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

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 Gv1 have been recorded. The IR and Raman spectra of the zero generation dendron Gv0 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 Gv1 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 Gv1 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 Gv1 dendron was interpreted by means of potential energy distributions. The strong band 1604 cm−1 shows marked changes of the optical density in dependence of the carbamate, ester or azomethyne substituents in the aromatic ring. The frequencies of ν(NH) and ν(CO) bands in the IR spectra reveal the presence of the different types of H-bonds in the studied dendrimers.

Graphical abstractStructure of dendrimer molecules Gv0 (1), Gv1 (2), and G1 (3). Experimental IR and Raman spectra of Gv0 (1, 2), Gv1 (3, 4) and G1 (5, 6).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The FTIR and FT Raman spectra of the dendrimers built of cyclotriphosphazene core with terminal carbamate groups were studied. ► The structural optimization and normal mode analysis were performed for dendron. ► Dendron molecule has a concave lens structure. ► FTIR spectra reveal the presence of the different types of H-bonds in the dendrimers.