Polyoxovanadates with Ethylidene-Pyridine Functionalized Bisphosphonate Ligands: Synthesis, Structure, Spectroscopic Characterization, Magnetic, and Antibacterial Studies

Thakre, D and Ali, SR and Mehta, S and Alam, N and Ibrahim, M and Sarma, D and Mondal, A and De, M and Banerjee, A (2021) Polyoxovanadates with Ethylidene-Pyridine Functionalized Bisphosphonate Ligands: Synthesis, Structure, Spectroscopic Characterization, Magnetic, and Antibacterial Studies. In: Crystal Growth and Design .

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Abstract

Reaction of ethylidene-pyridyl functionalized bisphosphonates with vanadium containing oxo compounds has afforded three different bisphosphonate-polyoxovanadate derivatives, viz., (VIVO2)(VV2O5)2{O3P-C(O)(CH2-2-C5NH4)-PO3}210- (1), (VIVO2)(VV2O5)2{O3P-C(O)(CH2-3-C5NH4)-PO3}210- (2), (VIVO)3(O){O3P-C(OH)(CH2-4-C5NH4)-PO3}38- (3), obtained in aqueous ammonium acetate buffer solutions (pH 4.7). Polyanions 1 and 2 were synthesized by the reaction of V2O5 with 1-hydroxy-2-(2-pyridyl) ethylidene-1,1-bisphosphonic acid (L1) and 1-hydroxy-2-(3-pyridyl) ethylidene-1,1-bisphosphonic acid (L2), respectively. Polyanion 3 was obtained by the reaction of VOSO4 with 1-hydroxy-2-(4-pyridyl) ethylidene-1,1-bisphosphonic acid (L3), in the presence of pyrazine. Single-crystal X-ray diffraction and elemental analysis reveal that all the polyanions are crystallized as ammonium salts, (NH4)4H6(VIVO2)(VV2O5)2{O3P-C(O)(CH2-2-C5NH4)-PO3}2·9H2O (1a), (NH4)4H6(VIVO2)(VV2O5)2{O3P-C(O)(CH2-3-C5NH4)-PO3}2·8H2O (2a), and (NH4)2H6(VIVO)3(O){O3P-C(OH)(CH2-4-C5NH4)-PO3}3·26H2O (3a), respectively. Polyanions 1 and 2 crystallize in the non-centrosymmetric space group P21212 and have an S-shaped assembly containing two different sets of vanadium atoms, based upon their oxidation state and different coordination environments. Polyanion 3 crystallizes in the centrosymmetric trigonal space group R3c and is observed to have a highly symmetric trinuclear structure. The polyanions have been characterized in solution with 1H and 31P NMR and optical spectroscopy, and in the solid state with detailed magnetic analysis. The magnetic studies under an external dc field showed paramagnetic behavior in agreement with the presence of V(IV) ions for 1a-3a. Furthermore, in vitro studies of the synthesized bisphosphonate-polyoxovanadate compounds were observed to exhibit peroxidase-like activity, and hence were employed to enhance the antibacterial activity of H2O2 solution at very low concentrations, thereby minimizing the possibilities of other side effects. Isostructural derivatives of compounds 1a and 2a with L3, viz., (NH4)4H6(VIVO2)(VV2O5)2{O3P-C(O)(CH2-4-C5NH4)-PO3}2·11H2O(4a), has been identified using infrared spectroscopy and characterized with NMR spectroscopy and elemental analysis. Similarly, an isostructural derivative of 3a with L2, viz., (NH4)2H6(VIVO)3(O){O3P-C(OH)(CH2-3-C5NH4)-PO3}3·21H2O (5a), has also been identified using infrared spectroscopy and characterized with elemental analysis. © 2021 American Chemical Society.

Item Type:	Journal Article
Publication:	Crystal Growth and Design
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society
Keywords:	Chelation; Hydrogen peroxide; Infrared spectroscopy; Ligands; Magnetism; Nuclear magnetic resonance spectroscopy; Salts; Single crystals; Synthesis (chemical); Vanadium pentoxide, Anti-bacterial activity; Anti-bacterial studies; Coordination environment; Optical spectroscopy; Paramagnetic behavior; Peroxidase-like activities; Single crystal x-ray diffraction; Spectroscopic characterization, Spectrum analysis
Department/Centre:	Division of Chemical Sciences > Organic Chemistry Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	28 Nov 2021 09:52
Last Modified:	28 Nov 2021 09:52
URI:	http://eprints.iisc.ac.in/id/eprint/70000

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