Synthesis, structure, characterization and spectroscopic properties of Cu+ complexes with extended π•••π interactions

A series of Cu(I) complexes, [Cu-2(pfan)(2)(4,4 '-bipyridine)(PPh3)(2)](BF4)(2) (1), [Cu-2(4,4 '-bipyridine)(2,2 ' bipyridine) (2)(PPh3)(2)](BF4)(2) (2), [Cu-2(bpe)(2,2 '-bipyridine)(2)(PPh3)(2)](BF4)(2) (3), [Cu-2(bpe)(phen)(PPh3)(2)](BF4) (2) (4), [Cu-2(bpe)(pfan)(2)(PPh3)(2)](BF4)(2) (5) (phen = 1,10-phenanthroline, bpe = 1,2-bis(4-pyridyl) ethylene, pfan = ((pyridin-2-yl) formylidene) anilin), have been synthesized and characterized by IR, 1H NMR, P-31 NMR, UV-Vis spectrum and X-ray crystal structure analysis. The structural analysis displays that each Cu+ in the complexes is four coordinate N3P, and adopts a distorted-tetrahedral geometry, and 1D chain of 1-5 is formed by four tapes of` pi center dot center dot center dot pi interactions between chelating ligands except that 5 is built by pi center dot center dot center dot pi interaction of phenylene rings from PPh3. All these reveal that the change of chelating or bridging ligand might be the key of construction of 1D pi-stacking chain. UV-Vis spectra and DFT studied indicate the absorption spectrum of 4, compared to 3, is red shift. In addition, the emission spectrum of complexes 2, 3 and 4 in acetonitrile are also observed. (C) 2013 Elsevier B. V. All rights reserved.