Structures, electronic and luminescent properties of Cu(I)-quinoline complex at different temperatures and its application to red light-emitting diode

摘要

A mononuclear Cu(I) complex, Cu(dppb)(2,2'-biquinoline)]BF4(1) (dppb = 1, 2-bis(diphenyl phosphino)benzene), has been synthesized and characterized at 100 K, 150 K, 200 K, 250 K and 298 K. The structural analysis reveals that the rise of temperature from 100 K to 298 K leads to the increasement of molecular size, such as the unit-cell parameters and volume, and the change of bond lengths, bond angles, C-H center dot center dot center dot pi and pi center dot center dot center dot pi interactions. DFT calculations indicate that the HOMO -> LUMO energy gap and Mulliken atomic charges are changed by the increase of temperature from 100 K to 298 K, and the component of the HOMOs and LUMOs are barely changed at 100-298 K, which is in accordance with the variation of DOS and PDOS at different temperatures. Meanwhile, the surprising broad blue-yellow excitation bands are observed at 100-298 K and the maximum emission is increasing with the blue shift from 735 nm at 100 K to 685 nm at 298 K. Furthermore, the emission decay time of complex 1 reaches 3 mu s at 298 K. In addition, copper(I) complex 1 is used to fabricate the monochromatic LED, which emits a red light.