Combined Experimental and Computational Study of V-Substituted Lindqvist Polyoxotungstate: Screening by Docking for Potential Antidiabetic Activity.

In the current work, a novel vanadotungstate compound, (C6H9N2)4[V2W4O19]·2H2O (1), is isolated by a simple stepwise synthesis method and characterized by a combined experimental and computational study. Molecular docking is conducted for the first time for this kind of substituted Lindqvist polyoxometalates to elucidate for potential antidiabetic activity. Hence, the modeling results revealed a significant docking score of the reported compound to bind to the active sites of α-glucosidase with the lowest binding energy of -5.7 kcal/mol, where the standard drug acarbose (ACB) had -4.6 kcal/mol binding energy. The stability of binding was enhanced by strong H-bonding, van der Waals, and electrostatic interactions occurring in the three-dimensional (3D) supramolecular network of polyanionic vanadotungstate subunits templated with organic moieties as shown by X-ray diffraction and Hirshfeld analyses. Furthermore, density functional theory (DFT) calculations supported with photophysical measurements are also discussed to predict the most chemical and biological reactivity. In this view, the complete description of electronic and biological features of (1) is enhanced by determination of the highest occupied molecular orbital (HOMO)/least unoccupied molecular orbital (LUMO) energy, electronic density, ionization potential, electron affinity, etc. These chemical descriptors, intermolecular interactions, docking score, and binding free energy estimation are essential in understanding the reactivity of this bioactive compound offering potential inhibition of the α-glucosidase enzyme.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, and Physicochemical Study of an Anhydrous Organic Acidic Cyclohexaphosphate.

The new organic-inorganic hybrid [5-Cl-2-(CH3)C6H3NH3]4H2P6O18 has been synthesized by the slow evaporation method. X-ray diffraction on a single crystal shows that this acidic cyclohexaphosphate crystallized in the monoclinic space group C 2/c with a = 33.89(11) Å, b = 9.16(16) Å, c = 13.68(3) Å, ß = 91.35(2)°, V = 4244.9(19) Å3 and Z = 4. 31P MAS-NMR and 13C CP/MAS-NMR results are in accordance with X-ray findings. Fluorescent study shows the blue photoluminescence. Furthermore, FT-IR analysis was studied and the complete vibrational assignments were done. Intermolecular interactions were analyzed using Hirshfeld surface analysis and the associated 2D fingerprint plots.

Crystal structure of 2-methyl-piperazine-1,4-diium bis-(hydrogen maleate).

In the title salt, C5H14N2 (2+)·2C4H3O4 (-), the asymmetric unit contains two independent 2-methyl-piperazinium dications, which comprise a racemic pair, and four hydrogen maleate monoanions. In the roughly planar hydrogen maleate anions, intra-molecular O-H⋯O hydrogen bonds generate S(7) rings. In the crystal, the four independent anions are linked to the 2-methyl-piperazinium cations through N-H⋯O hydrogen bonds, forming two-dimensional layered structures lying parallel to (001).

Crystal structure of 2,5-di-methyl-anilinium hydrogen maleate.

The crystal structure of the title salt, C8H12N(+)·C4H3O4 (-), consists of a 2,5-di-methyl-anilinium cation and an hydrogen maleate anion. In the anion, a strong intra-molecular O-H⋯O hydrogen bond is observed, leading to an S(7) graph-set motif. In the crystal, the cations and anions pack in alternating layers parallel to (001). The ammonium group undergoes inter-molecular N-H⋯O hydrogen-bonding inter-actions with the O atoms of three different hydrogen maleate anions. This results in the formation of ribbons extending parallel to [010] with hydrogen-bonding motifs of the types R (4) 4(12) and R (4) 4(18).

Tri-chlorido-(1-ethyl-piperazin-1-ium)cobalt(II).

In the title complex, [Co(C6H15N2)Cl3], the Co(2+) ion is coordinated in a distorted tetra-hedral fashion by three chloride ions and one N atom of the piperazine ring; the ring adopts a chair conformation with the N-Co and N-CEt bonds in equatorial orientations. In the crystal, mol-ecules are connected by N-H⋯Cl hydrogen bonds, generating (10-1) sheets.

Piperazine-1,4-diium bis-(hexa-hydroxido-hepta-oxidohexa-borato-κ(3) O,O',O'')cobaltate(II) hexa-hydrate.

In the title hydrate, (C4H12N2)[Co{B6O7(OH)6}2]·6H2O, both the dication and dianion are generated by crystallographic inversion symmetry. The Co(2+) ion in the dianion adopts a fairly regular CoO6 octa-hedral coordination geometry arising from the two O,O',O''-tridentate ligands. In the crystal, the dianions and water mol-ecules are linked by O-H⋯O hydrogen bonds, generating a framework with large [100] channels, which are occupied by the organic dications. N-H⋯O and C-H⋯O hydrogen bonds consolidate the structure.

Bis[tris-(phenanthroline-κ(2) N,N')cobalt(II)] undeca-tungsto(VI)vanado(V)phosphate dihydrate.

In the title hydrated salt, [Co(C12H8N2)3]2[PVW11O40]·2H2O, the complete Kegggin ion is generated by crystallographic inversion symmetry, which imposes statistical disorder on the O atoms of its central PO4 group. The V atom is statistically disordered over all the metal sites of the anion. In the cation, the Co(2+) ion is coordinated by three bidentate 1,10-phenanthroline (phen) ligands, generating a distorted CoN6 octa-hedron. Possible very weak intra-molecular C-H⋯π inter-actions occur in the cation. In the crystal, the components are linked by O-H⋯O and C-H⋯O inter-actions, building a three-dimensional network featuring one-dimensional voids along the c-axis direction.

1-Phenyl-piperazine-1,4-diium tetra-chlorido-cobalt(II).

In the title mol-ecular salt, (C10H16N2)[CoCl4], the piperazine ring of the phenyl-piperazine dication adopts a chair conformation and the phenyl ring occupies an equatorial orientation. In the tetra-chlorido-cobaltate(II) dianion, the Co-Cl bond lengths for the chloride ions not accepting hydrogen bonds are significantly shorter than those for the chloride ions accepting such bonds. In the crystal, the components are linked by N-H⋯Cl hydrogen bonds, generating [001] chains.

Bis(2-meth-oxy-benzyl-ammonium) di-aqua-bis-(di-hydrogen diphosphato-κ(2) O,O')cobaltate(II) dihydrate.

The title compound, (C8H12NO)2[Co(H2P2O7)2(H2O)2]·2H2O, crystallizes isotypically with its Mn(II) analogue. It consists of alternating layers of organic cations and inorganic complex anions, extending parallel to (100). The complex cobaltate(II) anion exhibits -1 symmetry. Its Co(2+) atom has an octa-hedral coordination sphere, defined by two water mol-ecules in apical positions and two H2P2O7 (2-) ligands in equatorial positions. The cohesion between inorganic and organic layers is accomplished by a set of O-H⋯O and N-H⋯O hydrogen bonds involving the organic cation, the inorganic anion and the remaining lattice water mol-ecules.

m-Xylylenediaminium dinitrate.

The asymmetric unit of the title salt, C8H14N2 (2+)·2NO3 (-), contains two independent dications and four independent nitrate anions. The crystal structure consists of discrete nitrate ions, three of which stack in layers parallel to (001) at z = 0 and 0.5. These layers are connected via m-xylylenediaminium dications. The fourth anion is sandwiched by the two independent organic cations in the asymmetric unit. In the crystal, the ions are connected by a large number of bifurcated and non-bifurcated N-H⋯O(O) hydrogen bonds, forming sheets parallel to (100). These sheets are connected by C-H⋯O hydrogen bonds, forming a three-dimensional network.

1,1,4,7,7-Penta-methyl-diethylenetri-ammonium trinitrate.

In the title compound, C9H26N3 (3+)·3NO3 (-), the triprotonated 1,1,4,7,7-penta-methyl-diethylenetri-amine mol-ecules are linked to the nitrate anions by multiple bifurcated N-H⋯(O,O) and weak C-H⋯O hydrogen bonds. The organic cation is characterized by N-C-C-N torsion angles of -176.2 (2) and 176.6 (2)°.

Propane-1,2-di-ammonium chromate(VI).

In the title mol-ecular salt, (C3H12N2)[CrO4], each chromate anion accepts six N-H⋯O and C-H⋯O hydrogen bonds from nearby propane-1,2-di-ammonium cations. Three of the four O atoms of the chromate anion accept these bonds; the remaining Cr-O bond length is notably shorter than the others. In the crystal, the anions and cations stack in layers lying parallel to (100): the hydrogen-bonding pattern leads to a three-dimensional network.

Bis(2,6-di-methyl-anilinium) di-aqua-bis-(di-hydrogen diphosphato-κ(2) O,O')cobaltate(II).

In the title compound, (C8H12N)2[Co(H2P2O7)2(H2O)2], the Co(2+) ion lies on a crystallographic inversion centre and adopts a slightly distorted octa-hedral CoO6 coordination geometry arising from two chelating diphosphate [H2P2O7](2-) ligands and two trans water mol-ecules. In the crystal, the components are linked by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds and weak aromatic π-π stacking [shortest centroid-centroid separation = 3.778 (2) Å] inter-actions. (001) layers of alternating organic cations and complex inorganic anions are apparent.

1-Methyl-piperazine-1,4-dium bis-(hydrogen oxalate).

In the crystal structure of the title compound, C5H14N2 (2+)·2HC2O4 (-), the two crystallographically independent hydrogen oxalate anions are linked by strong inter-molecular O-H⋯O hydrogen bonds, forming two independent corrugated chains parallel to the b axis. These chains are further connected by N-H⋯O and C-H⋯O hydrogen bonds originating from the organic cations, forming a three-dimensional network. The diprotonated piperazine ring adopts a chair conformation, with the methyl group occupying an equatorial position.

Tetra-kis(2-amino-5-chloro-pyridinium) di-hydrogen cyclo-hexa-phosphate.

In the crystal structure of the title compound, 4C5H6ClN2 (+)·H2P6O18 (4-), the [H2P6O18](4-) anions are interconnected by O-H⋯O hydrogen bonds, leading to the formation of infinite ribbons extending along the a-axis direction. These ribbons are linked to the organic cations, via N-H⋯O and C-H⋯O hydrogen bonds, into a three-dimensional network. The six P atoms of the [H2P6O18](4-) anion form a chair conformation. The complete cyclohexaphosphate anion is generated by inversion symmetry.

Bis(4-amino-pyridinium) hexa-aqua-nickel(II) bis-(sulfate).

In the title compound, (C5H7N2)2[Ni(H2O)6](SO4)2, the Ni(II) cation is located on an inversion centre and is coordinated by six aqua ligands in a slightly distorted octa-hedral coordination environment. The [Ni(H2O)6](2+) ions are connected through an extensive network of O-H⋯O hydrogen bonds to sulfate anions, leading to the formation of layers parallel to (001). The 4-amino-pyridinium cations are located between these layers and are connected to the anionic framework by N-H⋯O hydrogen bonds. Weak π-π inter-actions between the pyridine rings, with a centroid-centroid distance of 3.754 (9) Å, provide additional stability to the crystal packing.

Hexa-kis-(3-chloro-2-methyl-anilinium) cyclo-hexa-phosphate dihydrate.

In the organic/inorganic salt hydrate, 6C7H9ClN(+)·P6O18 (6-)·2H2O, the cyclo-hexa-phosphate anion resides on an inversion centre. The asymmetric unit consists of three cations, one half-anion and a water mol-ecule. In the crystal, the water mol-ecules and the [P6O18](6-) anions are linked by O-H⋯O hydrogen bonds, generating infinite layers parallel to the ab plane. These layers are inter-connected by the organic cations through N-H⋯O hydrogen bonds.

N'-(2,4-Di-nitro-phen-yl)acetohydrazide monohydrate.

In the crystal structure of the title compound, C8H8N4O5·H2O, the organic and lattice water mol-ecules are linked together via N-H⋯O and O-H⋯O hydrogen bonds. A C-H⋯O inter-action is also observed between the organic mol-ecules. These hydrogen bonds and inter-actions lead to the formation of a three-dimensional network. An intra-molecular N-H⋯O hydrogen bond also occurs. The dihedral angle between the acetyl group and the almost planar hydrazide moiety [maximum deviation from the least-squares plane is 0.209 (2) Šfor one of the nitro O atoms] is 88.5 (3)°.

5-Amino-1H-1,2,4-triazol-4-ium hydrogen oxalate.

In the title salt, C2H5N4 (+)·C2HO4 (-), the hydrogen oxalate anions form corrugated chains parallel to the c axis, linked by inter-molecular O-H⋯O hydrogen bonds. The 5-amino-1H-1,2,4-triazol-4-ium cations are connected into centrosymmetric clusters via weak C-H⋯N hydrogen bonds forming nine-membered rings with an R 3 (3)(9) motif. These clusters are inter-connected via anions through N-H⋯O hydrogen bonds, building a three-dimensional network.

m-Xylylenediaminium di-aqua-bis-[di-hydrogen diphosphato(2-)]cobaltate(II) dihydrate.

In the title complex, (C8H14N2)[Co(H2P2O7)2(H2O)2]·2H2O, the Co(II) ion lies on an inversion center and is coordinated by two bidentate diphosphate ligands and two water mol-ecules in a slightly distorted octa-hedral coordination geometry. The m-xylylenediaminium cation is located on a twofold rotation axis. In the crystal, a three-dimensional supra-molecular assembly is constructed by O-H⋯O and N-H⋯O hydrogen bonds between the organic cations, complex anions and uncoordin-ated water mol-ecules.