Luminescence Enhancement and Temperature Sensing Properties of Hybrid Bismuth Halides Achieved via Tuning Organic Cations.

Bismuth-halide-based inorganic-organic hybrid materials (Bi-IOHMs) are desirable in luminescence-related applications due to their advantages such as low toxicity and chemical stability. Herein, two Bi-IOHMs of [Bpy][BiCl 4 (Phen)] ( 1 , Bpy = N -butylpyridinium, Phen = 1,10-phenanthroline) and [PP14][BiCl 4 (Phen)]·0.25H 2 O ( 2 , PP14 = N -butyl- N -methylpiperidinium), containing different ionic liquid cations and same anionic units, have been synthesized and characterized. Single-crystal X-ray diffraction reveals that compounds 1 and 2 crystallize in the monoclinic space group of P 2 1 / c and P 2 1 , respectively. They both possess zero-dimensional ionic structures and exhibit phosphorescence at room temperature upon excitation of UV light (375 nm for 1 , 390 nm for 2 ), with microsecond lifetime (24.13 μs for 1 and 95.37 μs for 2 ). Hirshfeld surface analysis has been utilized to visually exhibit the different packing motifs and intermolecular interactions in 1 and 2 . The variation in ionic liquids makes compound 2 have a more rigid supramolecular structure than 1 , resulting in a significant enhancement in photoluminescence quantum yield (PLQY), that is, 0.68% for 1 and 33.24% for 2 . In addition, the ratio of the emission intensities for compounds 1 and 2 shows a correlation with temperature. This work provides new insight into luminescence enhancement and temperature sensing applications involving Bi-IOHMs.