LUMO Orbitals Research Articles

Rearrangement of Diferrocenyl 3,4-Thiophene Dicarboxylate

Treatment of 3,4-(ClC(O))2-cC4H2S (1) with [FcCH2OLi] (2-Li) (Fc = Fe(η5-C5H5)(η5-C5H4)) in a 1:2 ratio gave 3,4-(FcCH2OC(O))2-cC4H2S (3). Compound 3 decomposes in solution during crystallization to produce FcCH2OH (2) along with 3,4-thiophenedicarboxylic anhydride (4). The cyclic voltammogram of 3 exhibits a reversible ferrocene-related redox couple (E1/2 = 108 mV, vs. Cp2Fe/Cp2Fe+) using [NnBu4] [B(C6F5)4] as the supporting electrolyte. DFT calculations reveal that the energy values of the LUMO orbitals of 3 (3,4-thiophene core) show 1 eV higher energies than that one of 2,5-(FcCH2OC(O))2-cC4H2S (5), both compounds’ HOMO orbitals are close to each other. Compound 4 was characterized by single X-ray structure analysis. It forms a band-type structure based on intermolecular O1···S1 interactions being parallel to (110) and (1–10) in the solid state, while electrostatic C···O interactions between the C=O functionalities of adjacent molecules connect both 3D-networks. Hirshfeld surface analysis was used to gain more insight into the intermolecular interactions in 4, the enrichment ratios (E) suggest that O···H, S···S, and O···C are the most favored intermolecular interactions, as shown by E values above 1.20. The relevance of the weak O···H, O···O, and O···C contacts in stabilizing the molecular structure of 4 was highlighted by the interaction energies between molecular pairs.

Regulating the excited state behaviors of 2-benzooxazol-2-yl-4,6-di-tert-butyl-phenol fluorophore by solvent polarity: A theoretical simulation

• The enhanced hydrogen bonding provides the impetus to promote the ESIPT reaction. • Photo-induced increased electronic densities around N atom plays vital roles in attracting hydroxyl proton. • Non-polar solvents are more favorable for the ESIPT behavior of BDTBP compound. In view of the unique luminescent characteristics, ESIPT materials have attracted lots of eyes. Given promising highly efficient green-emitting material, 2-benzooxazol-2-yl-4,6-di- tert -butyl-phenol (BDTBP) reveals important properties in designing Schiff base optical sensors. In this work, solvent dependent excited state behavior and ESIPT process of BDTBP has been explored theoretically. Analyses of chemical structural variations and infrared (IR) vibrational spectra in both S 0 and S 1 state, the enhanced intramolecular hydrogen bonding interactions could be clearly found that promotes ESIPT tendency. Particularly, BDTBP in nonpolar solvents with stronger hydrogen bond reveals the easier PT tendency. Paying attention to the changes of HOMO and LUMO orbitals, it could be found the charge transfer happens in the excited-state molecules, the reorganization of charge densities should be conducive to promoting the ESIPT process. Simulated potential energy curves indicated the ultrafast ESIPT reaction occurs for BDTBP fluorophore, which could be regulated and controlled via solvent polarity.

Ab initio study for superior sensitivity of graphyne nanoflake towards nitrogen halides over ammonia.

Graphyne (GYN) has received immense attention in gas adsorption applications due to its large surface area. The adsorption of toxic ammonia and nitrogen halides gaseous molecules on graphyne has been theoretically studied at ωB97XD/6-31 + G(d, p) level of DFT. The counterpoise corrected interaction energies of NH3, NF3, NCl3, and NBr3 molecules with GYN are - 4.73, - 2.27, - 5.22, and - 7.19kcalmol-1, respectively. Symmetry-adapted perturbation theory (SAPT0) and noncovalent interaction index (NCI) reveal that the noncovalent interaction between analytes and GYN is dominated by dispersion forces. The significant change in electronic behavior, i.e., energies of HOMO and LUMO orbitals and NBO charge transfer correspond to the pronounced sensitivity of GYN towards considered analytes, especially NBr3. Finally, TD-DFT calculation reveals a decrease in electronic transition energies and shifting of adsorption to a longer wavelength. The recovery time for NX3@GYN is observed in nanoseconds, which is many orders of magnitude smaller than the reported systems. The recovery time is further decreased with increasing temperature, indicating that the GYN benefits from a short recovery time as a chemical sensor.

Computer Aided Drug Design of 1,2,3-Triazole Fused Bioactive Derivative Targeting Glucosamine-6-Phosphate Synthase (GlmS) – XRD, Computational Crystallography, and Molecular Simulation Approach

The crystal structure of a 1,2,3-triazole fused heterocyclic derivative 2-(1-Benzyl-5-methyl-1H-1,2,3-triazol-4-yl)-4-(2,4-dichlorophenyl)-6-phenyl pyridine (DICLPY; 4h) is reported. The structural characterization is done by single crystal X-ray technique. The Hirshfeld surfaces (HS) and 2D fingerprint graphs are generated to investigate the inter atomic contacts contribution for structure by CrystalExplorer 17.5 program. The pairwise interaction energies between neighboring molecules are computed at the B3LYP/6-31G(d,p) method. This interaction energy analysis showed that the total stability of the DICLPY structure is mainly contributed by the dispersion force factor followed by the coulomb potential force factor. The DFT-based HOMO, LUMO orbitals and molecular electrostatic potential map are studied to identify the reactivity of our molecule. In-silico molecular docking technique is used to inspect the DICLPY compound as a possible antibacterial agent by docking with Glucosamine-6-phosphate synthase protein (PDB ID: 2VF5) using PyRx and AutoDock Vina programs. The molecular dynamics simulation is performed to examine the physical movement of our molecule DICLPY with Glucosamine-6-phosphate synthase protein for 100 ns time period. MD simulation revealed the greater stability of DICLPY and Glucosamine-6-phosphate synthase protein complex during the simulation period.

Donor acceptor groups effect, polar protic solvents influence on electronic properties and reactivity of 2-Chloropyridine-4-carboxylic acid

The computational reckoning of 2-Chloropyridine-4-carboxylic acid (2CP4CA) was accomplished employing DFT/B3LYP with the root set as 6–311++G(d, p). The impact of polar protic solvents which are eco-friendly solvents (water, methanol, ethanol, 1-propanol) on 2CP4CA were analysed. To examine the solvent effect, vibrational investigations and NLO reports of 2CP4CA in dissimilar solvents were executed. Geometrical properties were also established in gas phase for 2CP4CA. Exercising VEDA program, the entire vibrational assignment was accomplished. Donor-acceptor exchanges were ascertained utilizing NBO scrutiny technique. Thermodynamic properties of 2CP4CA were analysed at different temperatures. By applying TD - DFT approach, theoretic UV–Vis absorption spectrum was procured in different solvents. In order to evaluate the complete electron concentration and sensitive spots of 2CP4CA, MEP coupled with FMO analyses were employed. HOMO along with LUMO orbitals and energy band gap were acquired for 2CP4CA employing dissimilar polar protic solvents. Additionally, ELF, LOL and charge transfer studies were also executed. RDG analysis has been exercised for revealing non-covalent interactions.

Multi-component self-assembled heteroleptic Cu(I) complex with defective coordination site as a fluorescent probe to detect Zn2+

Heteroleptic copper(I)–phosphine complexes have attracted considerable attention due to their diverse structures and photophysical properties. In this work, a novel heteroleptic binuclear copper (I) complex C1·2BF4ˉ was designed and synthesized by using hexaazatriphenylene (L1) and 4, 5-Bis(diphenylphosphino)-9, 9-dimethylxanthene (dppd) as functional ligands. Such dinuclear structure with defective site was fully characterized by NMR, single-crystal X-ray diffraction analysis, and electron spray ionization mass spectrometry (ESI-MS). UV-vis and fluorescence spectrum revealed that the well-defined Cu(I) complex had a green emission at 518 nm in acetonitrile solution, and a red emission at 824 nm in the solid state. The DFT calculation demonstrated that the energy gap between LUMO and HOMO orbitals reached 1.20 eV. Furthermore, such heteroleptic Cu(I) complex showed high sensitivity and selectivity towards Zn2+ in acetonitrile solution in “turn-on” mode, which can be attributed to the coordination interaction between Zn2+ and defective binding site of probe C1·2BF4−. The LOD for Zn2+ was calculated to be 0.298 µM, and the reversible “on-off” fluorescence sensing behavior can be recovered by alternative treatment with EDTA tetrasodium and Zn2+ salts in solution. The Cu(I) complex probe C1·2BF4ˉ had reversible redox property with weak electrochemical responses towards Zn2+ ions.

Experimental and Computational Structural Studies of 2,3,5-Trisubstituted and 1,2,3,5-Tetrasubstituted Indoles as Non-Competitive Antagonists of GluK1/GluK2 Receptors.

The blockade of kainate receptors, in particular with non-competitive antagonists, has—due to their anticonvulsant and neuroprotective properties—therapeutic potential in many central nervous system (CNS) diseases. Deciphering the structural properties of kainate receptor ligands is crucial to designing medicinal compounds that better fit the receptor binding pockets. In light of that fact, here, we report experimental and computational structural studies of four indole derivatives that are non-competitive antagonists of GluK1/GluK2 receptors. We used X-ray studies and Hirshfeld surface analysis to determine the structure of the compounds in the solid state and quantum chemical calculations to compute HOMO and LUMO orbitals and the electrostatic potential. Moreover, non-covalent interaction maps were also calculated. It is worth emphasizing that compounds 3 and 4 are achiral molecules crystallising in non-centrosymmetric space groups, which is a relatively rare phenomenon.

Designing of the indacenodithiophene core-based small molecules for optoelectronic applications: A DFT approach

With the intention of utilizing computational methods to amplify the photovoltaic ability of organic solar cells, DFT (density functional theory) and TD-DFT (time-dependent density functional theory) methods were employed on five newly-designed indacenodithiophene based A-D-A (acceptor–donor-acceptor) type small molecules. These (IDT1-IDT5) non-fullerene acceptor-based molecules have a central core of the O-IDTBR molecule with the substitution of different substantial acceptors on the peripheral edges. The optical parameters, electrical properties, and charge transfer abilities of these molecules were carefully analyzed through MPW1PW91/6-31G (d, p) method. Some optical, as well as chemical, parameters of IDT1, IDT4, and IDT5 were found to be superior to the reference molecules. It was also revealed from the frontier molecular orbitals (FMOs) and density of states (DOS) graphs that newly attached acceptor groups significantly enhanced the distribution of charge density in the molecules under study, especially in IDT1. The ability to consistently transfer charges was disclosed through the TDM graphs. The charge transfer mobilities of some of the molecules being comparable to the reference molecule, with that of IDT2 being the lowest, envisioned better maneuverability of the charge carriers. The open-circuit voltage of the IDT1 with PC61BM acceptor and all others with PTB7-Th donor was calculated, given that IDT1 having higher HOMO and LUMO orbitals will act as an acceptor, vice versa. Lastly, the high values of fill factor predicted remarkable power conversion efficiency of all the investigated molecules. Consequently, all the computed parameters commend the ability of our modified molecules in the field of photovoltaics.

Heteroleptic Copper(I) complexes of bipyridine glycoluril and phosphine ligands: Photophysical and computational studies

A series of heteroleptic copper(I) complexes of the type [Cu(bpg)(PP)]PF6 (1–4) have been synthesized where bpg = [4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f] [1,10]-phenanthroline-6,13-dione] and PP are phosphine derived ancillary ligands (triphenyl phosphine (PPh3), 1,2 bis(diphenylphosphino)ethane (dppe), bis[(2-diphenylphosphino)phenyl]ether (POP) and 1,3 bis(diphenylphosphino)propane (dppp)). All copper(I)-phosphine complexes were thoroughly characterized by elemental analyses, IR, 1H NMR, 13C NMR, 31P NMR and ESI-MS, UV–visible, emission spectroscopy and DFT calculations. The crystal structure of 1 contains two Cu(I) molecules in asymmetric unit which localizes in distorted tetrahedral geometry with N2P2 coordination core. The UV–visible spectra indicated that ancillary phosphine ligands significantly affect the MLCT band of the copper(I) complexes. The bands in the UV–visible spectra fit well with the TD-DFT calculations and are assigned to the contribution of HOMO-2 → LUMO, HOMO-1 → LUMO and HOMO → LUMO orbitals. These Cu(I) complexes exhibit green emission in CH2Cl2 at room temperature with emission wavelengths at 545–572 nm. Cyclic voltammetric data revealed that steric hindrance of diphosphine ligands affected the oxidation potential of Cu(I) complexes.

5-Methoxy-1-methyl-2-{[4-(2-hydroxyphenyl)piperazin-1-yl]methyl}-1Hindole (KAD22) with Antioxidant Activity

: Compound KAD22 (5-methoxy-1-methyl-2-[4-(2-hydroxyphenyl)piperazin-1-yl]methyl-1H-indole) was designed as a potential dopamine D2 receptor agonist with antioxidant activity for possible treatment of Parkinson’s disease. The compound was obtained from 5-methoxy-1-methyl-1H-indole-2-carbaldehyde and 2-(piperazin-1-yl)phenol. KAD22 showed no affinity to dopamine D2 receptor but it is a potent antioxidant. Experimental and computational structural studies (conformational analysis, HOMO and LUMO orbitals, electrostatic potential map, non-covalent interaction plot, spectral properties, ligand-receptor interactions) of KAD22 were performed to address its biological activity.

DFT Simulation of Geometry and Electronic Structure of Fullerenol - Cisplatin Conjugate as Agent of Cancer Therapy

Fully optimized structures of the fullerenol (Fl=C60(OH)24) - cisplatin conjugate (Fl + Cis) were obtained using the DFT simulation. The DFT/B3LYP/SV/Lanl2DZ level of theory has been used. From the results of calculation of the structural parameters, it can be concluded, that the interaction of Fl with Cis in vacuum leads to the increase of the Pt-N bond length compared to the result for Cis and decrease of the Pt-Cl bond length. The solvation effect for the Fl + Cis complex leads to the decrease of the Pt-N bond length compared to the result for vacuum and increase of the Pt-Cl bond length compared to the result for vacuum and increase of the Pt-Cl bond length compared to the result for vacuum. From the results of the calculation of structural parameters for the Fl with Cis conjugate, it can be concluded that the Pt-N bond in the aqueous solution is enhanced while the Pt-Cl bond is weakened, which can affect the biological activity of the Cis in this complex. The influence of the localization of HOMO and LUMO orbitals on the biological activity of the conjugate under consideration was analyzed. The paper presents the results of DFT simulation of the atomic and electronic structure of water-soluble cisplatin conjugate derivatives and nanocarbon structures, such as fullerenol Fl, as well as the results of studying the possible mechanisms of their biological activity.

Sensing behaviour of monocyclic C18 and B9N9 analogues toward chemical warfare agents (CWAs); quantum chemical approach

This study describes the first demonstration of using monocyclic C18 and B9N9 as active materials for the sensing and removing of chemical warfare agents (CWAs) such as formaldehyde (Fd), phosgene (Ph), and thiophosgene (TPh). The sensitivities and adsorption capacities of both C18 and B9N9 analogues toward considered molecules are thoroughly characterized by optimized geometries, energetic stabilities, electronic behaviour, and optical properties at the M05-2X-D3/6-31++G(d,p) method of density functional theory (DFT). In the complexes, the analytes interact through the active cavity of the monocyclic (ring) systems. It is found from the BSSE corrected energies that the adsorption of analytes on B9N9 is energetically more favorable than that on C18. Based on the adsorption energies, the sensitivity of surfaces toward formaldehyde and phosgene is higher than the thiophosgene molecule. The adsorption energies of Fd@B9N9, Ph@B9N9 and Thp@B9N9 complexes are −7.47, −7.45, and −4.96 kcal mol−1, respectively which is about 2.19, 1.56, and 0.69 kcal mol−1 exothermic than Fd@C18, Ph@C18, and Thp@C18 complexes, respectively. Symmetry adapted perturbation theory (SAPT0), reduced density gradient (RDG) and quantum theory of atoms in molecule (QTAIM) results illustrate that dispersion forces play an important role in stabilizing these complexes. The variations of the electronic properties are explained based on HOMO LUMO orbitals, the density of state (DOS), NBO charge transfer, and UV-Vis analysis. The significant variations in the electronic parameters reveal that CWAs can bind more strongly with these ring systems which is more pronounced in B9N9. Therefore, these monocyclic systems may be considered a potential candidate for sensor application.

Synthesis and Structural Characterization of a New 1,2,3-Triazole Derivative of Pentacyclic Triterpene

The new 30-substituted triazole derivative of 3,28-O,O′-diacetylbetulin was obtained in the copper(I) catalyzed azide-alkyne cycloaddition (CuAAC). The title compound was characterized by NMR, IR, HR-MS, and X-ray diffraction techniques. The X-ray diffraction study showed that the 1,2,3-triazole derivative crystallizes in the orthorhombic space group P212121, Z = 4, and unit cell parameters are as follows a = 9.4860(10) Å, b = 13.9440(2) Å, and c = 30.2347(4) Å. The molecular packing is stabilized by intermolecular hydrogen interactions C-H…O. The Hirshfeld surface analysis showed the presence of the O…H interactions with a percentage of the 16.5% in the total Hirshfeld area. The MEP analysis showed that the nucleophilic regions are located near the oxygen atoms of the acyl and carbonyl groups of betulin moiety and the sulfur atom in the triazole linker. The HOMO and LUMO orbitals are located near the triazole moiety. The obtained results indicated that this new betulin derivative is more reactive with electrophilic than nucleophilic molecules.

Electronic transitions in noncovalent BODIPY dimers: TD-DFT study

Theoretical computations have been performed on the absorption spectra of (8-R-TMB)2 dimers with varying character of substituents at the 8 position (meso) at monomers units (R = NH2, OH, CH3, H, COH, CF3, CN). The obtained results (TD-CAM-B3LYP) show that the first four lower transitions of studied dimers (S0 → Si, i = 1–4) are intrinsically linked with delocalized HOMO and LUMO orbitals of the two monomers, which constitute a dimer. For all the dimers, S0 → S1 and S0 → S3 transitions are strongly forbidden, whereas S0 → S2 and S0 → S4 are allowed. There is a good agreement between the TD-CAM-B3LYP theory and the simple model of exciton coupling for two identical chromophores with the planes of two moieties, which are stacked upon each other. Intensities of the allowed transitions depend strongly on the nature of the substituent at the meso position. For the dimers with monomer units bearing electron-donor groups, S0 → S2 transitions are more intense compared with S0 → S4 ones. As the donor properties of the meso substituents diminish and electron acceptor properties enlarge, the intensity of these transitions becomes lower, whereas that of S0 → S4 transitions becomes higher. For the dimers with NH2 and CN substituents, the almost inverse ratio of intensities of the transitions discussed is observed (for example, f = 0.80 and 0.06 (in the case of NH2) and f = 0.09 and 0.72 (CN) for S0 → S2 and S0 → S4, respectively). Protonation of the tertiary amine function drastically ‘switches off’ its electron-donating properties. As a result, the red shift of the bands and redistribution of intensities of the allowed S0 → S2 and S0 → S4 transitions is predicted for protonated forms of the (8-NH2-TMB)2 dimer. This peculiarity can be of especial importance for the design of dimers with a sensor function.

Dioxomolybdenum (VI) and oxomolybdenum (IV) complexes with N, O, and S bidentate ligands, syntheses, spectral characterization, and DFT studies

Two dioxomolybdenum (VI) complexes with the chemical formula [MoO2(acac)(HPY)], [MoO2(DTO)(HPY)], and oxomolybdenum (IV) complexes [MoO(acac)(HPY)], [MoO(DTO)(HPY)] have been prepared and characterized by different spectral techniques such as (FTIR, UV-Vis., Mass, 1H NMR) spectra, magnetic susceptibility, and theoretical studies. The ligands used in this study were acetylacetone, 2-hydrazinopyridine, and dithiooximid. The spectroscopic data and the theoretical calculations suggested distorted octahedral structures for the dioxomolybdenum(VI) complexes. The dioxomolybdenum(VI) complexes were diamagnetic. The oxomolybdenum(IV) complexes are paramagnetic and have distorted square pyramidal structures. Theoretical calculations of the free ligands and the prepared complexes have been done by using DFT calculations using (G 09 W) software. The complexes were very stable and their energies ranged from (−708.85 to −921.99 a.u.) whereas the free (HPY) and (DTO) ligands were (−359.06 and −984.54 a.u.), respectively. The prepared complexes are polar (8.11–10.80 Debye) for Mo(VI), and (6.63–13.72 Debye) for Mo(IV). The HOMO orbital energies of the Mo(VI) complexes are (−0.229, and −0.377 a.u.), respectively whereas for the Mo(IV) complexes are (−0.192, −0.318 a.u.), respectively while for the (HPY) and (DTO) ligands are (−0.216, −0.262 a.u.). The LUMO orbitals energies of the Mo(VI) complexes are (−0.124, and −0.247 a.u.) and for the Mo(IV) are (−0.093, −0.208 a.u.), respectively.

Theoretical investigation of the complexation, structural, and electronic properties of complexes between oseltamivir drug and cucurbit[n = 6–9]urils

The structural geometries of cucurbit[n]uril CB[n] with n = 6–9 and their complexes with oseltamivir (OST) drug were obtained using the density functional theory computations. The stationary points of the most stable complexes were confirmed using vibrational frequency calculation. The complexation energies and electronic properties of CB[n]/OST complexes were investigated. The calculated results indicate that the intermolecular interactions in all the studied complexes occur via a large number of dipole–dipole interactions, especially hydrogen bonds between oxygen atoms of CB[n] and hydrogen atoms of amine of oseltamivir drug. The negative complexation energies of CB[n]/OST complexes in both gas and water phases indicate that the host–guest complexes are exothermic process and the complexes are more stable than its bare CB[n]. In addition, the CB[7]/OST complex is more stable than that of all studied CB[n]/OST complexes. The frequency calculation results of the most stable complexes for each of CBs indicate that complexations occur via a spontaneous process. The NBO analysis of complexes shows the transferring of partial charge from CB[n]s to oseltamivir which correspond to their MEP contours. The HOMO and the LUMO orbitals are localized on the oseltamivir in CB[n]/OST complexes. After drug complexation, the electronic properties also display that the energy gaps of CB[n] are significantly changed. All of the complexation properties point out that CB[n]s can act as a host for appropriately oseltamivir guest, even in aqueous solution.

Syntheses, crystal structures, antibacterial activities and non-linear optical properties based on DFT calculation of two substituted benzyl piperidinium salts tetrahalogenated copper(II)

This paper presents the syntheses, composition analysis and structural characterization of two ionic complexes, [4NO2BzPid]2[CuX4] ([4-NO2BzPid]+= 4-nitro-1-benzylpiperidinium, X = Cl(1) and Br(2)). Two complexes crystallize in chiral space group P6(4)(No. 172), and comprise two [4NO2BzPid]+cations and a [CuX4]2– anion in which the piperidine ring shows a boat structure while the [CuX4]2– anion exhibits a tetrahedron geometry. The intermolecular energy, the energy gap between the HOMO and LUMO orbitals, and the first hyperpolarizability were carried out based on the DFT calculation. The low energy gap (2.24 ev for 1 and 2.01 ev for 2) explains the eventual charge transfer interactions taken place between the [CuX4]2−anion and [4NO2BzPid]+cation. The first hyperpolarisability (βtot) of two salts is 9.3 and 16.0 times greater than that of the standard KDP crystal showing that two complexes are good materials for NLO application. The results of antibacterial experiments show that two complexes exhibit good bactericidal activity for S. aureus and E. coli.

Density Functional Theory Calculation of Electronic Structure of Fe-N-C, Fe-O-C, Fe-P-C, Fe-S-C Single-atom Catalysts Systems

Single atom catalysts (SACs) have emerged as a novel class of heterogeneous catalysts which exhibit superior catalytic performance in various reaction, CO oxidation, CO2 conversion, oxygen reduction reaction (ORR), etc. It is challenging to explore electronic structure and catalytic mechanics of SACs when the single metal atom is bonding with different dopants via experimental methods, which influence the catalytic efficiency directly. In this paper, Density Functional Theory (DFT) calculations, an ab initio simulation methods, have been carried out to investigate the properties of Fe-N-C, Fe-O-C, Fe-P-C, and Fe-S-C with oxo or hydroxyl group, four common SACs models. Geometry structure of Fe-N-C, Fe-O-C, Fe-P-C, Fe-S-C, and after each has bonded with oxo or hydroxyl group are studied. Formation energy of the Single Atom Catalyst (SAC), oxygen formation energy, and hydrogen atom transfer energy of the four SACs models are also calculated. In order to investigate the electronic structure of the four SACs, we examined the HOMO LUMO gap values for each system. In addition, we plotted the corresponding HOMO and LUMO orbitals of each SACs models and with oxo or hydroxyl group. Through analyzing the data, I anticipated that Fe-N-C model is the easiest to synthesis and the most stable among the four models. Our work discloses the microscopic property of SACs and provides valuable suggestions to experimental scientists.

On the experimental and theoretical calculations of rotameric conformations of a new Schiff base derived from amantadine

Herein, the condensation of amantadine with the aldehyde piperonal resulted in a new Schiff base (1). This molecule was fully characterized by elementary analysis, infrared (IR), ultraviolet-visible (UV-Vis), 13C, 1H nuclear magnetic resonance (NMR) and high-resolution mass spectroscopy, logP (logarithm of partition coefficient), as well as single-crystal X-ray diffraction (SCXRD). The crystal structure crystallizes in the triclinic P1¯ space group with only one molecule of the Schiff base in the asymmetric unit, presenting the adamantane ring disordered over two positions. The crystal self-assembly is stabilized by weak interactions, such as analyzed by Hirshfeld surface. Using the DFT calculation, an energy barrier of 9.075 kcal.mol−1 was found between the two complementary conformations observed experimentally to the adamantane group. The computed infrared spectra (in vacuum and solution) are in good agreement with the experimental data. The energy of the HOMO orbitals was also calculated, in which energy values ​​range -7.4030–7.6027 eV, while LUMO orbitals are in the range of -0.3610–0.5717 eV, in which the polar solvents promoted greater stabilization in the border orbitals. The chemical potential (μ) from 3.467 to 3.520 eV indicate that the structure is stable. The magnitude of the chemical hardness (η) [6.934–7.041 eV] suggests the resistance to deformation of the electronic cloud over small electrostatic disturbances, showing that the system is not very polarizable. This result can be useful to further studies to investigate the coordination ability of compound 1 with hard metal ions.

Synthesis, characterization and SOD activity of bisbenzimidazole-based copper(II) complexes

Three bisbenzimidazole-copper(II) coordination complexes, [Cu(MIDB)(NO3)(CH3OH)](NO3) (1), [Cu(MIDB)(H2O)2](NO3)2 (2), and [Cu(ODB)2](ClO4)2 (3) (MIDB =N-methyl bis(benzimidazol-2-ylmethyl) amine; ODB = bis(2-benzimidazolylmethyl) ether), were synthesized and characterized. The component ions in their crystals are linked by N-H...O, O-H...O, C-H...π and π...π interactions into three-dimensional networks which are quantitatively manifested by the Hirshfeld surface analysis. Their frontier molecular orbital compositions and natural charge population were conducted theoretically at the DFT/(UB3LYP)/6-31G+(d, p) level for the copper coordination units, indicating that the HOMO and LUMO orbitals are mainly contributed by the benzimidazole groups and the coordination bonds are stabilized by the delocalized stabilization energy between the lone-pair bonding orbitals from N and/or O atoms and the lone-pair anti bond orbitals of the copper center. The cyclic voltammetry showed irreversible one-electron redox reactions for the three complexes in DMF solutions. SOD activity of 1 (IC50=1.34 µM) was slightly better than that of 3 (IC50=1.36 µM) by using the NBT method.