Synthesis of novel pyridyl containing phospholanes and their polynuclear luminescent copper() complexes

A novel type of cyclic P,N-ligands, pyridyl containing phospholanes, has been synthesized in a moderate yield by the reaction of primary phosphines with 1,4-dichlorobutane in a superbasic medium. A series of homo tetranuclear octahedral Cu 4 I 4 L 2 , dinuclear tetrahedral Cu 2 I 2 L 3 , and dinuclear "head-to-tail" Cu 2 I 2 L 2 luminescent complexes with these ligands were obtained. All the compounds were characterized using a range of spectroscopic and computational techniques, and in the case of some Cu 4 I 4 L 2 and Cu 2 I 2 L 3 complexes, by single crystal X-ray diffraction. The structural diversity of the obtained complexes was reflected in their photophysical properties: phosphorescence spectra of the compounds display emission in broad spectral range of 471-615 nm. TD-DFT computations allow the assignment of a single emission band around 550 nm for Cu 2 I 2 L 3 complexes and 471 nm for Cu 2 I 2 L 2 complex to a vertical triplet-singlet transition from a metal-to-ligand and halide-to-ligand charge-transfer 3 (M + X)LCT excited state, whereas a second band at around 600 nm in the spectra of octahedral Cu 4 I 4 L 2 complexes was assigned predominantly to Cu 4 I 4 cluster-centered ( 3 CC) excited state. Cu( i ) complexes with novel cyclic phosphine ligands were obtained. Phosphorescence spectra display emission in broad spectral range of 471-615 nm.