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Highlights: [•] FT-IR spectrum of the title compound was recorded and compared with the theoretical results. [•] The theoretical calculations were made using DFT/B3LYP/6-31G(d,p) method. [•] By using TD-DFT/6-31G method, electronic spectra for title compound have been predicted. [•] Chemical reactivity has been explained with the aid of global and local electronic descriptors. [•] The computed value of first hyperpolarizability have been also predicted. [ABSTRACT FROM AUTHOR]

Abstract: A detailed spectroscopic analyses of a newly synthesized ethyl 2-cyano-3-[5-(hydrazinooxalyl–hydrazonomethyl)-1H-pyrrol-2-yl]-acrylate (3) have been carried out using 1H and 13C NMR, UV–Visible, FT-IR and mass spectroscopic techniques. All the quantum chemical calculations have been carried out using DFT level of theory, B3LYP functional and 6-31G(d,p) as basis set. The 1H and 13C NMR chemical shifts are calculated using gauge including atomic orbitals (GIAOs) approach in DMSO-d 6. TD-DFT is used to calculate the energy (E), oscillatory strength (f) and wavelength absorption maxima (λ max) of various electronic transitions and their nature within molecule. Natural bond orbital (NBO) analysis is carried out to investigate the various intra and intermolecular interactions in dimer and their corresponding second order stabilization energy (E (2)). A combined theoretical and experimental vibrational analysis confirms the existence of dimer and the binding energy of dimer is calculated as 9.21kcal/mol using DFT calculations. To determine the energy and nature of different interactions topological parameters at bond critical points (BCPs) have been analyzed by Bader’s ‘atoms in molecules’ (AIMs) theory in detail. Electrophilic charge transfer (ECT) is calculated to investigate the relative electrophilic or nucleophilic behavior of reactant molecules involved in chemical reaction. Global electrophilicity index (ω =5.5836eV) shows that title molecule (3) is a strong electrophile. The local reactivity descriptors such as Fukui functions , local softness and electrophilicity indices analyses are performed to determine the reactive sites within molecule. [Copyright &y& Elsevier]

Abstract: A new ethyl-4-{[(2,4-dinitrophenyl)-hydrazono]-ethyl}-3,5-dimethyl-1H-pyrrole-2-carboxylate (EDPHEDPC) has been synthesized and characterized by FT-IR, 1H NMR, UV–vis, DART-Mass spectroscopy and elemental analysis. Quantum chemical calculations have been performed by DFT level of theory using B3LYP functional and 6-31G(d,p) as basis set. The 1H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO as solvent. The time dependent density functional theory (TD-DFT) is used to find the various electronic transitions and their nature within molecule. A combined theoretical and experimental wavenumber analysis confirms the existence of dimer. Topological parameters such as electron density (ρ BCP), Laplacian of electron density (▿2 ρ BCP), kinetic electron energy density (G BCP), potential electron density (V BCP) and the total electron energy density (H BCP) at bond critical points (BCP) have been analyzed by Bader''s ‘Atoms in molecules’ AIM theory in detail. The intermolecular hydrogen bond energy of dimer is calculated as −12.51kcal/mol using AIM calculations. AIM ellipticity analysis is carried out to confirm the presence of resonance assisted intra and intermolecular hydrogen bonds in dimer. The calculated thermodynamic parameters show that reaction is exothermic and non-spontaneous at room temperature. The local reactivity descriptors such as Fukui functions (f k +, f k −), local softnesses (s k −, s k +) and electrophilicity indices (ω k +, ω k −) analyses are performed to determine the reactive sites within molecule. Nonlinear optical (NLO) behavior of title compound is investigated by the computed value of first hyperpolarizability (β 0). [Copyright &y& Elsevier]