Syntheses, crystal structures, optical properties, antibacterial activity and DFT calculations of two substituted benzyl triphenylphosphinium picrates

Abstract

Two new organic hybrid materials, namely, 4-chlorobenzyl triphenylphosphinium picrate and 4-iodobenzyl triphenylphosphinium picrate [4ClBzTPP][PIC](1) and [4IBzTPP][PIC](2), have been grown by slow evaporation solution growth technique and characterized by elemental analysis, spectroscopy, thermal analysis, powder and single crystal XRD. Two new picrates crystallize in triclinic space group P−1 and consist of a pair of [4ClBzTPP]+/[4IBzTPP]+ cations and picrate anions. The one-dimensional anionic chain are constructed by the non-bonded O···O and N···O interactions. Experimental vibrational bands (IR and Raman) have been discussed and assigned. The HOMO-LUMO energy gap explains the charge transfer interactions in the molecules. TG-TDA technique reveals that two materials were stable up to 215 °C and 253 °C, respectively. Excited by 250 nm ultraviolet light, two materials emit main luminescent emissions bands at about 374 nm and 524 nm in solid state at room temperature. In addition, two picrates show good antibacterial activities against Escherichia coli and Staphylococcus aureus. The results of DFT calculations based on the structures of 1 and 2 indicate that the first hyperpolarizability value (βtot) of two crystals are 5.8 and 32.3 times that of KDP, respectively, which show good nonlinear optical properties.