Theoretical explorations on the molecular structure and IR frequencies of 3-phenyl-1-tosyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine in view of experimental results

Explorations on the electronic structure and spectroscopic IR assignments of 5-methyl-2-(2-oxopropyl)-pyrazolo[5,1-b]quinazolin-9(3H)-one molecule

In the present work, theoretical investigations on a quinazoline derivate, 5-methyl-2-(2-oxopropyl)pyrazolo[5,1-b]quinazolin-9(3H)-one, have been carried out through quantum mechanical density functional B3LYP/6-31G(d,p) method to explore its electronic structure and vibrational features. The normal modes analysis was executed to predict the contributions of different vibrational modes at the required frequencies in the infrared region and the spectral peaks have been assigned accordingly. Besides, certain electronic properties that are associated with chemical reactivity like, HOMO-LUMO energy gap, molecular electrostatic potential, Mulliken partial charges, etc have been estimated and discussed herein. It has been established that the molecule is chemically reactive and may be used in designing drugs as COX-2/5-LOX inhibitor.

Electronic structure and vibrational assignments of 2,5-bis[4-(n-cyclobutyldiaminomethyl)phenyl]furan

Several DNA minor groove binders exhibit numerous therapeutic applications. The crystal structure demonstrating 2,5-bis[4-(N-cyclobutyldiaminomethyl)phenyl]furan binding within the minor groove of DNA has been reported by Simpson et al (2000 Bioorg. Med. Chem. Lett. 10 2593). In the present study, computational investigations on the title compound have been carried out which comprise geometry optimization, HOMO-LUMO, dipole moment, Molecular electrostatic potential(MEP), thermodynamic parameters, and IR assignments using the B3LYP/6-31G** method. The true minimum was long-established by the nonappearance of negative wavenumbers. A comparison of optimized parameters with crystallographic structure demonstrates slight variations in the conformations of the cyclobutyl groups. A small HOMO-LUMO gap indicates the high chemical reactivity and inter molecule charge transferability. The vibrational spectra of the molecule calculated in 400–3800 cm−1 region, reproduce reliable IR assignments. Bearing in mind the high pharmaceutical significance of minor groove binders and a variety of flexible options accessible for lead optimization will be a bountiful ground for the development of drugs targeting minor grooves.

Speculative analysis on the electronic structure, IR assignments and molecular docking of N-{4-[(4-amino-3-phenyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)sulfonyl]phenyl}acetamide, an anti-amoebic agent

An exhaustive quantum mechanical calculations on a pharmaceutically critical molecule N-{4-[(4-amino-3-phenyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)sulfonyl]phenyl}acetamide have been investigated through the B3LYP/6-31G∗∗ Density Functional and HF/6-31G∗∗ Wave Function techniques. Physicochemical parameters along with the advanced electronic structure parameters like; MEP (molecular electrostatic potentials) and highest occupied & lowest unoccupied molecular orbitals (HOMO-LUMO) analysis have additionally been scanned over both methods. The computed HOMO-LUMO energy demonstrates that charge exchange takes place inside the molecule. The estimated small HOMO-LUMO energy gap, through both methods, indicates that the molecule is chemically reactive. Further, the IR vibrational spectra of the molecule have been assigned in the region 400-4000 cm⁻¹ through the DFT technique. The anticipated vibrational assignments have been compared with the experimental values accounted for in the literature. To comprehend the mode of binding, docking investigations of the molecule alongwith the co-crystallized metronidazole (MNZ) molecule were accomplished with O-acetyl-serine-sulfhydrylase (OASS) enzyme using GLIDE-SP and GLIDE-XP modules. Docking simulations and reported biological activities (IC50) demonstrate that the title molecule may act as a lead molecule for constraining the progression of Entamoeba histolytica illness.