Resonance Raman spectroscopic and density functional theoretical study on microsolvated 2-Thiocytosine clusters with
Yaoliang Deng1, Xin Liu1, Yanying Zhao1
1Department of Chemistry and Engineering Research Center for Eco-dyeing and Finishing of Textiles, Key Laboratory of Advanced Textiles Materials and Manufacture Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Abstract:
Microsolvation effects on the excited state deactivation dynamics of 2-thiocytosine (2tC) were studied in hydrogen-bonded 2tC clusters with protic solvents using resonance Raman, FT-IR, FT-Raman, UV-vis spectroscopy combining with density functional theoretical calculation. Two protic solvents, water (H2O) and methanol (MeOH), and one aprotic solvent, acetonitrile (MeCN), were used to investigate the 2tC(H2O)1-5, 2tC(MeOH)1-5, and 2tC(MeCN)1-3 microsolvated clusters. In CH3OH and H2O solvents, most of the Raman shifts were due to the vibration modes of 2tC(solvent)n (solvent = H2O, CH3OH; n = 1-4) clusters via intermolecular NH⋯O hydrogen bonds (HB). The intermolecular >NH⋯O hydrogen bond interactions, which are the key constituents of stable thione structure of 2tC, revealed the spectra difference of 2tC in CH3CN, CH3OH and H2O. With the aid of electronic structural and vibration frequency calculations, the observed Raman spectra were assigned to the low energy isomers of 2tC(solvent)2 (solvent = H2O, CH3OH) clusters in water and methanol and 2tC(CH3CN) in acetonitrile solvents. 2tC(solvent)2 clusters in water and methanol may prohibit or promote excited state proton transfer reaction from sulfur atom to neighbor nitrogen atom due to the hydrogen bonding chain between 2tC and protic solvent molecules. Our experimental and theoretical studies confirmed that the hydrogen bond sites were located on the specified functional group SCNH of 2tC with solvent molecules.
Related Concept Videos
Chemical Shift: Internal References and Solvent Effects
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...
Stereoisomerism of Cyclic Compounds
Chemical and Solubility Equilibria


