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A new series of triorganotin(IV) complexes of sparfloxacin (HL) having general formula R 3 SnL (where L is the monoanion of sparfloxacin (HL) and R = Me (1)/n-Bu (2)/Ph (3)/Cy (4)) have been synthesized and characterized by elemental analysis, IR, NMR ( 1 H, 13 C, 119 Sn), 2D-HETCOR, ESI-MS and UV-Vis studies. These investigations suggest that, in these 1:1 monomeric derivatives the sparfloxacin ligand acts as monoanionic bidentate coordinating through the O carboxylate and O pyridone , and the polyhedron around tin is intermediate between pseudotetrahedral and cis-trigonal bipyramidal, with O pyridone and two organic groups in equatorial plane and the carboxylate oxygen and the third organic group in axial positions. The proposed structures have been validated by density functional theory (DFT) based quantum chemical calculations at B3LYP/6-31G(d,p)/Def2-SVP(Sn) level of theory. A detailed electronic structure calculations were performed at this level of theory to calculate atomic charges at the selected atoms, molecular electrostatic potential (MEP) map to assign sites on the surface of the molecules, the selected conceptual-DFT based global reactivity descriptors to obtain an insight into the structure and reactivity behaviour, and the frontier molecular orbital analysis to analyze the nature of frontier orbitals. All the complexes were screened for their in vitro antibacterial activity against two Gram-positive and five Gram-negative bacterial strains. All the complexes exhibited promising antibacterial activity as compared to sparfloxacin against all the chosen strains.

AbstractThe quantum-chemical calculations based on density functional theory (DFT) have been performed on the diphenyltin(IV) derivative of glycyl-phenylalanine (H

New triorganotin(IV) derivatives of ciprofloxacin (HL) with general formula R3Sn(L) (where R = Me (1)/Cy (2) and L is the monoanion of ciprofloxacin) have been synthesized and structurally characterized on the basis of elemental analysis, IR, Raman, multinuclear (1H‐, 13C‐ and 119Sn‐) NMR, ESI‐MS, UV‐Visible, and emission spectroscopy. A distorted trigonal bipyramidal geometry around tin has been tentatively proposed for these triorganotin(IV) derivatives in which the ligand may act as monoanionic bidentate coordinating through the Ocarboxylate and Opyridone. The proposed structure has been validated by density functional theory (DFT)‐based electronic structure calculations at B3LYP/6‐31G(d,p)/Def2‐SVP(Sn) level of theory. The atomic charges have been calculated at the selected atoms, and the reactive sites have been assigned on the surface of the molecules through molecular electrostatic potential map. The frontier molecular orbitals and selected conceptual‐DFT‐based global reactivity descriptors have been calculated to obtain an insight into the structure and reactivity behavior of the complexes. A comparative analysis of the experimental vibrational frequencies and simulated harmonic frequencies indicates good correlation between them. The complexes were screened for their in vitro antibacterial activity against two Gram‐positive and five Gram‐negative bacterial strains. The results revealed that both the complexes exhibited promising antibacterial activity against the chosen strains (MIC: 0.062‐0.125 μg/mL).

New diorganotin(IV) complexes of a Schiff base (HL) having general formula R2Sn(L)Cl (where L is the monoanion of HL and R = n‐Bu or Ph) have been synthesized and characterized using elemental analysis, infrared, NMR (1H, 13C, 119Sn) and UV–visible spectroscopies and mass spectrometry. These investigations suggest that in these 1:1 monomeric derivatives the Schiff base ligand acts in a monoanionic bidentate manner coordinating through the Ophenolic and Nazomethine, with proposed distorted trigonal bipyramidal geometry around tin with Ophenolic and two organic groups in the equatorial plane and the Nazomethine and the third organic group in axial positions. The proposed structures have been validated by density functional theory (DFT)‐based quantum chemical calculations at the B3LYP/6‐31G(d,p)/Def2‐SVP (Sn) level of theory. The simulated UV–visible spectrum was obtained with the time‐dependent DFT method in the gas phase and in the solvent field with the integral equation formalism–polarizable continuum model. A comparative analysis of the experimental vibrational frequencies and simulated harmonic frequencies indicates a good correlation between them. An insight into the intramolecular bonding and interactions among bonds in organotin(IV) complexes of HL was obtained by means of natural bond orbital analysis. The topological and energetic properties of the electron density distribution for the tin–ligand interaction in R2Sn(L)Cl have been theoretically calculated at the bonds around the central tin atom in terms of atoms‐in‐molecules theory. The R2Sn(L)Cl complexes were screened for their in vitro antifungal activity against chosen fungal strains.

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