Synthesis, Structural Characterisation, DFT Studies, and Spectroscopic Properties of Copper(I) Complexes with Extended C–H⋅⋅⋅π Interactions

Abstract

Two new CuI compexes, [Cu(phen)(PPh2(o-C6H4CHO))2](BF4)2 (1) and [Cu2(4,4′-bipy)(phen)2(PPh2(o-C6H4CHO))2](BF4)2·2CH3CN (2) (4,4′-bipy = 4,4′-bipyridine, PPh2(o-C6H4CHO) = o-(diphenylphosphino)benzaldehyde), have been synthesised and characterised by IR and UV-vis spectroscopy and X-ray crystal structural analysis. Structural analysis shows that the crystal structure of 1 contains 1D infinite chains formed by intermolecular C–H⋯π interactions, and the ordered-layer-lattice BF4– are located between the chains. For 2, intermolecular C–H⋯π and π⋯π interactions lead to the construction of 1D supramolecular arrays and 2D networks, and the ordered-layer-lattice CH3CN and BF4– are located between these networks. Density of states (DOS) and partial density of states (PDOS) studies indicate that the constitution of energy bands might be related to the change of ligands, with PPh2(o-C6H4CHO) showing the largest contributions to the HOMO of 2 and LUMO of 1. The UV-vis absorption spectra of 1 and 2 reveal that the absorption spectrum of 2 is red-shifted compared with 1. Moreover, the emission spectra of 1 and 2 in acetonitrile are also observed in the region of 480–700 nm.