Room-Temperature Phosphorescence with Excitation-Energy Dependence and External Heavy-Atom Effect in Hybrid Zincophosphites

Room-temperature phosphorescence (RTP) materials have gained much attention, because of their applications in chemical sensing, optoelectronics, and security systems. Transition-metal complexes, particularly those of IrIII, PtII, RuII, and AuI, have preciously been investigated in the quest for excellent RTP materials. Recently, the pure organic molecules caught the eyes of researchers. Although great achievement has been reached, expanding the available types of RTP materials and hunting for top-performing RTP materials are still significant to promote the development of RTP materials. In this work, we report a series of isostructural hybrid zincophosphite [Zn3(HPO3)2(tib)2]X2 (X- = Cl-, Br-, I-; tib = 1,3,5-tris(1-imidazolyl)-benzene), which feature a cationic host structure and an anionic guest (X-). Because of the restriction of molecular vibrations/rotations of organic luminogens (tib) and the heavy-atom effect of the guest halide ion (X-), the title compounds exhibit almost pure RTP with absolute phosphorescence quantum yields of 5.8%-9.1%. More interestingly, unique excitation-energy-dependent phosphorescence has been observed in these hybrid materials. The phosphorescence origin has also been illustrated by theoretical calculations. Our work provides new insights into the design of RTP materials. Considering the structural diversity together with the rich host-guest chemistry of metal-phosphite/phosphate, we offer a new avenue to explore superior crystalline RTP materials.