Novel copper(I) complexes with extended π⋯π interactions: Synthesis, structure, characterization and spectroscopic properties

•Two new copper (I) complexes were synthesized and characterized.•The weak interactions play an important role in the construction of supramolecular structures.•Crystal packing variations of complexes are related to the change of anions.•DFT studies display that the stability may be 2 > 1.

Based on ligand N,N′-bis(pyridin-2-ylmethylene)biphenyl-4,4′-diamine (pmbb), two compounds of [Cu2(pmbb)(CH3CN)2(PPh3)2](ClO4)2·2DMF (1) and [Cu2(pmbb) (PPh3)2(Cl)2] (2) have been synthesized and structurally characterized by IR, 1H NMR, 31P NMR and X-ray crystal structure analysis. Structural analysis reveals that both of these complexes contain the 1D embrace arrays, with different variations in π-stacking patterns and intermolecular C–H⋯π interactions. Crystal structure of 1 contains 1D tape-like arrays constructed by C–H⋯π and π⋯π interactions, and the ordered-layer-lattice DMF and ClO4− are located between one-dimensional arrays. For 2, π-stacking interactions lead to the construction of 1D arrays and 2D sheet. The UV–Vis absorption spectra of complexes 1 and 2 reveal that π-stacking types may play an important role in optical absorption. DFT studies indicate the stability may be 2 > 1. In addition, the emission spectrum of complex 1 in acetonitrile solvent and thermogravimetric analysis of 2 are also observed.

Graphical abstractTwo copper(I) complexes have been synthesized and characterized by IR, 1H NMR, 31P NMR, UV–Vis spectrum, thermogravimetric analysis and X-ray crystal structure analysis. The structural analysis reveals that changing of anions will lead to the formation of different supramolecular structures with extended π⋯π interactions. DFT studies show the stability may be 2 > 1. The luminescent properties of 1 are observed.Figure optionsDownload full-size imageDownload as PowerPoint slide