Synthetic, XRD, non-covalent interactions and solvent dependent nonlinear optical studies of Sulfadiazine-Ortho-Vanillin Schiff base: (E)-4-((2-hydroxy-3-methoxy- benzylidene) amino)-N-(pyrimidin-2-yl)benzene-sulfonamide

A facile and concise route to (hydroxybenzoyl)pyrido[2,3-d]pyrimidine heterocycle derivatives: synthesis, and structural, spectral and computational exploration

In this work, we report the efficient synthesis of novel (hydroxybenzoyl)pyrido[2,3-d]pyrimidine heterocycle derivatives: 6-(2-hydroxy-5-methylbenzoyl)-1-methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione (6a), 6-(5-fluoro-2-hydroxybenzoyl)-1-methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione (6b), 6-(5-ethyl-2-hydroxybenzoyl)-1-methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione (6c) and 6-(2-hydroxy-5-isopropylbenzoyl)-1-methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione (6d). The chemical structures of the title compounds were ascertained by spectral techniques including 1H, 13C NMR, UV-visible and FT-IR spectroscopy as well as single-crystal X-ray diffraction analysis. Additionally, density functional theory (DFT) and time-dependent (TD-DFT) computation were adopted to analyze the electronic structures of 6a-d. Compounds 6a-d were computed in the ground state for FT-IR spectroscopic and natural bond orbital (NBO) analysis by DFT/B3LYP with the 6-311+G(d,p) basis set. UV-vis spectroscopic and HOMO and LUMO energy values for 6a-d were determined via TD-DFT/B3LYP with the 6-311+G(d,p) basis set. The optimized geometric parameters, UV-vis findings, and vibrational frequencies indicate good consistency with the experimental data. NBO analysis was conducted to explore the interactions and charge transfer among different orbitals in the title compounds. The HOMO and LUMO band gap (ΔE) values for 6a-d were found to be 3.93, 3.91, 4.10 and 3.91 eV, respectively. Molecular electrostatic potential (MEP) analysis explored the reactivity of the title compounds by predicting their nucleophilic as well as electrophilic sites.

Electron Donor and Acceptor Influence on the Nonlinear Optical Response of Diacetylene-Functionalized Organic Materials (DFOMs): Density Functional Theory Calculations

Herein, we report the quantum chemical results based on density functional theory for the polarizability (α) and first hyperpolarizability (β) values of diacetylene-functionalized organic molecules (DFOM) containing an electron acceptor (A) unit in the form of nitro group and electron donor (D) unit in the form of amino group. Six DFOM 1–6 have been designed by structural tailoring of the synthesized chromophore 4,4′-(buta-1,3-diyne-1,4-diyl) dianiline (R) and the influence of the D and A moieties on α and β was explored. Ground state geometries, HOMO-LUMO energies, and natural bond orbital (NBO) analysis of all DFOM (R and 1–6) were explored through B3LYP level of DFT and 6-31G(d,p) basis set. The polarizability (α), first hyperpolarizability (β) values were computed using B3LYP (gas phase), CAM-B3LYP (gas phase), CAM-B3LYP (solvent DMSO) methods and 6-31G(d,p) basis set combination. UV-Visible analysis was performed at CAM-B3LYP/6-31G(d,p) level of theory. Results illustrated that much reduced energy gap in the range of 2.212–2.809 eV was observed in designed DFOM 1–6 as compared to parent molecule R (4.405 eV). Designed DFOM (except for 2 and 4) were found red shifted compared to parent molecule R. An absorption at longer wavelength was observed for 6 with 371.46 nm. NBO analysis confirmed the involvement of extended conjugation and as well as charge transfer character towards the promising NLO response and red shift of molecules under study. Overall, compound 6 displayed large <α> and β_tot, computed to be 333.40 (a.u.) (B3LYP gas), 302.38 (a.u.) (CAM-B3LYP gas), 380.46 (a.u.) (CAM-B3LYP solvent) and 24708.79 (a.u.), 11841.93 (a.u.), 25053.32 (a.u.) measured from B3LYP (gas), CAM-B3LYP (gas) and CAM-B3LYP (DMSO) methods respectively. This investigation provides a theoretical framework for conversion of centrosymmetric molecules into non-centrosymmetric architectures to discover NLO candidates for modern hi-tech applications.