Formation of the unstable cis-formic acid in solid argon matrix is induced by direct excitation of the 6<--0 transition of the nu(OH) vibration of the trans-formic acid. The experiment utilizes strongly focused laser beam that produces relatively high isomerization rate despite the low cross section of the absorption. Raman spectroscopy in a backscattering geometry is used for detection of the reactants and the products. This experimental arrangement allow us to use the same laser source for simultaneous pumping and Raman excitation, and it also guarantees that the excited and probed volumes overlap. The presented method has a high potential for solid state investigations of chemical reactions on the ground electronic state.
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http://dx.doi.org/10.1063/1.2955985 | DOI Listing |
Phys Chem Chem Phys
January 2025
Institute of Chemistry, Department of Fundamental Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748 - Butantã, São Paulo, 05508-900, Brazil.
The conformational isomerization of nitrous acid (HONO) promoted by excitation of the or stretching normal coordinates is the first observed case of an infrared-induced photochemical reaction. The energy captured by the excited normal modes is redistributed into a highly excited vibrational level of the torsion normal coordinate, which is the isomerization reaction coordinate. Herein, we present simple numerical methods to qualitatively investigate the coupling between the normal coordinates and the possible gateways for vibrational energy redistribution leading to the isomerization process.
View Article and Find Full Text PDFJ Org Chem
January 2025
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
The copolymerization of ethylene with polar monomers presents a significant challenge. While palladium catalysts have shown promise, nickel catalysts are more economical but suffer from poor activity. Previous studies suggest that the isomerization step involved in the nickel-catalyzed polymerization may influence the catalyst activities.
View Article and Find Full Text PDFSoft Matter
January 2025
Department of Physics, Central University of Karnataka, Kadaganchi, Kalaburagi, Karnataka-585367, India.
The isomerization kinetics of a liquid crystalline azobenzene dimer, comprising cyanoazobenzene and naphthalene (NAZ6), were investigated at the air-water interface. The Langmuir monolayers of NAZ6 in both its and states were analyzed using surface manometry techniques. The results revealed that NAZ6 molecules in the -state displayed the coexistence of a disordered liquid-expanded phase and an ordered liquid-condensed phase, whereas no such phase transition was observed in the -state.
View Article and Find Full Text PDFMolecules
January 2025
Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Effectively regulating the rotary motions of molecular rotors through external stimuli poses a tremendous challenge. Herein, a new type of molecular rotor based on azobenzene-strapped mixed (phthalocyaninato)(porphyrinato) rare earth triple-decker complex is reported. Electronic absorption and H NMR spectra manifested the reversible isomerization of the rotor between the configuration and the configuration.
View Article and Find Full Text PDFMolecules
January 2025
Department of Organic Chemistry, University of Valencia, E-46100 Burjassot, Spain.
The natural products combretastatins A-1 and A-4 are potent antimitotic and vascular-disrupting agents through their binding at the colchicine site in tubulin. However, these compounds suffer from a low water solubility and a tendency to isomerize to the inactive stilbenes. In this study, we have prepared a series of 18 -restricted triazole analogues of combretastatin A-4 (CA-4), maintaining, in all cases, the 3,4,5-trimethoxy phenyl ring A, with the aim of investigating the substitution pattern on the B-ring in a systematic way.
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