Lowest Unoccupied Molecular Orbital Energy Gap Research Articles

Molecular properties of a triazole-Ce(III) complex with antioxidant activity: structure, spectroscopy, and relationships with related derivatives. Influence of the ligands in the complex.

A novel Ce(III) complex with the triazole ligand 2b, which presents four H-bonded sites with amino acids of the MMP-2 receptor, was synthesized. The experimental IR and Raman spectra of this Ce(III) complex were well-interpreted based on their comparison to the theoretical scaled spectra using the scaling equations determined by two procedures and four density functional theory (DFT) levels. Therefore, the structure predicted for the synthesized Ce(III) complex was clearly characterized and confirmed. The potential antioxidant action of this complex was compared with the analogous La(III) complex, and it was found that the coordination of ligand 2b with Ce(III) improves the ligand's ability to participate in single-electron transfer (SET), as observed in the ABTS·+ assay, and this complex seems to scavenge the stable radical much more actively compared to its La(III) counterpart. Additionally, interactions with potassium superoxide and sodium hypochlorite indicate a high pro-oxidant behavior of the complex. The effects of different ligands on the geometric parameters, atomic charges, and molecular properties of the Ce(III) complex were analyzed at four DFT levels, and several relationships were clearly established. These relationships can facilitate the selection of new ligands with improved properties in the design of novel lanthanide-triazole carboxylate complexes with promising biological activity. The ligand size increase in the complexes facilitates the electronic transfer of negative charge, and the low HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap indicates a large reactivity and low energy for their excitation.

Exploring Electronic and Conformational Attributes of an Organic Donor‐Bridge‐Acceptor Molecular System

AbstractThis research explores the electronic properties and conformational dynamics of the ZnP‐COPV‐ (Zinc Porphyrin ‐ Carbon bridged Oligo Phenylenevinylene ‐ Fullerene) organic semiconductor via specialized Density Functional Theory (DFT) and Molecular Dynamics (MD) computational techniques. First, through DFT calculations, essential HOMO (Highest Occupied Molecular Orbital), LUMO (Lowest Unoccupied Molecular Orbital), and Molecular Electrostatic Potential (MEP) electronic attributes are meticulously dissected providing insights into the intricate charge transfer processes between the constituent donor‐acceptor moieties. Furthermore, MD simulations are employed to unveil the molecular system's multifaceted conformational flexibility and stability. The Root‐mean‐squared deviation (RMSD), end‐to‐end distance, and torsional angles quantitative analysis of conformational attributes support the carbon‐bridged oligo‐phenylenevinylene (COPV) molecular wire's ‐skeleton planar and rigid conformation. This minimal end‐to‐end distance variation (within Å) compared to the initially extended structure and the constrained torsional motion (within for ZnP‐COPV and for COPV‐) after thermalization showcases COPV's ability to maintain structural rigidity over time, aligning with the concept of effective ‐conjugation. Finally, through the lens of time dependent (TD)‐DFT, the dynamic evolution of the HOMO–LUMO energy gap, TD‐DFT excitation energies and oscillator strengths are explored as the molecular structure transforms over time. The observed energy gap variation underscores the molecule's adaptability in the face of structural modifications, hinting at an intriguing connection between structural stability and enhanced electronic properties. The research provides a comprehensive understanding of the intricate interplay between conformational dynamics and electronic attributes in organic semiconductors, providing quantitative insights crucial for designing stable, high‐performance materials for cutting‐edge optoelectronic applications and helping advance the collective understanding of sustainable energy conversion.

Polarizable Continuum Models and Green's Function GW Formalism: On the Dynamics of the Solvent Electrons.

The many-body GW formalism, for the calculation of ionization potentials or electronic affinities, relies on the frequency-dependent dielectric function built from the electronic degrees of freedom. Considering the case of water as a solvent treated within the polarizable continuum model, we explore the impact of restricting the full frequency-dependence of the solvent electronic dielectric response to a frequency-independent (ϵ∞) optical dielectric constant. For solutes presenting small to large highest-occupied to lowest-unoccupied molecular orbital energy gaps, we show that such a restriction induces errors no larger than a few percent on the energy level shifts from the gas to the solvated phase. We further introduce a remarkably accurate single-pole model for mimicking the effect of the full frequency dependence of the water dielectric function in the visible-UV range. This allows a fully dynamical embedded GW calculation with the only knowledge of the cavity reaction field calculated for the ϵ∞ optical dielectric constant.

Spectroscopic (FT-IR, FT-Raman, NMR and UV–vis), quantum calculation, molecular structure, solvent interaction, ADME and molecular docking investigation on 4-oxo-4h-1-benzopyran-2-carboxylic acid

The present work, spectroscopic and quantum computational study has been carried out for the molecule 4-oxo-4H-1-benzopyran-2-carboxylic acid. The stable conformer of the title molecule was identified using Potential Energy Surface (PES) scan. The structural and geometrical parameters of the stable conformer of the molecule were determined by Density Functional Theory (DFT) using B3LYP method along with the basis set 6-311++G(d,p) through Gaussian 09 W software. The theoretical and experimental investigations such as Vibrational (FT-IR and FT-Raman), UV–visible and NMR analysis were done. The FT-IR were recorded in the region of (4000–400 cm−1) and FT-Raman in the region of (4000–100 cm−1), and the vibrational bands were compared with the theoretical values. Carbon NMR and Proton NMR spectra have been analyzed in DMSO solution. The theoretical chemical shift values were determined using Gauge Independent Atomic Orbital (GIAO) method. The intermolecular and intra-molecular bonding of orbitals and transfer of charge were studied using the Natural Bond Orbital (NBO) analysis. The respective transitional study was done through UV–vis's spectra and theoretical values predicted using TD-DFT (Time Dependent – DFT) method for both gas and solvent (ethanol) state. HOMO (Highest Occupied Molecular Orbital) – LUMO (Lowest Unoccupied Molecular Orbital) energy gap results prove the exchange of charges inside the molecule. Molecular Electrostatic Potential (MEP) is used to identify the nucleophilic and electrophilic sites of the molecule. To check the bioactive nature of the title molecule the drug-likeness was determined. Molecular docking is used to analyze the biological activity of the title molecule. The distribution of torsional angles in a protein structure is viewed by the Ramachandran plots of the molecules.

Significance of anchoring group design on light harvesting efficiency of dye-sensitized solar cells and non-linear optical response

Dye-sensitizers designed from coumarin backbone are widely utilized in solar light harvesting due to their versatile performance in dye-sensitized solar cells (DSSC). They are well-known as non-linear optical (NLO) materials. In this case study, we have designed coumarin-based sensitizers containing thiophene as a common spacer with the different acceptor-anchoring groups, ethyl-2-cyanoacrylate (SPDSSC 1) and 2-cyanoacrylic acid (SPDSSC 2). Density functional theory (DFT) and time-dependent- DFT (TD-DFT) computational calculations of these molecules predict superior light harvesting capability and NLO properties. The calculated HOMO–LUMO energy gap of these dyes showed an inverse relation with chemical potential and electrophilicity index and was directly related to hardness and hyperhardness. It was also seen β0 and γ and PCE follow a similar trend. Further, computations of sensitizers@TiO2 indicated sensitizers with ethyl-2-cyanoacrylate bonded with TiO2 cluster via unidentate linkage, whereas 2-cyanoacrylic acid containing sensitizer involved bidentate bonding with TiO2. Apart from this, sensitizers with 2-cyanoacrylic acid anchors showed much planer geometry. Also, the quantitative analysis of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) and MEP plots showed that more electron clouds shifted to the TiO2 cluster in the sensitizer with 2-cyanoacrylic acid (SPDSSC 2) than ethyl-2-cyanoacrylate (SPDSSC 1). Further, both molecules were taken as sensitizers in the DSSC device. SPDSSC 2 showed higher power conversion efficiency than SPDSSC 1. Overall, results disclosed that sensitizers with ethyl-2-cyanoacrylate having two oxygen atoms in their anchoring part could bind with only carbonyl oxygen. And this monodentate binding of ethyl-2-cyanoacrylate with TiO2 leads to poor charge transfer in the semiconductor's conduction band, resulting in poor DSSC performance.

Unveiling controlling factors of the S0/S1 minimum-energy conical intersection (3): Frozen orbital analysis based on the spin-flip theory.

Conical intersections (CIs), which indicate the crossing of two or more adiabatic electronic states, are crucial in the mechanisms of photophysical, photochemical, and photobiological processes. Although various geometries and energy levels have been reported using quantum chemical calculations, the systematic interpretation of the minimum energy CI (MECI) geometries is unclear. A previous study [Nakai et al., J. Phys. Chem. A 122, 8905 (2018)] performed frozen orbital analysis (FZOA) based on time-dependent density functional theory (TDDFT) at the MECI formed between the ground and first electronic excited states (S0/S1 MECI), thereby inductively clarifying two controlling factors. However, one of the factors that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap became close to the HOMO-LUMO Coulomb integral was not valid in the case of spin-flip TDDFT (SF-TDDFT), which is frequently used as a means of the geometry optimization of MECI [Inamori et al., J. Chem. Phys. 152, 144108 (2020)]. This study revisited the controlling factors using FZOA for the SF-TDDFT method. Based on spin-adopted configurations within a minimum active space, the S0-S1 excitation energy is approximately represented by the HOMO and LUMO energy gap ΔεHL, a contribution from Coulomb integrals JHL″ and that from the HOMO-LUMO exchange integral KHL″. Furthermore, numerical applications of the revised formula at the SF-TDDFT method confirmed the control factors of S0/S1 MECI.

Quantum chemical and experimental studies on the extraction of acid blue 80 and acid red 1 from their aquatic environment using tetrabutylammonium bromide based deep eutectic solvents

In this study, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy, HOMO–LUMO energy gap, chemical potential (µ), electronegativity (χ), electrophilicity index (ω), global hardness (η), and global softness (s) of dyes; acid blue 80 (AB80), acid red 1 (AR1) and deep eutectic solvents: tetrabutylammonium bromide with glycerol {[TBAB][Gly]}, tetrabutylammonium bromide with decanoic acid {[TBAB][DA]} and tetrabutylammonium bromide with oleic acid {[TBAB][OA]} were predicted and calculated using quantum chemical calculation. The polarity of all the studied molecules also predicted in terms of screening charge density and plotted sigma profile and sigma potential. Further, the extraction experiment was conducted for the extraction of acid blue 80 (AB80) and acid red 1 (AR1) using tetrabutylammonium bromide with decanoic acid {[TBAB][DA]} and tetrabutylammonium bromide with oleic acid {[TBAB][OA]} as the potential solvent. The process was characterized by means of distribution coefficient and efficiency. Finally, the extraction process feasibility was studied and discussed in terms of and

Molecular dynamics, transport property, and surface stoichiometry of plasma polymerized cyclohexane thin films

The properties of cyclohexane (CHex) and plasma polymerized cyclohexane (PPCHex) thin films are studied, and the results are compared with those obtained using a computing model (under the density functional theory framework). Quantum chemical calculations are performed to calculate their molecular electrostatic potential (MEP), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gaps, thermodynamic stability, chemical reactivity, and vibrational properties. The HOMO–LUMO energy gap sharply decreased in the case of the PPCHex thin film compared to that of CHex. Gibbs free energy shows a similar phenomenon where the enthalpy of PPCHex (formation) is almost six times higher than that of CHex. The computed FTIR spectra indicate good agreement with the experimental results. RMS roughness shows a smooth surface, and it is compared with the FESEM image. Moreover, the dielectric constant and electrical conductivity of the PPCHex thin films are also studied.

One Pot Efficient Synthesis of 1,3-di(Naphthalen-1-yl)Thiourea; X-Ray Structure, Hirshfeld Surface Analysis, Density Functional Theory, Molecular Docking and In-Vitro Biological Assessment

1,3-di(Naphthalen-1-yl)Thiourea was synthesized in good yield from a cheaper amine through one pot synthesis technique. The exact structure was elucidated with single crystal X-ray Diffraction. In silico studies in terms of Hirshfeld analysis, density functional theory and molecular docking were carried out. The thiourea was optimized with hybrid functional B3LYP method and 6-31G(d,p) basis set. Bond angles and bond lengths determined from XRD were compared with these obtained from DFT and are in close agreement to each other. The HOMO (highly occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy gap is 4.915 eV. In 2D fingerprinting analysis (Hirshfeld), H∙∙∙H contacts are responsible for the stability of the crystalline structure. The antibacterial studies against five different strains depicted good potential of the thiourea toward tested bacteria. The enzyme inhibition potential of the compound was determined against esterase which concluded that understudied molecule has ability to inhibit both enzymes with good efficiency. Furthermore, docking analysis also supported the spectrophotometric results of the compound toward enzyme inhibition. On the basis of the biological studies either in term of wet or dry lab, it was concluded that synthesized compound has much potential to use as therapeutic agent in the future.

Computational Design of Rhenium(I) Carbonyl Complexes for Anticancer Photodynamic Therapy.

New Re(I) carbonyl complexes are proposed as candidates for photodynamic therapy after investigating the effects of the pyridocarbazole-type ligand conjugation, addition of substituents to this ligand, and replacement of one CO by phosphines in [Re(pyridocarbazole)(CO)3(pyridine)] complexes by means of the density functional theory (DFT) and time-dependent DFT. We have found, first, that increasing the conjugation in the bidentate ligand reduces the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gap of the complex, so its absorption wavelength red-shifts. When the enlargement of this ligand is carried out by merging the electron-withdrawing 1H-pyrrole-2,5-dione heterocycle, it enhances even more the stabilization of the LUMO due to its electron-acceptor character. Second, the analysis of the shape and composition of the orbitals involved in the band of interest indicates which substituents of the bidentate ligand and which positions are optimal for reducing the HOMO–LUMO energy gap. The introduction of electron-withdrawing substituents into the pyridine ring of the pyridocarbazole ligand mainly stabilizes the LUMO, whereas the HOMO energy increases primarily when electron-donating substituents are introduced into its indole moiety. Each type of substituents results in a bathochromic shift of the lowest-lying absorption band, which is even larger if they are combined in the same complex. Finally, the removal of the π-backbonding interaction between Re and the CO trans to the monodentate pyridine when it is replaced by phosphines PMe3, 1,4-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA), and 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP) causes another extra bathochromic shift due to the destabilization of the HOMO, which is low with DAPTA, moderate with PMe3, but especially large with CAP. Through the combination of the PMe3 or CAP ligands with adequate electron-withdrawing and/or electron-donating substituents at the pyridocarbazole ligand, we have found several complexes with significant absorption at the therapeutic window. In addition, according to our results on the singlet–triplet energy gap, all of them should be able to produce cytotoxic singlet oxygen.

Quantum Chemical Analysis of the Corrosion Inhibition Potential by Aliphatic Amines.

Destructive corrosion processes lead to the loss of primary mechanical properties of metal construction materials, which generates additional costs during their maintenance connected with repairs and protection. The effectiveness of corrosion inhibitors can be determined by using many methods, in particular quantum chemical modeling. The subject of the theoretical analyses presented in this work involves the anticorrosion properties of amines with various chemical structures. Evaluation of the corrosion inhibition properties of selected amines was performed on the basis of the HOMO–LUMO energy gap, dipole moment (µ), electronegativity (χ) determined as a result of the energy of the highest occupied molecular orbital (HOMO) and the energy of the lowest unoccupied molecular orbital (LUMO). Moreover, the HSAB (Hard and Soft Acids and Bases) theory was used to explain the reactivity of the analyzed amines, while the Mulliken population analysis was used to determine their electrostatic interactions with the surface of protected metal. The obtained results indicate that the protonation reaction of aliphatic amines leads to a change in the nature of the formation of a coordination bond with the surface of the protected metal. In turn, the quantum chemical calculations showed that the protonation reaction of aliphatic amines leads to a decrease in their corrosion inhibition efficiency. Most of the analyzed parameters indicated that tertiary amines are characterized by the highest corrosion inhibition efficiency.

Facile synthesis of aminoalkyl naphthols and single crystal X-ray, computational studies on 1-[morpholino(thiophen-2-yl)methyl]naphthalen-2-ol

• One-pot, three-component organic synthesis. • Single crystal XRD confirms the formation of compound. • Crystalized compound compared with the theoretical calculation of DFT. • The HOMO–LUMO energy gap reveals the chemical stability of the compound. An efficient, eco-friendly protocol is developed for the synthesis of 1- (α-aminoalkyl)-2-naphthol derivatives via one-pot three-component reaction of 2-naphthol, aromatic aldehydes and piperidine or morpholine in the presence of Amberlite IRA-400 Cl resin as a catalyst. This approach carries characteristics of one-pot synthesis, high yield, and mild, clean reaction conditions with the recyclable catalyst. One of the products ( 4p ), crystalized in trigonal crystal system with P32 space group, was obtained and compared with the theoretical calculation of popular Density Functional Theory (DFT), B3LYP/6-311++G(d,p) basis set. The energy of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) was calculated. All theoretical calculations agree with the experimental values.

Molecular docking and density functional theory studies of potent 1,3-disubstituted-9H-pyrido[3,4-b]indoles antifilarial compounds

The interaction of three potent antifilarial compounds (4C, 4F, and 3F) with filarial proteins thioredoxin, glutathione s-transferase and cyclophilin were investigated using molecular docking and density functional theory (DFT) studies. Molecular docking was performed using YASARA tool, Hex 8.0.0 Cuda tool and PatchDock server and docked complex were visualized by Discovery Studio 3.0. The predicted binding energy of antifilarial compounds 4C (−247.6, −243.8, −256.8 kcal mol−1), 4F (−242.6, −246.4, −232.4 kcal mol−1) and 3F (−272.4, −248.5, −277.7 kcal mol−1) with filarial protein 4FYU, 5D73, and 1A33, respectively. Docking results were strongly supported by molecular dynamics data and molecular mechanics-generalized born surface area (MM-GBSA) calculations. The optimized geometries of all three compounds were used for calculating the energies of the frontier molecular orbitals highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The lowest HOMO–LUMO energy gap in compound 3F suggested that it is the most bioactive molecule among all these three compounds, which is in accordance with the docking results of these compounds. The interaction energies between ligand and protein are mainly due to hydrogen bonds, hydrophobic interactions, and van der Waals interactions which give the stability to the complex. The structural information and docking studies of different filarial proteins with antifilarials obtained from this study could aid in screening and designing new antifilarial or selective inhibitors for chemotherapy against filariasis.

Experimental and Theoretical Studies of a Spirostannole and Formation of a Pentaorganostannate.

A new spirostannole, 1,1′,3,3′-tetrakis(5-methylthiophen-2-yl)-4,4′,5,5′,6,6′,7,7′-octahydro-2,2′-spirobi[benzo[c]stannole] (4), is synthesised and the molecular structure is compared with the optimised geometry from DFT calculations. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are twice degenerated and show a small HOMO–LUMO energy gap of 3.2 eV. In addition, cyclic voltammetry measurements are conducted and three redox processes are observed. Absorption and emission spectra show maxima at λabs,max 436 nm and λem,max 533 nm, respectively. Spirostannole 4 is a strongly absorbing material, but an extremely weak emitter in solution at 295.15 K. However, when the solution is cooled from 280 to 80 K, the emission becomes visible. The reaction of spirostannole 4 with methyllithium is monitored by NMR spectroscopy at 238.15 K. The 119Sn{1H} NMR signal shifts from −36.0 (4) to −211.0 ppm, which is indicative of the formation of the lithium pentaorganostannate 5. The complex is thermally instable at 295.15 K, but insights into the molecular structure and electronic behaviour are obtained by DFT and TD-DFT calculations.

Designing of benzodithiophene core-based small molecular acceptors for efficient non-fullerene organic solar cells.

Nowadays, organic solar cells (OSCs) with non-fullerene electron acceptors provide the highest efficiencies among all studied OSCs. To further improve the efficiencies of fullerene-free organic solar cells, end-capped acceptor modification is made with strong electron withdrawing groups. In this report, we have theoretically designed five new novel Benzodithiophene core-based acceptor molecules (H1-H5) with the aim to study the possible enhancement in photophysical, optoelectronic, and photovoltaic properties of newly designed molecules. The end-capped acceptor modification of famous and recently synthesized FBDIC molecule has been made with strong electron withdrawing groups. Density functional theory and time-dependent-density functional theory are extensively used to study the structural-property relationship, optical properties and various geometrical parameters like frontier molecular orbitals alignment, excitation and binding energy, transition density matrix along with open circuit voltage, density of states and dipole moment. Commonly, low reorganization energies (hole and electron) afford high charge mobility and our all designed systems are enriched in aspect (λe=0.0044-0.0104eV and λh=0.0060-0.0090eV). Moreover, H1-H5 molecules demonstrate red-shifting in absorption spectrum (λmax=741-812nm) as compare to R (λmax=728nm). Low excitation and binding energies with low HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap of H1-H5 suggested that designed molecules are better and suitable candidates for high performance organic solar cell. Results of all analysis indicate that this theoretical framework demonstrates that end-capped acceptors modification is a simple and effective alternative strategy to achieve the desirable optoelectronic properties. Therefore, H1-H5 are recommended to experimentalist for out-looking future developments of highly efficient solar cells.

Theoretical Analysis on Heteroleptic Cu(I)-Based Complexes for Dye-Sensitized Solar Cells: Effect of Anchors on Electronic Structure, Spectrum, Excitation, and Intramolecular and Interfacial Electron Transfer.

Two groups of heteroleptic Cu(I)-based dyes were designed and theoretically investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Different anchors were integrated into the dye skeleton to shed light on how the type of anchor influenced the electronic structure, absorption spectrum, electron excitation, and intramolecular and interfacial electron transfer of dyes. The results indicated that, compared with other dyes, the dyes with cyanoacrylic acid and nitric acid exhibited more appropriate electron distributions in frontier molecular orbitals (FMOs), lower HOMO (the highest occupied molecular orbital) –LUMO (the lowest unoccupied molecular orbital) energy gaps, broader absorption spectral ranges as well as improved spectral characteristics in the near-infrared region and better intramolecular electron transfer (IET) characteristics with more electrons transferred to longer distances, but smaller orbital overlap. Among all the studied Cu(I)-based dyes, B1 and P1 (with cyanoacrylic acid anchoring group) exhibited the best interface electronic structure parameters with a relatively short electron injection time (τinj) and large dipole moment (μnormal), which would have a positive effect on the open-circuit photovoltage (Voc) and short-circuit current density (Jsc), resulting in high power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Our findings are expected to provide a new insight into the designing and screening of high-performance dyes for DSSCs.

Synthesis, Single Crystal X-Ray Structure, Hirshfeld Surface Analysis, DFT Computations, Docking Studies on Aurora Kinases and an Anticancer Property of 3-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-6-methoxy-4H-chromen-4-one

The isoflavone compound 3-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-6-methoxy-4H-chromen-4-one (6) was prepared and structurally characterized using NMR, mass spectrum and X-ray crystallography. Compound 6, C18H14O5, was crystallized in the monoclinic space group P21/n with the cell parameters; a = 7.1869(4) Å, b = 10.2764(6) Å, c = 19.6771(10) Å, β = 99.442(2)°, V = 1433.57(14) Å3, Z = 4. In the title compound, the chromenone ring system is slightly twisted from planarity and the dihedral angle formed between the plane of the chromenone ring and benzene ring is 47.75°. Several intermolecular hydrogen bonds make the crystal stabilized in the three-dimensional structure, which was confirmed by Hirshfeld surface analysis. Density functional theory (DFT) calculations at the B3LYP/6-311++G(d,p) level were carried out and the calculated geometric parameters were compared with the experimental results. A frontier molecular orbital calculation was performed to reveal that the energy values of highest occupied molecular orbital (HOMO) and lowest un-occupied molecular orbital (LUMO) were −5.8223 eV and −1.8447 eV, and the HOMO–LUMO energy gap was 3.9783 eV. A clonogenic long-term survival assay of compound 6 against HCT116 human colon cancer cells showed an anti-cancer ability, with GI50 value of 24.9 μM. Docking experiments within the active sites of aurora kinase A and B were carried out to explain the anti-cancer property of compound 6.

Photophysical and Electrocatalytic Properties of Rhenium(I) Triazole-Based Complexes

A series of [Re(N^N)(CO)3(Cl)] (N^N = diimine) complexes based on 4-(pyrid-2-yl)-1,2,3-triazole (1), 1-benzyl-4-(pyrimidin-2-yl)-1,2,3-triazole (2), and 1-benzyl-4-(pyrazin-2-yl)-1,2,3-triazole (3) diimine ligands were prepared and their photophysical and electrochemical properties were characterized. The ligand-based reduction wave is shown to be highly sensitive to the nature of the triazole-based ligand, with the peak potential shifting by up to 600 mV toward more positive potential from 1 to 3. All three complexes are phosphorescent in solution at room temperature with λmax ranging from 540 nm (1) to 638 nm (3). Interestingly, the complexes appear to show inverted energy-gap law behaviour (τ = 43 ns for 1 versus 92 ns for 3), which is tentatively interpreted as reduced thermal accessibility of metal-centred (3MC) states from photoexcited metal to ligand charge transfer (3MLCT) states upon stabilisation of the N^N-centred lowest unoccupied molecular orbital (LUMO). The photophysical characterisation, supported by computational data, demonstrated a progressive stabilization of the LUMO from complex 1 to 3, which results in a narrowing of the HOMO–LUMO energy gap (HOMO = highest occupied molecular orbital) across the series and, correspondingly, red-shifted electronic absorption and photoluminescence spectra. The two complexes bearing pyridyl (1) and pyrimidyl (2) moieties, respectively, showed a modest ability to catalyse the electroreduction of CO2, with a peak potential at ca. −2.3 V versus Fc/Fc+. The catalytic wave that is observed in the cyclic voltammograms is slightly enhanced by the addition of water as a proton source.

Identification of Potential Carbonic Anhydrase Inhibitors for Glaucoma Treatment Through an In-Silico Approach

Glaucoma is a neurodegenerative disease and second leading cause of blindness in western world. The disease is characterized by an elevated intraocular pressure. Carbonic anhydrase plays a major role by forming aqueous humor and its inhibition can reduce intraocular pressure by partially suppressing the secretion of aqueous humor. Thus in this study, we proposed to identify the potential novel compounds targeting the carbonic anhydrase. The diversity set-II molecules library consisting of 1880 compounds from National Cancer Institute were virtually screened (molecular docking) against human carbonic anhydrase protein. For the obtained best compounds, the nature of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), which determine nucleophilic and electrophilic activity, were calculated by using density functional theory (DFT). The in silico screening suggested 5 best compounds that are effective in comparison to the dorzolamide, a widely used carbonic anhydrase inhibitor for glaucoma treatment. Of the five compounds, 4-nitro-7-[(1-oxidopyridin-1-ium-2-yl) thio] benzofurazan (ZINC01757986) exhibited the better binding affinity (− 9.2 cal/mol) in comparison to dorzolamide (− 7.2 kcal/mol). The DFT studies on novel identified compound, ZINC01757986 exhibited less HOMO–LUMO energy gap, low hardness and more softness (0.2305 eV, 0.1152 eV and 8.6805 eV) when compared to dorzalamide (0.9536 eV, 0.4768 eV and 2.0973 eV). These studies emphasize that ZINC01757986 can be used as potential carbonic anhydrase inhibitor and lead compounds for the development of an effective anti-glaucoma drug. The results emphasize that these compounds could be potential lead molecules for further structure-based discovery of antiglaucoma drugs.

Structured water chains in external electric fields

ABSTRACTWe study the structural, energetic and electronic properties of the structured water chain clusters within the density functional theory. We refer the structured water chains to those water clusters that have specific geometric patterns stretched along one direction. External electric field required to keep the structures open chain, thereby preventing them to form closed structures, is applied along the length of the chain. The structures are essentially periodic with basic repeating unit consisting of the corner- or edge-sharing 4-, 5- or 6-membered ring water clusters. Our calculations underscore the possible existence of such structured water clusters in the electrostatic environments, which we simulate in its simplicity employing a dipolar, uniform and static electric field. Analysis reveals that the 5-membered ring water chain clusters, i.e. the pentamer chain clusters have the lowest average dipole moment per water molecule while the threshold field, that marks the onset of the field-induced closure of the HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap, is highest, followed by that for the tetramer and hexamer chains. The results suggest that the pentamer chains are the most stable clusters over a wide range of electric fields.