Lowest Unoccupied Molecular Orbital Energy Research Articles

Optical and photovoltaic properties of substituted alizarin dyes for dye-sensitized solar cells application

ABSTRACT This paper presents the theoretical study on photovoltaic and absorption properties of alizarin derivatives. Optimization of structures and calculations were performed by density functional theory and time-dependent density functional theory using B3LYP hybrid functional and 6–31 G (d,p) basis set. The dyes were formed by substituting 2-hexylthiophene mixed with carboxylic acid and 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid. The performed substitution shows improvement in most of the properties. The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of molecular dyes showed positive effect upon electron injection to semiconductor and subsequent regeneration by the electrolyte. Almost all necessary and important parameters to demonstrate the usefulness of molecular dyes as photo-sensitizers are detailed discussed. Based on the discussion and analysis, all considered molecules are proved to be useful in dye-sensitized solar cells using TiO2 semiconductor and couple electrolyte. Collectively, dyes DY3 and DY2 showed better results than others with LHE and V oc of 0.2142 and 0.6722 eV, respectively, for DY3 and 0.7033 and 0.6224 eV, respectively, for DY2.

Immobilization of CO2 at Room Temperature Using the Specific Sub‐NM Space of 1D Uneven‐Structured C60 Polymer Film

AbstractImmobilization and reuse of CO2 are urgent tasks for sustaining the global environment. Here it is demonstrated that CO2 can be immobilized by reaction with H2O at room temperature (RT) in the specific sub‐nm space of 1D uneven‐structured C60 polymer (1D polymer) film, even though the reaction does not occur at RT in the gas phase (activation energy: 2 eV). First‐principles calculations reveal that the CO2 molecule is stacked as a bridge between the concave portions of adjacent 1D polymer frameworks via locally induced Coulomb interactions. Such induced charge polarization activates CO2 both by weakening its double‐bonds and by lowering its lowest unoccupied molecular orbital energy due to the bending motion. In addition, the flexible π orbitals of the 1D polymer provide the optimal Coulomb field to stabilize the transition state of the CO2 + H2O reaction remarkably. These factors work together to make the reaction possible at RT.

A new chlorinated non-fullerene acceptor based organic photovoltaic cells over 12% efficiency

The method to fluorinate the terminal group has achieved remarkable success and been widely used to fine-tune the intrinsic properties of organic acceptor materials. Referring to chlorination, however, it gets less attention and remains ambiguous effect on organic photovoltaic (OPV) cells. Herein, a new non-fullerene acceptor named Y19 was reported with benzotriazole as the electron-deficient core and 2Cl-ICs as the strong electron-withdrawing end groups. Y19 exhibits a wide film absorption band from 600 nm to 948 nm and low LUMO (the lowest unoccupied molecular orbital) energy level of −3.95 eV Photovoltaic devices based on PM6:Y19 show high-power conversion efficiency (PCE) of 12.76 % with high open-circuit voltage (Voc) of 0.84 V, short-circuit current density (Jsc) of 22.38 mA/cm2 and fill factor (FF) of 68.18 %. Broad external quantum efficiency (EQE) response of over 60 % in the range of 480–860 nm can be obtained. This study demonstrates that chlorination, as a low-cost molecular design strategy, has its own superiorities to improve device performance and promote the potential application in OPV.

Synthesis and characterization of homoleptic triply cyclometalated iridium(III) complex containing 6-(pyridin-2-yl)isoquinoline moiety for solution-processable orange-phosphorescent organic light-emitting diodes

The design and synthesis of a novel homoleptic triply cyclometalated iridium(III) complex containing the 6-(pyridin-2-yl)isoquinoline moiety [Ir(pyiq)3] was demonstrated for the first time. The performance of a phosphorescent organic light emitting diode (PHOLED) based on Ir(pyiq)3 is described with adoption of tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 2,2′,2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) which are co-host materials showing excellent compatibilities as well as CBP host with the prepared phosphorescent dopants. The photoluminescence (PL) of Ir(pyiq)3 produced orange emission with maximum emission peak at 583 nm. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital energy (LUMO) levels of Ir(pyiq)3 were −5.41 eV and −3.20 eV. An optimized solution-processed device doped with Ir(pyiq)3 had a maximum external quantum efficiency (EQE) of 8.71% and a maximum current efficiency (CE) of 22.51 cd/A. This correspond to 17% higher efficiency than that with bis(2-phenylbenzothiozolato-N,C2′)iridium(acetylacetonate) (bt)2Ir(acac), which is commonly used in orange PHOLEDs. This study rationalizes the promising application of new trimeric organometallic complex that possesses isoquinoline and pyridine in solution-processed PHOLEDs with good quantum and power efficiency.

Novel intramolecular charge transfer effect-based ligands and aggregation-induced emission-active europium complexes: synthesis, characterization, and fluorescence properties.

Two novel coumarin derivatives and the corresponding europium complexes were prepared using a simple procedure. The pH response of the ligand and the aggregation-induced emission (AIE) properties of the target europium complex were studied. The ligand had an intramolecular charge transfer (ICT) effect and was linearly and sharply responsive under acidic conditions. The goal europium complexes exhibited excellent AIE performance when subjected to increasing concentrations of target europium complex or proportion of poor solvent. The effect of substituents on fluorescence strength or thermogravimetric and electrochemical properties was further investigated. The target complexes displayed the typical fluorescence of europium. The fluorescence amplitude of the target europium complexes was enhanced by the addition of electron-donating groups to ligands. Thermogravimetric research findings indicated that the target complexes possessed extreme thermal stability. Electrochemistry discovery findings indicated that the highest occupied molecular orbit energy level of EuL1 was greater than EuL2 , but the lowest unoccupied molecular orbit energy level was smaller than that of EuL2 . These complexes could be applied in medicinal chemistry, substance chemistry, and fluorescence labelling areas.

Novel porphyrin polymers: synthesis and photoelectric property

A series of novel porphyrin monomers with different tail lengths were synthesized through the Alder–Longo method, and the corresponding polymers were successfully synthesized via radical polymerization. The structures of the porphyrin monomers and polymers were all depicted through proton nuclear magnetic resonance (1H-NMR) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and the photophysical and electrochemical properties were confirmed through UV–Vis spectroscopy, photoluminescence spectroscopy, and cyclic voltammetry. The results showed that the polymers exhibited a deep highest occupied molecular orbital (HOMO) energy level and a large optical band gap, demonstrating their usefulness in photovoltaic devices. All of the porphyrin monomers formed a typical columnar phase, and the cleaning point of these porphyrin monomers reduced with the increasing length of the alkoxy tail chain. Thermogravimetric analysis demonstrated that the polymers had excellent thermal stability; the decomposition temperature was higher than 400 °C. The UV absorption spectrum of the polymers was between 400 and 670 nm. Compared with the absorption peak of the solution, the absorption peak after film formation presented a certain redshift. The HOMO level was lower than the stable critical level of the conjugated polymer in air (− 5.2 eV), indicating that the polymer is stable in air. In addition, the lowest unoccupied molecular orbital energy level was 0.49–0.64 eV, which was higher than that of the recipient PCBM, indicating that the polymers can be used as a donor material for solar cells.

Visible-Light-Driven Anti-Markovnikov Hydrocarboxylation of Acrylates and Styrenes with CO 2

Light-driven carbon dioxide (CO2) capture and utilization is one of the most fundamental reactions in Nature. Herein, we report the first visible-light-driven photocatalyst-free hydrocarboxylation ...

Lightweight, Flexible and High Energies Absorption Property of PbO2 Doped Polymer Blend for Various Renewable Approaches

This work reports a theoretical study to investigate the electronic structure and optimized geometry for (PVA-PEG-PbO2) (78Atom) by using DFT at B3LYP level with bases set LanL2DZ. The electronic characteristics which contain total energy, cohesive energy, energy of highest occupied molecular orbital (HOMO), energy of lowest unoccupied molecular orbital (LUMO), energy gap, ionization potential, electronic affinity, hardness, softness, electronegativity and electrophilicity. The spectroscopic characteristics (IR, NMR and UV) for (PVA-PEG-PbO2) (78Atom) were investigated at the same large level of theory. The results showed that the functional used in the description of the studied molecular systems has been proved its validity in calculating the geometrical parameters and it is a suitable for studying the geometry optimization and calculating the HOMO and LUMO energies for the organic molecular systems. The final results indicated to the PVA-PEG-PbO2 structure can be considered as promising materials for various renewable energies approaches.

Fluorine Effects for Tunable C–C and C–S Bond Cleavage in Fluoro-Julia–Kocienski Intermediates

Classical Julia–Kocienski fluoroolefination represents an indispensable platform for the construction of monofluoroalkenes. Nevertheless, its complex multistep mechanistic manifold along with the u...

Preparation of Metal Complexes of 4,5-Dichlorphthalic Acid as Nanoscale and Electronic Properties

Here phthalic acid metal complexes with acid function were synthesized. Fourie transform infrared spectroscopy (FT- IR), X-ray diffraction analysis (XRD), Scanning electron microscopy-Energy Dispersive Spectrometry (SEM+EDS) devices were used for structure analysis. The structural parameters of the copper and zinc complexes of 4,5-dichlorphthalic acid were determined by the LanL2DZ basis base set of B3LYP method. Electronic properties such as HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies and molecular electrostatic potential (MEP) were obtained. Stability, charge delocalization of molecules resulting from hyperconjugative interactions were analyzed using natural bond orbital (NBO) analysis. The comparison of the theoretical and experimental FT-IR spectra of Zn and Cu-4,5-dichlorphthalic acid (DCPA) were made and R = 0.97204 for Cu and R = 0.97929 for Zn complex were found in linear fit studies. Two characterization results were found to be consistent.

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.

Isoindigo (IID)‐Based Semiconductor with F⋯S Interaction Locked Conformation for High‐Performance Ambipolar Bottom‐Gate Top‐Contact Field‐Effect Transistors

AbstractThe development of high‐performance ambipolar polymer semiconductors is critical to organic electronics. Herein, isoindigo (IID)‐based copolymers PIIDDTBT and PIIDDTffBT are synthesized and characterized. Both polymers have suitable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels for hole and electron injection. Density functional theory calculation reveals F⋯S intramolecular interactions are formed in PIIDDTffBT, which locks the molecular conformation and leads to a more planar backbone. Thin film transistor characterization shows both polymers display ambipolar charge carrier transport behavior. The hole/electron mobilities are 0.29/0.1 cm2 V−1 s−1 for PIIDDTffBT and 0.053/0.013 cm2 V−1 s−1 for PIIDDTBT in the bottom‐gate/top‐contact (BGTC) device structures. The hole/electron mobilities of PIIDDTffBT are one of the highest values for IID‐based ambipolar polymer transistors in BGTC device structure. Atomic force microscopy and X‐ray diffraction results reveal PIIDDTffBT films have higher film quality, crystallinity, and more ordered microstructures, being ascribed to the F⋯S interactions locked backbone. These results demonstrate that the introduction of F⋯S interactions is an effective strategy to design high‐performance ambipolar polymer semiconductors.

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.

Electrochemical and Quantum Chemical Studies of 5-[(4-Chlorophenoxy) Methyl]-4H-1,2,4-Triazole-3-Thiol on the Corrosion Inhibition of 6061 Al Alloy in Hydrochloric Acid

Corrosion inhibition studies of 5-[(4-chlorophenoxy) methyl]-4H-1, 2, 4-triazole-3-thiol (CMTT) on 6061 Al alloy in 0.05 M HCl were carried out at different concentrations and temperatures. Weight loss method, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed in the study. Higher concentration and temperature were found to improve the efficiency of inhibitor. Highest corrosion resistance of 95.29% was recorded with 100 ppm CMTT at 333 K. Adsorption of the inhibitor was spontaneous as indicated by Langmuir adsorption isotherm. Thermodynamic parameters, SEM, AFM results indicated that inhibitor used protects the alloy from corrosion. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (l) and Mulliken charges are calculated. Quantum chemical calculations also endorsed experimental information and the adsorption of inhibitor molecules onto the metal surface.

Decimal Solvent-Based High-Entropy Electrolyte Enabling the Extended Survival Temperature of Lithium-Ion Batteries to −130 °C

Freezing and crystallization of commercial ethylene carbonate-based binary electrolytes, leading to irreversible damage to lithium-ion batteries (LIBs), remain a significant challenge for the survi...

Theoretical investigation on QSAR of (2-Methyl-3-biphenylyl) methanol analogs as PD-L1 inhibitor

Cancer is one of the most serious issues in human life. Blocking programmed cell death protein 1 and programmed death ligand-1 (PD-L1) pathway is one of the great innovations in the last few years, a few numbers of inhibitors can be able to block it. (2-Methyl-3-biphenylyl) methanol derivative is one of them. Here, the quantitative structure-activity relationship (QSAR) established twenty (2-methyl-3-biphenylyl) methanol derivatives as the programmed death ligand-1 inhibitors. Density functional theory at the B3LPY/6-31+G(d,p) level was employed to study the chemical structure and properties of the chosen compounds. Highest occupied molecular orbital energy EHOMO, lowest unoccupied molecular orbital energy ELUMO, total energy ET, dipole moment DM, absolute hardness η, absolute electronegativity χ, softness S, electrophilicity ω, energy gap ΔE, etc., were observed and determined. Principal component analysis (PCA), multiple linear regression (MLR) and multiple non-linear regression (MNLR) analysis were carried out to establish the QSAR. The proposed quantitative models and interpreted outcomes of the compounds were based on statistical analysis. Statistical results of MLR and MNLR exhibited the coefficient R2 was 0.661 and 0.758, respectively. Leave-one-out cross-validation, rm2 metric, rm2 test, and “Golbraikh & Tropsha’s criteria” analyses were applied for the validation of MLR and MNLR, which indicate two models are statistically significant and well stable with data variation in the external validation towards PD-L1. The obtained results showed that the MNLR model predicts the bioactivity more accurately than MLR, and it may be helpful and supporting for evaluation of the biological activity of PD-L1 inhibitors.

Persistent prevalence of supramolecular architectures of novel ultrasonically synthesized hydrazones due to hydrogen bonding [X–H⋯O; X=N]: Experimental and density functional theory analyses

In this study, a series of novel pyridine-based hydrazone derivatives comprising (E)-2-((6-chloropyridin-2-yl)oxy)-N′-(2,3-dihydroxybenzylidene) acetohydrazide (CPBAH), (E)-2-((6-chloropyridin-2-yl)oxy)-N′-(4-fluorobenzylidene) acetohydrazide (CPFBH), (E)-N′-((4-chlorobenzylidene)-2-((6-chloropyridin-2-yl)oxy) acetohydrazide (CBCPH), and (E)-N′-(4-bromobenzylidene)-2-((6-chloropyridin-2-yl)oxy) acetohydrazide (BBCPH) were rapidly synthesized via ultrasonication at room temperature and their structures were unambiguously confirmed by spectral analysis and X-ray crystallography. Quantum chemical insights into the optimized geometry, nonlinear optical (NLO) properties, frontier molecular orbitals (FMOs), and natural bond orbitals (NBOs) were obtained for CPBAH, CPFBH, CBCPH, and BBCPH by density functional theory at the B3LYP/6-311G (d,p) level. Furthermore, NBO analysis was conducted at the ωB97XD/6-311G (d,p) level. Single crystal X-ray diffraction analyses showed that intra- and intermolecular attractive forces were responsible for structural stabilization. Indeed, the production of non-covalent directional interactions such as intra- and intermolecular hydrogen bonds is a key concept in materials architecture, where they depend mainly on small compact acceptors comprising nitrogen and oxygen atoms. Furthermore, the intra- and intermolecular hydrogen bonding networks (X–H⋯O; X = N) and conjugative interactions in the solid state were explored based on the NBOs and natural population analysis. Hirshfeld surface analysis was conducted to quantify the non-covalent interactions. CO⋯H–N intermolecular hydrogen bonds form the six-membered rings in CPBAH, CPFBH, CBCPH, and BBCPH. The crystal structures are also stabilized by C–H…Cg, C–F…Cg, and C–Cl…Cg interactions. The charge transfer processes in the compounds were estimated based on the FMOs. The highest occupied molecular orbital and lowest unoccupied molecular orbital energies were used to obtain the global reactivity parameters. Overall, the results calculated for CPBAH, CPFBH, CBCPH, and BBCPH were in excellent agreement with experimental data. The computational analyses also indicated that the compounds investigated have remarkable NLO properties.

Ion-Solvent Chemistry-Inspired Cation-Additive Strategy to Stabilize Electrolytes for Sodium-Metal Batteries

Summary Building stable electrolytes is one of the key technologies for sodium (Na)-metal batteries as the reactive nature and the dendritic growth of Na-metal anodes. Herein, a paradigmatic and rational strategy of cation additive was proposed to stabilize electrolytes for Na metal batteries. Three principles, including the electrode potential of introduced cations, the lowest unoccupied molecular orbital energy level decrease of solvents after coordinating with cations, and the interaction strength between cations and solvents, were proved through first-principles calculations and molecular dynamics simulations. Li+ was predicted to be a good cation additive candidate for Na metal batteries. Finite element method simulations, in situ optical microscopic observations, and electrochemical tests further validated the resisted Na dendritic growth due to the electrostatic shield effect and enhanced electrolyte stability after introducing Li+ additives. The proven cation additive strategy affords emerging chances for rational electrolyte design for stable and safe Na metal batteries.

Investigation of HMG-CoA reductase inhibitory and antioxidant effects of various hydroxycoumarin derivatives.

Cardiovascular diseases are one of the primary causes of deaths worldwide, and the development of atherosclerosis is closely related to hypercholesterolemia. As the reduction of the low-density lipoprotein cholesterol level is critical for treating these diseases, the inhibition of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, which is essentially responsible for cholesterol biosynthesis, stands out as a key solution to lower plasma cholesterol levels. In this study, we synthesized several dihydroxycoumarins and investigated their antioxidant and in vitro HMG-CoA reductase inhibitory effects. Furthermore, we carried out in silico studies and examined the quantum-chemical properties of the coumarin derivatives. We also performed molecular docking experiments and analyzed the binding strength of each coumarin derivative. Our results revealed that compound IV displayed the highest HMG-CoA reductase inhibitory activity (IC50 = 42.0 µM) in vitro. Cupric-reducing antioxidant capacity and ferric-reducing antioxidant power assays demonstrated that coumarin derivatives exhibit potent antioxidant activities. Additionally, a close relationship was found between the lowest unoccupied molecular orbital energy levels and the antioxidant activities.

Synthesis and Photophysical Properties of (Cl2Ph)Salen‐based Indium Complexes

Herein, to elucidate the effect of substituent electronic properties on the photophysical properties of indium‐based organometallic luminophores, we prepare a series of indium complexes (1–5) with salen ligands bridged by an electron‐withdrawing 4,5‐dichlorophenylene (Cl2Ph) unit. The structures of all the complexes are fully confirmed by 1H and 13C NMR spectroscopy as well as elemental analysis. In particular, the molecular structure of 3, confirmed by X‐ray crystallography, is monomeric and the central indium atom adopts a square‐pyramidal geometry. The UV/Vis and fluorescence spectra of 1–5 show typically salen‐centered intramolecular charge transfer transitions with gradual bathochromic shifts as the electron‐donating ability of the substituents increases. This feature is further supported by electrochimical studies. Furthermore, the lowest unoccupied molecular orbital energy levels of 1–5 are considerably lower (approximately −3.70 eV) than those of salen‐based indium complexes with other aryl‐bridging units owing to the reduced electron‐donating effect of the (Cl2Ph)salen group.