DFT study of structure, IR and Raman spectra of the first generation dendron built from cyclotriphosphazene core with terminal carbamate and ester groups

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• 作者：V.L. Furer^a ; ^{furer@kgasu.ru} ; A.E. Vandyukov^b ; S. Fuchs^c ; J.P. Majoral^c ; A.M. Caminade^c ; V.I. Kovalenko^b ; ^{koval@iopc.ru}
• 关键词：Dendrimers ; IR spectra ; Raman spectra ; Normal vibrations ; DFT
• 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
• 出版年：2012
• 期刊代码：99_13861425
• 类别：ch
• 出版时间：June, 2012
• 卷：91
• 期：Complete
• 页码：97-105
• 文件大小：833 K

摘要

The FTIR and FT-Raman spectra of the first generation dendron built from the cyclotriphosphazene core, five arms OC₆H₄CHNN(CH₃)P(S) with ten carbamate terminal groups and one ester function G_v1 have been recorded. The IR and Raman spectra of the zero generation dendron G_v0 and first generation dendrimer G₁ with the same core and terminal groups were also examined. The structural optimization and normal mode analysis were performed for dendron G_v1 on the basis of the density functional theory (DFT). The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that G_v1 has a concave lens structure with planar OC₆H₄CHNN(CH₃)P(S) fragments and slightly non-planar cyclotriphosphazene core. The carbamate groups attached to different arms show significant deviations from a symmetrical arrangement relative to the local planes of repeating units. The experimental IR spectrum of G_v1 dendron was interpreted by means of potential energy distributions. The strong band 1604 cm^鈭? shows marked changes of the optical density in dependence of the carbamate, ester or azomethyne substituents in the aromatic ring. The frequencies of 谓(NH) and 谓(CO) bands in the IR spectra reveal the presence of the different types of H-bonds in the studied dendrimers.