A Series of Luminescent [(Xantphos)CuIL_N] Complexes and Their Luminescence Sensing Properties for VOCs Detection and TD‐DFT Calculation

ABSTRACT The design and research of luminescent and volatile organic compounds (VOCs) fluorescent sensing/stimuli–response materials are of great significance and challenge. We report herein a series of new [(Xantphos)CuIL N ] type complexes with tetrahedral CuIP 2 N coordination, showing luminescence from blue to red and luminescence sensing for VOCs detection (Xantphos is 4,5‐bis (diphenylphosphino)‐9,9‐dimethylxanthene, L N is N‐containing ligand). Firstly, six new complexes 1 – 6 were designed and ball‐milling synthesized by the ligand‐addition reaction of a raw material [(Xantphos)CuI] with different N‐containing ligands 2‐aminopyridine ( 1 ), 3‐cyanopyridine ( 2 ), 4‐cyanopyridine ( 3 ), 2‐(3′‐pyridyl)‐benzoxazole ( 4 ), 3‐I‐4‐aminopyridine ( 5 ), and imidazole ( 6 ). Time‐dependent density functional theory (TD‐DFT) calculations assign the low‐energy band (absorption edge) of 1 – 6 in UV–Vis absorption as a mixed (XL + ML)CT transition, the corresponding (XL + ML)CT excited state is also thought to be the source of photoluminescence (PL). Material 4 has the highest PL efficiency (~44%), which may benefit from its greatest structural rigidity. Material 5 exhibiting the worst PL efficiency should be related to the iodine atom in the L N ligand (I dominate the highest unoccupied orbitals of the S 1 and T 1 states). Based on its very weak PL, the corresponding thin‐film sensor ( 5 ) achieve significantly enhanced luminescence sensing (lighting‐up mode) for pyridine and 4‐methylpyridine vapor. The sensor also achieves the lowest detection limit (LOD = 2.51 ppm) and the fastest response speed (T 50 = 30 s) for pyridine. In addition, the series of materials also show interesting quenching and vapochromic luminescence sensing/stimuli–response for a variety of VOCs vapors.