Syntheses, Crystal Structures, Optical and Antibacterial Properties of Two Organic-Inorganic Hybrids Containing Pyridine-Substituted Triphenylphosphonium and Tetrachlorocobaltate/Copperate(Ii) Anion

Abstract

The purpose of this paper is to present the syntheses, crystal structures, vibrational spectra, optical and antibacterial properties for two new organic-inorganic hybrids, [Py(CH2)3TPP][CoCl4]·H2O(1) and [Py(CH2)3TPP][CuCl4](2), where [Py(CH2)3TPP]2+ is 1-(1'-pyridyl-propyl)-3-triphenyl phosphonium. Two hybrids were crystallized in the monoclinic space group P21/n. Two hybrids consist of a [Py(CH2)3TPP]2+ cation and a tetrahedral [CoCl4]2−/[CuCl4]2− anion, where the crystal structure is stabilized by C−H...Cl, O−H...Cl and C−H...O hydrogen bonds due to the presence of a water molecule in 1, and the crystal structure of 2 is stabilized by C−H...Cl hydrogen bonds. Experimental vibrational bands (IR and Raman) have been discussed and assigned. The intermolecular energy, the energy gap between HOMO and LUMO orbitals, as well as the first hyperpolarizabilities were predicted based on DFT calculations. The low energy gap (1.26 eV for 1 and 1.20 eV for 2) is responsible for the interpretation of the charge transfer interactions that eventually occur between the cation and the anion. The first hyperpolarizabilities (βtot) of 1 and 2 are 82 and 237 times as high as that of the standard KDP crystal, respectively, indicating that the two as-prepared hybrids are excellent materials for NLO applications. Furthermore, it is found that both salts exhibit good bactericidal activity against E. coli and S. aureus.

Keywords: Pyridine-substituted triphenylphosphonium, Tetrachlorocobalt/copper(II), Crystal structures, Non-linear optical properties, Antibacterial activity.