Search

Developing luminescent radicals with tunable emission is a challenging task due to the limitation of alternative skeletons. Herein, a series of carbene‐triphenylamine hybrids were prepared by the direct C2‐arylation of N‐heterocyclic carbenes with 4‐bromo‐N,N‐bis(4‐methoxyphenyl)aniline. These hybrids showed multiple redox‐active properties and could be converted to carbon‐centered luminescent radicals with blue‐to‐cyan emissions (λmax: 436–486 nm) or nitrogen‐centered luminescent radicals with orange emissions (λmax: 590–623 nm) through chemical reduction or oxidation, respectively. The radical species were characterized by electron paramagnetic resonance spectroscopy, ultraviolet‐visible spectroscopy, and single‐crystal X‐ray diffractometry analysis. Notably, the corresponding nitrogen‐centered radicals exhibited good stability in atmospheric air, and their thermal decomposition temperatures were determined to be above 200 °C. In addition, spectral and theoretical calculations indicate that all radicals exhibit anti‐Kasha emissions. [ABSTRACT FROM AUTHOR]

• Butyl 1‑hydroxy-2-naphthoate have been obtained. • The crystal structures were characterized by single crystal X–ray diffraction. • The melting point and the emission peaks can be modulated by the substitute. • The luminescent maxima are relative to the close contacts of C···C. To explore the new luminescent materials, two compounds based on hydroxynaphthene group have been prepared. Compound 2 was synthesized through the esterification of compound 1 in the acid conditions. They have been characterized by IR, EA and single crystal X-ray diffraction. Single X-ray diffraction reveals that compounds 1 and 2 belong to the P 2 1 / n and P 2 1 / c , respectively. It is obviously observed that there exist C/O H⋯O and the packing interactions among the aromatic rings. The solid-state fluorescent spectra reveal that the maxima of compounds 1 and 2 are 448 and 415 nm, respectively. The luminescent emission maxima are in accordance with the stacking interactions of compounds. The melting points of both compounds can be found to be 190–192 °C and 78–80 °C, respectively. The Hirshfeld surface analysis further reveals that the close contacts C⋯C are responsible for the luminescent peaks, and the O⋯H/H⋯O close bonds can account for the melting points of both compounds. Two compounds based on hydroxynaphthene group have been prepared, which have been characterized by IR, EA and single crystal X-ray diffraction. The fluorescence maxima of compounds 1 and 2 are 448 and 415 nm, respectively. The melting point of both compounds 190–191 °C and 78–80 °C, respectively. The Hirshfeld surface analysis further confirm that the close contacts C⋯C are responsible for the luminescent peaks, and the O⋯H/H⋯O close bonds can account for the melting points of both compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A novel one-step preparation method for core-shell CdS/SiO2 nanoparticles was proposed using 3-mercaptopropyl-trimethoxysilane (MPS) as stabilizing agent in MeOH, in which CdCl2·2.5H2O and Na2S·9H2O were used as the source of Cd and S, respectively. And the photostability of the nanoparticles was further investigated. The morphology and structure of products was characterized by scanning probe microscope and FT-IR spectra, respectively. Furthermore, the influences of Zn and Cu doped in the products, individually, on the fluorescence property were discussed. The results showed that the products were ball-shaped and silica-coated with a uniform size, the spectra of Zn-doped was blue shifted, however, the spectra of Cu-doped was red shifted, the core-shell CdS/SiO2 nanoparticles was more steady compared with thioglycolic acid-capped CdS nanoparticles. [Copyright &y& Elsevier]