LUMO Research Articles

Crystalline 1D Linear Conjugated Polymers with a Quinoidal Unit As Metal‐Free Electrocatalysts for Oxygen Reduction

AbstractCrystalline and soluble 1D linear conjugated polymers (LCPs) have garnered considerable interest as cost‐effective and efficient metal‐free electrocatalysts for the oxygen reduction reaction (ORR) due to their high exposure of catalytic sites and ease of processing. However, difficulties remain in achieving excellent ORR performance for 1D LCPs by conventional molecular design. Herein, it is demonstrated the utilization of quinoidal units as a promising strategy to develop 1D LCPs for ORR. The incorporation of quinoidal unit not only results in polymers with strong inter‐ and intra‐molecular interactions and low‐lying LUMO (lowest unoccupied molecular orbital) energy levels, but also provides polymers with good crystallinity and commendable charge carrier mobilities. The electronic properties of these polymers are fine‐tuned through the introduction of additional heteroatoms and/or substituents in the monomers and comonomers to understand and optimize their ORR catalytic activity. Evaluation of their catalytic performances reveals a remarkable half‐wave potential and limiting current density of up to 0.74 V (vs reversible hydrogen electrod) and 7.50 mA cm−2, respectively. Notably, these performances are achieved without the addition of carbon nanomaterials as support. This study offers a new insight into the design of highly efficient metal‐free organic electrocatalysts.

Exploring Aromaticity Effects on Electronic Transport in Cyclo[n]carbon Single-Molecule Junctions.

Cyclo[n]carbon (Cn) is one member of the all-carbon allotrope family with potential applications in next-generation electronic devices. By employing first-principles quantum transport calculations, we have investigated the electronic transport properties of single-molecule junctions of Cn, with n = 14, 16, 18, and 20, connected to two bulk gold electrodes, uncovering notable distinctions arising from the varying aromaticities. For the doubly aromatic C14 and C18 molecules, slightly deformed complexes at the singlet state arise after bonding with one Au atom at each side; in contrast, the reduced energy gaps between the highest occupied and the lowest unoccupied molecular orbitals due to the orbital reordering observed in the doubly anti-aromatic C16 and C20 molecules lead to heavily deformed asymmetric complexes at the triplet state. Consequently, spin-unpolarized transmission functions are obtained for the Au-C14/18-Au junctions, while spin-polarized transmission appears in the Au-C16/20-Au junctions. Furthermore, the asymmetric in-plane π-type hybrid molecular orbitals of the Au-C16/20-Au junctions contribute to two broad but low transmission peaks far away from the Fermi level (Ef), while the out-of-plane π-type hybrid molecular orbitals dominate two sharp transmission peaks that are adjacent to Ef, thus resulting in much lower transmission coefficients at Ef compared to those of the Au-C14/18-Au junctions. Our findings are helpful for the design and application of future cyclo[n]carbon-based molecular electronic devices.

Cl©Li5Cl5-: A Star-like Superhalogen Anion Featuring a Planar Pentacoordinate Chlorine at the Center.

Among the known planar pentacoordinate atoms, chlorine is missing due to its large radius and high electronegativity. Herein, we report the first star-like superhalogen anion D5h Cl©Li5Cl5- (1), which contains a planar pentacoordinate chlorine (ppCl) at the center. Computer structural searches and high-level calculations reveal that 1 is a true global minimum (GM) on the potential energy surfaces. Molecular dynamics simulations indicate it is kinetically stable against isomerization or decomposition. Although detailed chemical bonding analyses reveal one delocalized 6c-2e σ bond over the Cl©Li5 central unit and five delocalized 3c-2e σ bonds along the periphery, while aromaticity has very little beneficial effect on stability, instead, ionic interaction dominates the stability of the system. More encouragingly, with the large HOMO-LUMO energy gap of 7.66 eV and vertical detachment energy of 7.87 eV, the highly chemically inert 1 can be viewed as a typical superhalogen anion and is possible to be synthesized and characterized in future experiments.

Novel emissive styryl dyes from 9-methoxy anthracene: Synthesis, photophysical, thermal stability, viscosity, and DFT study

Novel styryl colorants based on anchoring methoxy with anthracene as a donor linked with various active methylene acceptor groups to derive a conjugated π-system along with push-pull geometry were synthesized and well characterized. Photophysical properties were studied in different polarity solvents. The impact of solvent polarizability is delivered in redshifts in absorption and emission spectra, in addition to enhancing the quantum yield. The benzoxazole and benzimidazole moieties in 4c and 4d demonstrated heat stability of more than 300 °C. Fluorescent intensity is directly proportional to the viscosity and 4a demonstrates a notable viscosity sensor through 1.36 fold increase in intensity. In comparison to other styryl dyes, 4c and 4d were shown to have higher values in DMSO for polarizability (53.3496 × 10−24 esu and 53.7459 × 10−24 esu) and first-order hyperpolarizability (86.3467 × 10−30 esu and 89.1941 × 10−30 esu) as well as second-order hyperpolarizability (1768.9121 × 10−36 esu and 1740.6940 × 10−36 esu) due to presence of heterocyclic character. NLO properties of all the styryl dyes 4a-4e are within the fundamental boundary limits. The 4d (benzoxazole) dye exhibited a small HOMO-LUMO energy gap of 2.8825 eV, whereas the 4b and 4e dyes had a larger band gap due to the presence of a carbonyl group.

Exo‐6b2‐Methyl‐Substituted Pentabenzocorannulene: Synthesis, Structural Analysis, and Properties

Abstractexo‐6b2‐Methyl‐substituted pentabenzocorannulene (exo‐PBC‐Me) was synthesized by the palladium‐catalyzed cyclization of 1,2,3‐triaryl‐1H‐cyclopenta[l]phenanthrene. Its bowl‐shaped geometry with an sp3 carbon atom in the backbone and a methyl group located at the convex (exo) face was verified by X‐ray crystallography. According to DFT calculations, the observed conformer is energetically more favorable than the endo one by 39.9 kcal/mol. Compared to the nitrogen‐doped analogs with intact π‐conjugated backbones (see the main text), exo‐PBC‐Me displayed a deeper bowl depth (avg. 1.93 Å), redshifted and broader absorption (250–620 nm) and emission (from 585 to more than 850 nm) bands and a smaller optical HOMO–LUMO gap (2.01 eV). exo‐PBC‐Me formed polar crystals where all bowl‐in‐bowl stacking with close π ⋅ ⋅ ⋅ π contacts is arranged unidirectionally, providing the potential for applications as organic semiconductors and pyroelectric materials. This unusual structural feature, molecular packing, and properties are most likely associated with the assistance of the methyl group and the sp3 carbon atom in the backbone.

DFT study of Cun (n = 1–3) cluster-modified WSe2 monolayers for the detection of SF6 decomposition gases (H2S, SO2, SOF2 and SO2F2)

The role of SF6 in gas-insulated equipment is crucial for insulation and arc extinction. When subjected to electrical faults, thermal faults, and mechanical failures in insulation devices, SF6 can decompose into H2S, SO2, SOF2, and SO2F2. This study conducted first-principles simulations to analyze the effect of Cun (n = 1–3) cluster-modified monolayer WSe2 on sensing H2S, SO2, SOF2, and SO2F2 gases during SF6 decomposition. The optimal doping positions of Cun-WSe2 clusters at n = 1, 2, and 3 were determined, showcasing their superiority over pure WSe2 in terms of band gap, frontier orbitals, and density of states. Subsequently, a detailed investigation was carried out on the adsorption effects of the four gases at the optimal doping positions, including parameters such as adsorption distance, adsorption energy, charge transfer, differential charge density, and density of states. It was found that when the number of copper atoms in the cluster increased to 3, the banding energy sharply rose to -2.395 eV. Simulation results demonstrated the adsorption behavior of H2S on Cun (n = 1–3)-WSe2 demonstrates remarkable affinity, with an increasing adsorption energy as the number of Cu atoms rises. Notably, Cun (n = 1–3)-WSe2 exhibits favorable desorption times for SO2. At 378 K, the desorption time for SO2@Cu3-WSe2 is 14.7 s. At 498 K, desorption times for SO2@Cu1-WSe2 and SO2@Cu2-WSe2 are 7.59 s and 2.85 s, respectively. When the number of copper atoms is 2, the cluster-modified system desorbs SOF2 at room temperature in only 0.89 s. Moreover, Cun (n = 1–3)-WSe2 displays strong adsorption towards SO2F2, characterized by prolonged desorption times, rendering it a promising adsorbent for SO2F2 removal. This study aims to highlight the adsorption effects of different numbers of Cu atomic clusters in the Cun-WSe2 system on SF6 decomposition gas, further advancing research for developing high-performance SF6 decomposition gas sensors.

Study of chemical reactivity and molecular interactions of the hydrochlorothiazide-4-aminobenzoic acid cocrystal using spectroscopic and quantum chemical approaches

In this study, the molecular, electronic, and chemical properties of the drug hydrochlorothiazide (HCTZ) are determined after cocrystallization with 4-aminobenzoic acid (4-ABA). Analysis has been performed to understand how those variations lead to alteration of physical properties and chemical reactivity in the cocrystal HCTZ-4ABA. IR and Raman characterizations were performed along with quantum chemical calculations. A theoretical investigation of hydrogen bonding interactions in HCTZ-4ABA has been conducted using two functionals: B3LYP and wB97X-D. The results obtained by B3LYP and wB97X-D are compared which leads to the conclusion that B3LYP is the best applied function (density functional theory) to obtain suitable results for spectroscopy. The chemical reactivity descriptors are used to understand various aspects of pharmaceutical properties. Natural bond orbital (NBO) analysis and quantum theory of atoms (QTAIM) are used to analyze nature and strength of hydrogen bonding in HCTZ-4ABA. QTAIM analyzed moderate role of hydrogen bonding interactions in HCTZ-4ABA. The calculated HOMO-LUMO energy gap shows that HCTZ-4ABA is chemically more active than HCTZ drug. These chemical parameters suggest that HCTZ-4ABA is chemically more reactive and softer than HCTZ. The results of this study suggest that cocrystals can be a good alternative for enhancing physicochemical properties of a drug without altering its therapeutic properties.

Photo-Modulation of Atomically Thin Molybdenum Diselenides Functionalized with Photochromic Molecules

Two-dimensional (2D) transition metal dichalcogenide semiconductors have garnered significant attention due to their extraordinary electrical and optical properties. It has been increasingly important to develop strategies for modulating their properties. A number of methods have been introduced, including doping, electric and magnetic fields, mechanical strain, etc. Herein, we report a novel approach of using photochromic molecules to modulate optoelectronic properties of monolayer MoSe2 with light. We have synthesized photochromic diarylethene (DAE) molecules that can switch between two isomeric forms, referred to as open and closed, under UV and visible light, respectively. The DAE molecules formed a uniform layer with a thickness of approximately 2 nm on monolayer MoSe2. Our density functional theory (DFT) calculations suggest that the TMD and DAE will align their band energy levels such that UV irradiation moves the lowest unoccupied molecular orbital (LUMO) energy of DAE in between the conduction band minimum (CBM) and valence band minimum (VBM) of MoSe2. This will facilitate photoexcited electron transfer from MoSe2 to DAE LUMO. Experimentally, we have confirmed our predictions by observing a strong quenching of photoluminescence (PL) and an increase of electrical conductivity in MoSe2. In contrast, visible light induced isomerization to the open form of DAE and expanded its energy levels, moving the LUMO level above the MoSe2 CBM. Therefore, the PL was retained and there was no significant change in electrical conductivity. We showed that this photoswitching can dynamically modulate the optoelectronic properties by demonstrating multiple cycles of PL emission and quenching, by alternating UV and visible light repeatedly. Lastly, our Kelvin probe force microscopy (KPFM) revealed that the potential of MoSe2 monolayers can also be modulated with photochromic molecules and external light irradiation. Our work elucidates photo-processes and exciton mechanisms at the hybrid interfaces and lays the foundation for novel applications including new phototransistors and other 2D optoelectronic devices.

Metallophthalocyanines as Outstanding Hole Transporting Materials in Perovskite Solar Cells

Perovskite solar cells (PSCs) are promising candidates to reach the market to complement the current offer of photovoltaic cells although for such a thing they still have to overcome some challenges such as long-term stability. The hole transporting layer (HTL) is a crucial component in n-i-p PSC, since it must favor an adequate movement of charges and protect the perovskite layer from environmental conditions. In this sense, the commonly used HTL, spiro-OMeTAD, does not provide PSCs with sufficient stability and is too expensive. Cheaper molecular materials such as metallophthalocyanines are proving to be a good alternative, as they provide greater stability.[1]In this communication, we will present novel ZnPcs and CuPcs monomers[2] (see as examples Figure 1), among others, as efficient, stable, and low cost HTMs in PSCs. The MPcs are substituted with functional groups that possesses a very good solubility in a wide range of organic solvents, adequate HOMO LUMO levels and their photovoltaics performance as high stable solution processing in a wide range of perovskite solar cell devices.

Electron-Accelerator-Induced Fast Electron Transfer for Enhancing Electrochemiluminescence of Gold Nanoclusters and Its Bioanalysis Application: A Novel Avenue for Developing High-Efficient Emitters.

Herein, the gold nanoclusters/CaFe2O4 nanospheres (Au NCs/CaFe2O4) heterostructure as a novel electrochemiluminescence (ECL) emitter was developed. Excitingly, Au NCs/CaFe2O4 displayed highly efficient and greatly stable ECL based on the newly defined electron-accelerator p-type semiconductor CaFe2O4 NS-induced fast electron transfer; it solved one key obstacle of metal NC-based ECL emitters: sluggish through-covalent bond electron transport kinetics-caused inferior ECL performance. Specifically, on account of the energy level matching between emitter Au NCs and electron-accelerator CaFe2O4 NSs, the valence band (VB) of the electron-accelerator could provide abundant holes for rapidly transporting the electrogenerated electron from the highest occupied molecular orbital (HOMO) of Au NCs to the electrode, generating massive excited species of Au NCs for strong ECL emission. Notably, Au NCs/CaFe2O4 emerged 5.4-fold higher ECL efficiency with 3.5-fold higher electrochemical oxidation current in comparison with pure Au NCs, exhibiting great prospects in extensive lighting installations, ultrasensitive biosensing, and high-resolution ECL imagery. As applications, an ECL bioassay platform was constructed with Au NCs/CaFe2O4 as an emitter and U-like structure-fueled catalytic hairpin assembly (U-CHA) as a signal amplifier for fast and trace analysis of aflatoxin B1 (AFB1) with the detection limit (LOD) down to 2.45 fg/mL, which was 3 orders of magnitude higher than that of the previous ECL biosensors with much better stability. This study developed an entirely new avenue for enlarging the ECL performance of metal NCs, and it is a very attractive orientation for directing the reasonable design of prominent metal NC-based ECL emitters and broadening the practical application of metal NCs.

Sonoinduced Tumor Therapy and Metastasis Inhibition by a Ruthenium Complex with Dual Action: Superoxide Anion Sensitization and Ligand Fracture.

Photoresponsive ruthenium(II) complexes have recently emerged as a promising tool for synergistic photodynamic therapy and chemotherapy in oncology, as well as for antimicrobial applications. However, the limited penetration power of photons prevents the treatment of deep-seated lesions. In this study, we introduce a sonoresponsive ruthenium complex capable of generating superoxide anion (O2•-) via type I process and initiating a ligand fracture process upon ultrasound triggering. Attaching hydroxyflavone (HF) as an "electron reservoir" to the octahedral-polypyridyl-ruthenium complex resulted in decreased highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps and triplet-state metal to ligand charge transfer (3MLCT) state energy (0.89 eV). This modification enhanced the generation of O2•- under therapeutic ultrasound irradiation at a frequency of 1 MHz. The produced O2•- rapidly induced an intramolecular cascade reaction and HF ligand fracture. As a proof-of-concept, we engineered the Ru complex into a metallopolymer platform (PolyRuHF), which could be activated by low-power ultrasound (1.5 W cm-2, 1.0 MHz, 50% duty cycle) within a centimeter range of tissue. This activation led to O2•- generation and the release of cytotoxic ruthenium complexes. Consequently, PolyRuHF induced cellular apoptosis and ferroptosis by causing mitochondrial dysfunction and excessive toxic lipid peroxidation. Furthermore, PolyRuHF effectively inhibited subcutaneous and orthotopic breast tumors and prevented lung metastasis by downregulating metastasis-related proteins in mice. This study introduces the first sonoresponsive ruthenium complex for sonodynamic therapy/sonoactivated chemotherapy, offering new avenues for deep tumor treatment.

Correlation between Molecular Docking and the Stabilizing Interaction of HOMO-LUMO: Spirostans in CHK1 and CHK2, an In Silico Cancer Approach.

Checkpoint kinases 1 and 2 (CHK1 and CHK2) are enzymes that are involved in the control of DNA damage. At the present time, these enzymes are some of the most important targets in the fight against cancer since their inhibition produces cytotoxic effects in carcinogenic cells. This paper proposes the use of spirostans (Sp), natural compounds, as possible inhibitors of the enzymes CHK1 and CHK2 from an in silico analysis of a database of 155 molecules (S5). Bioinformatics studies of molecular docking were able to discriminate between 13 possible CHK1 inhibitors, 13 CHK2 inhibitors and 1 dual inhibitor for both enzymes. The administration, distribution, metabolism, excretion and toxicity (ADMETx) studies allowed a prediction of the distribution and metabolism of the potential inhibitors in the body, as well as determining the excretion routes and the appropriate administration route. The best inhibition candidates were discriminated by comparing the enzyme-substrate interactions from 2D diagrams and molecular docking. Specific inhibition candidates were obtained, in addition to studying the dual inhibitor candidate and observing their stability in dynamic molecular studies. In addition, Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) interactions were analyzed to study the stability of interactions between the selected enzymes and spirostans resulting in the predominant gaps from HOMOCHKs to LUMOSp (Highest Occupied Molecular Orbital of CHKs-Lowest Unoccupied Molecular Orbital of spirostan). In brief, this study presents the selection inhibitors of CHK1 and CHK2 as a potential treatment for cancer using a combination of molecular docking and dynamics, ADMETx predictons, and HOMO-LUMO calculation for selection.

Synthesis, X-ray Crystallography, Spectroscopic Characterizations, Density Functional Theory, and Hirshfeld Surface Analyses of a Novel (Carbonato) Picket Fence Iron(III) Complex.

An Fe(III)-carbonato six-coordinate picket fence porphyrin complex with the formula [K(2,2,2-crypt)][FeIII(TpivPP)(CO3)]·C6H5Cl·3H2O (I) has been synthesized and characterized by UV-Vis and FT-IR spectra. The structure of (carbonato)(α,α,α,α-tetrakis(o-pivalamidophenyl)porphinato)ferrate(III) was also established by XRD. The iron atom is hexa-coordinated by the four nitrogen atoms of the pyrrol rings and the two oxygen atoms of the CO32- group. Complex I, characterized as a ferric high-spin complex (S = 5/2), presented higher Fe-Np (2.105(6) Å) and Fe-PC (0.654(2) Å) distances. Both X-ray molecular structure and Hirshfeld surface analysis results show that the crystal packing of I is made by C-H⋯O and C-H⋯Cg weak intermolecular hydrogen interactions involving neighboring [FeIII(TpivPP)(CO3)]- ion complexes. Computational studies were carried out at DFT/B3LYP-D3/LanL2DZ to investigate the HOMO and LUMO molecular frontier orbitals and the reactivity within the studied compound. The stability of compound I was investigated by analyzing both intra- and inter-molecular interactions using the 2D and 3DHirshfeld surface (HS) analyses. Additionally, the frontier molecular orbital (FMO) calculations and the molecular electronic potential (MEP) analyses were conducted to determine the electron localizations, electrophilic, and nucleophilic regions, as well as charge transfer (ECT) within the studied system.

Effective Coupling Model to Treat the Odd-Even Effect on the Current-Voltage Response of Saturated Linear Carbon Chains Single-Molecule Junctions.

The calculation of the electrical charge transport properties of alkanes C n H 2n S 2 with (n = 4-11) was performed to understand the odd-even effect on its current-voltage response. The extended molecule and broadband limit models were used to describe the molecular junction and covalent coupling with the electrodes. It was shown that among the participating molecular orbitals, HOMO and HOMO-1 are the ones with the most charge transport contribution. Moreover, the odd-even effect is caused by the alternation of the eigenvalues of some frontier orbitals as a function of the number of carbons, especially the HOMO that dominates the electrical transport. It could also be noted that when the current is analyzed outside the resonance, the relationship with the number of carbons exponentially decays, confirming the reports in the literature. To the best of our knowledge, a first principle study of the odd-even effect in symmetric systems composed by linear saturated carbon chains covalently coupled to electrodes has not been reported yet.

Thionation‐Induced Enhancement of Optical and Electronic Properties in NDI Molecule for Molecular Electronic Applications: A Computational Study Using DFT/TD‐DFT and QTAIM Theory

AbstractThe study investigates the impact of thionation on N,N'‐di(dodecyl)‐4,5,8,9‐naphthalene diimide (NDI) through computational methods such as density functional theory (DFT/TD‐DFT), quantum theory of atoms in molecules (QTAIM), and Landauer theory (LT). Thionation, involving the replacement of diamide oxygens with sulfurs in NDI, significantly enhances quantum‐electronic/thermoelectric properties. Computational analyzes of energy of frontier orbitals HOMO/LUMO, dipole moment, polarizability, first superpolarizability, UV spectrum, and cohesive energy show the superior performance of the thione structure (M2) compared to the pristine structure (M1). Thionation decreased the energy gap from 01.3 eV (in M1 structure) to 1.87 eV (in M2 structure). The absorption wavelength in the pristine structure (M1) is calculated to be 507 nm, which increased to 1067 nm after thionation (M2). Cohesive energy values for each of M1 and M2 structures are calculated as 12.76 and 12.89 Kcal mol−1, respectively, which indicates the improvement of stability after thionation. After connecting M1 and M2 to gold electrodes (Au‐M1‐Au and Au‐M2‐Au) and applying electric fields, the Au‐M2‐Au structure shows a lower energy gap, lower thermoelectric activity and higher conductivity at field intensities with higher than 140 × 10−4 (a.u.), indicating its use as a field‐effect molecular device (such as molecular wire or molecular switch).

Ternary nanostructure of CdS-rGO-Ag for enhanced photoelectrochemical application.

In the present study, we have synthesized the ternary nanostructure of CdS-rGO-Ag by using the solvothermal method for the enhanced photocatalytic as well as electrocatalytic activity of the material. The optical properties of the prepared samples were characterized by using UV-visible spectroscopy and photoluminescence (PL) spectroscopy. A decline in the energy gap of CdS-rGO-Ag nanostructure to 1.90 ± 0.05 from 2.40 ± 0.08eV (CdS) is observed and may be attributed due to the rGO-Ag-induced creation of trap states in between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of CdS. The observed significant PL quenching also confirms the inclusion of trap states in the prepared nanostructure CdS-rGO-Ag, suggesting efficient photoactivity. The enhanced photocatalytic activity of CdS-rGO-Ag for methylene blue (MB) dye degradation supports the photocatalytic activity of prepared nanostructures. Furthermore, the photoelectrochemical catalytic activity of the CdS-rGO-Ag catalyst investigated by using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) depicts the improved current density, lowering of overpotential. The decrement in charge transfer resistance and enhancement in photocurrent density under light illumination indicates the better photoelectrochemical performance of CdS-rGO-Ag.

The Ether‐Adduct of a Lewis Superacidic, Dicoordinate Aluminum Hydride Cation and the Ion Affinities of Solvent‐Adducts

AbstractAluminum reagents are widely used as strong Lewis acids for organic transformations and catalysis. In recent years, a variety of Al‐Lewis superacids could be accessed by preparation of aluminum cations paired with weakly‐coordinating anions or by use of perfluorinated substituents at the metal. While the majority of these Al‐Lewis superacids is composed of a tricoordinate Al‐metal atom, examples for dicoordinate Al species are very scarce. In this study, we report the preparation of [(Mes*)Al(H)(OEt2)]+[Al(ORF)4]− (Mes*=2,4,6‐tBu3‐C6H2, RF=C(CF3)3) by reaction of protonated ether [H(OEt2)2]+[Al(ORF)4]− with [Mes*AlH2]2. Structural analysis supported by computed frontier orbitals and atomic charges reveals that the cation is best described as diethylether adduct of dicoordinate [(Mes*)Al(H)]+ and acts as synthon to this low‐coordinate cation. To incorporate the masking of the coordination site by the ether, the enthalpy of dissociation is included in the computed fluoride‐ and hydride ion affinities (XIA) and entropic effects are treated by defining a “free ion affinity” (fXIA), basing on the Gibbs energy change. Hereby, the Lewis acidity of free Lewis acids as well as their solvent adducts can be estimated.

Regulating the electronic structure to construct root-soil-like S-scheme BiVO4/Nd-TiO2 heterojunction for visible degradation and hydrogen evolution

Step-scheme (S-scheme) heterojunctions offer a novel and practical approach to drive electron migrating. However, matching semiconductor energy levels significantly restricts the range of available options. Herein, we propose a S-scheme BiVO4/Nd-TiO2 (BVNT) heterojunction with a unique 1D/3D “root-soil” structure designed to operate milder matching conditions. The 25 wt% BiVO4/Nd-TiO2 (BVNT-25) demonstrates excellent photocatalytic performance, achieving a robust H2 evolution of 538.44 μmol·g−1·h−1 and effective degradation Methylene Blue (MB) within approximately 120 min. DFT results indicate the impurity level of Nd triggers upgraded photocatalytic performance of Nd-TiO2. Meanwhile, Nd induces the lowest unoccupied molecular orbital (LUMO) to generate new front orbitals to facilitate the reaction. XPS and work function indicated that an internal electric field (IEF) from BiVO4 to Nd-TiO2 was generated after hybridization, which allows electrons to move along opposite paths under visible light like S-scheme. SEM, UV–vis DRS, and PL results confirm that the significant photocatalytic activity is also attributed to the multi-path transfer of electrons and well-distributed nanostructures. This work presents a new strategy for fabricating S-scheme heterojunctions in the fields of energy and environment.

Synthesis, Characterization and Energetic Properties of Hydroxymethyl-Bishomocubanone Derivatives.

The present work reports synthesis, characterization and theoretical insights on novel hydroxymethyl-bishomocubanone derivatives. Twelve new bishomocubanes (BHCs) were synthesized and fully characterized by various spectroscopic techniques and single crystal X-ray analysis. The densities of the title compounds were in the range of 1.30-1.59 g/cm3. Density-functional theory (DFT) based calculations at B3LYP/6-311++G(d,p) level of theory were performed on ten selected BHC based cage compounds. Propulsive and ballistic properties of newly synthesized hydroxymethyl-bishomocubanone derivatives in solid and liquid propulsion systems were calculated, and the results suggested that these compounds are superior to conventional fuel RP1 and binder HTPB. The detonation parameters revealed that these compounds are not explosive in nature and safe to use as solid propellants. Furthermore, kinetic and thermal stabilities of the title compounds were determined by HOMO-LUMO energy gap, ESP maps, impact sensitivity (h50) and bond dissociation energies (BDEs) followed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Three compounds, a dinitroazide (Isp,vac=310.98 s), a dinitrate (Isp,vac=309.51 s), and a dinitronitrate (Isp,vac=309.20s) were found to be excellent candidates for volume limited applications.

Zn(II) and Cd(II) complexes of dithiocarbamate ligands: synthesis, characterization, anticancer, and theoretical studies

ABSTRACT A potassium 4-(ethoxycarbonyl)phenyldithiocarbamate, (4-etphdtc), and 6-ethoxybenzothiazol)-dithiocarbamate, (6-etbedtc), ligands have been isolated and four metal dithiocarbamate complexes of the type [M(4-etphdtc)2] and [M(6-etbedtc)2] (M = Zn, Cd;) were synthesized and characterized by elemental analysis and spectroscopic techniques (FT-IR,1H and13C{1H}-NMR, HRMS, UV–vis). Thermogravimetric studies of all four complexes were performed and the final product of the thermal decomposition was metal sulfides. The theoretical study with density functional theory (DFT) has been utilized to optimize the structures of the complexes for HOMO–LUMO energy calculation. Non-bonding orbitals (NBO) analysis was performed to determine the numerous hyper-conjugative interactions responsible for the stability of the compound. In addition, Molecular Electrostatic Potential (MEP) analysis was conducted to identify the compounds’ electron-rich, electron-poor, reactive sites, and bonding characteristics. The Electron Localization Function (ELF), and AIM Charges are also calculated. In vitro cytotoxicity, the complexes were examined against cervical cancer cells (HeLa) to assess their reactivity. Molecular docking studies were conducted to confirm the biological activity by simulating the binding orientation and affinity of the ligands and their complexes against VEGFR-2 kinase, The investigated ligands interact with the binding site as; hydrophilic (Lys868, Glu885, His1026, Cys1045, and Asp1046) and hydrophobic (Val889 and Leu889) for 4-etphdtc; hydrophilic (Lys868, Glu885, Cys1045, and Asp1046) and hydrophobic (Val889, Leu889, Leu1035, and Phe1047) for 6-etphdtc. The calculated binding free energy values for Zn(4-etphdtc)2 and Zn(6-etphdtc)2complexes are – 9.700 kcal/mol, – 10.003 kcal/mol, respectively.