Theoretical Insights into the Absorption and Emission Properties of Blue Luminescent Copper(I) Complexes Based on the Pyrazolyl-Pyridine Ligands

The ground geometrical and electronic structures, charge transfer (CT) behaviors, absorption, and emission properties of the three copper(I) complexes [Cu(pypz)(POP)](+) (1), [Cu(pympz)(POP)](+) (2), and [Cu(pytfmpz)(POP)](+) (3) (pypz=1-(2-pyridyl)pyrazole, pympz=3-methyl-1-(2-pyridyl)pyrazole, and pytfmpz=3-trifluoromethyl-1-(2-pyridyl)pyrazole), have been investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The vertical absorption energies of the all copper(I) complexes are well reproduced by TD-DFT calculations based on the CT amount calculations. The triplet emission properties of the all copper(I) complexes were correctly evaluated at BMK/LANL2DZ/6-31G* level of theory. In addition, the thermally activated delayed fluorescence properties of 1-3 were discussed in detail based on the spatial separation of the HOMO and LUMO and vertical excited energies. These theoretical insights should be expected to provide some guides for the design and synthesis of efficient luminescent copper(I) complexes. (c) 2014 Wiley Periodicals, Inc.