J Phys Chem C Nanomater Interfaces
April 2024
A series of steady-state and time-resolved spectroscopies were performed on a set of eight carbene-metal-amide (cMa) complexes, where M = Cu and Au, that have been used as photosensitizers for photosensitized electrocatalytic reactions. Using ps-to-ns and ns-to-ms transient absorption spectroscopies (psTA and nsTA, respectively), the excited-state kinetics from light absorption, intersystem crossing (ISC), and eventually intermolecular charge transfer were thoroughly characterized. Using time-correlated single photon counting (TCSPC) and psTA with a thermally activated delayed fluorescence (TADF) model, the variation in intersystem crossing (ISC), ( → ) rates (∼3-120 × 10 s), and Δ values (73-115 meV) for these compounds were fully characterized, reflecting systematic changes to the carbene, carbazole, and metal.
View Article and Find Full Text PDFThe photoionization dynamics of indole, the ultraviolet-B chromophore of tryptophan, were explored in water and ethanol using ultrafast transient absorption spectroscopy with 292, 268, and 200 nm excitation. By studying the femtosecond-to-nanosecond dynamics of indole in two different solvents, a new photophysical model has been generated that explains many previously unsolved facets of indole's complex solution phase photochemistry. Photoionization is only an active pathway for indole in aqueous solution, leading to a reduction in the fluorescence quantum yield in water-rich environments, which is frequently used in biophysical experiments as a key signature of the protein-folded state.
View Article and Find Full Text PDFThe photoluminescence properties of organic-inorganic pyridinium lead bromide [(pyH)PbBr] and iodide [(pyH)PbI] compounds were investigated as a function of temperature. The inorganic substructure consists of face-sharing chains of PbX octahedra. Diffuse reflectance spectra of the compounds show low energy absorption features consistent with charge transfer transitions from the PbX chains to the pyridinium cations.
View Article and Find Full Text PDFHexafluorobenzene and many of its derivatives exhibit a chemoselective photochemical isomerization, resulting in highly strained, Dewar-type bicyclohexenes. While the changes in absorption and emission associated with benzene hexafluorination have been attributed to the so-called "perfluoro effect", the resulting electronic structure and photochemical reactivity of hexafluorobenzene is still unclear. We now use a combination of ultrafast time-resolved spectroscopy, multiconfigurational computations, and non-adiabatic dynamics simulations to develop a holistic description of the absorption, emission, and photochemical dynamics of the 4π-electrocyclic ring-closing of hexafluorobenzene and the fluorination effect along the reaction coordinate.
View Article and Find Full Text PDFFecal pollution of surface waters presents a global human health threat. New molecular indicators of fecal pollution have been developed to address shortcomings of traditional culturable fecal indicators. However, there is still little information on their fate and transport in the environment.
View Article and Find Full Text PDFWe describe three new, allopatric species of springsnails (genus Pyrgulopsis) from western California (Pyrgulopsis lindae, Pyrgulopsis ojaiensis, Pyrgulopsis torrida) that were previously identified as Pyrgulopsis stearnsiana. The new species are differentiated from Pyrgulopsis stearnsiana and each other both by mtCOI sequences (3.9-9.
View Article and Find Full Text PDFLongitudinal and transverse relaxation times of multicomponent nanoparticle (NP) chains are investigated for their potential use as multifunctional imaging agents in magnetic resonance imaging (MRI). Gold NPs (ca. 5 nm) are arranged linearly along double-stranded DNA, creating gold NP chains.
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