Unoccupied Molecular Orbitals Research Articles

Fabrication of high-efficiency perovskite solar cells using benzodithiophene-based random copolymeric hole transport material

The design of donor-acceptor (D-A)-based random copolymers-type hole transporting materials (HTMs) are important for achieving superior performance of perovskite solar cells (PSCs) with high durability. In this work, a 2-alkylthienyl-substituted benzodithiophene (BDTT)-based random copolymer (denoted as RCP-BDTTPD), containing 2-ethylhexylthiophene-substituted benzo[1,2-b:4,5-b′]dithiophene (BDTT as an electron-donor; M1) and two different side-chain functionalized thieno[3,4-c]-pyrrole-4,6‑dione as the electron-acceptors (M2 and M3), is prepared and applied as an efficient interfacial HTM for PSCs. The optical, electrochemical, and electronic properties of RCP-BDTTPD are shown to be structurally and energetically viable to serve as HTM for PSCs. The RCP-BDTTPD has deeper highest occupied molecular orbitals (HOMO; −5.53 eV) and lowest unoccupied molecular orbitals (LUMO; −3.57 eV) energy levels. This is shown to be energetically suitable for realizing better compatibility with Cs-containing formamidinium/methylammonium (FAMA) mixed-cation perovskite as light absorber having HOMO energy level (−5.85 eV). The RCP-BDTTPD possessing gradient band alignment with perovskite, which is shown to be highly significant for the extraction of charge carriers, resulting in higher hole mobility of PSCs. RCP-BDTTPD delivered a reasonably good Voc of 1.10 V and higher Jsc of 19.01 mAcm−2 and, champion power conversion efficiency (PCE) up to 15.30 % with hole mobility (1.34×10−3 cm2V−1s−1) and high durability (Encapsulated cell retention of its PCE about 98 % over 16 h under harsh environment: Temp. ∼85 °C, RH∼85 %). This work demonstrating a potential application of RCP-BDTTPD based HTMs for the fabrication of high-performance PSCs with high durability as well as low cost.

Cobalt single-site molecular Catalyst-mediated electrochemical Hydrodechlorination for detoxification of halogenated Antibiotics: Performance, reaction pathway and mechanism

Electrocatalytic hydrodehalogenation (ECHD) offers a promising approach for detoxification of the halogenated antibiotics via hydrogenolysis of the C-X bonds (X = F, Cl or Br). Herein we demonstrated that the commercially-available cobalt phthalocyanine (CoPc) molecules with a high-loading of −[Co-N4]- moieties (Co wt%: 10.8 %) were exceptionally active for hydrogenolysis of the C-Cl bonds in florfenicol (FLO). It afforded an impressive mass activity of 6.2 gFLO h−1 g-1Co, a low Co leaching of 0.34 μg/L and a strong tolerance to interference from impurities in water, significantly surpassing reported Co/Fe/Ni-based particle and single-site counterparts. Mechanistic studies revealed that the ECHD on CoPc underwent a direct electron transfer manner rather than the atomic hydrogen (H*)-mediated indirect way, and the ECHD efficacy was affected by both the electron and proton transfer kinetics. The single-atom Co, with its d orbitals constituting the lowest unoccupied molecular orbitals of CoPc, served as the primary active site. It facilitated both electron and proton transfer, as well as the cleavage of the C-Cl bond but not the C-F bond. In a continuous-flow cell, the CoPc/C-driven ECHD reduced the antibacterial activity of a FLO-contaminated natural lake water sample by 90.8 % with an energy consumption of 0.19 kwh g-1FLO. This study highlighted great promise of the single-atom metal-bearing molecular catalyst toward the sustainable detoxification of halogenated antibiotics-contaminated water.

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

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

Structural characterisation of a cyanomesogen by X-ray diffraction and computational methods

The work reports the structural analysis of a cyanomesogen namely, p-cyanobenzylidene p-nonyloxyaniline belonging to the Schiff base class of compounds. It exhibits a partial bilayer/inter-digitated smectic Ad phase and a nematic phase. Polarising Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC) studies have been carried out to study phase sequence and transition temperatures. Micro-structural parameters, like molecular length, spacing, crystallite size, activation energy and micro-strain, have been estimated and pair correlation function (PCF) studies have been done for exhibited mesophases using the X-ray diffraction technique. The study investigated the surface, electronic and optical properties of a compound by computational studies like Density Functional Theory (DFT) and Hirshfeld surface analysis (HSA) methods using the DFT B3LYP/6-311++G(d,p) level basis set. The results reveal that the polarity associated with the polar groups and alkoxy chain lengths, contributes majorly to the mesomorphic characteristics and stability. The Highest Occupied Molecular Orbitals (HOMO) and Lowest Unoccupied Molecular Orbitals (LUMO) analyses of the DFT optimised molecule give electronic and geometrical parameters, atomic charge distribution, polarisability factors which are used to interpret the characteristics of the mesophases and their suitability for electro-optical and non-linear optical applications of the compound in terms of the predicted data.

Importance of Orbital Invariance in Quantifying Electron-Hole Separation and Exciton Size.

A fundamental tenet of quantum mechanics is that properties should be independent of representation. In self-consistent field methods such as density functional theory, this manifests as a requirement that properties be invariant with respect to unitary transformations of the occupied molecular orbitals and (separately) the unoccupied molecular orbitals. Various ad hoc measures of excited-state charge separation that are commonly used to analyze time-dependent density-functional calculations violate this requirement, as they are based on incoherent averages of excitation amplitudes rather than expectation values involving coherent superpositions. As a result, these metrics afford markedly different values in various common representations, including canonical molecular orbitals, Boys-localized orbitals, and natural orbitals. Numerical values can be unstable with respect to basis-set expansion and may afford nonsensical results in the presence of extremely diffuse basis functions. In contrast, metrics based on well-defined expectation values are stable, representation-invariant, and physically interpretable. Use of natural transition orbitals improves the stability of the incoherent averages, but numerical values can only be interpreted as expectation value in the absence of superposition. To satisfy this condition, the particle and hole density matrices must each be dominated by a single eigenvector so that the transition density is well described by a single pair of natural transition orbitals. Counterexamples are readily found where this is not the case. Our results suggest that ad hoc charge-transfer diagnostics should be replaced by rigorous expectation values, which are no more expensive to compute.

Molecular insights into 5-hydroxymethylfurfural: a computational, spectroscopic, and docking investigation

The quantum chemical properties of 5-hydroxymethylfurfural were investigated using Density Functional Theory alongside vibrational spectroscopy. Key outcomes included optimizing molecular structure, vibrational frequencies, and various molecular parameters. By comparing DFT results with experimental infrared spectra, molecular motion was clarified. Reactive sites were identified through Molecular Electrostatic Potential and Fukui function analyses. Hirshfeld surface analysis revealed insights into the crystal structure’s intermolecular interactions and hydrogen bonding. Time-dependent Density Functional Theory combined with the Polarizable Continuum Model provided Ultraviolet spectra, highlighting charge transfer between the highest occupied and lowest unoccupied molecular orbitals. The compound’s electronegativity (4.7239) and electron affinity were assessed. Biological studies, including drug-likeness evaluations and molecular docking, also demonstrated potential physiological benefits, mainly through the compound’s low binding energy. A 100-nanosecond molecular dynamics simulation of the 5-HMF-4LB4 complex revealed its stability and dynamic behavior through analyses of Root Mean Square Deviation, Root Mean Square Fluctuation, hydrogen bonding, Solvent Accessible Surface Area, and radius of gyration.

BODIPY Photosensitizers Functionalized with Mannose for Fluorescence Cell-imaging and Photodynamic Therapy

The synthesis of four water-soluble mannose-tethering BODIPY-based photosensitizers (PSs) with varying substituents (-H, -OMe, -NO2 and -I) in the para-phenyl moiety attached to the meso-position of the BODIPY core, offering tumor-targeting and photodynamic therapeutic (PDT) potentials, is reported. The PDT capability of the synthesized PSs was investigated using the cervical cancer cell line HeLa. Owing to the heavy atom effect, BODIPY I, enhanced the intersystem crossing (ISC) to produce singlet oxygen (1O2) and maintained a high fluorescence quantum yield (ΦF) of 0.71. In contrast, the electron-donating methoxy substituent (BODIPY OMe) caused a notable perturbation in the occupied frontier molecular orbitals, subsequently achieving a higher 1O2 generation capability with a high ΦF of 0.85. Conversely, substitution with the electron-withdrawing nitro group (BODIPY NO2) resulted in a perturbation of unoccupied frontier molecular orbitals and generated a forbidden dark S1 state, negatively affecting both fluorescence and 1O2 generation efficiencies. The cytotoxicity of the synthesized water-soluble BODIPY PSs in the dark and under LED irradiation against the HeLa cell line was also assessed, with BODIPY I, OMe and H showing favorable PDT activity. Collectively, the performance of the mannose-conjugated BODIPY PSs in this study contributed promising results for the development of photodynamic therapeutic agents for cancer treatment.

Investigation of aluminum nitrate nanotube as the smart carriers for targeted delivery of gemcitabine anti-lung cancer drug

The potential of aluminum nitrate nanotube as a drug carrier for anti-lung cancer drug gemcitabine is examined based on the density functional theory (DFT) calculations. The adsorption geometries of gemcitabine drug onto the surface of nanotube are investigated for various orientation in order to attain the most stable configuration. Significant interaction is observed between the double bonded oxygen atom of the gemcitabine drug and aluminum atom of the nanocage. The charge transfer analysis indicates that there is significant interaction along with considerable charge transfer between gemcitabine and the aluminum nitrate nanotube. The electronic properties such as highest occupied molecular orbital, lowest unoccupied molecular orbitals energy levels, energy gap, chemical hardness, chemical potential, electrophilicity index, and dipole moment for the best three configurations of the complexation are examined. The recovery time calculations are also performed at 298.15 K temperature in order to study the drug desorption process on the targeted site. The stability of the complex is compared in both gas and aqueous medium. Eventually, this work interprets that aluminum nitrate nanotube can be considered to be suitable candidates for delivering gemcitabine anti-lung cancer drug in a biological system.

Supramolecular structure, DFT calculation and vibrational characterization of melamin-1-ium oxalurate monohydrate

Crystallization from an aqueous solution of melamine with parabanic acid was taken in a molar ratio of 1:1 leads to the formation of melamin-1-ium oxalurate monohydrate (MOX) crystals. The compound crystallizes in the centrosymmetric space group P21/n of the monoclinic system with four molecules per unit cell. The molecular geometry and vibrational frequencies of MOX in the ground state have been calculated by using the density functional hybrid function B3LYP 6–31+G(d) basis set. The results of optimized molecular structure are presented and compared with the experimental X-ray diffraction data. Furthermore, Fourier Transform Infrared (FT-IR) and Raman Spectra were used to conduct vibrational characterization to study the compound's structural groups. The calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies show that charge transfer occurs in the molecule and other related electronic properties have also been calculated. Besides, Molecular Electrostatic Potential (MEP) was performed to identify the possible electrophilic and nucleophilic sites. First order hyperpolarizability results establish the nonlinear response of the grown MOX crystal with respect to the electric field. Further, the crystal packing behaviour of MOX was studied quantitatively with the aid of Hirshfeld surface analysis.

Synthesis, spectral characterization, anti-cancer activity evaluation, and molecular docking of substituted 1,2-bis(3-butyl-2,6-diphenylpiperidin-4-ylidiene)hydrazone derivatives

A series of 1,2-bis(3‑butyl‑2,6-diphenylpiperidin-4-ylidiene)hydrazone derivatives of the substituted compounds 1–7, were confirmed by the characterization of IR & 1H-, NMR spectrum, together with X-ray crystallography and Mass spectroscopy also incredibly revealed. Docking analysis of the synthesized compounds employed under the protein from PDB code as 5cqh1, 4i40, 5fan, 7nud, 6Ya1 offers more inhibition values from 2D and 3D structures of the compounds, followed by Anti-cancer activity of the carcinoma cell line displayed that, highly potent to be active in nature. The in-vitro performance of -Cl substituted compound 6 (high anticancer activity) was in good correlation with its protein binding behaviour (strong binding). The increasing order of anticancer effect was 5>7>1>2>4>3>6 and the increasing order of binding ability on proteins were 7>3>4>1>2>5>6. The computational investigations were aligned with experimental techniques using Density Functional Theory (DFT) with a 6–31 G (d, p) basis set. Calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies revealed Mulliken charges and charge transfer phenomena occurring within the molecule. Analysis of the Molecular Electrostatic Potential (MEP) unveiled reactive sites, with high electron density regions depicted in red and low electron density regions in blue.

Large Orbital Moment and Dynamical Jahn-Teller Effect of AlCl-Phthalocyanine on Cu(100).

Submonolayer amounts of chloroaluminum-phthalocyanine on Cu(100) were studied with scanning tunneling spectroscopy. The molecule can be prepared in a fourfold symmetric state whose conductance spectrum exhibits a zero-bias feature similar to a Kondo resonance. In magnetic fields, however, this resonance splits far more than expected from the spin of a single electron. Density functional theory calculations reveal a charge transfer of 1.3 electrons to the degenerate lowest unoccupied molecular orbitals. These orbitals are mixed by the orbital momentum operator L[over ^]_{z} with a large matrix element corresponding to m_{L}≈2.7. Dehydrogenation of a ligand lifts the degerenracy of the lowest unoccupied molecular orbital, reduces the splitting in magnetic fields, and induces a polarity dependence of the spectra. Using model calculations of the spin, orbital, and vibrational degrees of freedom we show that a dynamical Jahn-Teller effect reproduces the main experimental observations.

Computational, molecular docking and spectroscopic insights of drug–drug interaction between Ibuprofen and Paracetamol

The combination of existing drugs or drug–drug interaction enthralls researcher because of their potential applications in multiple diseases and better efficacy. The present work is undertaken to study the interaction between two drugs, Ibuprofen and Paracetamol, using Density Functional Theory and spectroscopic techniques (Infrared and Raman spectroscopy). The molecular modeling of the two drugs indicates their interaction through intermolecular hydrogen bonds (O34-H53-O2 and (O1-H33-O34), which is observed in Natural Bond Orbital and atoms in molecules analysis of the compound (Ibuprofen + Paracetamol). The experimental Raman, Surface Enhanced Raman Spectroscopy and Infrared spectra of the physical mixture (Ibuprofen + Paracetamol) are found close to their computed wavenumbers. The interacting state, that is, Ibuprofen + Paracetamol is optimized using B3LYP/6-31G ++ (d, p) model under density functional theory framework and different computed quantum chemical parameters such as, dipole moment, ionization energy, electron affinity, electrophilicity index, chemical potential, hardness and the Highest Occupied and Lowest Unoccupied Molecular Orbital energies and energy gaps are calculated and compared to the monomer state of the drugs. The lowering of energy gap and increased in dipole moment of combined drug molecules show potency as an effective hybrid drug. The molecular docking study of the combined drug molecule against the 4PH9 receptor shows a better binding affinity with its residues through hydrogen bonding and hydrophobic interaction.

A unique approach to address avoided crossings in the charge stabilization curve for LUMO identification.

In quantum chemistry, Lowest Unoccupied Molecular Orbital (LUMO) is important for studying various chemical processes, including photochemical reactions, electron attached states, and electron excites states. Recently, an effective method has been introduced that involves the use of the Parametric Equation of Motion (PEM) in conjunction with the nuclear charge stabilization method for precise identification of true LUMO. However, the inclusion of extra diffuse functions in the basis set, which is necessary for describing electron-attached and electron-excited states, can cause issues due to the presence of the same symmetry states, leading to avoided crossing. Identifying the true LUMO among these avoided crossings is challenging due to the mixing of states and the exchange of their orbital character. This article introduces a modification of the PEM to identify the true LUMO by preventing the stabilization of specific states involved in avoided crossings. The present method is highly effective and requires minimal computational cost.

Synthesis of phthalocyanine/C3N4 structures and investigation of photocatalytic activities in the oxidation reaction of 4-nitrophenol

Photocatalytic oxidation is an advanced oxidation technique widely preferred for the removal of pollutants in wastewater. In this work, paramagnetic metallo-phthalocyanines EB2 and EB3 (Co(II)phthalocyanine and Cu(II)phthalocyanine) have been synthesized and characterized. They were interfaced with C3N4 (graphitic carbon nitride) to prepare metallophthalocyanines/C3N4 structures (EB2-C3N4 and EB3-C3N4) using ultrasonic methods. New structures were identified with FT-IR, SEM and TGA. The photocatalytic performances of EB2-C3N4 and EB3-C3N4 for reaction with p-nitrophenol (p-NP) were established. The product selectivity for industrially important benzaldehyde was 85.1% for EB2-C3N4 and 80.6% for EB3-C3N4. EB2-C3N4 showed good potential for p-NP photocatalyic oxidation with high turn-over number (TON) and turn-over frequency (TOF) (390 and 1565) over 15 min. Upon excitation of EB2-C3N4 and EB3-C3N4 with light, 4-nitrophenol was easily reduced to hydroquinone, prompted by electron transfer from C3N4 to phthalocyanine and from phthalocyanine to 4-nitrophenol. Computational investigations were used to determine the energies of the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO) of EB2, EB3 and C3N4.

Rosmarinic Acid as a Potential Multi-targeted Inhibitor for SAR-CoV-2: An In silico Virtual Screening Approach

Background: Rosmarinic acid, a natural compound found in various plants like rosemary and lemon balm, may have potential as a multi-targeted inhibitor for SARS-CoV-2, a strain of virus responsible for COVID-19. SARS-CoV-2, a fusion protein of S1 and S2 subunits, has multiple precursors angiotensin-converting enzyme2 (ACE2), transmembrane serine protease 2 (TMPRSS2), papain-like protease (PLpro), and 3-chymotrypsin-like protease (3CLpro). The chemical interaction of Rosmarinic acid with SARS-CoV-2 is of major interest reported here. Objective:: The quantitative study of Rosmarinic acid with various precursors of SARS-CoV-2 has been accounted for in detail. Furthermore, the conformational flexibility of Rosmarinic acid has also been investigated during the interaction with four different precursors of SARS-CoV-2. Methods: This investigation delves deeply into the analysis of various aspects, including geometric parameters, atomic charge, the energy gap between the highest occupied and lowest unoccupied molecular orbitals, dipole moments, and the analysis of non-covalent interactions (NCI). Furthermore, the study incorporates molecular docking techniques in conjunction with thorough quantum chemical calculations to provide comprehensive insights. Results: Rosmarinic acid shows promise as a versatile inhibitor of SARS-CoV-2, the virus responsible for COVID-19. It can target multiple key precursors of the virus, including TMPRSS2, angiotensin- converting enzyme2, 3CLpro, and PLpro, found in the fusion protein comprising S1 and S2 subunits. This study delves into the quantitative analysis of Rosmarinic acid's interactions with these precursors. Its adaptable structure allows it to engage with them effectively. Various molecular parameters, including atomic charge, energy gap between molecular orbitals, dipole moment, and noncovalent interactions, are comprehensively explored. Conclusion: Combining molecular docking and quantum mechanics, the findings suggest Rosmarinic acid's potential as a multi-targeted SARS-CoV-2 inhibitor.

SF6 Negative Ion Formation in Charge Transfer Experiments.

In the present work, we report an update and extension of the previous ion-pair formation study of Hubers, M.M.; Los, J. Chem. Phys.1975, 10, 235-259, noting new fragment anions from time-of-flight mass spectrometry. The branching ratios obtained from the negative ions formed in K + SF6 collisions, in a wide energy range from 10.7 up to 213.1 eV in the centre-of-mass frame, show that the main anion is assigned to SF5- and contributing to more than 70% of the total ion yield, followed by the non-dissociated parent anion SF6- and F-. Other less intense anions amounting to <20% are assigned to SF3- and F2-, while a trace contribution at 32u is tentatively assigned to S- formation, although the rather complex intramolecular energy redistribution within the temporary negative ion is formed during the collision. An energy loss spectrum of potassium cation post-collision is recorded showing features that have been assigned with the help of theoretical calculations. Quantum chemical calculations for the lowest-lying unoccupied molecular orbitals in the presence of a potassium atom are performed to support the experimental findings. Apart from the role of the different resonances participating in the formation of different anions, the role of higher-lying electronic-excited states of Rydberg character are noted.

Superexchange Electron Transfer and Protein Matrix in the Charge-Separation Process of Photosynthetic Reaction Centers.

In type-II reaction centers, such as photosystem II (PSII) and reaction centers from purple bacteria (PbRC), light-induced charge separation involves electron transfer from pheophytin (PheoD1) to quinone (QA), occurring near a conserved tryptophan residue (D2-Trp253 in PSII and Trp-M252 in PbRC). This study investigates the route of the PheoD1-to-QA electron transfer, focusing on the superexchange coupling (|HPheoD1···QA|) in the PSII protein environment. |HPheoD1···QA| is significantly larger for the PheoD1-to-QA electron transfer via the unoccupied molecular orbitals of D2-Trp253 ([Trp]•--like intermediate state, 0.73 meV) compared to direct electron transfer (0.13 meV), suggesting that superexchange is the dominant mechanism in the PSII protein environment. While the overall impact of the protein environment is limited, local interactions, particularly H-bonds, enhance superexchange electron transfer by directly affecting the delocalization of molecular orbitals. The D2-W253F mutation significantly decreases the electron transfer rate. The conservation of D2-Trp253/D1-Phe255 (Trp-M252/Phe-L216 in PbRC) in the two branches appears to differentiate superexchange coupling, contributing to the branches being either active or inactive in electron transfer.

Exploring boratrane's potential to enhance the thermal stability of phenol-formaldehyde resins by borate bridge as a crosslinker and the mechanistic formation of boron species in carbonaceous materials: A comprehensive study

In advanced material science, we explore the potential of boratrane, a promising agent for enhancing thermal stability. By combining rigorous Density Functional Theory (DFT) calculations with groundbreaking experimental analyses, we reveal the intricate interplay of radical intermediates and mechanisms underlying the thermal evolution of boratrane-infused materials. Our innovative approach illuminates dynamic structural transformations and elucidates boratrane's pivotal role in fortifying thermal resilience. The DFT calculations identify radical intermediates and mechanisms of thermal degradation, highlighting the role of borate bridges in delocalizing π-electrons in aromatic rings through Gibbs free energy (∆GRXN), Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO), and electrostatic potential (ESP) analyses. Fukui function analysis provides insights into the reactivity of these structures towards free radical attacks. Our findings demonstrate that boratrane-modified resins exhibit a stable BO4- structure, which prevents self-condensation of boratrane to B2O3 and enhances the thermal stability of oxygenated resins. This improvement is due to the formation of intramolecular hydrogen bonds, contributing to helix-like structures that strengthen the resin. The mechanism by which the BO4- structure terminates radical agents and transforms into carbonaceous material is elucidated through thermodynamic values, revealing the plausible reactions and chemical structure of boron in the resulting material.

Role of H2O Adsorption in CO Oxidation over Cerium-Oxide Cluster Anions (CeO2)nO- (n = 1-4).

Water (H2O) is ubiquitous in the environment and inevitably participates in many surface reactions, including CO oxidation. Acquiring a fundamental understanding of the roles of H2O molecules in CO oxidation poses a challenging but pivotal task in real-life catalysis. Herein, benefiting from state-of-the-art mass-spectrometric experiments and quantum chemical calculations, we identified that the dissociation of a H2O molecule on each of the cerium oxide cluster anions (CeO2)nO- (n = 1-4) at room temperature can create a new atomic oxygen radical (O•-) that then oxidizes a CO molecule. The size-dependent reactivity of H2O-mediated CO oxidation on (CeO2)nO- clusters was rationalized by the orbital compositions (O2p) and energies of the lowest unoccupied molecular orbitals of active O•- radicals modified by H2O dissociation. Our findings not only provide new insights into H2O-mediated CO oxidation but also demonstrate the importance of H2O in modulating the reactivity of the O•- radicals.

Design, synthesis, and characterization of a novel pH-responsive azo dye incorporating a 1,3,4-thiadiazole ring for advanced textile applications

This study presents the synthesis and comprehensive characterization of a novel azo dye derived from 2-(5-amino-1,3,4-thiadiazol-2-yl) phenol (1a). The synthesis was initiated by reacting salicylic acid with thiosemicarbazide in the presence of phosphorus oxychloride (POCl3), yielding an 89 % conversion to compound 1a. The subsequent diazotization and coupling of 1a under alkaline conditions led to the formation of the azo dye (1b). Structural elucidation was confirmed through Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The incorporation of the 1,3,4-thiadiazole ring is significant due to its known influence on enhancing dye stability, reactivity, and potential biological activities, while the salicylic acid moiety contributes to the dye's pH responsiveness. A notable pH-dependent color transition from yellow (pH < 6.0) to red (pH > 8.0) was observed, driven by protonation-induced resonance changes. Computational studies, including Frontier Molecular Orbital (FMO) analysis, revealed a Highest Occupied Molecular Orbital (HOMO)-Lowest Unoccupied Molecular Orbital (LUMO) gap of 1.94 eV, indicating efficient electronic transitions critical for its color properties. Molecular Electrostatic Potential (MEP) and Fukui function analyses provided further insights into the dye's reactivity and potential applications. The dyeing properties were rigorously assessed through K/S values, CIELAB color space, and fastness properties on cotton fabric, demonstrating varied color depths and hues influenced by different mordants, with copper and manganese significantly enhancing color intensity. Colorfastness tests revealed good to fair durability, with untreated fabrics showing optimal performance. This thorough characterization underscores the promising potential of this newly synthesized azo dye for applications in pH-responsive textiles and functional materials, highlighting its relevance for advanced textile and material science applications.