A mixed experimental and DFT study on ethyl 4-[3-(4-dimethylamino-phenyl)-acryloyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate

Antimycobacterial, antimicrobial activity, experimental (FT-IR, FT-Raman, NMR, UV-Vis, DSC) and DFT (transition state, chemical reactivity, NBO, NLO) studies on pyrrole-isonicotinyl hydrazine

As part of a study of pyrrole hydrazone, we have investigated quantum chemical calculations, molecular geometry, relative energy, vibrational properties and antimycobacterial/antimicrobial activity of pyrrole-2-carboxaldehyde isonicotinyl hydrazone (PCINH), by applying the density functional theory (DFT) and Hartree Fock (HF). Good reproduction of experimental values is obtained and with small percentage error in majority of the cases in comparison to theoretical result (DFT). The experimental FT-IR and Raman wavenumbers were compared with the respective theoretical values obtained from DFT calculations and found to agree well. In crystal structure studies the hydrated PCINH (syn-syn conformer) shows different conformation than from anhydrous form (syn-anti conformer). The rotational barrier between syn-syn and syn-anti conformers of PCINH is 12.7kcal/mol in the gas phase. In this work, use of FT-IR, FT-Raman, ¹H NMR, ¹³C NMR and UV-Vis spectroscopies has been made for full characterization of PCINH. A detailed interpretation of the vibrational spectrum was carried out with the aid of normal coordinate analysis using single scaling factor. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. The calculated nature of electronic transitions within molecule found to be π→π*. The electronic descriptors study indicates that PCINH can be used as robust synthon for synthesis of new heterocyclic compounds. The first static hyperpolarizability (β₀) of PCINH is calculated as 33.89×10^-30esu_, (gas phase); 68.79×10^-30 (CHCl₃), esu; 76.76×10^-30esu (CH₂Cl₂), 85.16×10^-30esu (DMSO). The solvent induced effects on the first static hyperpolarizability were studied and found to increase as dielectric constants of the solvents increases. Investigated molecule shows better NLO value than Para nitroaniline (PNA). The compound PCINH shows good antifungal and antibacterial activity against Aspergillus niger and gram-positive bacteria Bacillus subtilis, respectively. The compound also shows good antituberculosis activity against Mycobacterium tuberculosis H37Rv using the microplate alamar blue assay (MABA).

Study on Pyrrole 4-Pyrazoline Derivatives: Experimental and Quantum Chemical Approaches

As part of a study on pyrrole derivatives we report here a combined experimental and quantum chemical study of pyrrole 4-pyrazoline biheterocyclic derivatives. The structure of the synthesised compounds have been studied using experimental IR, UV, 1H and 13C NMR spectroscopic analyses along with density functional theory (DFT) calculations using the B3LYP functional with 6–311+G (d,p) basis set. The global, local reactivity, and thermodynamic parameters support the analysis. All the experimental vibrational bands have been discussed and assigned to normal modes on the basis of our calculations. In addition, the computed 1H and 13C NMR data, obtained by DFT calculations, are found to be in good agreement with the experimental data and serve as valuable tools in identifying the products. The vibrational analysis shows red shifts in vN–H and vC=O stretching vibrations as a result of dimer formation. The theoretical electronic absorption spectra have been calculated by using time dependent-DFT methods. The static first hyperpolarizability (β0) values for the synthesized pyrrole–pyrazoline derivatives 4A–D are calculated as 16.97 × 10–30, 47.64 × 10–30, 65.40 × 10–30, 65.39 × 10–30 esu, respectively, and increase from 4A to 4C as a result of the addition of an –NO2 acceptor in 4B and two –NO2 group acceptors in 4C. However, an additional –Cl group in 4D on the phenyl ring attached to the pyrazoline moiety does not result in a clear change from 4C. The calculated static and dynamic hyperpolarizability results show that the investigated molecules might be used as non-linear optical materials.

Vibrational spectra, electronic absorption, nonlinear optical properties, evaluation of bonding, chemical reactivity and thermodynamic properties of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate molecule by ab initio HF and density functional methods

In this work, detailed vibrational spectral analysis of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate (EHCHEDPC) molecule has been carried out using FT-IR spectroscopy and potential energy distribution (PED). Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method, using 6-31G(d,p) and 6-311+G(d,p) basis sets. The other carried outwork cover: structural, thermodynamic properties, electronic transitions, bonding, multiple interaction, chemical reactivity and hyperpolarizability analysis. The results of the calculation were applied to the simulated spectra of (EHCHEDPC), which show excellent agreement with observed spectra. The vibrational analysis shows red shift in both group, the proton donor (pyrrole N-H) and proton acceptor (C=O of ester) indicating the presence of intermolecular hydrogen bonding. Time dependent density functional theory (TD-DFT) has been used to find electronic excitations and their nature. The results of natural bond orbital (NBOs) analysis show the charges transfer and delocalization in various intra- and intermolecular interactions. The binding energy of intermolecular multiple interactions is calculated to be 12.54 kcal mol(-1) using QTAIM calculation. The electronic descriptors analyses reveal the investigated molecule used as precursor for heterocyclic derivatives synthesis. First hyperpolarizability (β0) has been computed to evaluate non-linear optical (NLO) response.