Methylammonium lead halide perovskite-based solar cells have demonstrated efficiencies as high as 24.2 %, highlighting their potential as inexpensive and solution-processable alternatives to silicon solar cell technologies.P oor stability towards moisture,u ltraviolet irradiation, heat, and ab ias voltage of the perovskite layer and its various device interfaces limits the commercial feasibility of this material for outdoor applications.Herein, we investigate the role of hydrogen bonding interactions induced when metal halide perovskite crystals are crosslinked with alkyl or p-conjugated boronic acid small molecules (-B(OH) 2 ). The crosslinked perovskite crystals are investigated under continuous light irradiation and moisture exposure.These studies demonstrate that the origin of the interaction between the alkylorp-conjugated crosslinking molecules is due to hydrogen bonding between the -B(OH) 2 terminal group of the crosslinker and the Io ft he [PbI 6 ] 4À octahedra of the perovskite layer.A lso,t his interaction influences the stability of the perovskite layer towards moisture and ultraviolet light irradiation. Morphology and structural analyses,aswell as IR studies as afunction of aging under both dark and light conditions showthat p-conjugated boronic acid molecules are more effective crosslinkers of the perovskite crystals than their alkylc ounterparts thus imparting better stability towards light and moisture degradation.

Ribosomally synthesized post-translationally modified peptides (RiPPs) are ubiquitous and represent a structurally diverse class of natural products. The ribosomally encoded precursor polypeptides are often extensively modified posttranslationally by enzymes that are encoded by coclustered genes. Radical S-adenosyl-L-methionine (SAM) enzymes catalyze numerous chemically challenging transformations. In RiPP biosynthetic pathways, these transformations include the formation of C−H, C−C, C−S, and C−O linkages.In this paper, we show that the Geobacter lovleyi sbtM gene encodes a radical SAM protein, SbtM, which catalyzes the cyclization of a Cys/SeCys residue in a minimal peptide substrate. Biochemical studies of this transformation support a mechanism involving H-atom abstraction at the C-3 of the substrate Cys to initiate the chemistry. Several possible cyclization products were considered. The collective biochemical, spectroscopic, mass spectral, and computational observations point to a thiooxazole as the product of the SbtM-catalyzed modification. To our knowledge, this is the first example of a radical SAM enzyme that catalyzes a transformation involving a SeCys-containing peptide and represents a new paradigm for formation of oxazole-containing RiPP natural products.

Methylammonium lead halide perovskite‐based solar cells have demonstrated efficiencies as high as 24.2 %, highlighting their potential as inexpensive and solution‐processable alternatives to silicon solar cell technologies. Poor stability towards moisture, ultraviolet irradiation, heat, and a bias voltage of the perovskite layer and its various device interfaces limits the commercial feasibility of this material for outdoor applications. Herein, we investigate the role of hydrogen bonding interactions induced when metal halide perovskite crystals are crosslinked with alkyl or π‐conjugated boronic acid small molecules (‐B(OH)2). The crosslinked perovskite crystals are investigated under continuous light irradiation and moisture exposure. These studies demonstrate that the origin of the interaction between the alkyl or π‐conjugated crosslinking molecules is due to hydrogen bonding between the ‐B(OH)2 terminal group of the crosslinker and the I of the [PbI6]4− octahedra of the perovskite layer. Also, this interaction influences the stability of the perovskite layer towards moisture and ultraviolet light irradiation. Morphology and structural analyses, as well as IR studies as a function of aging under both dark and light conditions show that π‐conjugated boronic acid molecules are more effective crosslinkers of the perovskite crystals than their alkyl counterparts thus imparting better stability towards light and moisture degradation.