Reversible Luminescent Switching Induced by Heat/Water Treatment in a Zero-Dimensional Hybrid Antimony(III) Chloride

Recently zero-dimensional (0-D) inorganic-organic metal halides (IOMHs) have become a promising class of optoelectronic materials. Herein, we report a new photoluminescent (PL) 0-D antimony(III)-based IOMH single crystal, namely [H(2)BPZ][SbCl5]center dot H2O (BPZ = benzylpiperazine). Photophysical characterizations indicate that [H(2)BPZ][SbCl5]center dot H2O exhibits singlet/triplet dual-band emission. Density functional theory (DFT) calculations suggest that [H(2)BPZ][SbCl5]center dot H2O has the large energy difference between singlet and triplet states, which might induce the dual emission in this compound. Temperature-dependent PL spectra analyses suggest the soft lattice and strong electron-phonon coupling in this compound. Thermogravimetric analysis shows that the water molecules in the lattice of the title crystal could be removed by thermal treatment, giving rise to a dehydrated phase of [H(2)BPZ][SbCl5]. Interestingly, such structural transformation is accompanied by a reversible PL emission transition between red light (630 nm, dehydrated phase) and yellow light (595 nm, water-containing phase). When being exposed to an environment with 77% relative humidity, the emission color of the dehydrated phase was able to change from red to yellow within 20 s, and the red emission could be restored after reheating. The red to yellow emission switching could be achieved in acetone with water concentration as low as 0.2 vol%. The reversible PL transition phenomenon makes [H(2)BPZ][SbCl5]center dot H2O a potential material for luminescent water-sensing.

Automated summary

Recently, a new photoluminescent 0-D antimony(III)-based inorganic-organic metal halide single crystal was reported. This crystal exhibits singlet/triplet dual-band emission and has a large energy difference between singlet and triplet states. The crystal also shows reversible PL emission transition between red and yellow light, making it a potential material for luminescent water-sensing.