Biswas, Sohag published the artcileAqueous hydroxyl group as the vibrational probe to access the hydrophobicity of amide derivatives, Formula: C2H5NO, the main research area is methylformamide water solvation mol rotation hydrogen bond vibrational spectra.
First principles mol. dynamics (FPMD) simulations of relatively dilute aqueous solutions of N-methylformamide (NMF), N, N-dimethylacetamide (DMA), N-methylacetamide (NMA) were carried out to elucidate the effects of variation of hydrophobicity of amide mols. on structure, dynamics and spectral properties of solvating water mols. A quant. anal. of dangling OH groups of water mols., one of the consequences of hydrophobicity, around the amide mols. was performed to explore the structure of surrounding water mols. We observe that DMA has the most hydrophobic character among the three amide mols.; the lifetime of dangling OH mode of water mols. and the number of such modes are found to be more inside the solvation shell of DMA as compared to NMA and NMF mols. Overall this lifetime is more inside the solvation shell of amides compared to the bulk water mols. for all aqueous solutions of amides. Rotational dynamics calculation suggests significant retardation of OH bonds of water near the amide oxygen atom (O) due to the Ow-Hw···O strong hydrogen bonds. A moderate slowdown of reorientational dynamics is also observed for OH modes that are close to the hydrophobic surface of DMA in its aqueous solution Vibrational d. of states (VDOS) and frequency distribution calculations point out the higher average stretching frequency (∼3600-3850 cm-1) of free OH groups. Hydrogen bond lifetime calculations conceive that DMA, having three Me groups, makes stronger hydrogen bonds through the C=O moiety. Vibrational spectral diffusion of bulk water and solvation shell water mols. were also calculated in combination with wavelet transform and frequency-frequency autocorrelation functions. The C=O group affected OH stretching frequency bands for aqueous solutions of NMF and NMA mols. are more pronounced than that of DMA. However, N-H affected OH frequency bands are less pronounced for NMA and DMA due to the presence of more number of hydrophobic Me groups. Going from NMF to DMA, the OH frequency bands inside the amide solvation shells shift towards the higher value due to the enhancement of hydrophobicity. The vibrational spectral diffusion of OH modes around C=O and N-H (N for DMA) groups, as well as for bulk water mols., is also investigated. Three time scales were found for these calculations for all the cases. The fast time scales in the range ∼50-100 fs are due to the amide-water intact hydrogen bonding, and two slower time scales in the range ∼0.6-3.90 ps and ∼10-20 ps were found. The time scales in the range of ∼0.6 to 3.90 ps can be attributed to carbonyl-water and N-H-water hydrogen bonding, and the very long time scales are due to the escape dynamics water mols. from the solvation shell of C=O and N-H (N for DMA) groups.
Journal of Molecular Liquids published new progress about Bond length. 123-39-7 belongs to class amides-buliding-blocks, name is N-Methylformamide, and the molecular formula is C2H5NO, Formula: C2H5NO.
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics