Synthesis of Fluorescent Rhodium(II) and Iridium(II) Complexes Promoted by 2,6-Bistetrazolate Pyridine Ligand

Abstract

Tridentate N-donor ligand 2,6-bistetrazolate pyridine (H2pytz) has been prepared from 2,6-pyridinedicarbonitrile and used for coordination with transition metals [M(pytz)2](NHEt3)2, (M =Rh, Ir). The structure of Rh and Ir complexes was determined by UV, FT-IR, 1H NMR, XRD and elemental analysis. Moreover, the absorption spectra of complexes were shifted towards the visible region (367.2 nm for Rh and 370.8 nm for Ir). The π-excessive, lone pair nitrogen donors and extended unsaturation of ligand triggers the visible fluorescence spectra upto 528.5 nm for rhodium complex and 557.5 nm for iridium complex. The antibacterial activity results revealed that S. aureus and E. coli showed maximum response followed by K. pneumoniae and B. cereus, respectively. The maximum zone of inhibition of complexes was observed at 6 mg/mL concentration viz. S. aureus, 15.0 ± 1.15 mm for rhodium complex and E. coli, 14.6 ± 1.15 mm for iridium complex. Therefore, 2,6-bistetrazolate pyridine (H2pytz) ligand tune the photo-physical properties of the complexes as well as their applications in the biological fields.