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

Abstract

Reaction of ethylidenepyridyl-functionalized bisphosphonates with vanadium containing oxo compounds has afforded three different bisphosphonate-polyoxovanadate derivatives, viz. 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,Polyanions 1 and 2 crystallize in the non-centrosymmetric space group P21212 and have an Sshaped assembly containing two different sets of vanadium atoms, based upon their oxidationstate and different coordination environments. Polyanion 3 crystallizes in the centrosymmetric trigonal space group R𝟑 ̅ c and is observed to have a highly symmetric trinuclear structure. The polyanions have been characterized in solution with 1 H and 31 P 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 3 possibilities of other side effects. Isostructural derivatives of compounds 1a and 2a with L3, viz. 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)2[H6(V IV O)3(O){O3P-C(OH)(CH2-3-C5NH4)-PO3}3]•21H2O (5a), has also been identified using infrared spectroscopy, and characterized with elemental analysis.

Exploration of Vanadium(IV)-Based Single-Ion Magnet Properties in Diphosphonate-Supported Mixed-Valent Polyoxovanadates

“…, were determined by single-crystal X-ray diffraction. 27,28 Both the complexes were found to be isostructural with each other and crystallized in the same noncentrosymmetric orthorhombic space group of P2 1 2 1 2, with the only difference being in the locations of the counterions and cocrystallized solvent water molecules.…”

One‐Pot Microwave‐Assisted Synthesis, in Vitro Anti‐inflammatory Evaluation and Computer‐Aided Molecular Design of Novel Sulfamide‐Containing Bisphosphonates Derivatives

“…1 H NMR and 13 C NMR spectra were recorded on a Bruker Avance III or JEOL spectrometer at 400 MHz and 100 MHz respectively, with TMS as an internal standard in CDCl 3 or DMSO-d 6 . 31 P NMR spectra were recorded on a Bruker Avance III spectrometer and were referenced to the external H 3 PO4 at 162 MHz. Standard abbreviations indicating multiplicity were as follows: s = singlet, d = doublet, dd = doublet of doublets, t = triplet, dt = doublet of triplets, q = quadruplet and m = multiplet.…”

“…The IR and 1 H, 13 C, 31 P NMR spectra of the synthesized compounds are availaible in the supporting information.…”

“…However, an additional bioactive functionalized moiety in the bisphosphonate molecule such as 1H‐indazole, 1H‐pyrazolo[3,4‐b]pyridine and 1H‐pyrazolo[3,4‐b]quinolone, [22] 2‐amino‐ benzothiazole, [23] nitrogen and sulfur, [24] sulfonylamino, [25] fluoro‐substituted amine, [26] pyrazole, [27] acrylamide‐derived monomer, [28] amino acid, [29] hyaluronic acid, [30] and ethylidene‐pyridine bisphosphonate polyoxovanadates complexes, [31] give new derivatives for this class of molecules and offer promising and remarkable biological and industrial applications.…”

“…[11] Furthermore, these compounds have gained considerable attention in the field of medicinal chemistry due to their role in many biological activities, including anti-inflammatory, [12] antioxidant, [13] antifungal, [14,15] antibacterial and antiviral, [16] anticancer, [17] antiparasitic, [18] herbicidal, [19] as well as chelating agents. [20,21] However, an additional bioactive functionalized moiety in the bisphosphonate molecule such as 1H-indazole, 1Hpyrazolo [3,4-b]pyridine and 1H-pyrazolo [3,4-b]quinolone, [22] 2amino-benzothiazole, [23] nitrogen and sulfur, [24] sulfonylamino, [25] fluoro-substituted amine, [26] pyrazole, [27] acrylamide-derived monomer, [28] amino acid, [29] hyaluronic acid, [30] and ethylidene-pyridine bisphosphonate polyoxovanadates complexes, [31] give new derivatives for this class of molecules and offer promising and remarkable biological and industrial applications.…”