Showing papers on "HOMO/LUMO published in 2022"

Biochar co-doped with nitrogen and boron switching the free radical based peroxydisulfate activation into the electron-transfer dominated nonradical process

Abstract: In this study, N/B co-doped biochars were employed as metal-free activators of peroxydisulfate (PDS) for tetracycline degradation, more importantly, the roles of dopants and the relative contribution of radical vs nonradical oxidations were comprehensively investigated. Integrating with electron paramagnetic resonance and kinetics calculations, we showed that co-doping N and B into biochars not only boosted the catalytic activity but also switched the radical PDS-activated process into the electron transfer-dominated nonradical process. Compared with pristine biochar/PDS systems (22%), the nonradical contribution of N/B co-doped biochar/PDS systems increased to 59%, exhibiting outstanding stability and selectivity. Galvanic oxidation tests and theoretical simulations unveiled that doped biochars as conductive tunnels accelerate the potential difference-driven electron transfer from the highest occupied molecular orbital of pollutants to the lowest unoccupied molecular orbital of PDS due to the lower energy gap. This study provided new insights into the critical role of heteroatom-doped carbocatalysts in PDS nonradical activation.

Reactivity, stability, and thermodynamics of para-methylpyridinium-based ionic liquids: Insight from DFT, NCI, and QTAIM

Abstract: Ionic liquids (ILs) have lately piqued scientific attention due to their potential applications in green transition technologies such as catalysis, electrochemistry, and photovoltaic. The investigation of structural stability, reactivity, topological analysis, and thermodynamics of 4-methylpridine (4-picoline) based ILs is carried out using an advanced computational electronic structure theory technique based on first principle density functional theory (DFT). The ILs were modeled based on the interaction of 4-methylpridine (4-picoline) ion (cation) with borate, nitrate, phosphate, carbonate, and sulfate anions which have been chemically symbolized respectively as follows: [PMHP]+[HBO3]−, [PMHP]+[HNO3]−, [PMPH]+[HPO3]−, [PHMP]+[HCO3]−, and [PHMPM]+[HSO4]−. The energy difference between HOMO - LUMO of the studied compounds were found to show a general decreasing trend in the order: [PMHP][H2BO3] > [PMHP][NO3]> [PMPH][H2PO3]> [PHMP][HCO3]> [PHMPM][HSO4] with the borate ([PMHP][H2BO3]) and sulfate ([PHMPM][HSO4]) ILs having the relatively highest and least energy gap of 6.30 and 4.14 eV respectively. Strong interaction energies of 329.50 kca/mol, 114.41 kcal/mol, 107.12 kcal/mol, 98.19 kcal/mol and 87.86 kcal/mol involving the bonding, anti – bonding and lone pair orbitals associated with the pair of ILs were obtained as a trend: [PMHP][HSO4] > [PMHP][HCO3] > [PMPH][H2BO3] > [PHMP][NO3] > [PHMPM][H2PO3]. The intermolecular hydrogen bond (H-bond) analysis between the cation and anions ILs pairs obtained from quantum theory of atoms-in-molecules (QTAIM) reveals strong, weak, and electrostatic bonds. [PMPH]+[HSO4]− ILs pair was observed to possess the highest binding energy of -20.06 kcal/mol in the same way energy decomposition analysis (EDA) reveals a relatively strong orbital interaction in the [PMPH][HSO4] ILs due to the increase in electrostatic interaction of the four O-atoms in the sulfate anion, the analysis of the thermodynamic results indicates that the syntheses of the ILs are exothermic and spontaneous.

Synthesis, characterization, DFT studies, and molecular modeling of azo dye derivatives as potential candidate for trypanosomiasis treatment

Abstract: This research aims to synthesize four compounds (CMP1, CMP2, CMP3 and CMP4) and determine their suitability for the formulation of the drugs for the treatment of sleeping sickness caused by Trypanosoma cruzi, a vector-borne parasitic disease, commonly referred to as sleeping sickness. The synthesized azo dyes have been spectroscopically analyzed using UV–vis and FT-IR techniques along with detailed functional groups comparison through vibrational assignment. All theoretical computation was carried out within the framework of density functional theory (DFT) at the B3LYP/ 6–311++G(d) method and molecular properties such as frontier molecular orbital (FMO), natural bond orbital (NBO), nonlinear optics (NLO), condensed fukui function, and Total density of state (TDOS) have been evaluated. The results of the HOMO-LUMO energy analysis indicate that CMP4 possesses the largest energy gap of 3.327 eV compared to the rest of the compounds and has the highest stability. For the NBO analysis, CMP1 showed its highest stabilization energy with of 1243.14 kcal/mol, CMP2 at 47,120.45 kcal/mol, CMP3 at 694.91 kcal/mol, and CMP4 at 9471.63 kcal/mol. NLO shows CMP2 with the highest dipole moment of 10.59D and CMP1 with the lowest dipole moment of 2.5435D. All ligands exhibited higher binding affinities with 3ick and 5qq5 which suggest formation of stable complex with this protein compared to the standard drug. Therefore, molecular electronic structure and molecular docking investigation indicates that the azo compounds have unique reactivity and bioactivity towards vector-borne parasitic disease caused by Trypanosoma cruzi.

Quantum Computational Investigation of (E)-1-(4-methoxyphenyl)-5-methyl-N′-(3-phenoxybenzylidene)-1H-1,2,3-triazole-4-carbohydrazide

Abstract: The title compound was synthesized and structurally characterized. Theoretical IR, NMR (with the GIAO technique), UV, and nonlinear optical properties (NLO) in four different solvents were calculated for the compound. The calculated HOMO–LUMO energies using time-dependent (TD) DFT revealed that charge transfer occurs within the molecule, and probable transitions in the four solvents were identified. The in silico absorption, distribution, metabolism, and excretion (ADME) analysis was performed in order to determine some physicochemical, lipophilicity, water solubility, pharmacokinetics, drug-likeness, and medicinal properties of the molecule. Finally, molecular docking calculation was performed, and the results were evaluated in detail.

Perylene Diimide-Based Oligomers and Polymers for Organic Optoelectronics

Abstract: ConspectusPerylene diimide (PDI) as a classical dye has some advantages, such as structural diversity, tunable optical and electronic properties, strong light absorption, high electron affinity, and good electron-transporting properties and stability. The PDI-based oligomers and polymers are good candidates for n-type semiconductors in organic electronics and photonic devices.A polymer solar cell (PSC) that converts sunlight into electricity is a promising renewable and clean energy technology and has some superiorities, such as simple preparation and being lightweight, low cost, semitransparent, and flexible. For a long time, fullerene derivatives (e.g., PCBM) have been the most important electron acceptors used in the active layer of PSCs. However, PCBM suffers from some disadvantages, for example, weak absorption, a large amount of energy loss, and unstable morphology. Compared to PCBM, PDI-based materials present some advantages: intense visible-light absorption; lowest unoccupied molecular orbital (LUMO) energy levels can be modulated to achieve a suitable charge separation driving force and high open-circuit voltage (VOC); and the molecular configuration can be adjusted to achieve morphology stability. Thus, PDI-based oligomers and polymers are widely used as electron acceptors in the active layer of PSCs. In addition, PDI-based oligomers and polymers are widely used as n-type semiconductors in other electronic and photonic devices, such as organic field-effect transistors (OFETs), light-emitting diodes, lasers, optical switches, and photodetectors.In this Account, we present a brief survey of the developments in PDI-based oligomers and polymers and their applications in organic electronic and photonic devices, especially in solar cells and field-effect transistors. Although parent PDI dyes exhibit strong absorption, large electron affinity, and high electron mobility, the initial bulk-heterojunction PSCs based on PDI acceptors yielded a very low power conversion efficiency (ca. 0.1%). The highly planar configuration of parent PDI causes strong intermolecular π–π stacking, large crystalline domains, and severe donor/acceptor (D/A) phase separation, leading to a low exciton dissociation efficiency and poor device performance. Starting in 2007, our group designed linear-shaped PDI dimers with different bridges, star-shaped PDI trimers, and PDI polymers to overcome excess crystallization and PDI aggregation and to achieve appropriate D/A miscibility and phase separation. Molecular design strategies were developed to promote the planarity of the backbone and down-shifted LUMO level of PDI polymers, which is beneficial for strong intermolecular π–π stacking, high mobility, and good air stability of OFETs. Beyond PSC and OFET applications, PDI polymers can also be used in perovskite solar cells and two-photon absorption. Future research directions toward the performance optimization of PDI oligomers and polymers are also proposed.

Achieving 16% Efficiency for Polythiophene Organic Solar Cells with a Cyano‐Substituted Polythiophene

Abstract: Polythiophenes (PTs) are promising electron donors in organic solar cells (OSCs) due to their simple structures and excellent synthetic scalability. However, the device performance of PT‐based OSCs is rather poor due mainly to large photon energy losses and an unfavorable active layer morphology. Herein, the authors report a new PT, which is abbreviated as P5TCN‐2F and features cyano‐group substituents for high‐efficiency OSCs. The cyano‐group endows P5TCN‐2F with a deep‐lying highest occupied molecular orbital energy level, which thereby contributed to high open‐circuit voltage in OSCs as a result of reduced non‐radiative recombination energy loss. Moreover, the cyano‐group leads to strong interchain interaction, improved polymer crystallinity, and appropriate miscibility with the prevailing non‐fullerene acceptors. Consequently, P5TCN‐2F offers over 15% power conversion efficiency when blended with various Y‐series non‐fullerene acceptors (Y6, Y6‐BO, eC9, and L8‐BO). Particularly, a champion efficiency of 16.1% is obtained by the P5TCN‐2F:Y6 blend, which is largely higher than that of any previous PT‐based OSCs. Moreover, the average figure of merit of the active layer based on P5TCN‐2F is much superior to that of benzodithiophene‐based polymers. These results suggest the renaissance of PT‐based OSCs and have opened an avenue to access high‐performance materials for the large‐scale production of OSC modules.

Isogenous Asymmetric–Symmetric Acceptors Enable Efficient Ternary Organic Solar Cells with Thin and 300 nm Thick Active Layers Simultaneously

Abstract: Integrating desirable light absorption, energy levels, and morphology in one matrix is always the aspiration to construct high‐performance organic solar cells (OSCs). Herein, an asymmetric acceptor Y6‐1O is incorporated into the binary blends of acceptor Y7‐BO and donor PM6 to prepare ternary OSCs. Two isogenous asymmetric–symmetric acceptors with similar chemical skeletons tend to form alloy‐like state in blends due to their good compatibility, which contributes to optimizing the morphology for efficient charge generation and extraction. The complementary absorption of two acceptors helps to improve the photon harvesting of ternary blends, and the higher lowest unoccupied molecular orbital (LUMO) energy level of Y6‐1O offers the chance to uplift the mixed LUMO energy levels of acceptors. Combining the aforesaid benefits, the ternary OSCs with 10 wt% Y6‐1O produce a top‐ranked power conversion efficiency (PCE) of 18.11% with simultaneously elevated short‐circuit current density, open‐circuit voltage, and fill factor in comparison to Y7‐BO‐based binary devices. Furthermore, the optimized ternary OSCs with ≈300 nm active layers obtain a champion PCE of 16.61%, which is the highest value for thick‐film devices reported so far. This work puts forward an avenue for further boosting the performance of OSCs with two isogenous acceptors but different asymmetric structures.

Adsorption properties of metal functionalized fullerene (C59Au, C59Hf, C59Ag, and C59Ir) nanoclusters for application as a biosensor for hydroxyurea (HXU): insight from theoretical computation

Abstract: Abstract This theoretical study was conducted to evaluate the efficiency of fullerene C60 and its metal functionalized nano clusters (C59Au, C59Hf, C59Ag and C59Ir) as a sensor for hydroxyurea (HXU). The various conclusions concerning the adsorption and sensing properties of the studied nano surfaces were achieved using density functional theory (DFT) at the M062X-D3/gen/LanL2DZ/def2svp level of theory. Among the nano clusters studied for this interaction, analysis of the HOMO–LUMO energy differences (Eg) showed that HXU@C59Hg (H2) reflects the least energy gap of 3.042 eV, indicating its greater reactivity, sensitivity and conductivity. Also, the adsorption phenomenon in this current study is best described as chemisorptions owing to the negative adsorption enthalpies observed. Thus, the adsorption energy (EAd) follows an increasing pattern of: HXU@C60 (C1) (−0.218 eV) < HXU@C59Ir (I1) (−1.361 eV) < HXU@C59Au (A1) (−1.986 eV) < HXU@C59Hf (H1) (−2.640 eV) < HXU@C59Hg (H2) (−3.347 eV). Least Eg, highest EAd and non-covalent nature of interaction attributed to C59Hg surface are sufficient to show that, among all studied surfaces, C59Hg surface emerged as the most suitable adsorbent for the adsorption of HXU. Hence, it can be used in modeling future adsorbent material for hydroxyurea.

End-capped group modification on cyclopentadithiophene based non-fullerene small molecule acceptors for efficient organic solar cells; a DFT approach.

Abstract: Four acceptor-donor-acceptor (A-D-A) type cyclopentadithiophene core-based non-fullerene small acceptor molecules were designed with the objective to improve the proficiency of photovoltaic cells. A comprehensive density functional theory (DFT) analysis was done by employing B3LYP functional with 6-31G(d,p) basis set to study optoelectronic properties of R as well as M1-M4 molecules, while the time-dependent self-consistent field (TDSCF) was utilized to analyze their excited state calculations. Several essential characteristics must be refined in order to enhance the efficiency of small molecular acceptors, i.e., the density of states (DOS), HOMO-LUMO band gap, transition density matrix (TDM), dipole moment, reorganization energy, light-harvesting efficiency, and open-circuit voltage, etc. In comparison to the R molecule, all the derived molecules show better maximum absorption (in chloroform solvent) with a range of 886-951 nm and a smaller band gap with a range of 1.65-1.55 eV M2 retains the least exciton binding energy of 0.24 eV, and amongst all the investigated molecules M3 molecule has the least interaction coefficient values so, it possesses better charge transport probability. The reorganization energy values in eV for both electron (0.00579) and hole (0.00737) are the least for M3 molecule, so this molecule exhibits better charge mobility for electron and hole. VOC of R and M1-M4 molecule was calculated by theoretically computing the values of their complexes with PTB7-Th donor molecule.

Tuning the optoelectronic properties of indacenodithiophene based derivatives for efficient photovoltaic applications: A DFT approach

Abstract: In this study, five novel push-pull acceptor molecules with A-B-D-B-A arrangement have been formulated in the quest to boost the organic solar cells (OSCs), with respect to their electrical, optical, and chemical characteristics. Substitution of end-capped acceptor moieties in non-fullerene materials is an effective approach of molecular modeling, which finely tunes the optoelectronic attributes of OSCs. The recently altered molecules (Y1-Y5) were flanked with different electron withdrawing units carrying indacenodithiophene (IDT) as the central electron donating core. The density functional theory (DFT) and time-dependent density functional theory (TD-DFT) analysis were executed at B3LYP functional with 6-31G (d,p) basis set to investigate the geometrical as well as optical parameters such as quantum mechanical descriptors, light harvesting efficiency, ionization potential energy, absorption properties, electron affinity, dipole moment, molecular electrostatic potential, transition density matrix, the density of states, and reorganization energies. All of these studied molecules revealed greater electronic transitions, superior optical properties, fast charge mobilities, and better solubility in the polar solvent when compared to the reference molecule. Amongst all these derived molecules, Y1 emerged as a distinctive candidate, exhibiting the highest maximum absorption wavelength (884 nm) in chloroform along with the smallest energy gap (1.72 eV) as well as the lowest optical gap (1.40 eV). Moreover, it has the highest electron affinity and ionization potential energy, least interaction coefficient, exciton binding energy, and reorganization energy (λe = 0.00340 eV), which can be ascribed to its potent electron withdrawing moieties, which intensifies the transfer of charge between the donor and acceptor units within a molecule. We expect these modifications in the terminal groups around the central core to provide strong theoretical strategies to construct and amplify the photovoltaic parameters of OSCs in the future.

Layer‐by‐Layer Processed PM6:Y6‐Based Stable Ternary Polymer Solar Cells with Improved Efficiency over 18% by Incorporating an Asymmetric Thieno[3,2‐b]indole‐Based Acceptor

Abstract: Although much research on device engineering have brought about significant improvements in PM6:Y6‐based polymer solar cell (PSCs) performance, there is still a lack of relevant research to solve the problems caused by the over‐aggregation of Y6 and the long‐term stability of the device morphology. Herein, a newly designed and synthesized low‐bandgap asymmetric small molecule acceptor TIT‐2Cl based on thieno[3,2‐b]indole core is elaborately introduced into PM6:Y6‐based PSCs to suppress the over‐aggregation of Y6 molecules with significantly increased efficiency from 15.78% to 17.00%. Moreover, the addition of TIT‐2Cl contributes to improved light harvesting, the lowest unoccupied molecular orbital level of Y6:TIT‐2Cl, charge separation, transport, and extraction. Simultaneously, the PSCs are further prepared by using the progressive spin‐coating method of layer‐by‐layer (LBL). Due to the formation of vertical phase distribution and the improvement of carrier transport performance, the champion efficiency of LBL‐type ternary PSCs reaches 18.18%, which is the highest efficiency reported for PM6:Y6‐based PSCs, along with superior stability and compositional insensitivity. Therefore, the results show that the combination of ternary strategy by incorporating appropriate asymmetric molecules and the LBL method is an effective means to fabricate highly efficient stable PSCs.

Green Synthesis of Lactone‐Based Conjugated Polymers for n‐Type Organic Electrochemical Transistors

Abstract: As new and better materials are implemented for organic electrochemical transistors (OECTs), it becomes increasingly important to adopt more economic and environmentally friendly synthesis pathways with respect to conventional transition‐metal‐catalyzed polymerizations. Herein, a series of novel n‐type donor–acceptor‐conjugated polymers based on glycolated lactone and bis‐isatin units are reported. All the polymers are synthesized via green and metal‐free aldol polymerization. The strong electron‐deficient lactone‐building blocks provide low‐lying lowest unoccupied molecular orbital (LUMO) and the rigid backbone needed for efficient electron mobility up to 0.07 cm2 V−1 s−1. Instead, polar atoms in the backbone and ethylene glycol side chains contribute to the ionic conductivity. The resulting OECTs exhibit a normalized maximum transconductance gm,norm of 0.8 S cm−1 and a μC* of 6.7 F cm−1 V−1 s−1. Data on the microstructure show that such device performance originates from a unique porous morphology together with a highly disordered amorphous microstructure, leading to efficient ion‐to‐electron coupling. Overall, the design strategy provides an inexpensive and metal‐free polymerization route for high‐performing n‐type OECTs.

Synthesis, crystal structure, Hirshfeld surface investigation and comparative DFT studies of ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate

Abstract: The ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1), a thiazole ester, was synthesized by refluxing 1-(2-nitrobenzylidene)thiosemicarbazide and ethyl bromopyruvate. The compound is characterized by spectrometric, spectroscopic and single crystal (SC-XRD) techniques. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. All theoretical calculations were performed by DFT quantum chemical methods using 6-311G(d,p) and cc-pVTZ basis sets and compared. Theoretical harmonic frequencies of ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1) were optimized. Confirmation of hydrogen bonding sites was analyzed by molecular electrostatic potential (MEP) and Mulliken population analysis. The vibrational frequencies of characteristic functional groups and chemical shifts were found in good agreement with experimental assignments. Frontier molecular orbital (FMO) revealed relatively small HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gape, which speaks off the nearly planar geometry and extended conjugation, as compared to the substituents with no conjugation possible. It has also been observed that -NO2 substituent plays a vital role for this relatively small HOMO-LUMO gape and overall electronic properties when compared with similar thiazole carboxylates (2-6, Table 6). Ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1) was also evaluated for its anti-oxidant and anti-microbial activities.