Search results for "PHOTOCHEMISTRY"
showing 10 items of 2034 documents
Effects of substitutions on cyclopentadienyl rings in complexes with molybdenum-mercury bonds. 95Mo and 199Hg NMR studies
1995
NMR data for 95Mo and 199Hg nuclei have been obtained for new di- and trimetallic complexes Cp′(CO)3MoHgX containing molybdenum-mercury bonds and bulky and/or potentially bifunctional substituted cyclopentadienyl ligands; Cp′=C5HMe2Ph2, C5Me4Bz, C5Bz5, C5H4PPh2 and C5Me4PPh2 (Bz=CH2C6H5; Me =CH3; Ph=C6H5); X=Cp′(CO)3Mo, Cl, Br, 1, SCN. They are discussed within the context of our earlier results reported for analogous complexes with the cyclopentadienyl ligands bearing methyl groups. With the exception of phenyl substituted rings, a rather narrow range of 95Mo chemical shifts is found for the compounds with the same number of different substituents on cyclopentadienyl ligands. An outstandin…
Fluorination of Cu(001) Surface by C60F48 Molecule Adsorption
2019
Copper surface functionalization by defluorination of C60F48 molecules with submonolayer and monolayer coverages on the Cu(001) crystal is studied by X-ray photoelectron spectroscopy. At room tempe...
Short hydrogen bonds enhance nonaromatic protein-related fluorescence
2021
Significance Intrinsic fluorescence of nonaromatic amino acids is a puzzling phenomenon with an enormous potential in biophotonic applications. The physical origins of this effect, however, remain elusive. Herein, we demonstrate how specific hydrogen bond networks can modulate fluorescence. We highlight the key role played by short hydrogen bonds, present in the protein structure, on the ensuing fluorescence. We provide detailed experimental and molecular evidence to explain these unusual nonaromatic optical properties. Our findings should benefit the design of novel optically active biomaterials for applications in biosensing and imaging.
FI-chemiluminometric study of thiazides by on-line photochemical reaction
2004
The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550 cm long x 0.8 mm ID piece of PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and be…
Assessment of the Potential Energy Hypersurfaces in Thymine within Multiconfigurational Theory: CASSCF vs. CASPT2
2016
The present study provides new insights into the topography of the potential energy hypersurfaces (PEHs) of the thymine nucleobase in order to rationalize its main ultrafast photochemical decay paths by employing two methodologies based on the complete active space self-consistent field (CASSCF) and the complete active space second-order perturbation theory (CASPT2) methods: (i) CASSCF optimized structures and energies corrected with the CASPT2 method at the CASSCF geometries and (ii) CASPT2 optimized geometries and energies. A direct comparison between these strategies is drawn, yielding qualitatively similar results within a static framework. A number of analyses are performed to assess t…
Evaluation of gliadins-diglycosylated cyanidins interaction from litchi pericarp through ultraviolet and fluorescence measurements
2017
The low stability of anthocyanins limits their use in industry, which can be surpassed by gliadins linkage. This work was aimed to study the anthocyanins-gliadins bonding properties. HPLC-DAD-ESI-M...
Correction: Phenothiazine-based dyes for efficient dye-sensitized solar cells
2016
Correction for ‘Phenothiazine-based dyes for efficient dye-sensitized solar cells’ by Zu-Sheng Huang et al., J. Mater. Chem. C, 2016, 4, 2404–2426.
Electrochromic absorbance changes in the chlorophyll-c-containing alga Pleurochloris meiringensis (Xanthophyceae)
1994
Flash-induced absorbance changes were measured in the Chl-c-containing alga Pleurochloris meiringensis (Xanthophyceae) between 430 and 570 nm. In addition to the bands originating from redox changes of cytochromes, three major positive and tow negative transient bands were observed both 0.7 and 20 ms after the exciting flash. These transient bands peaking at 520, 480 and 451 nm and 497 and 465 nm, respectively, could be assigned to an almost homogeneous shift of the absorbance bands with maxima at 506, 473 and 444 nm, respectively. The shape of the absorbance transients elicited from PS I or PS II was identical, and the two photosystems contributed nearly equally to the absorbance changes. …
Study of Mechanisms of Light-Induced Dissociation of Ru(dcbpy)(CO)2I2 in Solution down to 20 fs Time Resolution
2006
Mechanisms of the light-induced ligand exchange reaction of (trans-I) Ru(dcbpy)(CO)2I2 (dcbpy = 4,4'-dicarboxylic acid-2,2'-bipyridine) in ethanol have been studied by transient absorption spectroscopy. Ultraviolet 20 fs excitation pulses centered at 325 nm were used to populate a vibrationally hot excited pi bipyridyl state of the reactant that quickly relaxes to a dissociative Ru-I state resulting in the release of one of the carbonyl groups. Quantum yield measurements have indicated that about 40% of the initially exited reactant molecules form the final photoproduct. A 62 fs rise component in the transient absorption (TA) signal was observed at all probe wavelengths in the visible regio…
ChemInform Abstract: Methylium Ions with OPV Chains - New NIR Dyes.
2010
Carbinols, which contain three OPV chains, were generated in convergent syntheses. The extension of the conjugation leads to a bathochromic effect that shifts the absorption from the UV into the visible region. The carbinol series has a convergence limit of the absorption at λmax = 415 nm. The corresponding carbenium ions exhibit a stronger bathochromic shift with the increasing number of repeating units in each chain. Thus, NIR dyes were obtained which show a convergence limit at λmax = 879 nm. The charge distribution in the ground state of the carbocations is discussed on the basis of 13C NMR spectroscopic data.