A series of pure-blue-light emitting Cu(i) complexes with thermally activated delayed fluorescence: structural, photophysical, and computational studiesElectronic supplementary information (ESI) available: Fig. S1-S4: NV-Vis DRS, PXRD, IR spectra, and emission decay curves. CCDC 1486056-1486059. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6dt03965k

Four mononuclear Cu( i )-halide complexes containing phosphines and pyridine ligands with strong electron donor substituents, [CuCl(PPh 3 ) 2 (4-NMe 2 py)] ( 1 ), [CuI(PPh 3 ) 2 (4-NH 2 py)] ( 2 ), [CuI(POP)(4-NH 2 py)] ( 3 ), and [CuI(POP)(4-NMe 2 py)]·0.5(Et 2 O) ( 4 ), (PPh 3 = triphenylphosphine, 4-NMe 2 py = 4-(dimethylamino)pyridine, POP = bis[(2-diphenyl-phosphino)phenyl]ether, 4-NH 2 py = 4-aminopyridine, Et 2 O = diethyl ether) were synthesized and studied with regard to their structural, photophysical properties and theoretical calculations. The complexes exhibit pure blue thermally activated delayed fluorescence ( λ max = 442 ( 1 ), 436 ( 2 ), 464 ( 3 ), and 448 nm ( 4 )) in crystalline at room temperature. Emission lifetime analyses and density functional theory (DFT) calculations show that the blue-light emission at room temperature is the singlet (metal + halide)-to-ligand charge transfer state, ( 1 (M + X)LCT), while that at 77 K is the state of 3 (M + X)LCT transition character, owing to the small singlet-triplet energy gaps (Δ E = 660-1680 cm −1 ). X-ray diffraction structure analysis, photophysical studies and theoretical calculations suggest that the much larger torsion angle between the N-heterocyclic rings and N-Cu-X planes of complex 3 than that of 1 , 2 and 4 might causes the bathochromic shift of luminescence, although these complexes containing similar heterocycle ligands. Four Cu( i ) complexes exhibiting pure blue delayed fluorescence were synthesized and their structures and photophysical properties were studied.