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Herein, we reported the imino phosphonate compounds: (4‐methoxy‐benzylidene‐amino‐phenyl‐methyl‐phosphonic acid diethyl ester (MBPDE), 4‐hydroxy‐benzylidene‐amino‐phenyl‐methyl‐phosphonic acid diethyl ester (HBPDE) and 4‐hydroxy‐3‐methoxy‐benzylidene‐amino‐phenyl‐methyl‐phosphonic acid diethyl ester (HMBPD) form the chemical reaction of diethyl (α‐amino benzyl)phosphonate hydrochloride and substituted benzaldehyde. These compounds were characterized by various spectroscopic techniques: FT‐IR, Mass, UV–VIS, 1H NMR and 13 C NMR. Additionally, the optimized molecular structures, FT‐IR, natural bond orbitals (NBOs), frontier molecular orbitals (FMOs), non‐linear optical (NLO) properties were calculated by the density functional theory (DFT) using the B3LYP functional with the 6–311+G(d,p) basis set. Moreover, UV–Visible spectrum of MBPDE, HBPDE and HMBPD were predicted in different solvents using the time dependent TD‐DFT [B3LYP/6‐311+G(d,p)] method using Polarizable Continuum Model (PCM). The non‐linear optical (NLO) properties were calculated by M06 functional with the 6–311+G(d,p) basis set. A synergistic relationship is observed between the experimental and theoretical findings. NBO analysis provided insights about the stability and charge delocalization of the entitled molecules. The global reactivity descriptors were achieved through HOMO‐LUMO energies. The efficiency of the entitled molecules concerning charge transfer and participation in diverse chemical reactivities were figured out perceptibly by applying the frontier molecular orbitals (FMOs) analysis. The average polarizability <α> values: 277.184, 261.332 and 280.254 a.u. of the MBPDE, HBPDE and HMBPD were determined respectively. The total first hyperpolarizability (βtot) values of the MBPDE, HBPDE and HMBPD were also obtained to be 992.900, 781.527 and 1107.526 a.u. respectively. The compound HMBPD comprising of higher magnitude of average polarizability and the total first hyperpolarizability (βtot) values than MBPDE and HBPDE molecules. Moreover, NLO properties of urea molecule were found smaller in comparison to the MBPDE, HBPDE and HMBPD. The medicinal importances of these novel compounds as well as its contribution towards nonlinear optical field are our future targets. [ABSTRACT FROM AUTHOR]

The new aminocoumarin derivatives 3‐[1‐(3‐hydroxyanilino)ethylidene]‐3H‐chromene‐2,4‐dione, (1), 3‐[1‐(4‐hydroxyanilino)ethylidene]‐3H‐chromene‐2,4‐dione, (2), and 3‐[1‐(2‐hydroxyanilino)ethylidene]‐3H‐chromene‐2,4‐dione, (3), all C17H13NO4, were synthesized by reacting an equimolar amount of 3‐acetyl‐4‐hydroxycoumarin and the corresponding aminophenol in absolute ethanol. Structural and spectroscopic analysis of these phases revealed that derivatives (1) and (2) are isomers of previously reported (3) [Brahmia et al. (2013). Acta Cryst. E69, o1296]. The crystal structures of meta derivative (1) and para derivative (2) were ab initio determined from powder X‐ray diffraction data using the direct‐space approach. Both (1) and (2) adopt the orthorhombic space group P212121. These isomers show hydrogen bonds and rich π–π stacking, together with π...H interactions, which are built by conjugated systems of coumarin and phenol rings. In the crystalline lattice, the packing of (1) and (3) are mainly stabilized through O—H...O hydrogen bonding between neighbouring coumarin molecules, while hydrogen bonds between coumarin and water molecules build the stable crystal structure of derivative (2). A big similarity in the skeletons of the IR spectra of these isomers was noticed. Derivative (2) exhibits two weak bands which were not present in the spectra of the other two derivatives, at 2370 and 2948 cm−1, which can be assigned to the O—H vibrations of the solvent (H2O) trapped in the structure of (2). These aminocoumarin derivatives display absorption maxima in the visible region, attributed to π–π delocalization involving the whole electronic system of the compounds with a considerable charge‐transfer character originating from the aminophenyl ring and pointing towards the coumarin system which is characterized by a high electron‐accepting character. Additionally, the isolated molecular ground‐state geometries were optimized at the PBE0/TZP level and the electronic properties, molecular electrostatic potential and Hirshfeld charges were determined. [ABSTRACT FROM AUTHOR]

A novel pyrazolyl chromene derivative (Probe 1 ) displaying aggregation induced emission (AIE) properties that capable of sensing of multiple metal ions has been designed and synthesized. The multi analyte probe exhibits selective sensing for Cu 2+ and Ni 2+ ions via fluorescence turn-off mechanism and ratiometric selectivity for Hg 2+ ions in aqueous media. The extent of binding of the probe with sensitive metal ions has been demonstrated. The experimental results were further investigated by computational means by optimizing the ground state geometries of Probe 1 and its various metal complexes for Probe 1 -Ni, Probe 1 -Hg and Probe 1 -Cu using density functional theory (DFT) at B3LYP/6-31+g(d,p) (LANL2DZ) level. On the basis of binding energies, the stability of metal complexes has been studied. In Probe 1 -Ni and Probe 1 -Cu complexes, charge transfer has been observed from Probe 1 to metal ions revealing ligand to metal charge transfer (LMCT) while in Probe1-Hg complex LMCT as well as intra-molecular charge tranfer (ICT) within Probe 1 . [ABSTRACT FROM AUTHOR]

Abstract: Eleven tautomers and rotamers of rhodanine, R1–R11, were studied theoretically at MP2/6-311G+(d,p), CBS-QB3, B3LYP/6-311+G(d,p), B3LYP/6-31+G(d,p) and MPW1K/6-31+G(d,p). Optimized geometrical parameters of all the eleven forms were computed and compared with the available X-ray results. The geometry of MP2/6-311G+(d,p), and B3LYP/6-311+G(d,p) methods shows the best agreement with the experimental results. Thermodynamic parameters for the eleven forms were calculated at the above levels in the gas phase and water utilizing PCM method. Tautomer R1 is the most stable tautomer in all cases both in gas phase and in aqueous solution as also known from experimental data. Consideration of the solvent causes some reordering of the relative stability of rhodanine conformers. Natural charges and electric dipole moment were computed at different levels. The transition states for the rhodanine tautomerization and rotamerization processes were studied for selected systems at different levels. Energy barriers of rotamerization processes are only 10% of that for the proton transfer tautomerization processes. [Copyright &y& Elsevier]

• DFT and molecular dynamic studies of liver cirrhosis biomarker volatiles. • PTN_Ga@AlNNT and LMN_Ga@AlNNT possessed the highest and least energy gap. • PTN_Ga@AlNNT have the highest fraction of electronic transfer for the studied systems. • In@ AINNT have the highest stabilization energy. • Molecular dynamic show that the nanomaterials induced conformational changes. In the realm of scientific curiosity, the quest to develop groundbreaking biosensor technology and materials that cater to the urgent societal demands in healthcare, environment, food safety, and beyond has reached unprecedented heights. In this study, we delve into the captivating world of cutting-edge research, harnessing the power of density functional theory (DFT) at the B3LYP-GD3(BJ)/def2-SVP level of theory to investigate the adsorption, conductivity, reactivity, and dynamical stability of biomarker volatiles of liver cirrhosis: limonene (LMN), methanol (MTN), and pentanone (PTN) on aluminum nitride nanotube (AlNNT) and its metals doped Indium (In) and Gallium (Ga) designed surfaces. From the evolution in band gap analysis, PTN_Ga@AlNNT was noticed to have obtained least energy gap of 3.035 eV whereas, LMN_Ga@AlNNT system had the highest energy gap of 4.330 eV. The calculated fraction of electronic transfer for the studied systems were observed as thus; −2.48936, −0.798342 and −6.321428571 for LMN_Ga@AlNNT, MTN_Ga@AlNNT and PTN_Ga@AlNNT respectively. The perturbation energy analysis presents an increasing stabilization energy of Aluminum nanotube doped with Gallium (Ga) and indium (In) surface to followed the trend; In@ AINNT > Ga@ AINNT. Results from the Molecular Dynamic simulation suggest that the nanomaterials studied induced conformational changes in all six complexes during the simulation, as evidenced by the changes in energy and temperature. Also, from the UV– Vis analysis, the excited states in all three instances are single-A states, which implies they have spin quantum number S = 0. We hope this research work will contribute to the development efficient biosensor materials. [ABSTRACT FROM AUTHOR]

• DFT study for the detection and adsorption of buprofezin insecticide. • Heteroatoms doped on a Pt-coordinated graphitic carbon nitride (Pt@C 3 N 4). • Negative adsorption energies observed for interacting surfaces doped with B, N, P, S and Si. • Strong chemisorption was observed in the BPF_S_Pt@C 3 N 4 which had highest adsorption. • Heteroatom doping of Pt@C 3 N 4 materials for maintaining environmental sensing applications. As global agriculture seeks to reduce the reliance on conventional insecticides with potentially harmful effects for modern agriculture and insect-pest control practices, we improve the appeal of buprofezin as a safe and sustainable pest control option. Herein, we conducted theoretical investigations to explore the adsorption efficacy, sensibility, and reactivity of heteroatoms (B, N, P, S and Si) doped on a custom-engineered platinum-encapsulated graphitic carbon nitride (Pt@C 3 N 4) as enhanced sensor materials for the adsorption of buprofezin (BPF) insecticide within the framework of density functional theory (DFT) computation at the B3LYP-GD3BJ/def2svp level of theory. Consequently, the notable variations observed in the energy gap of the studied surfaces when interacted with buprofezin accounted for the reactivity, stability, conductivity, work function, and overall adsorption potentials of the sensor material which projects the doped surfaces as a suitable sensor material for sensing buprofezin (BPF). More so, the negative adsorption energies observed for interacting surfaces doped with B, N, P, S and Si suggest the strong propensity to trap buprofezin molecule better as a considerably strong chemisorption was observed especially in the BPF_S_Pt@C 3 N 4 which had highest adsorption of -51.355 kcal/mol. With firm conviction, this research study will be helpful and provide useful knowledge as background research for future study and experimental researchers to uncover the potentials in heteroatom doping of Pt@C 3 N 4 materials for maintaining ecological balance and environmental sensing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Structure elucidation and optimization were accomplished using spectral data and the DFT technique. • Solute-Solvent interactions reported on UV–Visible investigation, using TD-DFT, comprehension of stability, and biological activity. • Multiwave function analysis, such as ELF, LOL, and RDG, were performed to better understand surface electron density, delocalization, localized orbital, and weak interaction. • The FMO, MEP, and Hirshfeld charges of the molecule, as well as one electron transport pathway, were discovered. • The antioxidant activity and anti-inflammatory impact were investigated, and the in-vitro bioassay results were verified. Eremostachys vicaryi Benth. Ex Hook. f. (Labiatae), a Pakistani (Baluchistan) herbal medicinal plant commonly known as "Stagh," which has a sharp taste and smell. It acts as an antiseptic and antimicrobial agent and is used for fish poisoning, treating skin diseases, and holding a cooling effect. Following the assessment of the plant extract's cytotoxic and phytotoxic assays using phytochemical screening, the antioxidant and anti-inflammatory properties of the pure ingredients that were separated from the ethyl acetate soluble fractions have been evaluated. The bioassay-guided fractionation and purification of E. vicaryi B. crude methanol extract yielded two isoflavones (1–2) that showed promising antioxidative activities with DPPH and cytochrome-c-reduction assays. Compounds 1 and 2 have shown considerable anti-inflammatory efficacy, 1 being a good inhibitor of the superoxide within the living system. Initial assumptions on the one-electron transfer process indicated that Compound 1 has a smaller ionization potential value compared to Compound 2 and so has greater antioxidant potential than its predecessor, isoflavone. Moreover, the anti-inflammatory and antioxidant activity of isoflavones was also probed by first-principles calculations. Based on the findings, it has been concluded that the crude extract of E. vicaryi B. and its organic components exhibit noteworthy phytotoxic and cytotoxic properties. The isolated pure isoflavones 1 and 2 showed significant antioxidant and anti-inflammatory activities. Solute-solvent interactions were studied and reported for both compounds. An analysis was conducted on the UV–Vis electronic transition for different solvents. Using a Multiwave function analyzer the topological findings such as ELF, LOL, and RDG were done to comprehend the surface electron density, delocalization, localized orbital, and weak interaction in the compounds. The antioxidant activity is evaluated by radical methods using DPPH, and cytochrome-c-reduction assays using ascorbic acid as a standard. Through cell-based respiratory burst testing, the anti-inflammatory activity of standard indomethacin was examined. The ground state geometries of isoflavones and reference compounds were optimized by Density Functional Theory- (DFT) by computing various electronic properties. In-vitro bioassay results were validated by first-principles calculations. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) residues threaten aquatic ecosystems by infiltrating water bodies and disrupting aquatic life, potentially affecting the food chain. In our quest to address this ecological concern, we embarked on a fascinating investigation exploring the photodegradation of tetracycline using nanocomposite materials: Ca 12 O 12 -PEDOT, Mg 12 O 12 -PEDOT, and Zn 12 O 12 -PEDOT within the framework of density functional theory (DFT) at the ωB97XD/def2svp method. The results obtained showed that tc@Ca 12 O 12 -PEDOT composite exhibited unparalleled stability with an adsorption distance of 1.922 Å, surpassing its counterparts tc@Mg 12 O 12 -PEDOT and tc@Zn 12 O 12 -PEDOT. The tc@Ca 12 O 12 _PEDOT system displayed a compact energy gap, suggesting its superior photon absorption capability from the valence band compared to the others. The sequential order of stabilization energies was observed as follows: Zn 12 O 12 -PEDOT > Mg 12 O 12 -PEDOT > Ca 12 O 12 -PEDOT, with values of 73.26 kcal/mol, 49.35 kcal/mol, and 10.66 kcal/mol, respectively. The analysis of charge transfer showed that tc@Mg 12 O 12 _PEDOT had the highest magnitude of charge transfer, followed by tc@Zn 12 O 12 _PEDOT and tc@Ca 12 O 12 _PEDOT. The characterization of the hole and electron separation through the computed back donation revealed a distinct pattern: tc@Zn 12 O 12 _PEDOT > tc@Mg 12 O 12 _PEDOT > tc@Ca 12 O 12 _PEDOT. The presence of t-index >0 indicated substantial hole and electron separation due to charge transfer. The investigation into hole and electron distribution exhibited a small Hole Distribution Index (HDI), signifying a narrow spatial extent of this charge separation. The order of spatial extent was found to be tc@Zn 12 O 12 _PEDOT > tc@Ca 12 O 12 _PEDOT > tc@Mg 12 O 12 _PEDOT. Similar conclusions can be drawn for the Electron Distribution Index (EDI). When comparing tc@Mg 12 O 12 _PEDOT with tc@Ca 12 O 12 _PEDOT, we observed a fascinating redshift in the first excited state (41.83 nm), second excited state (27.01 nm), and third excited state (7.59 nm). [Display omitted] • Excitation analysis, DFT study and photodegradation of tetracycline hybrid materials. • Sequential order of stabilization energies: Zn 12 O 12 -PEDOT > Mg 12 O 12 -PEDOT > Ca 12 O 12 -PEDOT. • The tc@Mg 12 O 12 _PEDOT displaying the highest magnitude of charge transfer. • The presence of t-index >0 indicated substantial hole and electron separation due to charge transfer. [ABSTRACT FROM AUTHOR]

The first-principles based DFT calculations were used to investigate the effect of transition metal (TM) doping on structural, electronic, optical and thermoelectric properties of Sn 1-x A x Se (A = Au and Ag). The PBE-GGA approximation is used to calculate ground state properties of TM doped SnSe. These compounds show the presence of type-II intermediate band (IB) at Fermi level. A considerable energy bandgap is present between IB and conduction band. Significant contributions from Ag/Au and Se-atom in valence bands of Sn 1-x A x Se (A = Au and Ag) are evident from presented DOS spectra. The calculated Fermi surfaces and Seebeck coefficient (S) confirms p-type nature of these semiconductors. From ε 2 (ω) spectra, it is evident that Sn 1-x A x Se (A = Au and Ag) absorbs maximum number of incident photons in infrared (at ∼0.5 eV) and visible (at ∼2.2 eV) regions. The calculated values of n (ω) are 2.27 and 2.58 for Sn 1-x Ag x Se and Sn 1-x Au x Se, respectively. We can confirm that Sn 1-x A x Se (A = Au and Ag) are promising candidates for energy applications (especially solar cells) based on their optoelectronic and thermoelectric properties. [Display omitted] • Electronic, optical and thermoelectric properties of Sn 1-x A x Se (A = Ag and Au) are investigated ab-initio. • Sn 1-x A x Se (A = Ag and Au) show type-II intermediate band in their band structures. • These compounds are p-type materials based on Fermi surface and Seebeck coefficient. • Optical spectra show major absorption peaks in visible region around 2.2 eV. • Among the considered compounds, Sn 1-x Au x Se shows the highest absorption. [ABSTRACT FROM AUTHOR]

Abstract Nitrido silicates are emerged as highly efficient luminescent materials (phosphors) that found considerable industrial application as white light emitting diodes (LEDs) have been studied with respect to band structure and related electronic structure parameters. They have tunable optical properties, as the band gap is of indispensable because it determines both the electrical and optical features of the material, which can be varied by the material composition (by doping technique). It is found also that the nitride (alumo) silicates "Sr 2 Si 5 N 8 : Eu2+" have wide industrial application as highly efficient red-emitting phosphor materials in pc-LEDs. In this report we apply density functional theory (DFT) within the GGA+U approach to study the structural, electronic and optical properties of Eu2+ and Ce3+ doped Sr 2 Si 5 N 8. The total energy has been optimized as a function of the unit cell volume. Electronic structure including, the electronic density of state (DOS), the band structure and the linear optical susceptibility are calculated for the relaxed structure applying the optimized lattice constant. The calculated optical dispersion of dielectric susceptibility are closely related to the corresponding electronic structure and our results are in very good agreement with experimental data. Graphical abstract Image 1 Highlights • Complex studies of band structure for Sr 2 Si 5 N 8 and doped compound with Eu2+and Ce+3 have been done. • Static value of real part for pure Sr 2 Si 5 N 8 is 2.1 while for Eu2+ doped Ce+3 2.6–2.9 • Plasmonic resonances appear at 12.5 eV and for doped – at 10.5 eV. • Main perspectives of eh further improvements of the optical constants are given. [ABSTRACT FROM AUTHOR]

Computational designing of four different series (D-G) of thiazolidinone was done starting from different amines which was further condensed with various aldehydes. These underwent in silico molecular investigations for density functional theory (DFT), molecular docking, and absorption, distribution metabolism, excretion, and toxicity (ADMET) studies. The different electrochemical parameters of the compounds are predicted using quantum mechanical modeling approach with Gaussian. The docking software was used to dock the compounds against choosing PDB file for chickenpox, human immunodeficiency, hepatitis, and monkeypox virus as 1OSN, 1VZV, 6VLK, 1RTD, 3I7H, 3TYV, 4JU3, and 4QWO, respectively. The molecular interactions were visualized with discovery studio and maximum binding affinity was observed with D8 compounds against 4QWO (- 13.383 kcal/mol) while for compound D5 against 1VZV which was −12.713 kcal/mol. Swiss ADME web tool was used to assess the drug-likeness of the designed compounds under consideration, and it is concluded that these molecules had a drug-like structure with almost zero violations. [Display omitted] • Forty-four Thiazolidinone were proposed theoretically. • DFT and Docking studies were conducted with different software against various virus PDB files. • ADMET assessment was conducted using online available software. • Homology modeling study of the effective proteins was made. [ABSTRACT FROM AUTHOR]

A comprehensive investigation on the photophysics of a π -conjugated potential push–pull chromophore system 4,4′-(1E,1′E)-2,2′-(Pyrazine-2,5-diyl)bis(ethene-2,1-diyl)bis(N,N-dimethylaniline) (PENDA) has been carried out spectroscopically. The optical absorption and emission properties of this molecule have been studied in different solvents. The molecule PENDA shows strong solvatochromic emission upon changing the solvent polarity from nonpolar to polar; indicating that emission state is of intramolecular charge transfer (ICT) character. The solvent effect on the spectral properties such as singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of PENDA have been studied in detail. Lippert–Mataga and Reichardt correlations were used to estimate the difference between the excited and ground state dipole moments (Δ μ ). Ground and electronic excited states geometric optimizations were performed using density functional theory (DFT) and time-dependent density functional theory (TDDFT), respectively, with the Gaussian 09 package. A solution of (8 × 10 −5 M) PENDA in THF, dioxane, CH 3 CN and CHCl 3 gives laser emission when pumped by a nitrogen laser pulse ( λ ex = 337.1 nm) of 800 ps duration and 1.48 mJ pulse energy. PENDA dye displays fluorescence quenching by colloidal silver nanoparticles (Ag NPs) in ethanol. The fluorescence data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching mechanism. [ABSTRACT FROM AUTHOR]

The electronic absorption, fluorescence spectra and photophysical parameters such as, molar absorptivity (ε), oscillator strength (f), transition dipole moment (μ 12), and fluorescence quantum yield (φ f) of BTBVB were determined in different solvents and micelles. Both electronic absorption and emission spectra are less sensitive to medium polarity which indicates little change in the dipole moment of singlet (S0) ground and excited state (S1) of BTBVB molecule upon excitation. The quantum yield for photochemical transformation (Ф c) of BTBVB was calculated in different organic solvents such as DMSO, DMF, EtOH and CHCl3 at room temperature. The dye solutions in DMSO, DMF, CHCl3 and EtOH give laser emission in the blue–green region upon excitation by a 337.1nm nitrogen pulse. The tuning range, gain coefficient (α) and emission cross-section (σ e) have been determined. Excitation energy transfer from BTBVB to rhodamine B was studied in n-butanol, methanol and ethylene glycol to improve the laser emission from RB dye when excited by nitrogen laser. Such an energy transfer dye laser system (ETDL) obeys a long range columbic energy transfer mechanism with a critical transfer distance, R 0, of 36Å and k ET equal 6×1012 M−1 s−1. The density functional theory (DFT) was used to optimize the ground and excited state geometry of the dye, the computed peaks of absorption and emission spectra are in a reasonable agreement with the experimental results. [ABSTRACT FROM AUTHOR]

A new highly selective fluorescent turn-on probe (RS4) possessing indolinium moiety has been designed and synthesized for the detection of cyanide ion. The probe RS4 displays instantaneous, highly selective and sensitive recognition of cyanide ion over other common anions via change in color and enhancement in fluorescence. Nucleophilic addition of cyanide to the indolinium C-atom leads to the enhancement in fluorescence (λ em 481 nm; Blueish-green emission) and decolourization due to different intramolecular charge transfer (ICT) process. The binding constant of the 1:2 RS4 /CN¯ adduct is determined to be 2.3 × 104 M−1. The limit of detection of cyanide by RS4 is estimated to be 21 nM. Density functional theory (DFT) based calculations strongly substantiate the results of the experimental investigations. Importantly, the probe detects cyanide ion in agro-products (cassava powder and bitter almond), which demonstrates its value to practical application. • The probe senses cyanide with color change and fluorescent enhancement. • The detection mechanism involves nucleophilic addition of CN− at indolinium C-atom. • Sensing mechanism was delineated using spectral and DFT studies. • The probe successfully sensed CN− of cyanogenic glycoside in agro-products. [Display omitted] [ABSTRACT FROM AUTHOR]

Cadmium sulfide has been the subject of wide studies due to its vast applications in solar cells. Bilayer system of Fe doped CdS, is used for synthesis of metal coated semiconductor nanocrystals to fabricate variety of electroluminescent and optical devices. The electronic and optical properties of Fe doped CdS nanostructures were investigated by first principles computations. The electronic properties (band structures and densities of states) have been estimated to evaluate the effect of the Fe doping on the electronic and optical properties of CdS nanostructure. Results show that the properties of CdS are changed when Fe is doped in the parent material. Calculations reveal a semiconducting nature with different behavior for both spin up and down band structures. Fe induced change in the studied properties nanostructured CdS is discussed. Absorption characteristics of Fe doped CdS may be related to the change among valence band and vacant d-orbitals of Fe. • The electronic and optical properties of Fe doped CdS nanostructures were investigated. • Via first principles studies in the framework of density functional theory (DFT). • The electronic properties have been estimated to evaluate the effect of the Fe doping. • We have discussed the Fe induced changes in these ground state properties of nanostructured CdS in details in this study. [ABSTRACT FROM AUTHOR]

Herein, two new thiazole derivatives: ethyl2-(2-benzylidenehydrazinyl)thiazole-4-carboxylate (3) and ethyl2-(2-(2-hydroxybenzylidene)hydrazinyl)thiazole-4-carboxylate (4) were synthesized by cyclization of 1-benzylidenethiosemicarbazide with ethyl bromopyruvate. The synthesis was validated by spectroscopic techniques like FTIR, 1H- NMR, 13C-NMR and chemical structure of title compounds 3 and 4 has been determined using SC-XRD. Ancillary to experimental analysis, DFT calculations with B3LYP/6-311 + G (d,p) level were performed for comparative analysis of FT-IR spectroscopic data, optimized geometry, frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties. Overall, experimental findings were supported by corresponding DFT computed results. TDDFT calculations were executed at M06/6-311 + G (d,p) level of theory to calculate the vertical electronic transition states. NBO analysis disclosed that intramolecular charge transfer and hyper-conjugative interactions among bonds provide stability to the investigated compounds 3 and 4. The global reactivity parameters calculated from energy of FMOs indicates that 3 and 4 enclose larger softness and fewer hardness values. NLO results of 3 and 4 were observed better than standard molecule recommended the NLO activity of said compounds. We hope that this joint experimental and computational insight may provide new ways for the utilization of title molecules as NLO material for optoelectronic applications. Image 1 • Two novel ethyl 2-(2-(2-substitutedbenzylidene)hydrazinyl)thiazole-4-carboxylate crystals were synthesized. • XRD, 1H NMR, 13C NMR, FT-IR and UV–Vis were performed for the characterization. • Computational study was done at B3LYP/6-311 + G (d,p) level for comparative analysis. • Comparative study reveals a good agreement between experimental and DFT results. • FMOs, NBO analysis and nonlinear optical (NLO) properties were calculated. [ABSTRACT FROM AUTHOR]

The pyrimidine ring is significantly distributed in nature due to its existence in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) as nitrogenous bases. The heterocyclic aromatic compounds have become an important pharmacophore due to promising applications in medicine and nonlinear optics (NLO) fields. Keeping in view of the significance of 4-thiopyrimidines derivatives, we selected phenyl pyrimidine derivatives namely: ethyl 4-((3-chlorobenzyl)thio)-6-methyl-2-phenylpyrimidine-5-carboxylate (1), (4-((4-chlorobenzyl)thio)-6-methyl-2-phenyl-pyrimidin-5-yl)methanol (2) and 4-((4-chlorobenzyl)thio)-5,6-dimethyl-2-phenylpyrimidine (3) for NLO study and comparative analysis. Overall, density functional theory (DFT) findings of structural parameters at B3LYP/6-311G(d,p) level show excellent concurrence with the experimental data which confirms the purity of 1 , 2 and 3. The vibrational analysis of 1 , 2 and 3 have been carried out by DFT calculations based on B3LYP/6-311G(d,p) level of theory. The natural bonding orbital (NBO) analysis has been used to get insight into non-covalent interactions. From DFT calculations, various parameters such as natural population analysis (NPA) atomic charges, HOMO–LUMO energies and global reactivity parameters have been obtained. The molecular electronic potential (MEP) and parametric molecular electrostatic potential (PMEP) have also been derived for 1 , 2 and 3. The photophysical properties of investigated molecules were estimated using time dependent DFT (TDDFT) at B3LYP/6-311G(d,p) level of theory. Nonlinear optical (NLO) analysis has also been carried out by DFT calculations with B3LYP/6-311G(d,p) functional. The NLO properties of 1 , 2 and 3 were observed larger as compared to the standard molecule indicating the considerable NLO character of all molecules especially recommended the NLO activity of 1 for optoelectronic associated hi-tech applications. Image 1 • Three novel phenyl pyrimidine derivatives 1 , 2 and 3 were studied. • Computational study was done at B3LYP/6-311G(d,p) level for comparative study. • Comparative study reveals a good agreement between XRD and DFT results. • FMO, NBO, global reactivity parameter, NPA, MEP, PMEP and NLO analysis were performed. • All studied compounds hold considerable NLO character and recommended for optoelectronic associated hi-tech applications. [ABSTRACT FROM AUTHOR]