Effect of the phosphonomethylene moiety on the structural, vibrational, energetic, thermodynamic and optical proprieties of ((Phenylcarbamoylmethyl-phosphonomethyl-amino)-methyl)-phosphonic acid: DFT investigation

Abstract An efficient method has been developed for the synthesis of ((Phenylcarbamoylmethyl-phosphonomethyl-amino)-methyl)-phosphonic acid (PCMPA) under solvent free conditions using microwave irradiation. PCMPA was obtained in high yield under mild conditions by reaction of the 2-Amino-N-phenyl-acetamide (APA) with formaldehyde and phosphorous acid under microwave irradiation. Comparison between conventional and microwave-assisted synthesis was done by comparing total reaction time and percentage yield. The PCMPA was characterized by FTIR, Elemental analysis, 1H, 13C, 31P NMR. Then, this molecule has been studied from a theoretical point of view in order to know the effects of the methylenephosphonic moiety, (–CH2-P(O)(OH)2), on their electronic, vibrational, thermodynamic and optical properties by means of Density Functional Theory (DFT) calculations, using the Gaussian09 program. The stable structure was optimized by using the hybrid B3LYP/6-31G method. In order to make comparative study between the started (APA) and obtained (PCMPA) molecules, different proprieties for this molecule were analyzed by means of the HOMO-LUMO proprieties, atomic. The global and local reactivity descriptors of the two molecules are calculated and discussed. Molecular electrostatic potential (MEP), Mulliken atomic charges and dipole moment were also performed by the DFT method.