Tuning the photophysical properties of a (P,N)ReI complex by adding a -NH- fragment into a P,N-bidentate ligand: The case of [P,N-{(C6H5)2(C5H4N)NHPRe(CO)3Br]

Abstract

© 2016 Elsevier Ltd. All rights reserved.The spectroscopic, electrochemical and photophysical properties of the new complex [P,N-{(C6H5)2(C5H4N)NHP}Re(CO)3Br] (RePNN) are reported. The UV-Vis spectrum in dichloromethane (DCM) shows an absorption maximum centered at 300 nm and a shoulder at 350 nm. These absorption bands have been characterized, having a πpy → π∗py and a MLCT character. Excitation at the first wavelength (higher energy) leads to an emission band centered at 365 nm. Cyclic voltammetry shows a fully irreversible oxidation wave around +1.45 V, assigned to ReI/ReII couple, whereas two irreversible reduction signals centered at -0.75 and -1.20 V are assigned to ligand reduction processes. The photophysical results show that emission from the RePNN complex comes exclusively from the ligand. The MLCT excited state shows to be non-emissive by coupling to vibrational modes leading to non-radiative decay path to ground state. The luminescent decay fits to a bi-exponential functio