Synthesis and Photophysical Properties of Copper(I) Complexes Obtained from 1,10‐Phenanthroline Ligands with Increasingly Bulky 2,9‐Substituents

Abstract

AbstractIn this paper, we describe the synthesis and the electronic properties of a series of [Cu(NN)2]+ systems. The NN ligands investigated are 2,9‐bis[(tert‐butyldimethylsilyloxy)methyl]‐1,10‐phenanthroline (1), 2,9‐bis[(triisopropylsilyloxy)methyl]‐1,10‐phenanthroline (2), 2,9‐bis[(tert‐butyldiphenylsilylmoxy)ethyl]‐1,10‐phenanthroline (3), 2,9‐bis[2,6‐bis(benzyloxy)phenethyl]‐1,10‐phenanthroline (4) and 2‐(1,3‐diphenylpropan‐2‐yl)‐9‐phenethyl‐1,10‐phenanthroline (5). The electrochemical properties and the ground state electronic absorption spectra of Cu(1)2–Cu(5)2 are in line with the classical behaviour of such [Cu(NN)2]+ derivatives. Whereas all the compounds exhibit MLCT luminescence centered around 630–650 nm, the emission quantum yields and the lifetimes are dramatically different as a function of stereoelectronic effects and/or the possibility of internal exciplex quenching when oxygen‐containing functional groups are attached to the phenanthroline ligands.