Synthesis, structure characterization and antimicrobial evaluation of 4-(substituted phenylazo)-3,5-diacetamido-1H-pyrazoles

Conformational analysis and quantum descriptors of two new imidazole derivatives by experimental, DFT, AIM, molecular docking studies and adsorption activity on graphene

1-[2-(2-hydroxy-3-methoxy-5-(4-methoxyphenylazo)benzaldeneamino)ethyl]-3-methyl-3H-imidazole (HMY) and 1-[2-(2-hydroxy-3-methoxy-5-(4-methylphenylazo)benzaldene amino)ethyl]-3-methyl-3H-imidazole (HMM) were synthesized and characterized using spectral analysis. Conformational analysis has been achieved using potential energy scan for different rotable bonds for obtaining the lowest energy conformer. Conformer with minimum energy is obtained along the dihedral angle N30-C31-C34-N37. QTAIM analysis gives nature and strength of hydrogen bonding interactions. UV-Vis, electrostatic potential and chemical descriptors are analyzed. Interaction of HMY and HMM with graphene is analyzed in terms of SERS activity. Chemical reactivity descriptors were investigated for graphene-drug systems. NLO activity of parent drugs and its graphene complexes show good activity. The wavenumber downshift of different modes is noted. Title molecules exhibit inhibitory activity against cytochrome C peroxidase. Interactions with graphene sheets are theoretically predicted for the title compounds.

Spectroscopic and quantum chemical investigations of substituent effects on the azo-hydrazone tautomerism and acid-base properties of arylazo pyridone dyes

A series of 5-(4-substituted arylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridone dyes was synthesized and the structure of the dyes was confirmed by UV-Vis, FT-IR, (1)H NMR and (13)C NMR spectroscopic techniques. The azo-hydrazone tautomeric equilibrium was found to depend on the substituents as well as on the acidity and basicity of the media. Ionization constant, pKa, of the dyes was determined by UV-Vis spectroscopy and correlated with the Hammett substituent constants, σp and σI. The interpretation of the effect of different substituent in phenyl ring of arylazo pyridone dyes on their spectroscopic and structural properties was based on quantum chemical calculations performed by the density functional theory (DFT/M06-2X) method. The DFT calculations confirmed the existence of two forms in water solution: hydrazone form in acidic and neutral media and anionic form in basic media. The different contribution of azo and hydrazone canonical forms of anionic form is observed for dyes with electron-donating and dyes with electron-withdrawing groups. The dependence of absorption spectra and determined pKa values to the substituent type seems to be mostly due to azo/hydrazone canonical structure ratio in their anionic form.