Synthesis, spectral characterization, molecular modeling, antibacterial and antioxidant activities and stability study of binuclear Pd(II) and Ru(III) complexes with novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl)methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] ligand: Application to detection of cholesterol.

A novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl) methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] Schiff base (L) and its binuclear palladium and ruthenium complexes have been prepared and characterized by ESI-MS, elemental analysis, NMR (1H NMR, 13C NMR, COSY, NEOSY and HSQC), FT-IR, ATR, UV-Visible spectra, TGA measurements, conductivity and cyclic voltammetry. The experimental results and the molecular parameters calculated using DFT method revealed a square planar geometry around Pd and octahedral geometry around ruthenium metal. The antibacterial activity of the ligand L and its complexes was evaluated against different human bacteria. In addition, the formation constants of the synthesized Schiff base-metal complexes and the systems formed with these chelates and cholesterol were estimated using spectrophotometric technique. The detection of cholesterol using novel Pd and Ru Schiff base complexes was studied using fluorometric method, and the measurements showed that the sensitive fluorometric response towards cholesterol analysis was determined using palladium complex. The limit of detection (LOD) of cholesterol calculated using this complex (4.6 µM) is lower (better) than LOD found using ruthenium complex (19.1 µM) and different compounds previously published around linear range of 0-5 mM.

K2V2O2(AsO4)2.

The vanadium oxide arsenate with formula K2V2O2(AsO4)2, dipotassium divanadium(IV) dioxide diarsenate, has been synthesized by solid-state reaction in an evacuated silica ampoule. Its structure is isotypic with K2V2O2(PO4)2. The framework is built up from corner-sharing VO6 octa-hedra and AsO4 tetra-hedra, creating an infinite [VAsO8](∞) chain running along the a- and c-axis directions. The K⁺ cations are located in hexa-gonal tunnels, which are delimited by the connection of the [VAsO8](∞) chains.

K(1.65)V(1.78)W(0.22)O(2)(AsO(4))(2).

The title potassium vanadium tungsten bis-(arsenate oxide) was synthesized by a solid-state reaction at 973 K. The crystal structure is isotypic with KVOPO(4) and contains a [MVAs(2)O(10)](∞) framework built up from single MO(6) (M = V+W) octa-hedra sharing corners with single VO(6) octa-hedra and AsO(4) tetra-hedra. This structure shows the existence of infinite [VAsO(8)](∞) and [MAsO(8)](∞) chains running along the a and c directions, respectively. All atoms are located on general positions. The metal position M is statistically occupied by 78% V and 22% W.