	Ho1			O1	128.6(3)	O6	Ni2		O11	88.4(4)
	O7	Ho1			O4	135.1(2)	O6	Ni2		O8	98.6(3)
	O7	Ho1			O8*	69.8(2)	O6	Ni2		O7	85.3(3)
	O7	Ho1			O8	85.6(2)	O6	Ni2		O5	179.5(3)
	O7	Ho1			O1	118.6(3)	O7	Ni2		O11	165.4(3)
	O2	Ho1			O4	72.7(3)	O7	Ni2		O8	79.0(3)
	Atom 1 O2	Atom 2 Ho1	O10	Distance [Å] 85.5(3)	Atom 1 O7	Atom 2 Ni2	O5	Distance [Å] 94.5(3)
	O2	Ho1			O8*	98.5(3)	N2	Ni2		O11	91.0(4)
	Ho1 O2	Ho1	O4		O8	2.574(7) 159.9(2)	Ni1 N2	Ni2	O3	O8	1.982(8) 172.3(3)
	Ho1 O2	Ho1	O8*		O7	2.329(8) 74.2(2)	Ni1 N2	Ni2	O2	O6	2.016(7) 89.0(3)
	Ho1 O2	Ho1	O8		O1	2.362(7) 63.9(3)	Ni1 N2	Ni2	O9	O7	2.093(8) 102.1(4)
	Ho1 O2	Ho1	O7		O5	2.342(7) 127.6(2)	Ni1 N2	Ni2	N1	O5	2.003(9) 90.6(3)
	Ho1 O5	Ho1	O1		O4	2.602(8) 63.7(2)	Ni2 O5	Ni2	O8	O11	2.162(7) 91.8(3)
	Ho1 O5	Ho1	O2		O10	2.247(7) 106.7(3)	Ni2 O5	Ni2	O6	O8	2.015(7) 81.8(3)
	Ho1 O5	Ho1	O5		O8*	2.287(7) 100.3(3)	Ni2 Ho1	O8	O7	Ho1*	2.036(8) 106.4(3)
	Ho1 O5	Ho1	O10		O8	2.287(8) 72.5(2)	Ni2 Ni2	O8	N2	Ho1*	2.026(9) 102.2(3)
	Ni1 O5	Ho1	O6		O7	2.336(9) 158.0(2)	Ni2 Ni2	O8	O5	Ho1	2.036(7) 99.6(3)
	Ni1 O5	Ho1	O7		O1	2.056(7) 75.1(3)	Ni2 Ni2	O6	O11	Ni1	2.151(10) 93.2(3)
						S13 S14

Table S12

 S12 Selected bond distances of 4 Selected bond distances of 6

	O2 O2	Dy1 Ho1			O4* O4	80.11(10) 80.14(16)	O6 O6	Mn1 Mn1		O9 O9	92.50(14) 92.7(2)
	Atom 1 O10 Atom 1 O10	Atom 2 Dy1* Atom 2 Ho1	O4 O4	Distance [Å] 136.18(11) Distance [Å] 136.19(17)	Atom 1 O5 Atom 1 O5	Atom 2 Mn1 Atom 2 Mn1	O9 O9	Distance [Å] 85.12(13) Distance [Å] 85.09(19)
	Dy1 O5 Ho1 O5	Dy1* Ho1	O2 O2		O4 O4	2.259(3) 65.46(10) 2.251(4) 65.38(15)	Ni1 O7 Ni1 O8	Mn1 Mn1	O2 O2	O9 O9	2.031(3) 88.02(12) 2.040(4) 88.16(18)
	Dy1 O8 Ho1 O7*	Dy1* Ho1	O10 O10		O4 O4	2.279(3) 75.28(10) 2.271(5) 75.41(15)	Ni1 N2 Ni1 N1	Mn1 Mn1	O7 O8	O9 O9	2.074(3) 96.20(14) 2.076(4) 96.5(2)
	Dy1 O8 Ho1 O7	Dy1 Ho1	O5 O5		O4* O4	2.318(3) 132.91(10) 2.315(4) 133.25(15)	Ni1 O6 Ni1 O6	O11 Mn1 O11 Mn1	O3 O3*	2.119(3) 98.50(13) 2.116(5) 98.93(19)
	Dy1 O7 Ho1 O8	Dy1* Ho1	O8* O8		O4 O4	2.321(3) 114.27(10) 2.390(4) 114.37(15)	Ni1 O5 Ni1 O5	Mn1 Mn1	O8 O7	O3 O3*	2.150(3) 83.49(12) 2.158(4) 82.94(17)
	Dy1 O1 Ho1 O2	Dy1 Ho1	O8 O7		O2 O1	2.342(3) 64.13(10) 2.328(4) 64.36(15)	Mn1 O7 Mn1 O8	Mn1 Mn1	O6 O6	O3 O3*	1.861(3) 77.63(11) 1.859(5) 77.86(16)
	Dy1 O1 Ho1 O10	Dy1 Ho1	O7 O7*	O10* O1	2.383(3) 73.62(12) 2.323(4) 73.22(18)	Mn1 N2 Mn1 N1	Mn1 Mn1	O5 O5	O3 O3*	1.932(3) 97.63(13) 1.930(5) 97.0(2)
	Dy1 Ho1 O1 O5	Dy1 Ho1	O4 O4		O5* O1	2.528(3) 2.523(5) 73.15(10) 72.81(15)	Mn1 Mn1 O9 O9	Mn1 Mn1	O7 O8	O3 O3*	1.960(4) 1.957(3) 162.17(11) 162.07(17)
	O1 O7*	Dy1 Ho1			O8* O1	143.78(11) 144.07(17)	Ni1 Ni1	O2 O2		Dy1 Ho1	106.65(13) 106.56(18)
	Dy1 O1 Ho1 O7	Dy1 Ho1	O1 O1		O8 O1	2.565(3) 125.48(10) 2.569(5) 125.81(16)	Mn1 Ni1 Mn1 Mn1	O3 O5	N2 N1	Mn1 Ho1	2.009(4) 95.20(12) 2.006(5) 103.35(18)
	Ni1 O1 Ni1 O8	Dy1 Ho1	O3 O3		O7* O1	2.006(3) 134.10(10) 2.020(4) 133.63(15)	Mn1 Mn1 Mn1 Ni1	O5 O3	O9 O9	Dy1* Mn1*	2.189(3) 103.25(13) 2.191(5) 94.83(17)
	Ni1 O1 Ni1 O4	Dy1 Ho1	N1 N2		O4* O1	2.014(4) 69.97(11) 2.023(6) 70.08(17)	Mn1 Mn1 Mn1 Mn1	O7 O8	O3 O3	Ni1 Ni1*	2.252(3) 102.72(13) 2.260(4) 102.81(19)
	Table S13 Selected bond angles of 4 O3 Ni1 N1 88.55(14) Table S15 Selected bond angles of 6 O3 Ni1 N2 88.4(2)	Mn1 Mn1	O7 O8		Dy1* Ho1	100.20(12) 99.82(17)
	Atom 1 O3 Atom 1 O3	Atom 2 Ni1 Atom 2 Ni1	Atom 3 O2 Atom 3 O2	Bond 174.95(12) Bond 174.85(18)	Atom 1 Ni1 Atom 1 Ni1*	Atom 2 O7 Atom 2 O8	Atom 3 Dy1 Atom 3 Ho1	Bond 103.58(12) Bond 103.30(17)
	N1 N2	Ni1 Ni1			O2 O2	Angles(°) 90.47(14) Angles(°) 90.8(2)	Ni1 Ni1	O8 O7		Dy1* Ho1*	Angles(°) 103.31(12) Angles(°) 102.98(18)
	O2 O3 O2 O3	Dy1 Ni1 Ho1 Ni1		O10* O7 O10 O8*	105.07(12) 80.91(12) 104.66(17) 81.05(17)	O3 Ni1 O3 Ni1	Ni1 O8 Ni1 O7		O11 Dy1 O11 Ho1	90.93(12) 100.02(12) 90.88(18) 100.16(18)
	O2 N1 O2 N2	Dy1 Ni1 Ho1 Ni1			O7 O5 O8*	132.18(11) 99.23(14) 132.02(15) 99.38(19)	N1 Dy1 N2 Ho1	Ni1 O8 Ni1 O7		O11 Dy1* O11 Ho1*	93.27(14) 106.80(11) 92.8(2) 106.90(16)
	O10 O2 O10 O2	Dy1* Ni1 Ho1 Ni1			O5 O7 O5 O8*	81.39(11) 94.36(12) 81.63(17) 94.06(17)	O2 O2	Ni1 Ni1		O11 O11	94.08(12) 94.25(18)
	O2 O2	Dy1 Ho1			O8* O7	100.46(11) 100.49(15)	O7 O8*	Ni1 Ni1		O11 O11	164.84(12) 165.11(18)
	O10 O10	Dy1* Ho1			O8 O7*	142.13(12) 142.27(18)	O3 O3	Ni1 Ni1		O8 O7	99.79(12) 100.06(17)
	O5 O5	Dy1* Ho1			O8 O7	101.56(10) 101.75(15)	N1 N2	Ni1 Ni1		O8 O7	171.29(13) 171.2(2)
	O2 O2	Dy1 Ho1			O8 O7	72.34(11) 72.73(15)	O2 O2	Ni1 Ni1		O8 O7	80.99(12) 80.56(16)
	O10* O10	Dy1 Ho1			O8 O7	88.38(11) 88.00(17)	O7 O8*	Ni1 Ni1		O8 O7	79.80(12) 79.98(16)
	O5* O5	Dy1 Ho1			O8 O7	155.15(11) 154.89(16)	O11 O11	Ni1 Ni1		O8 O7	89.11(12) 89.22(17)
	O8 O7	Dy1 Ho1			O8* O7*	73.20(11) 73.10(16)	O6 O6	Mn1 Mn1		O5 O5	177.29(13) 177.4(2)
	O2 O2	Dy1 Ho1			O7* O8	158.82(10) 158.92(15)	O6 O6	Mn1 Mn1		O7 O8	92.17(13) 92.04(19)
	O10 O10	Dy1* Ho1			O7 O8	75.91(11) 76.03(16)	O5 O5	Mn1 Mn1		O7 O8	86.45(13) 86.57(18)
	O5 O5	Dy1* Ho1			O7 O8	68.99(10) 69.06(15)	O6 O6	Mn1 Mn1		N2 N1	90.77(15) 90.7(2)
	O8 O7*	Dy1* Ho1			O7 O8	70.34(10) 70.53(15)	O5 O5	Mn1 Mn1		N2 N1	90.79(14) 90.9(2)
	O8 O7	Dy1 Ho1			O7* O8	86.61(10) 86.30(14)	O7 O8	Mn1 Mn1		N2 N1	174.74(1 174.5(2)
						S16 S18 S19

Figure S11. Molecular structure of Complex 6 with partial atomic numbering scheme. Solvent molecules and counter anions are omitted for clarity. S17 Table S14

Supporting Information

*E-mail: dray@chem.iitkgp.ac.in

Contents

Table S1

Summary of Crystallographic parameters for complexes 1-6 S3-4

Chart 1

Metal ion binding mode of ligand H2L S5


Keywords: Data Paper, SIGLE, OpenSIGLE, OpenGrey, EAGLE, Grey Literature, Gray Literature Subject Area: Science, Technology, Biomedical Science, Economics, Social Science, Humanities

OpenGrey, System for Information on Grey Literature in Europe, is your open access to 1 014 872 bibliographic references of grey literature produced in Europe and allows you to export records and locate the documents. Examples of grey (gray) literature include technical and research reports, doctoral dissertations, conference papers, official publications, and other types of grey literature. In 1980, this information resource first began as a bibliographic database under the name SIGLE. In 2006, the records migrated to OpenSIGLE -an open access database. In 2010 its name was changed to the OpenGrey Repository given that full-texts documents began to be ingested and preserved. And in 2020, Inist-CNRS (service provider) gave notice that OpenGrey will be discontinued. In order to guarantee open access to this resource, it is now archived as a database in DANS EASY -a data archive certified with the Nestor and CoreTrustSeal.

Methods Applied

• Steps

Each participating European organization used a standard record template (form) with the aid of manuals (e.g., Subject Category List and associated key terms as well as a Corporate Register with preferred Names/spellings). Each participating organization made a selection of their acquisitions for submission to the SIGLE database. If a document title was not in English, then an English translation was provided. As such, each SIGLE record contained informative titles in English and/or in the original language, the author's name, academic degree, and the research organization or educational institution, the document's date of publication and type, number of pages, report numbers, and language, as well as subject classifications. Many records include keywords and abstracts. Each national structure submitted records in their own language. A search through the entire database was made possible by providing an English translation of the title or English keywords. One of these fields was mandatory. Moreover, each record contained a clear mention of availability.

• Sampling strategy

The selection of records entered in the SIGLE database was made by several institutions representing the EAGLE member countries. The following list is not exhaustive. [START_REF] Schöpfel | From SIGLE to OpenSIGLE and beyond: An in-depth look at Resource migration in European context[END_REF].

Country Institution

• Quality Control

The SIGLE descriptive cataloguing rules were based on those of the International Nuclear Information System (INIS), and the subject classification scheme was a modified version of that endorsed by the Committee on Scientific and Technical Information (COSATI) of the US Federal Council for Science and Technology. Each member institution was responsible for the quality of their national records. The operating agent (technical processing center) played a key role in the quality control, rejecting non-compliant input. The SIGLE technical committee supervised the compliance with the agreed rules. However, "in operating SIGLE, no attempt has been made to be rigid in formulating rules of membership (...) considerable flexibility has enabled a number of countries to participate to a greater or lesser extent depending on their capabilities" (Wood & Smith, 1993, p.21). Furthermore, the last operating SIGLE agent and the host of the OpenSIGLE/OpenGrey repository, FIZ Karlsruhe and INIST-CNRS, executed complementary quality controls at different moments during the transfer, launch, and update of the metadata records [START_REF] Schöpfel | From SIGLE to OpenSIGLE and beyond: An in-depth look at Resource migration in European context[END_REF].

Dataset Description

File

  The sampling strategy of the former SIGLE records was decided by the EAGLE association, coordinated by the SIGLE technical committee, and carried out by the member institutions following agreed and explicit rules. Later input in the OpenSIGLE/OpenGrey repository that originated from the International Conference Series on Grey Literature was provided by GreyNet International, the Grey Literature Network Service. Regarding the property of the records and the database, all usage rights of the SIGLE database lapsed upon the complete liquidation of the association while the copyright on input remained with each member organization that supplied the records. EAGLE's last General Assembly asked the operating agent, FIZ Karlsruhe, for the interim preservation of the SIGLE records in XML format beyond the liquidation of SIGLE. This was for the purpose of archiving and integration into a new European non-profit project i.e., OpenSIGLE hosted and managed by INIST-CNRS. Nearly all of the former EAGLE members signed a declaration of intention regarding the future use of their existing input in the SIGLE database. The complete liquidation of EAGLE was formally published by the Luxemburg Register of Commerce and Societies onAugust 23, 2006

	Germany	Fachinformationszentrum Karlsruhe
	Germany	German National Library of Science and Technology (TIB)
	Spain	Centro de Informaciòn y Documentaciòn Cientìfica
	France	Institut de l'Information Scientifique et Technique-CNRS
	United Kingdom	British Library Document Supply Service
	Italy	Consiglio Nazionale delle Ricerche
	Luxembourg	Bibliothèque Nationale de Luxembourg
	Latvia	Latvian Academic Library
	Portugal	Fundação para a Ciência e a Tecnologia
	Russian Federation	VNTIC Scientific & Technical Information Centre of Russia
	Slovakia	Slovak Centre of Scientific and Technical Information
	Belgium	Université Catholique de Louvain
	Czech Republic	National Library of Technology

Former OpenGrey website: http://www.opengrey.eu/

OpenDOAR https://v2.sherpa.ac.uk/id/repository/2181

Wikipedia https://en.wikipedia.org/wiki/System_for_Information_on_Grey_Literature_in_Europe

History

The European database SIGLE (System for Information on Grey Literature) was created in 1980 in order to collect and to make available grey literature produced in the countries of the European Community by the intermediary of an online database. The main purpose was to provide access to documents, and incidentally to improve bibliographic coverage. SIGLE was launched with the support of the European Community. The base was produced from 1985 onwards by EAGLE (European Association for Grey Literature Exploitation), with an operating agent (KNAW, The British Library, FIZ Karlsruhe) and with input from several Member States of the European Community [START_REF] Wood | SIGLE: A Model for International Co-operation[END_REF][START_REF] Wessels | An Eagle's eye-view of grey literature research[END_REF]. Each country was represented by one or more documentation centers or libraries of national importance, and each national center held the national grey collection or at least, guaranteed the document supply of distributed holdings. Until 2005, the SIGLE database was distributed by BLAISE, STN, EI and Ovid (Silverplatter) and in the early nineties by SUNIST in France. Records were also sold to organizations like NERAC for specific use [START_REF] Schöpfel | From SIGLE to OpenSIGLE and beyond: An in-depth look at Resource migration in European context[END_REF].

In 2005, the members of EAGLE decided to dissolve the association and to stop the input of new documents. The database SIGLE was taken from all hosts proposing the database online. In the context of the Open Access movement and with the consent and approval of the former EAGLE members, EAGLE's last operating agent (FIZ Karlsruhe) transferred the SIGLE records to the French INIST-CNRS (Institut de l'Information Scientifique et Technique) which then launched the OpenSIGLE project, i.e., all former SIGLE records, in a simplified XML format, were made freely available on a DSpace open repository [START_REF] Schöpfel | MetaGrey Europe, a Proposal in the aftermath of EAGLE-SIGLE[END_REF][START_REF] Schöpfel | From SIGLE to OpenSIGLE and beyond: An in-depth look at Resource migration in European context[END_REF]Farace et al., 2009[START_REF] Farace | OpenSIGLE -Crossroads for Libraries, Research and Educational Institutions in the field of Grey Literature[END_REF].

In 2009-2010, GreyNet International joined OpenSIGLE, adding the preprints of the GL conference series to the repository. By providing full text access to the conference papers, it offered open access to international research on grey (gray) literature.

In 2011 OpenSIGLE changed its platform and its name and was relaunched as the open repository OpenGrey. OpenGrey provided new features and new content. Thus, all former SIGLE bibliographical records were searchable again, free of charge, with OpenGrey.

Contents

OpenGrey 1 is a multidisciplinary European database, covering science, technology, biomedical science, economics, social science and humanities. The records are in English. They include bibliographical data, the SIGLE classification codes with their wording, and possibly an English abstract (starting in 1997). Each record has either an English title and/or English keywords. Document types include technical or research reports, doctoral dissertations, conference papers, official publications, and other types of grey literature.

The OpenDOAR directory entry on the OpenGrey Repository 2 indicates 1,014,842 metadata, giving access to the full text of 18,158 items (data provided by the Jisc CORE service).

Its content in March 2021 shown in figures:

Scientific domain Records