DFT study of structure, IR and Raman spectra of the first generation dendrimer built from cyclotriphosphazene core with terminal 4-oxyphenethylamino groups

The FTIR and FT-Raman spectra of the first generation dendrimer G1 built from the cyclotriphosphazene core, six arms OC6H4CHNN(CH3)P(S)< and 12 4-oxyphenethylamino terminal groups OC6H4(CH2)2NH2 G1 have been recorded. The structural optimization and normal mode analysis were performed for dendrimer G1 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 G1 has a concave lens structure with planar OC6H4CHNN(CH3)P(S)< fragments and slightly non-planar cyclotriphosphazene core. The 4-oxyphenethylamino groups attached to different arms show significant deviations from a symmetrical arrangement relative to the local planes of repeating units. The experimental IR spectra of G1 dendron was interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed.