12 research outputs found
Conformation-Dependent Photophysics of Bifunctional Hydrogen Bond Donor/Acceptor Molecules
No full textA series of heteroazaaromatic molecules possessing both a hydrogen bond donor and acceptor groups linked by a single bond was studied using electronic absorption and fluorescence techniques, combined with quantum--chemical calculations. Fluorescence lifetimes and quantum yields strongly depend on the solvent. Double exponential decays are observed in alcohols. This was interpreted in terms of alcohol-induced syn-anti rotamerization in the ground electronic state. The driving force for the conformational change is provided by two factors: (a) solvent polarity increase; (b) the formation of two separate hydrogen bonds in the anti species. In the syn structure, formation of cyclic hydrogen bonds leads to rapid depopulation of the lowest excited singlet state via two competing mechanisms: proton transfer and enhanced internal conversion. The experimental results are rationalized by calculations which include specific and nonspecific solvent effects
Conformation-Dependent Photophysics of Bifunctional Hydrogen Bond Donor/Acceptor Molecules
No full textA series of heteroazaaromatic molecules possessing both a hydrogen bond donor and acceptor groups linked by a single bond was studied using electronic absorption and fluorescence techniques, combined with quantum--chemical calculations. Fluorescence lifetimes and quantum yields strongly depend on the solvent. Double exponential decays are observed in alcohols. This was interpreted in terms of alcohol-induced syn-anti rotamerization in the ground electronic state. The driving force for the conformational change is provided by two factors: (a) solvent polarity increase; (b) the formation of two separate hydrogen bonds in the anti species. In the syn structure, formation of cyclic hydrogen bonds leads to rapid depopulation of the lowest excited singlet state via two competing mechanisms: proton transfer and enhanced internal conversion. The experimental results are rationalized by calculations which include specific and nonspecific solvent effects
Effect of Sol Formation Conditions on the Structure and Properties of Anhydride-Cured Epoxy-Siloxane Composites
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Five Different Fluxional Processes in Polyfluorophenyl Palladium(II) Complexes with 2,4,6-Tris(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine. The Driving Effect of the Solvent
No full textEffects of Trifluoromethyl Substituents in a Tris(pyrazolyl)borate Ligand: A Structural and Spectroscopic Study of Analogous Platinum(IV) Trimethyl Complexes
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Zn(II)- or Rh(I)-Catalyzed Rearrangement of Silylated [1,1′-Bi(cyclopropan)]-2′-en-1-ols
No full textThe Influence of Presentation Format of Story on Narrative Production in Chinese Children Learning English-as-a-Second-Language: A Comparison Between Graphic Novel, Illustration Book and Text
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