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The full width at half maximum (FWHM) of emission spectra, which plays an important role in determining color purity, may not always receive sufficient attention in the design of emissive materials. Particularly for the red emitter, the traditional focus has been on emission maxima, yet broad FWHM values can significantly change the perceived color. For example, the red color (λ em =616-677 nm) emitted from reported Cu(I) complexes is perceived as orange to yellow if FWHM is large. To reduce FWHM, we incorporated a strained and rigid metalaphosphadicyclopenta[a,f]pentalene motif into Cu(I) complexes using trisphosphine ligands featuring a 1H-indene-2,3-diyl backbone (ITP). Herein, we present the synthesis, structure, and emission properties of ITP-MX and the congeners, showcasing genuinely deep-red emission with narrow FWHM values of 56 nm. These materials exhibit color coordinates close to pure red on the CIE diagram, unlike reported broader-emitting counterparts. Measurement of the entropy of disorder of the emissive crystal by a recently reported statistical mechanical method revealed a quantitative correlation between FWHM and the increase in the number of microstates (the degree of freedom) of the crystals and suggested that mechanical stress can increase the entropy of the crystal, which results in emission broadening., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A ligand-controlled regiodivergence in Ni-catalyzed rearrangement of vinylcyclopropanes to 1,4- or 1,5-disubstituted cyclopentenes is reported. The 1,4- or 1,5-disubstituted cyclopentene is selectively obtained depending on the choice of ligands. Detailed kinetic studies and density functional theory calculations on the catalytic cycle revealed that the product selectivity is determined at the reductive elimination step from the six-membered η 1 -allyl intermediate., (© 2023 Wiley-VCH GmbH.)

A rhodium(II)-catalyzed asymmetric cyclooligomerization of bifunctional monomers possessing triazolyl and vinyl groups at 2,3- and 3,4-positions on the thiophene ring is studied. Structurally interesting cyclic dimers in which thienylene and cyclopropylene units are alternately connected are obtained as the major components. The eight-membered rings in the center are non-planar and adopt a tub-shaped conformation. We also observe the phenomenon of racemization caused by a tub-to-tub ring-flipping, the activation energy of which is determined as 108 kJ mol -1 by electronic circular dichroism spectra measurement., (© 2021 Wiley-VCH GmbH.)

An chiral Rh II -catalyzed cyclooligomerization reaction of thiophenes having triazolyl and vinyl substituents at the 2- and 4-positions was studied. Structurally interesting cyclic trimers, having chirality that is ascribed only to the orientation of the 2,4-disubstituted thiophene rings, are obtained. The 2,4-disubstitution of the starting thiophene monomer allows production of each of the enantiomers. The observed electronic circular-dichroism spectra are in accord with those simulated by density-functional theory calculations., (© 2020 Wiley-VCH GmbH.)

Sulfonylation of 1H-tetrazoles with triflic anhydride in the presence of chiral rhodium(II) carboxylate dimers causes denitrogenation to generate α-azo rhodium(II) carbenoid species as new types of donor/acceptor carbenoids, which then readily react with styrenes to afford 3,5-diaryl-2-pyrazolines with a high degree of enantioselectivity., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An asymmetric synthesis of C 3 -symmetric triangular macrocycles is reported. 1-Methylsulfonyl-4-(4-vinylphenyl)-1,2,3-triazole undergoes a rhodium(II)-catalyzed cyclotrimerization to establish an enantiopure C 3 -symmetric triangular macrocycle motif. This method can be applied to the synthesis of an enantiopure hydrocarbon, which owes its chirality to asymmetric distribution of H/D atoms on the benzene rings., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A syn-selective aza-aldol reaction of boron aza-enolates, generated from N-sulfonyl-1,2,3-triazoles and 9-BBN-H, is reported. It provides a sequential one-pot procedure for the stereoselective construction of 1,3-amino alcohols, having contiguous stereocenters, starting from terminal alkynes., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)