No abstract

Low‐dimensional luminescent lead halide perovskites have attracted tremendous attention for their fascinating optoelectronic properties, while the toxicity of lead is still considered a drawback. Herein, we report a novel lead‐free zero‐dimensional (0D) indium‐based perovskite (Cs2InBr5⋅H2O) single crystal that is red‐luminescent with a high photoluminescence quantum yield (PLQY) of 33 %. Experimental and computational studies reveal that the strong PL emission might originate from self‐trapping excitons (STEs) that result from an excited‐state structural deformation. More importantly, the in situ transformation between hydrated Cs2InBr5⋅H2O and the dehydrated form is accompanied with a switchable dual emission, which enables it to act as a PL water‐sensor in humidity detection or the detection of traces of water in organic solvents.

A luminescent all-inorganic manganese-bismuth heterometallic Cs 4 MnBi 2 Cl 12 perovskite single crystal has been synthesized with a [BiCl 6 ] 3À -[MnCl 6 ] 4À -[BiCl 6 ] 3À triple-layered two-dimensional structure. Benefit from the effective energy transfer from [BiCl 6 ] 3À octahedron donor to luminescent [MnCl 6 ] 4À acceptor, Cs 4 MnBi 2 Cl 12 shows a photoluminescence quantum yield (PLQY) of up to 25.7% (~610 nm), 51-fold higher than the Bi unalloyed CsMnCl 3 $2H 2 O counterpart. Suggested by the theoretical calculations, Bi and Mn exhibit hybridization in conduction and valence band, which further results in a favorable low activation energy for exciton transfer (~23 meV). By virtue of all-inorganic chemical composition, Cs 4 MnBi 2 Cl 12 exhibits impressive stability toward moisture, light, and heat. Furthermore, Cs 4 MnBi 2 Cl 12 features strong soft X-ray attenuation and bright radiative luminescence under X-ray excitation, which pave a way for its application in medical flat-panel X-ray digital radiography. This work presents a new avenue toward fabrication of function-directed material with tailored photoelectric properties.

Arrestins ensure the timely termination of receptor signaling. The role of rhodopsin phosphorylation in visual arrestin binding was established more than 20 years ago, but the effects of the number of receptor-attached phosphates on this interaction remain controversial. Here we use purified rhodopsin fractions with carefully quantified content of individual phosphorylated rhodopsin species to elucidate the impact of phosphorylation level on arrestin interaction with three biologically relevant functional forms of rhodopsin: light-activated and dark phosphorhodopsin and phospho-opsin. We found that a single receptor-attached phosphate does not facilitate arrestin binding, two are necessary to induce high affinity interaction, and three phosphates fully activate arrestin. Higher phosphorylation levels do not increase the stability of arrestin complex with light-activated rhodopsin but enhance its binding to the dark phosphorhodopsin and phospho-opsin. The complex of arrestin with hyperphosphorylated light-activated rhodopsin is less sensitive to high salt and appears to release retinal faster. These data suggest that arrestin likely quenches rhodopsin signaling after the third phosphate is added by rhodopsin kinase. The complex of arrestin with heavily phosphorylated rhodopsin, which appears to form in certain disease states, has distinct characteristics that may contribute to the phenotype of these visual disorders.Arrestins play a key role in the regulation of G protein-coupled receptor signaling. Arrestins bind to active phosphorylated forms of their cognate receptors precluding further G protein activation, directing receptors to the coated pits for internalization, and switching the signaling to alternative G protein-independent pathways (reviewed in Refs. 1-3). Rhodopsin is now widely considered a prototypical G protein-coupled receptor, although its activation-dependent phosphorylation was discovered long before the existence of G protein-coupled receptor family was even suspected (4, 5). Visual (rod) arrestin was the first member of the family discovered, and the fact that its binding to light-activated rhodopsin is greatly enhanced by rhodopsin phosphorylation was established more than 20 years ago (6). Remarkable selectivity of rod arrestin for P-Rh* 3 is ensured by a sequential multi-site interaction mechanism. The first step involves low affinity "prebinding" of arrestin to rhodopsin-attached phosphates or to parts of rhodopsin that change conformation upon light-activation via phosphate or activation sensor sites, respectively. Following that, mobilization of additional hydrophobic binding sites occurs when both sensors are simultaneously engaged by an encounter of arrestin with P-Rh* (recently reviewed in . The role of receptor-attached phosphates in arrestin activation that "primes" it for high affinity binding and the mechanism of function of the "phosphate sensor" in arrestin molecule have been elucidated in great detail (reviewed in Ref. 3, 7). Rhodopsin has many phosphorylation sites and can be...

Although single-source white emissive perovskite has emerged as a class of encouraging light-emitting material, the synthesis of lead-free halide perovskite materials with high luminous efficiency is still challenging. Here, we report a series of zero-dimensional indium-antimony (In/Sb) alloyed halide single crystals, BAPPIn 2-2x Sb 2x Cl 10 (BAPP = C 10 H 28 N 4 , x = 0 to 1), with tunable emission. In BAPPIn 1.996 Sb 0.004 Cl 10 , bright yellow emission with near 100% photoluminescence quantum yield (PLQY) is yielded when it was excited at 320 nm, which turns into bright white-light emission with a PLQY of 44.0% when excited at 365 nm. Combined spectroscopy and theoretical studies reveal that the BAPP 4+ -associated blue emission and inorganic polyhedron-afforded orange emission function as a perfect pair of complementary colors affording white light in BAPPIn 1.996 Sb 0.004 Cl 10 . Moreover, the interesting afterglow behavior, together with excitation-dependent emission property, makes BAPPIn 2-2x Sb 2x Cl 10 as highperformance anti-counterfeiting/information storage materials.