Green phosphorescent Zn(II) halide complexes with N,N,N′,N′‐tetramethyl‐P‐indol‐1‐ylphosphonic diamide as ligand

Abstract

Tetrahedral Zn(II) complexes having general formula [ZnX2{O=P(NMe2)2Ind}2] (X= Cl, Br, I, NCS) were isolated from the reaction between the indol-1-yl substituted phosphoramide N,N,N',N'-tetramethyl-P-indol-1-ylphosphonic diamide (O=P(NMe2)2Ind) and anhydrous Zn(II) precursors under mild conditions. The structures of the three halide derivatives were ascertained by single-crystal X-ray diffraction. The bromo- and iodo-derivatives revealed to be appreciably luminescent in the green region upon excitation with light below 300 nm, with emission bands centred between 520 and 530 nm. The large Stokes shifts and the excited state lifetimes in the milliseconds range indicate that triplet excited states are involved in the emission. TD-DFT calculations indicated that the transition responsible of the luminescence is ligand-centred (3LC).