Molecular structure and IR spectra of [formula omitted] generation phosphorus dendrimer built from cyclophosphazene core with terminal phenoxy groups by DFT calculations

Abstract

The FT-IR (400–4000 cm −1) spectra of G c 1 ′ generation of phosphorus dendrimer, built from cyclotriphosphazene core, six O C 6 H 4 CH N N(CH 3 ) P(S)< arms, with terminal phenoxy groups and its all-D isotope species have been recorded and analyzed. The structural optimization and normal mode analysis were performed for G c 1 ′ molecule on the basis of the density functional theory (DFT). It was found that G c 1 ′ molecule has a concave lens structure. The internal skeleton of G c 1 ′ molecules exists in a single stable conformation with planar O C 6 H 4 CH N N(CH 3 ) P(S)< fragments and slightly non-planar cyclotriphosphazene core, but terminal groups may adopt various rotational isomers around C O bonds. The optimized geometric bond length and bond angles obtained by using DFT show the best agreement with the experimental data. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimers. The heat capacities and enthalpies of the seven generations of dendrimers were estimated based on the calculated values of the statistical sums.