DFT study and IR spectra of the phosphorus-containing G1 generation dendrimer

The infrared (150-3500 cm−1) spectra have been recorded for tris(4-N′-dichloro(thio)phosphonyl)-(N′-methyl-diazobenzene)monothiophosphate. This compound includes structural parts of elementoorganic dendrimers: a core, repeated units and terminal P-Cl groups. The structural optimization and normal mode analysis are performed for elementoorganic dendrimer on the basis of the ab initio density functional theory. It is found that the dendrimer exists in a single stable conformation with planar -O-C6H4-CHN-N(CH3)-P fragments. All these observations suggest that steric congestion does not disturb the construction of dendrimers even for the highest generations, and that terminal groups are readily available for further reactions. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimer. IR spectroscopy combined with ab initio DFT computation provides unique detailed information about the structure of the technologically relevant materials, which could not be obtained before with any other technique.