Ab-initio HF and density functional theory investigations on the synthesis mechanism, conformational stability, molecular structure and UV spectrum of N’-Formylkynurenine

Abstract

Tryptophan methyl ester (Trp-ME) degrades with singlet oxygen and produce compounds which are photosensitizers and may react to form other derivatives such as N’-Formylkynurénine (NFK) and kynurenine, which are the final products of this oxidation. In order to study and optimize the molecular structure of NFK and determine its different thermodynamic properties, we performed a conformational analysis by DFT/B3LYP method with 3-21G basis set. Six most stable conformations were observed through the analysis of the potential energy surfaces, obtained by a relaxed scan of the dihedral angles. The most stable form of NFK has been registered for D[Formula: see text], D[Formula: see text], D[Formula: see text], D[Formula: see text], D[Formula: see text], and D[Formula: see text]. The study was conducted by HF and DFT/B3LYP with 6-31G(d,p), 6-3[Formula: see text](d,p) and 6-31[Formula: see text](d,p) basis sets, on the optimized geometry of the most stable conformation and its thermodynamic and orbital properties. Two absorption bands were recorded at [Formula: see text][Formula: see text]nm and at [Formula: see text][Formula: see text]nm and were also determined by TD-DFT method. They showed good agreement with the UV experimental spectrum which confirms that it is a powerful tool to determine the dynamic and static properties of molecules. The surface of the electrostatic potential (ESP) of the NFK was also analyzed.

Molecular properties and In silico bioactivity evaluation of (4-fluorophenyl)[5)-3-phen-(4-nitrophenyl yl-4,5-dihydro-1H-pyrazol-1-yl]methanone derivatives: DFT and molecular docking approaches

“…The frontier orbital energies, such as the highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital (LUMO) and band gaps, are critical parameters for kinetic and thermodynamic stability studies, and prediction of reactivity and photochemical properties. 41 , 42 , 43 , 44 , 45 , 46 The frontier orbital molecular overlay revealed that the HOMO overlay was essentially on ring, extending over the two nitrogen atoms of the pyrazole ring, whereas the LUMO overlay was on the phenyl ring for M1, M3, M4 and M5 , and was on the benzoyl ring for M1 and M6 ( Figure 1 ). The calculated frontier molecular orbitals LUMO, HOMO and HOMO–LUMO (ΔEg) were, respectively, −2.50, −5.92 and 3.42 eV for M1 ; −2.77, −5.91 and 3.14 eV for M2 ; −2.85, −5.87 and 3.02 eV for M3 ; −2.43, −5.86 and 3.43 eV for M4 ; −2.42, −5.86 and 3.37 eV for M5 ; −2.90, −6.06 and 3.16 eV for M6 ; and −2.26, −6.10 and 3.83 for Ma .…”

The inhibition effect of garlic‐derived compounds on human immunodeficiency virus type 1 and saquinavir

“…Sharma et al emphasized that the smallest band gap and the negativity indicated the increasing activity of the compounds to inhibit HIV. Omri et al emphasized that identifying the most stable conformation of the molecule by analyzing thermodynamic, electronic and orbital properties by the theoretical study using HF and DFT/B3LYP with 6‐31G(d,p) basis sets were important methods.…”

“…Sharma et al [27] emphasized that the smallest band gap and the negativity indicated the increasing activity of the compounds to inhibit HIV. Omri et al [28] emphasized that identifying the most stable conformation of the molecule by analyzing thermodynamic, electronic and orbital properties by the The important substances against hydroxyl radicals come from the antioxidants. Antioxidants have reducing power to the radical agents; they take part in redox reactions by donating electrons or hydrogen atoms.…”

Synthesis, spectral characterization (FT-IR and NMR) and DFT (Conformational analysis, molecular structure, HOMO-LUMO, UV-vis, NLO) computational studies on 2,2’-((1E,1’E)-phenazine-2,3 dilbis(azanylylidene))bis(methanyly- lidene))diphenol

“…While the energy of HOMO is directly related to ionization potential and LUMO energy is to electron affinity. Recently, the energy gap between HOMO and LUMO has been used to confirm the bioactivity from ICT [Omri et al 2016; Kosar et al 2011]. The atomic orbital compositions of the frontier molecular orbitals are shown in Fig.…”