Photon Driven Transformation of Cesium Lead Halide Perovskites from Few-Monolayer Nanoplatelets to Bulk Phase.

Influence of light exposure on cesium lead halide nanostructures has been explored. A discovery of photon driven transformation (PDT) in 2D CsPbBr3 nanoplatelets is reported, in which the quantum-confined few-monolayer nanoplatelets will convert to bulk phase under very low irradiation intensity (≈20 mW cm-2 ). Benefiting from the remarkable emission color change during PDT, the multicolor luminescence photopatterns and facile information photo-encoding are established.

A Three-Photon Active Organic Fluorophore for Deep Tissue Ratiometric Imaging of Intracellular Divalent Zinc.

Deep tissue bioimaging with three-photon (3P) excitation using near-infrared (NIR) light in the second IR window (1.0-1.4 µm) could provide high resolution images with an improved signal-to-noise ratio. Herein, we report a photostable and nontoxic 3P excitable donor-π-acceptor system (GMP) having 3P cross-section (σ3 ) of 1.78×10(-80)  cm(6) s(2) photon(-2) and action cross-section (σ3 η3 ) of 2.31×10(-81)  cm(6) s(2) photon(-2) , which provides ratiometric fluorescence response with divalent zinc ions in aqueous conditions. The probe signals the Zn(2+) binding at 530 and 600 nm, respectively, upon 1150 nm excitation with enhanced σ3 of 1.85×10(-80)  cm(6) s(2) photon(-2) and σ3 η3 of 3.33×10(-81)  cm(6) s(2) photon(-2) . The application of this probe is demonstrated for ratiometric 3P imaging of Zn(2+) in vitro using HuH-7 cell lines. Furthermore, the Zn(2+) concentration in rat hippocampal slices was imaged at 1150 nm excitation after incubation with GMP, illustrating its potential as a 3P ratiometric probe for deep tissue Zn(2+) ion imaging.