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A theoretical model is proposed that allows the estimation of the quantum yield of phosphorescence of dye molecules in the vicinity of plasmonic nanoparticles. For this purpose, the rate constants of the radiative and nonradiative intramolecular transitions for rhodamine 123 (Rh123) and brominated rhodamine (Rh123-2Br) dyes have been calculated. The plasmon effect of Ag nanoparticles on various types of luminescence processes has been studied both theoretically and experimentally. We show that in the presence of a plasmonic nanoparticle, the efficiency of the immediate and delayed fluorescence increases significantly. The phosphorescence rate of the rhodamine dyes also increases near plasmonic nanoparticles. The long-lived luminescence , delayed fluorescence and phosphorescence is more enhanced for Rh123-2Br than for Rh123. The largest phosphorescence quantum yield is obtained when the dye molecule is at a distance of 4-6 nm from the nanoparticle surface. Our results can be used in the design of plasmon-enhancing nanostructures for light-emitting media, organic light-emitting diodes, photovoltaic devices, and catalysts for activation of molecular oxygen.
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http://dx.doi.org/10.1039/d4cp01281j | DOI Listing |
Luminescence
September 2025
Beijing Key Laboratory of Energy Conversion and Storage Materials, Beijing, China.
A novel aggregation-induced emission (AIE) system with superior performance was successfully developed through local chemical modification from thiophene to thiophene sulfone. This approach, leveraging easily accessible tetraphenylthiophene precursors, dramatically enhances the photophysical properties in a simple oxidation step. Notably, the representative 2,3,4,5-tetraphenylthiophene sulfone (3c) demonstrates remarkable solid-state emission characteristics with a fluorescence quantum yield of 72% and an AIE factor of 240, substantially outperforming its thiophene analog.
View Article and Find Full Text PDFChemistry
September 2025
Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
The coordination chemistry of the planar, doubly π-extended bipyridine analog, 6,6',7,7'-biphenanthridine (p-biphe), is presented. The phenanthridine units in p-biphe are fused together at the 6- and 7- positions, and the resulting rigid ligand is compared with the more flexible parent "biphe" fused only at the 6-positions. p-Biphe is intensely fluorescent in solution with a much higher quantum yield, but, unlike biphe, at 77 K the fluorescence is not accompanied by any significant phosphorescence.
View Article and Find Full Text PDFOrg Lett
September 2025
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
Helicenes are circularly polarized luminescence (CPL)-active but suffer from a fundamental tradeoff between fluorescence quantum yield (Φ) and luminescence dissymmetry factor (||). Herein, we present a strategy combining lateral π-extension and helical elongation in carbazole-embedded helicenes to address this challenge. Specifically, π-extended diaza[7]helicene () and diaza[9]helicene () were synthesized and characterized, revealing nearly a 2-fold increase in Φ and a 6-fold enhancement in || from to .
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States.
Ionization of alkanes to form radical cations activates their otherwise unreactive C-H bonds, facilitating important chemical processes such as hydrocarbon cracking. This work investigates the radical cation dissociation dynamics of hexane (CH) structural isomers by using femtosecond time-resolved mass spectrometry and quantum chemical calculations. All five isomers exhibit competition between the yields of fragment ions arising from direct C-C bond cleavage or dissociative rearrangement with hydrogen migration on dynamical time scales of ∼50-300 fs, suggesting that hydrogen migration in the metastable cations operates on such short time scales.
View Article and Find Full Text PDFACS Appl Mater Interfaces
September 2025
School of Chemistry & Materials Engineering, Fuyang Normal University, Fuyang 236037, China.
Halide perovskite quantum dots (QDs) have demonstrated outstanding performance in light-emitting applications. However, the performance of blue perovskite QDs lags far behind that of their red and green counterparts, especially those with color coordinates approaching (0.131, 0.
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