The FRET performance and aggregation-induced emission of two-dimensional organic-inorganic perovskite, and its application to the determination of Hg(II)

The authors describe the synthesis of a two-dimensional organic-inorganic perovskite of the type NH3(CH2)(10)NH3) PbBr4 by a fast precipitation method. The resulting powder under photoecitation at 270 nm exhibits yellow luminescence (peaking at 550 nm) in DMSO/water mixtures if the ratio is bigger than 4/6. On addition of Hg(II) and a rhodamine spirolactam, ring opening occurs and colorimetric and fluorescent responses can be seen. Specifically, the emission at 550 nm gradually decreases and a new emission peak appears at 585 nm (corresponding to the emission peak of RBEA-Hg(II) complex) while the color of the solution gradually turns to pink under visible light. The emission peak of the modified perovskite overlaps the 585 nm absorption of rhodamine B, and this results in a FRET effect whose Forster radius (donor-acceptor distance) is calculated from decay time data to be 10.4 angstrom. Based on these findings, a FRET-based assay for Hg(II) was worked that has a 2.4 mu M detection limit.