Lowest Unoccupied Molecular Orbital Values Research Articles

Exploration of Coumarin Derivative: Experimental and Computational Modeling for Dipole Moment Estimation and Thermal Sensing Application.

The Optical properties of the FBTC (1-((4-((5-chlorobenzo[d]oxazol-2-ylthio)methyl)-1H-1,2,3-triazol-1-yl)methyl)-3H-benzo[f]chromen-3-one) molecule were studied experimentally and theoretically. The spectra of absorption and fluorescence were recorded in various solvents to explore their Solvatochromic behavior and dipole moment at room temperature. To determine the ground and excited state of dipole moment experimentally and theoretically, we employed different Solvatochromic techniques, including microscopic solvent polarity functions developed by Lippert, Bakhshiev, Kawaski-Chamma-Viallet, and Reichardt's, as well as density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The stability of the excited state dipole moment in FBTC is higher. Using prime functional, FBTC was optimized in its ground state, and its HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital), energies were estimated. These values were then compared with those obtained through cyclic voltammetry. Based on the HOMO and LUMO values given, we calculated the global reactivity parameter and energy gap, which was found to be low at 3.77eV. This study also includes an estimation of electron absorption energies and oscillator strength. Natural population analysis (NPA), Milliken atomic charge, and molecular electrostatic potential (MESP) map are correlated. In addition, FBTC exhibited exceptional physiological temperature sensing behaviour from 20°C -65°C with high relative sensitivity and firm stability. Hence these results confirm that FBTC is a potential candidate for photonic devices and it's also applicable in optical temperature sensing.

Designing of novel organic semiconductors materials for organic solar cells: A machine learning assisted proficient pipeline

Typical research design associated with organic solar cells (OSCs) is conventionally considered time-consuming and laborious because the selection of the materials as the core, pi-acceptor, and terminal groups required for the engineering of these devices is done via hit and trial methodology. The advanced data-driven approaches, particularly machine learning (ML), have materialized as the robust technique for identifying the organic materials for the fabrication of the OSCs devices. The key parameters of highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and maximum absorption wavelength (λmax) were selected for developing the ML models. The molecular descriptor associated with each parameter was investigated and the relative contribution of the understudy descriptors in the training of the ML model was studied by using the relative importance test. The Hist gradient boosting (HGB) model exhibited the best results for performing the predictive analysis of all three parameters. Moreover, the chemical database was constructed based on the academic literature to develop the high-performance OSCs devices, and the trained HGB model was applied to predict the HOMO, LUMO, and λmax values for these newly designed OSCs devices. Synthetic accessibility of designed molecules is also predicted which revealed that the suggested new organic molecules can be easily commercialized via experimentation. Highly encouraging results in terms of the understudy key parameters were acquired by this ML approach indicating that the data-driven approaches hold extreme potential for engineering high-performance OSCs devices.

Imidazopyridine chalcones as potent anticancer agents: Synthesis, single-crystal X-ray, docking, DFT and SAR studies.

New imidazopyridine-chalcone analogs were synthesized through the Claisen-Schmidt condensation reaction. The newly synthesized imidazopyridine-chalcones (S1-S12) were characterized using spectroscopic and elemental analysis. The structures of compounds S2 and S5 were confirmed by X-ray crystallography. The global chemical reactivity descriptor parameter was calculated using theoretically (DFT-B3LYP-3-211, G) estimated highest occupied molecular orbital and lowest unoccupied molecular orbital values and the results are discussed. Compounds S1-S12 were screened on A-549 (lung carcinoma epithelial cells) and MDA-MB-231 (M.D. Anderson-Metastatic Breast 231) cancer cell lines. Compounds S6 and S12 displayed exceptional antiproliferative activity against lung A-549 cancer cells with IC50 values of 4.22 and 6.89 µM, respectively, compared to the standard drug doxorubicin (IC50 = 3.79 μM). In the case of the MDA-MB-231 cell line, S1 and S6 exhibited exceptionally superior antiproliferative activity with IC50 of 5.22 and 6.50 μM, respectively, compared to doxorubicin (IC50 = 5.48 μM). S1 was found to be more active than doxorubicin. Compounds S1-S12 were tested for their cytotoxicity on human embryonic kidney 293 cells, which confirmed the nontoxic nature of the active compounds. Further molecular docking studies verified that compounds S1-S12 have a higher docking score and interacted well with the target protein. The most active compound S1 interacted well with the target protein carbonic anhydrase II in complex with pyrimidine-based inhibitor, and S6 with human Topo IIα ATPase/AMP-PNP. The results suggest that imidazopyridine-chalcone analogs may serve as new leads as anticancer agents.

Spectroscopic analysis of 2-amino-1-naphthalenesulfonic acid, molecular docking, and evaluation of the electronic properties of several solvents

The spectral properties of 2-amino 1-naphthalene sulfonic acid were investigated using Fourier transform infrared, Raman, and ultra violet-visible techniques as well as density functional theory. Employing the distribution of potential energy, extensive analysis of vibrational spectrum assignments has been performed. Natural bond orbital was used to study the interactions between the donor and acceptor. The molecular electrostatic potential is used to quantify the visual bio-active portions of the molecule. The computed highest occupied molecular orbital and lowest unoccupied molecular orbital values for different solvents indicates the electron stimulation features. Elucidation of localized orbital locator, electron localization function, reduced density gradient, electron-hole distribution analysis, and drug-likeness are also executed. As revealed by molecular docking research, substituents that target amino acids have antiviral action.

Ambipolar Behavior of a Cu(II)–Porphyrin Derivative in Ternary Organic Solar Cells

Ternary architecture is a promising strategy to achieve high efficiency in organic solar cells. The alignment of third‐component frontier orbitals with those of donor and acceptor (D and A) is of essential importance. Herein, a new molecule VC11, consisting of a Cu(II)–porphyrin core linked to dicyanovinylene terminal acceptor units through (E)‐1,2‐di(thiophen‐2‐yl) ethene bridges, is described. The highest occupied molecular orbital and lowest unoccupied molecular orbital values of VC11 are −5.52 and −3.74 eV, respectively, lying between the corresponding values of PBDB‐T donor and Y6 acceptor, compounds used in the construction of the studied devices. The measured electron and hole mobilities reveal similar values, in the order of 10−4 cm2 Vs−1, indicating the ambipolarity of VC11, that can be used as donor or acceptor. The organic solar cells (OSCs) based on PBDB‐T:VC11, VC11:Y6, and PBDB‐T:Y6 show power conversion efficiencies (PCEs) of 10.84%, 7.89%, and 11.98%, respectively. VC11 is utilized along with PBDB‐T and Y6 to form a ternary active layer for assembling bulk heterojunction OSCs affording a remarkable PCE of 15.25%, significantly higher than those obtained for the corresponding binary devices. This enhancement of PCE originates from the additional charge separation offered by a cascaded energy‐level alignment and a fast charge transfer, due the ambipolarity of VC11.

Theoretical insight on the electronic structure and photophysical properties of three blue cyclometalated Ir(III) complexes based on the benchmark complex FIrpic

The electronic and photophysical properties of three blue cyclometalated Ir(III) complexes have been investigated by using the density functional theory (DFT) and time dependent density functional theory (TDDFT) methods. Both HOMO and LUMO values of complexes 1, 2 and 3 are in the order of 1 > 2 > 3. The lowest-lying singlet absorption for 1, 2 and three attributed to the configurations of the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) with the d(Ir)+π(A)→π*(A) [MLCT/ILCT] character. Complexes 1, 2 and three possess almost the same phosphorescence wavelength and transition characters.

Recent Advances in Molecular Design of Organic Thermoelectric Materials

Recent Advances in Molecular Design of Organic Thermoelectric Materials

P-Type Chemical Doping-Induced High Bipolar Electrical Conductivities in a Thermoelectric Donor–Acceptor Copolymer

P-Type Chemical Doping-Induced High Bipolar Electrical Conductivities in a Thermoelectric Donor–Acceptor Copolymer

Development of electrochemical and optoelectronic performance of new 7-{[1H-indol-3-ylmethylidene]amino}-4-methyl-2H-chromen-2-one dye

A new 7-{[1H-indol-3-ylmethylidene]amino}-4-methyl-2H-chromen-2-one dye (3) was synthesized by the reaction of 7-amino-4-methyl coumarin with indole-3-carbaldehyde in EtOH using GAA as a catalyst. The photophysical properties of the synthesized compound were studied using UV-visible and photoluminescence spectrophotometer. Redox onset potential for the dye compound was recorded through a cyclic voltammogram (CV), which aids to calculate the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) values. The experimental and theoretical HOMO–LUMO values were calculated using the density functional theory (DFT). Moreover, the I-V characteristics were evaluated by two-sense Keithley source in dark and light medium by using a mercury lamp as a light source. The results of the I-V study showed that the compound (3) possesses good light-absorbing capability with a high molar absorption extinction coefficient (0.80 × 10−5 Ɛ). Therefore, the I-V characteristics suggest the efficiency of obtained dye for photovoltaic uses.

Computational studies of ionic liquids as co-catalyst for CO2 electrochemical reduction to produce syngas using COSMO-RS

Transforming carbon dioxide (CO2) into value-added products through electrochemical reduction reaction (CO2ERR) is a promising technique due to its potential advantages using renewable energy. The main challenge is to find a stable catalytic system that could minimize the reaction overpotential with high faradaic efficiency and high current density. Ionic liquids (ILs) as electrolyte in CO2ERR have attracted attention due to the advantages of their unique properties in enhancing catalytic efficiency. For better performance, a systematic understanding of the role of ILs as electrocatalyst is needed. Therefore, this paper aims to correlate the performance of ILs as co-catalyst in (CO2ERR) with the lowest unoccupied molecular orbital (LUMO) energy level and the interaction energy as predicted by quantum chemical calculation using Conductor like Screening Model for Real Solvents (COSMO-RS) and Turbomole. The results show strong linearity (R2=0.98) between hydrogen bond energy (HB) and LUMO values. It is demonstrated that as HB increases, the LUMO value decreases, and the catalytic activity for CO2ERR also increases. This result allows further understanding on the correlation between the molecular structure and the catalytic activity for CO2ERR. It can serve as a priori prediction to aid in the design of new effective catalysts.

Novel synthesis, structure characterization, DFT and investigation of the optical properties of cyanine dye/zinc oxide [4-CHMQI/ZnO]C nanocomposite thin film

A novel synthesis of (E)-4-(4-carboxy-3-hydroxystyryl)-1-methylquinolin-1-ium iodide nanostructure thin film has been doped with zinc oxide nanoparticles to study the optical properties of nanocomposite films. Different characterization techniques for nanocomposite film such as Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, x-ray diffraction, scanning electron microscopy and optical properties have been used. The scanning electron microscopy showed a good dispersion of zinc oxide nanoparticles on nanocomposite film surface. The dielectric constant and optical conductivity increased and demonstrated wave-like performance with increasing zinc oxide nanoparticles ratio at hν range of 0.7eV – 5.0 eV. zinc oxide nanoparticles content increases lead to the formation of a wide variety of three dimension-semiconductor networks within nanocomposite film matrix which increase optical conductivity. The density functional theory by thee dimension molecular simulation software and Cambridge serial total energy package was used for optimization of novel cyanine dye and nanocomposite as isolated molecule. From the ultraviolet–visible spectrum of nanocomposite thin film, the direct and indirect optical energy gap values are 2.041 eV and 1938 eV by using Tauc`s equation, respectively, related to direct and indirect transitions of electrons. By using thee dimension molecular simulation software mothed with density functional theory simulation, the highest occupied molecular orbital and lowest unoccupied molecular orbital values for nanocomposite as isolated molecule are 4.735 eV and 3.531 eV, respectively. The simulated Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, x-ray diffraction and optical properties by Gaussian software and Cambridge serial total energy package are in great agreement with the experimental study. A successful choice for optoelectronics and solar cell applications are the novel cyanine dye thin film and its nanocomposite.

Structure-based drug design of peroxisome proliferator-activated receptor gamma inhibitors: ferulic acid and derivatives

Peroxisome proliferator-activated receptor gamma (PPARγ), ligand-activated transcription factor, is a key modulator of genes considered in diabetes development as well as treatment. Adipogenesis differentiation through PPARγ, CCAAT-enhancer protein alpha (C/EBPα) is identified as a critical mechanism in fat accumulation and weight gain. Polyphenols studied against adipocyte differentiation is taken up for consistent support and drug discovery. Structure-based drug design found useful to distinguish the underlying mechanism of receptor–ligand interaction and function. In this work, phenolic acids, ferulic acid and its derivatives are used as ligands. Molecular parameters have been set to filter and sort the 34 derivatives from ZINC and PubChem databases. Besides, for affinity and activity identification, troglitazone and resveratrol co-crystallized ligands have been studied. Absorption, distribution, metabolism, elimination and toxicity, density functional theory, highest occupied molecular orbital–lowest unoccupied molecular orbital values and docking scores define the drug candidate as a potential inhibitor. Residues Ser 342 and Arg 280 bind with the ligands by forming hydrogen bonds and hydrophobic contacts. Based on the docking score, pharmacophore properties and functional energy values of the top six compounds are chosen for molecular dynamics and simulation. Consistency and stability maintained throughout the simulation up to 50 ns were observed. Free binding energy values and standard deviation of receptor and ligand calculated using molecular mechanics–generalized Born and surface area solvation method (MM_GBSA) is found significant. Therefore, ferulic acid derivatives and phenolic acids could be a potential inhibitor for adipocyte differentiation and lipid accumulation. Communicated by Ramaswamy H. Sarma

Mechanosynthesis of Photochromic Oligophenyleneimines: Optical, Electrochemical and Theoretical Studies.

In this work, two oligophenyleneimines type pentamers with terminal aldehydes, designated as DAFCHO (4,4′-((((((2,5-bis(octyloxy)-1,4-phenylene)bis(methanylylidene))bis(azanyl ylidene))bis(9H-fluorene-7,2-diyl))bis(azanylylidene))bis(methanylylidene))bis(2,5-bis(octyloxy) benzaldehyde)) and FDACHO (4,4′-((((((2,5-bis(octyloxy)-1,4-phenylene)bis(methanylylidene))bis (azanylylidene))bis(4,1-phenylene))bis(azanylylidene))bis(methanylylidene))bis(2,5-bis(octyloxy) benzaldehyde)) were synthesized by mechanochemistry method using 2,5-bis(octyloxy) terephtal aldehyde and 2,7-diaminofluorene or 1,4-phenylenediamine. All compounds were spectroscopically characterized using 1H and 13C-NMR, FT-IR and mass spectrometry MALDITOF. The optical properties of the compounds were analyzed by UV-vis spectroscopy using different solvents. We observed that DAFCHO and FDACHO exhibit interesting photochromic properties when they are dissolved in chloroform and exposed to sunlight for 3, 5 and 10 min. The value of the energy band gap was calculated from the absorption spectra without irradiation Egap(optical). It was 2.50 eV for DAFCHO in chloroform solution, and it decreased to 2.34 eV when it is in films. For FDACHO, it was 2.41 eV in solution and 2.27 eV in film. HOMO (Highest Occupied Molecular Orbital), LUMO (Lowest Unoccupied Molecular Orbital) and Egap(electrochemical) values were obtained by electrochemical studies. The results indicate that the compounds can be considered as organic semiconductors since their values are 2.35 eV for DAFCHO and 2.06 eV for FDACHO. The structural and electronic properties of the compounds were corroborated with a DFT (Density Functional Theory) study.

Empirical Relationship between Chemical Structure and Redox Properties: Mathematical Expressions Connecting Structural Features to Energies of Frontier Orbitals and Redox Potentials for Organic Molecules

A set of mathematical expressions to predict redox potentials and frontier orbital energy levels for organic molecules as a function of structural features is proposed. This is achieved by using the principal component regression method on reduction potential (Ered), oxidation potential (Eox), highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) values calculated using density functional theory (DFT) on a training set consisting of 77 547 molecules from PubChem database. The first set of expressions allows prediction of Ered, Eox, HOMO, and LUMO values using molecular fingerprints alone with R2 of ca. 0.74, 0.82, 0.92, and 0.85, respectively, which can be used for preliminary screening of molecules before performing DFT calculations. In the second set of expressions, when we include DFT-calculated HOMO and LUMO values as additional descriptors, the R2 values of Eox and Ered predictions increase to 0.91 and 0.90, respectively. This more accurate approach for redox poten...

Electrochromism Properties of Polyimides Possessing Triphenylamine Moieties with Different Substituents

Two diamine monomers with methyl (CH3TPA) and methoxy (OCH3TPA) group substituents in the para position of the triphenylamine (TPA) moiety were synthesized by nucleophilic aromatic substitution using 4-fluoronitrobenzene with p-toluidine and p-anisidine, respectively. From these diamine monomers, electroactive polyimides (PI)s were prepared by the chemical imidization of poly(amic acid) solutions, which were prepared with 4,4′-oxydiphthalic anhydride (ODPA). 1H nuclear magnetic resonance and Fourier transform infrared spectroscopy confirmed that both PIs had been synthesized successfully. The measured inherent viscosity for ODPA-CH3TPA PI and ODPA-OCH3TPA PI was 0.42 and 0.49 dL/g, respectively. The glass transition temperatures for ODPA-CH3TPA PI and ODPA-OCH3PDA PI were 236°C and 238°C, respectively, and the thermal degradation temperature of both PIs was above 390°C. The band gaps of ODPA-CH3PDA and ODPA-OCH3PDA were 3.00 and 2.72 eV, respectively. The oxidation onset potential Eox of ODPA-CH3PDA PI and ODPA-OCH3PDA PI from cyclic voltammetry was 0.73 V and 0.65 V, respectively. The highest occupied molecular orbital and lowest unoccupied molecular orbital values differed according to the groups substituted into the triphenylamine moiety. After applying a voltage, the absorption peak intensity at 723 nm and 752 nm for ODPA-CH3TPA and ODPA-OCH3TPA, respectively, increased. The electrical properties varied according to the chemical structure of synthesized diamines.

Synthesis and photoinduced electron transfer characteristic of a bis (zinc porphyrin)‐perylene bisimide array

In this article, a donor–acceptor array consisting of two zinc porphyrin (ZnPOR) units attached to the 1,7‐positions of perylene‐3,4:9,10‐bis(dicarboximide) (PDI) was synthesized and characterized. This double‐wing molecule exhibits very broad absorption in the region from 300 to 900 nm. Especially, its lower energy absorption feature presumably arises from donor–acceptor interactions. The fluorescence emission spectra confirmed that photoinduced electron transfer occurred from POR to perylene bisimide moiety in this triad. In contrast to previously studied systems incorporating POR and PDI groups, this array shows the evidence of a relatively strong ground‐state electronic coupling between the donor and acceptor moieties. Additionally, highest occupied molecular orbital and lowest unoccupied molecular orbital values of the array were acquired by cyclic voltammetry (CV). The results showed that these energy values fulfill the energetic conditions required for the proposed electron transfer. More importantly, the photocurrent measurement showed that this molecule exhibits a high capacity to form a photoinduced charge‐separated state and to produce steady and prompt cathodic photocurrent responses. These results confirmed the role of this new array toward harvesting light energy and generating photocurrent during the operation of a photoelectrochemical cell. Copyright © 2011 John Wiley & Sons, Ltd.

Conjugated dendrimers with triazine peripheries and a distyrylanthracene core

AbstractWe describe the synthesis and luminescence characterization of conjugated dendrimers with triazine peripheries and a distyrylanthracene core that are suitable for electroluminescence applications. The dendrimers consist of dendritic triazine wedges with high electron affinity, stilbene branches, and a distyrylanthracene core as an emitting moiety. The dendrimers have lowest unoccupied molecular orbital values of about −2.7 eV. Photoluminescence studies have indicated that a cascade energy transfer occurs from the triazine wedges to the stilbene bridges and finally to the distyrylanthracene core. Thus, the emission wavelength is determined by the distyrylanthracene core unit. The energy‐transfer efficiency of the distyrylanthracene‐cored dendrimers is about 47 and 20% for the first and second generations, respectively. A preliminary electroluminescence property investigation has also been conducted. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5855–5862, 2006

Quantitative relationships between molecular structures, environmental temperatures and octanol–air partition coefficients of PCDD/Fs

A concise quantitative model that incorporates information on both environmental temperature ( T) and molecular structures, for logarithm of octanol–air partition coefficient ( K OA) to base 10 (log K OA) of PCDDs, was developed. Partial least squares (PLS) analysis together with 14 quantum chemical descriptors were used to develop the quantitative relationships between structures, environmental temperatures and properties (QRSETP) model. It has been validated that the obtained QRSETP model can be used to predict log K OA of other PCDDs. Molecular size, environmental temperature ( T), q + (the most positive net atomic charge on hydrogen or chlorine atoms in PCDD molecules) and E LUMO (the energy of the lowest unoccupied molecular orbital) are main factors governing log K OA of PCDD/Fs under study. The intermolecular dispersive interactions and thus the size of the molecules play a leading role in governing log K OA. The more chlorines in PCDD molecules, the greater the log K OA values. Increasing E LUMO values of the molecules leads to decreasing log K OA values, implying possible intermolecular interactions between the molecules under study and octanol molecules. Greater q + values results in greater intermolecular electrostatic repulsive interactions between PCDD and octanol molecules and smaller log K OA values.

Comparative AM1 study of the electronic structure of etiocholanes

Etiocholanes are metabolites of androstenedione (4-androsten-3,17-dione) and testosterone (17β-hydroxy-4-androsten-3-one). These compounds are produced by the action of 5-reductases which break the π double bond of the androstenes at C4 and C5. The most important etiocholanes are 5β-androstanedione (etiocholanedione), 3α-hydroxy-5β-androstan-17-one (etiocholanolone), 3β-hydroxy-5β-androstan-17-one (epietiocholanolone), and 17β-hydroxy-5β-androstan-3-one (5β-dihydrotestosterone; 5βDHT). Among their most important biological effects are depression of the central nervous system, relaxation of smooth muscle, and stimulation of sexual behavior. The intent of the present study is a determination of the effects of carbonyl and hydroxyl groups at C3 and C17 on the electronic structure of these androgens, in an attempt to gain some insight into their biological action. All calculations were of the semiempirical AM1 type. The decrease of enthalpy caused by an hydroxyl group was found to be twice that of a carbonyl group. The effect of two groups was found to be additive. Carbonyl groups on the other hand led to an increase of dipole moment and of the electrostatic charges on neighboring carbons that were higher than those produced by hydroxyl groups. Carbonyl groups at C17 pushed the highest occupied molecular orbital (HOMO) to higher energy whereas a carbonyl at C3 had little or no effect. However, in mono and di-keto structures, both HOMO and lowest unoccupied molecular orbital (LUMO) were located as expected closer to the carbonyl group. Etiocholanedione, a diketo structure, showed degeneracy of frontier orbitals with its related HOMO−1 and LUMO+1. Structures with mono-hydroxyl or di-hydroxyl functional groups showed the lowest HOMO values; the highest LUMO values and quasi degeneracy of HOMO−1 and LUMO+1. The HOMO and LUMO of etiocholane and for the mono and di-hydroxyl structures were observed diffused throughout the molecules in a “sausagelike” or “ribbonlike” fashion. These results might explain some metabolic steps. Likewise, the difference of intermolecular forces, i.e., dipole moments and charges displayed by the carbonyl and hydroxyl groups, might help to elucidate some biological effects. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 249–254, 1997