LUMO Orbitals Research Articles

New bis-isoxazole with monoterpenic skeleton: regioselective synthesis, spectroscopicinvestigation, electrochemical, and density functional theory (DFT) studies

A novel bis-isoxazole was synthesized from (R)-Carvone and p-methylbenzaldoxime, via two successive [3+2] cycloaddition reactions (32CA). The newly obtained bis-isoxazole has been fully characterized by HRMS and NMR spectroscopy. The HMBC experiment was performed to determine the stereo and the regioselectivity of the reaction. The electrochemical behavior of the studied compound, in oxidation and reduction processes, was examined using the cyclic voltammetry technique. In addition, the regioselectivity of the [3+2] cycloaddition reaction and the molecular structure of the title compound was performed by density functional theory (DFT). The HOMO and LUMO orbitals were investigated to determine the electronic properties of the synthesized compound. Besides, the global reactivity indexes were used to explain the regioselectivity for the formation of the bis-isoxazole, the theoretical results are in good agreement with experimental findings.

Theoretical study of the stability and reactivity of salicylic acid isomers by the DFT method

The FT-IR spectrum of salicylic acid (SA) was studied in the region 10-4000 cm-1. The optimized molecular geometry and fundamental vibration frequencies are interpreted using structural optimizations based on the Functional Density Theory (DFT) method. Additionally, we used B3LYP / 6-311G (d, p) to determine the chemical descriptor, the ionization potential (I), the electron affinity (A), the chemical potential (μ), the chemical hardness (η). Nonlinear optical descriptors (NLO) such as dipole moment (μ), polarizability (α), first hyperpolarizability (β) and second hyperpolarizability (γ), 3D maps of HOMO and LUMO orbitals, lengths and Bond angles of salicylic acid isomers are also determined by both DFT and MP2 (The Møller-Plesset theory of order 2 perturbation) methods. The overall descriptors and the non-linear optical properties confirmed that salicylic acid is the reactive molecule and para-hydroxybenzoic acid is the stable molecule. An electrostatic molecular potential (MEP) study was also performed to determine the reactivity of molecules.

Evaluation of the structure and characteristics of circumtrindene derivatives: a DFT study

The structures and properties of circumtrindene derivatives were studied at M062X/6-31+G(d,p) level of theory. The UV spectra of compounds were simulated by TD DFT methods. The calculated values of λmax (344 nm to 403 nm) were attributed to HOMO to LUMO electronic transitions of compounds. The frontier molecular orbitals have been studied based on NBO calculations and the results were used to estimate the HOMO—LUMO energy gap, ionization potential, electron affinity, electronegativity, electrophilicity index, global hardness, softness, and chemical potential of the compounds. Among the studied derivatives, the structure containing pyridine and furan rings possessed the highest ionization energy (9.007 eV), electron affinity (2.667 eV), electronegativity (5.837 eV), and was the most polar molecule. In addition, compound 7 had the smallest chemical potential (–5.837 eV), polarizability (328.560 a.u.) and the lowest energy levels of HOMO (–8.3672 eV) and LUMO (–3.3062 eV) orbitals. While the derivative having pyrrole rings had the highest softness (0.172 e/V), chemical potential (–4.272 eV), and the greatest λmax (403 nm) in the UV spectrum. In addition, this compound had the lowest hardness (2.912 eV), ionization energy (7.184 eV) and electronegativity (4.272 eV). Also, the aromaticity of individual rings was evaluated by calculating NICS and HOMHED indices. The NICS results showed that the peripheral 6-membered rings represented the best aromatic properties.

الوضعية الفراغية المثلى لاقترن الالين مع الميثفورمين باستخدام تقنية النمذجة الجزيئية DFT/B3LYP

This researchpaper includes the incorporation of Alliin at various energy levels and angles With Metformin using Gaussian 09 and Gaussian view 06. Two computers were used in this work. Samples were generated to draw, integrate, simulate and measure the value of the potential energy surface by means of which the lowest energy value was (-1227.408au). The best correlation compound was achieved between Alliin and Metformin through the low energy values where the best place for metformin to bind was through (CH2-). This is considered to be very useful for the industrial application of drugs. This level of calculation was used for physical and quantum properties such as total energy, HOMO and LUMO orbitals energies, and power gap. Besides, the calculation of FT-IR spectra in the range 400-4000 cm-1 was calculated in addition to the essential vibrational frequencies and the intensity of the vibrational bands. Moreover, the chemical displacement of the 1H and 13C NMR of the compound in the ground state was studied.

Insighting the functionally modified C60 fullerenes as an efficient nonlinear optical materials: A quantum chemical study

It is well-known that π-conjugation plays an important role to tune the nonlinear optical (NLO) response of donor-π-conjugated-acceptor compounds. Fullerenes (C60) are one of a few compounds who are abounded with π-conjugation and perhaps are the largest π-conjugation compounds. In the present study, we systematically designed C60 derivatives (2 (fulleropyrrolidine) and 2a-2c (fulleropyrrolidine tetrathiafulvalene derivatives where 2a, 2b and 2c are with n = 0, n = 1 and n = 2) through the use of pyrrolidine and tetrathiafulvalene moieties. We applied density functional theory (DFT) methods to calculate their respective geometrical structures, electronic properties, linear and nonlinear optical response properties along with their respective UV–Visible spectra using CAM-B3LYP functional and 6-31G* basis set. The isotropic polarizability (αiso) and anisotropic polarizability (αaniso) of 2c was found to be 131.52 × 10-24 and 47.01 × 10-24 esu, respectively. Amongst our designed compounds, the maximum second-order nonlinear optical polarizability amplitude (β//) of 2c was found to be 15.69 × 10-30 esu. Interestingly, 2c shows the highest third-order nonlinear polarizability amplitude <γ> of 284.29 × 10-36 esu that is about three times higher than parent compound 1. Additionally, frontier molecular orbitals (FMOs), molecular electrostatic potential maps (MEPs), transition density matrix (TDM) analysis indicate more effective charge redistribution from donor moiety to acceptor fragments. The density of states (DOS) diagrams reveal distinct electronic contributions of various fragments in the formation of HOMO and LUMO orbitals resulting in efficient intramolecular charge transfer (ICT) and robust third-order NLO response properties of functionalized fullerene derivatives. The current study may arouse the attention of the scientific society to utilize the extensive π-conjugation of functionalized fullerenes for designing efficient NLO materials.

Novel microporous B6N6 covalent organic framework (COF) as an electrochemical sensor for the ultra-selective detection of nitroaniline isomers; a DFT outcome

The density functional theory (DFT) simulations are performed to study the sensitivity and selectivity of a novel (star shape) boron nitride two-dimensional covalent organic framework (B6N6) towards adsorption of toxic nitroaniline isomers. The binding energies of nitroaniline isomers onto the B6N6 material have been evaluated with hybrid B3LYP functional along with third order Grimme dispersion (D3) method in order to accurately account for dispersion effects. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) illustrate that weak van der Waals forces are the main contributor in stabilizing the reported complexes. The BSSE corrected binding energies of oNA, mNA and pNA on B6N6 are -15.42, -14.73 and -14.34 kcal/mol, respectively. These results reveal that the sensitivity and selectivity of B6N6 decreases in the order of oNA > mNA > pNA. The effect of aromaticity of nitro-aniline isomers in stabilizing the complexes is studied through the ring critical point (RCP) based on Bader atoms in molecule analysis. The sensitivity of B6N6 for nitroaniline isomers is further justified by the electronic properties. For example, the density of states (DOS) reveal that the new occupied energies states appear between original HOMO and LUMO orbitals of pristine B6N6 upon complexation with nitroaniline isomers. The newly generated occupied orbitals are closer to the Fermi energy level which increase the conductivity of B6N6, thus the significant amount of NBO charge transfer is noticed. The amounts of charge transfer in oNA@B6N6, mNA@B6N6 and pNA@B6N6complexes are 0.05, 0.09 and 0.05 e−, respectively. The percentage contribution of orbitals in charge transfer is estimated by the orbital composition analysis. Finally, the effect of increasing concentration of nitroaniline molecules on the sensing properties of B6N6 is also studied, which shows that the binding energies are less negative per molecule by increasing the number of nitroaniline units. The findings of this study reveal that the B6N6 star like COF material shows excellent sensing abilities for the toxic molecules. In summary, B6N6 material is a valuable addition with ultrahigh sensitivity as well as selectivity for future electrochemical sensor devices.

Synthesis and photophysical properties of tricyclic boron compounds. Experimental and theoretical study

The one pot reaction of 5-formyl-2-furanboronic acid, arylamines (aniline, 2-aminoanthracene or 1-aminopyrene) and aminophenol derivatives (2-aminophenol, 2-amino-5-chlorophenol or 2-amino-5-nitrophenol) yielded tricyclic boronate species, involving an open furan ring process. The boron compounds obtained have a π delocalized structural skeleton having photophysical properties. All seven compounds showed colorimetric properties in solvents with different dielectric constant, and the solvatochromic effect was denoted from the UV–vis spectra. Compounds also showed luminescence when irradiated with UV to 365 nm, nevertheless low fluorescence quantum yield in DMSO was observed (8–33%). Compounds present stability in DMSO solution up to for 96 h but degradation is recorded in THF solution in only 2.5 h. Computational studies were carried out using DFT/PBE1PBE for S0 state and TD-DFT/PBE1PBE for S1 state. The effect of solvent on transition wavelengths was simulated using the polarizable continuum model (PCM). It was observed that the substitution of the hydrogen atom by the chlorine atom stabilize the HOMO and LUMO levels, therefore, the transition energy values decrease for those orbitals in chlorophenol derivative compounds (3, 5 and 7), in comparison with the aminophenol analogues (2, 4 and 6). Furthermore, energy difference between the HOMO – LUMO orbitals decrease for structures having a major π conjugation extension, thus, the band gap energy for pyrene and anthracene derivatives is smaller than in phenyl derivatives.

Structural and spectroscopic analysis of the Cis-Trans isomers of the captopril in the gaseous and aqueous phases

• Cis and trans isomers of captopril found by scan around a dihedral angle. • Comparison of the molecular frontier orbitals and chemical descriptors of captopril. • Comparative analysis of captopril vibrational spectra in cis and trans conformations. • Comparative analysis of MEP and Mulliken charges distribution of captopril isomers. Captopril is a drug widely used in hypertension treatment. This molecule has two isomeric forms ( cis and trans ) according to the dihedral angle ω (O4C18N5C15). In the present study, we theoretically rotated the dihedral angle in steps of 5° in the range of -180° to 180°, using the DFT calculation with the functional B3LYP and the basis set 6–31 G ++(d, p) both in a gaseous environment and in an aqueous solution. In each environment, we were able to find a minimum energy structures, calculate the energy of the frontier orbitals (HOMO and LUMO) for the captopril in the gas phase and in aqueous solution, as well as calculate their vibrational spectra. When analyzing the HOMO and LUMO orbitals, all conformations presented HOMO around the sulfur atom. LUMO, on the other hand, presented a higher concentration around the aromatic ring and the carboxyl group, mainly in aqueous solution. Although trans conformers have a larger energy gap, the cis conformers showed a better reactive index. The cis and trans conformers showed similar MEP. In addition, the Raman and infrared spectroscopy proved to be an excellent technique to identify the isomeric form of the captopril molecule, observing the stretching modes of the carbonyl groups. The geometry and surfaces of the molecular potentials provide support for identifying the formation of the hydrogen bond.

The complexation of levofloxacin hemihydrate with divalent metal ions in aqueous medium at variable temperatures: Combined UV–Visible spectroscopic and DFT studies

Herein, we have studied the binding of levofloxacin hemihydrate (LFH) drug with different metal ions e.g., alkali earth metal ions and transition metal ions through spectrophotometry and Density Function Theory (DFT) studies. The binding constant (Kf) of LFH with alkali earth metal ions was observed to be increased with the boost of temperature while the opposite trend was observed in the case of transition metal ions. The Kf values were experienced to be reduced with the increase of size of the alkali earth metal ions. The Kf values in case of transition metal follow the order Cu2+ > Ni2+ > Co2+ > Zn2+. The Gibbs free energy (ΔG0) of binding values reveal that binding phenomena are spontaneous in nature. The values of enthalpy (ΔH0) and entropy (ΔS0) of binding suggest that hydrophobic interactions are the key forces for the binding of LFH and alkali earth metal ions while electrostatic, dipole-dipole, ion-dipole, and hydrogen bonding are the key forces in case of transition metal ions. The enthalpy-entropy compensation parameters were also estimated and explained in detail. From the DFT study, the bond lengths, bond angles, HOMO and LUMO orbitals energy, band gap, hardness, and the highest wavelengths of the drug/ drug-metal complexes have been calculated and explained with appropriate reasoning.

Luminescent cationic/neutral Cu(I) complexes for use in light-emitting diodes: Synthesis, structural characterization, DFT studies and properties

Cationic and neutral mononuclear Cu(I) complexes, [Cu(PPh 3 ) 2 (PmH)]BF 4 (1a), [Cu(DPEphos) (PmH)]BF 4 (2a), [Cu(Xantphos) (PmH)]BF 4 (3a), [Cu(PPh 3 ) 2 (Pm)] (1b), [Cu(DPEphos) (Pm)] (2b) and [Cu(Xantphos) (Pm)] (3b) (PPh 3 = triphenylphosphine, DPEphos = bis(2-diphenylphosphinophenyl)ether, Xantphos = 9, 9-dimethyl-bis(diphenylphosphino)xanthenes, PmH = 2-(pyridin-2-yl)benzimidazole, Pm=(2-(Pyridin-2-yl)benzimidazolate), have been prepared and characterized by IR, 1 H NMR, 13 C NMR, 31 P NMR, XRD, elemental analysis and X-ray crystal structure analysis. The structural analysis shows that each of Cu(I) complexes includes a tetrahedral [Cu(NN) (PP)] + moiety, and temperature variation from 99 K to 298 K leads to the change of bonds lengths, angles and weak interactions. Meanwhile, theoretical calculations indicate that the differences between cationic and neutral Cu(I) complexes affect the composition of HOMO and LUMO orbitals, and the effect of temperature on Mülliken atomic charges is limited. Furthermore, neutral Cu(I) complexes 1b–3b show better luminescence in comparison to cationic Cu(I) complexes 1a-3a at room temperature, and temperature variations from 99 K to 298 K result in changing photoluminescence to some extent, which partly agrees with the related calculation results. In these cationic and neutral Cu(I) complexes, the maximum phosphorescent lifetime and quantum yield reach respectively 137 μs and 42% at room temperature. Moreover, cationic and neutral Cu(I) complexes are utilized to fabricate the monochromatic LEDs, showing favorable electroluminescence with the maximum EQE of 7.10%. Crystal structures, theoretical calculation and luminescent properties of cationic/neutral mononuclear Cu(I) complexes are investigated at room temperature and different temperatures, and then these Cu(I) complexes are applied to light-emitting diodes. • Crystal structures, electronic and luminescent properties of cationic/neutral Cu(I) complexes are investigated. • In these Cu(I) complexes, the maximum room-temperature phosphorescent lifetime and quantum yield reach 137 μs and 42%, respectively. • All Cu(I) complexes are used for fabricating monochromatic LED devices, showing favorable electroluminescence.

A new Fe3+ colorimetric sensor: Nitrophenyl bispyrazole derivative synthesis using Fe3O4@SiO2@Si-Pr-NH-(CH2)2-NH2 and its DFT study

The efficient synthesis of bispyrazole derivatives was reported in the presence of Fe3O4@SiO2@Si-Pr-NH-(CH2)2-NH2 as a nanomagnetic catalyst in solvent-free conditions. The UV–Vis spectroscopy study of 4,4'-((3-nitrophenyl)methylene)bis(3-methyl-1H-pyrazol-5-ol) derivative 6a was demonstrated that it could be used as a Fe3+ ion colorimetric chemosensor, which was shown an apparent color change from white to orange with high selectivity toward the addition of Fe3+ ion in CH3CN/H2O (1:9 v/v) as a solvent. The UV–Vis absorption was increased linearly, and its detection limit was calculated 2.19 × 10−6 M.The orientations of hydroxyl groups for 5-membered and 6-membered rings of the most stable configurations of the bispyrazoles cause generation of T-shaped conformations based on Independent Gradient Model (IGM) analysis, conformational stability of the considered complexes can be related to the formation of σ-π molecular interaction heterocyclic rings which confirms with the vibrational stretching modes of hydroxyl groups and the character of the Kohn-Sham HOMO and LUMO orbitals.

Abnormal White-Matter Functional Connectivity of Generalized Tonic-Clonic Seizures in Resting and Motor-Task States

Cationic and neutral mononuclear Cu(I) complexes, [Cu(PPh3)2(PmH)]BF4 (1a), [Cu(DPEphos) (PmH)]BF4 (2a), [Cu(Xantphos) (PmH)]BF4 (3a), [Cu(PPh3)2(Pm)] (1b), [Cu(DPEphos) (Pm)] (2b) and [Cu(Xantphos) (Pm)] (3b) (PPh3 = triphenylphosphine, DPEphos = bis(2-diphenylphosphinophenyl)ether, Xantphos = 9, 9-dimethyl-bis(diphenylphosphino)xanthenes, PmH = 2-(pyridin-2-yl)benzimidazole, Pm=(2-(Pyridin-2-yl)benzimidazolate), have been prepared and characterized by IR, 1H NMR, 13C NMR, 31P NMR, XRD, elemental analysis and X-ray crystal structure analysis. The structural analysis shows that each of Cu(I) complexes includes a tetrahedral [Cu(NN) (PP)]+ moiety, and temperature variation from 99 K to 298 K leads to the change of bonds lengths, angles and weak interactions. Meanwhile, theoretical calculations indicate that the differences between cationic and neutral Cu(I) complexes affect the composition of HOMO and LUMO orbitals, and the effect of temperature on Mülliken atomic charges is limited. Furthermore, neutral Cu(I) complexes 1b–3b show better luminescence in comparison to cationic Cu(I) complexes 1a-3a at room temperature, and temperature variations from 99 K to 298 K result in changing photoluminescence to some extent, which partly agrees with the related calculation results. In these cationic and neutral Cu(I) complexes, the maximum phosphorescent lifetime and quantum yield reach respectively 137 μs and 42% at room temperature. Moreover, cationic and neutral Cu(I) complexes are utilized to fabricate the monochromatic LEDs, showing favorable electroluminescence with the maximum EQE of 7.10%.

Plant-Derived and Dietary Hydroxybenzoic Acids-A Comprehensive Study of Structural, Anti-/Pro-Oxidant, Lipophilic, Antimicrobial, and Cytotoxic Activity in MDA-MB-231 and MCF-7 Cell Lines.

Seven derivatives of plant-derived hydroxybenzoic acid (HBA)—including 2,3-dihydroxybenzoic (2,3-DHB, pyrocatechuic), 2,4-dihydroxybenzoic (2,4-DHB, β-resorcylic), 2,5-dihydroxybenzoic (2,5-DHB, gentisic), 2,6-dihydroxybenzoic (2,6-DHB, γ-resorcylic acid), 3,4-dihydroxybenzoic (3,4-DHB, protocatechuic), 3,5-dihydroxybenzoic (3,5-DHB, α-resorcylic), and 3,4,5-trihydroxybenzoic (3,4,5-THB, gallic) acids—were studied for their structural and biological properties. Anti-/pro-oxidant properties were evaluated by using DPPH• (2,2-diphenyl-1-picrylhydrazyl), ABTS•+ (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric-reducing antioxidant power), CUPRAC (cupric-reducing antioxidant power), and Trolox oxidation assays. Lipophilicity was estimated by means of experimental (HPLC) and theoretical methods. The antimicrobial activity against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Salmonella enteritidis (S. enteritidis), and Candida albicans (C. albicans) was studied. The cytotoxicity of HBAs in MCF-7 and MDA-MB-231 cell lines was estimated. Moreover, the structure of HBAs was studied by means of experimental (FTIR, 1H, and 13C NMR) and quantum chemical DFT methods (the NBO and CHelpG charges, electrostatic potential maps, and electronic parameters based on the energy of HOMO and LUMO orbitals). The aromaticity of HBA was studied based on the calculated geometric and magnetic aromaticity indices (HOMA, Aj, BAC, I6, NICS). The biological activity of hydroxybenzoic acids was discussed in relation to their geometry, the electronic charge distribution in their molecules, their lipophilicity, and their acidity. Principal component analysis (PCA) was used in the statistical analysis of the obtained data and the discussion of the dependency between the structure and activity (SAR: structure–activity relationship) of HBAs. This work provides valuable information on the potential application of hydroxybenzoic acids as bioactive components in dietary supplements, functional foods, or even drugs.

Synthesis and spectral characterization of new azo dye derived from benzimidazole and its complexation with selected transition metal ions

The preparation and spectral characterisation of 2-[6-(benzimidazolylazo)] as an organic heterocyclic azo dye compound containing benzimidazole. The reaction of benzimidazole diazoniumbromid with 2,4-dibromo phenol in alkaline alcoholic solution yielded -2,4-dibromo phenol (BIADBrP). Spectral analyses have been used to study the structure of the azo dye ligand such as H1NMR, mass spectrum,IR, UV-Vis and element analysis. New six complexes with CO(III), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) ions were prepared and identification by several physiochemical techniques; such as C.H.N element, magnatic susceptibility, atom absorption, molar conductivity, IR and electronic spectra. The used techniques showed the formation of all complexes 1:2 [M:L] complexes and suggested octahedral geometry with d2sp3 hybridization of Co(III) and sp3d2 with residulechelat complexes. The coordination number of the metal ion is found to be six with binding through the phenolate O, azo N3 and with the imidazole N3 atom. The stability, geometrical, and electrical features of metal complexes have also been studied theoretically. The energy levels of the ligand and metal complexes’ high occupied molecular orbital HOMO and low unoccupied molecular orbital LUMO were used to compute electrochemical potential, electrophilicity index, and chemical hardness.

Insights into the spectral, thermal and morphological effects of co-oligomerization of pyrrole with luminol: A comparative experimental and computational study

The present study reports for the first time, synthesis of co-oligomers of pyrrole with luminol via chemical polymerization technique. Co-oligomerization was investigated by 1H NMR, FTIR spectroscopic studies showed that oligomerization occurred after the monomer feed ratio which formed blocks, the later carrying the same monomer ratio as the feed ratio. By applying DFT method, optimized geometries of the oligomers and co-oligomers, distribution of HOMO and LUMO orbitals, Mulliken charge were computed. The same theory with the above basis set was used to compute Fukui’s indices: f+, f− and fo to find out nucleophilic, electrophilic, and free radical points of attack on luminol and pyrrole monomers as well as dimers. Thermal degradation of co-oligomers was explored by TGA/DTG methods which revealed prominent degradation peak of luminol moiety. Since the co-oligomer is unexplored, modification of the molecular structure as well as opto-electronic properties could be attempted for designing bioimaging agents.

Theoretical Study of The Reaction of Ketene with Methanimine Using DFT Method

&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;The Density Functional Theory (DFT) method was used to investigate the stepwise mechanism of the [2+2] cycloaddition (22CA) reaction of ketene with methanimine at the B3LYP/6-311++G(d,p) level of theory. Two modes of attack between reactants were investigated, yielding Azetidin-2-one from path1 and Azetidin-2-one from path2 as two possible products passing through two different transition states. The geometry of transition states and products was analysed. The study of stationary points and energetic parameters shows that the reaction mechanism is stepwise and that Azetidin-2-one P1 is thermodynamically and kinetically more favoured than Azetidin-3-one P2. The analysis of the frontier molecular HOMO and LUMO orbitals shows that the Azetidin-2-one P1 is more stable due to its higher energy gab. The global electronic flux from the strong nucleophilic ketene R1 to the methanimine R2 is predicted using conceptual density functional theory (CDFT) indices. Reactant’s electrophilic and nucleophilic Fukui functions were also investigated.

Oxovanadinum (IV) complexes with bidentate ligands synthesis, characterization, and comparison between experimental and theoretical

Four oxovanadium (IV) complexes with different ligands have been prepared and characterized by different spectral techniques such as (FTIR, UV–Vis., Mass) spectra, magnetic susceptibility, and DFT theoretical studies. Ligands used in this study were 8-hydroxyquinoline (HQ), oxalate (ox), dithiooximid (DTO), and 3-aminopyridine (APY). All the spectroscopic data and the theoretical calculations confirmed that the oxovanadium (IV) complexes are paramagnetic and have distorted square pyramidal structures. The FTIR spectra explain that the ligands were bidentate by (N, O), (O, O), (N, N) ligands, and monodentate (N-donor) 3-aminopyridine ligand. The mass spectral data confirmed that the complexes are mononuclear. Theoretical calculations of the free ligands and the prepared complexes have been done by using DFT calculations with proper basis sets for each other. The complexes were very stable and their energies ranged from (−775.86 to −1164.09 a.u.) and were very different from that of the free (HQ, ox, DTO and APY) ligands. The prepared complexes are more polar (5.69 to 15.54 Debye) than the free ligands. The HOMO orbitals energies of the complexes are ranged from (−0.098 to −0.392 a.u.), whereas the ligands are ranged from (−0.216 to −0.262 a.u.), and the LUMO orbitals energies of the oxocomplexes are ranged from (−0.007 to −0.296 a.u.)

Effect of fluorination on the adsorption properties of aromatic heterocycles toward methyl halides: A quantum chemical study

Despite the numerous publications describing the synthesis and electronic properties of fluorinated furan, thiophene and pyrrole, the systematic overview of their adsorption applications is still lacking. In this study, the effect of fluorination on the adsorption properties of furan (C4H4O), thiophene (C4H4S), pyrrole (C4H4NH) and benzene (C6H6) are investigated with the help of density functional theory (DFT) calculations. Herein, the adsorption energies of CH3X (X = F, Cl & Br) on C4H4O, C4H4S, C4H4NH and C6H6 and their fluorinated analogues are calculated using ωB97XD/6-31+G(d, p) level of theory. The results of the adsorption energies and symmetry adapted perturbation theory (SAPT0) reveal that the adsorption affinity of adsorbent is enhanced upon fluorination due to the increasing dispersion forces. To comprehensively investigate the variation in the electronic properties of nonfluorinated and fluorinated systems, the HOMO, LUMO orbitals and NBO charges are analyzed. The isosurfaces of orbitals show that the electron density is more localized onto the fluorinated adsorbents which are probably due to the presence of multiple electronegative fluorine atoms. Owing to the electron-withdrawing nature of fluorine, the electronic charges are transferred from CH3X to fluorinated adsorbents while the charges are shifted from nonfluorinated adsorbents to CH3X. Furthermore, the TD-DFT calculations reveal that the electronic transition energies are significantly decreased in most of the fluorinated complexes especially, CH3X@C4F4S and CH3X@C4F4NH. With these findings, it can be postulated that fluorine substitution can significantly surge the electronic and adsorption properties of sensor materials.

Theoretical Study on Understanding the Effects of Core Structure and Energy Level Tuning on Efficiency of Nonfullerene Acceptors in Organic Solar Cells

AbstractNonfullerene acceptors (NFAs) are a new focus in organic photovoltaics (OPVs), and continue to progress upon the drawbacks of many fullerene‐based electron acceptors. The aim of this work is to identify some important parameters that influence the efficiency of NF‐acceptors in OPVs. These results provide an enhanced understanding of the effect of the NFAs core structure (electron rich/poor group) on the photophysical and optoelectronic properties. In addition, the effect of the small ΔLUMO value (the subtle difference in energy between LUMO+1 and LUMO orbitals of NFAs; LUMO=lowest unoccupied molecular orbitals) on ultrafast charge transfer and charge separation processes in OPVs, recently identified as a key factor for all top rated high performing NFAs, is studied. So far, ΔLUMO‐based theoretical studies are limited to individual NFAs; here, for the first time, the authors have extended to the respective donor/acceptor complexes as well. Finally, based on the first‐principles density functional theory calculations with the seven reported NFAs, , P3HT, and the seven newly modeled donor–acceptor complexes, this study sheds light on important factors that will provide trends and guidelines for further rational design of more efficient NF‐acceptors for OPVs.

Complexation of free-base and 3d transition metal(II) phthalocyanines with endohedral fullerenes H@C60, H2@C60 and He@C60: The effect of encapsulated species

We studied theoretically the bonding of unsubstituted free-base phthalocyanine H2Pc and its 3d transition metal complexes MPc (MMn, Fe, Co, Ni, Cu, Zn) with endohedral non-metalofullerenes H@C60, H2@C60 and He@C60, by using PBE functional with Grimme's dispersion correction and DNP basis set. The calculated formation energies, geometries and electronic parameters (energies and distribution of HOMO and LUMO orbitals, electrostatic potential and spin density plots) were analyzed and compared to those of the dyads formed between the same series of unsubstituted Pcs and empty-cage C60. Particular differences were found in MnPc coordination pattern and the resulting frontier orbital distribution.