Natural Bond Orbital Analysis Research Articles

Structurally Innovative Benzimidazole‐fused Ionic Organoselenium Compounds: Prevalence of Se···N/Se Chalcogen Bonds with the Selenocyanate Receptor

The non‐covalent interactions in molecules play important roles towards their applications in various aspects such as molecular recognition, catalysis, supramolecular chemistry, structural biology, pharmacology etc. Interestingly, among various non‐bonding interactions, chalcogen bonding (ChB) has been extensively studied in different facets of crystal engineering over the last several years. The present study demonstrates the presence of Se···N or Se···Se ChB in the benzimidazole‐fused cyclic selenazonium selenocyanates (6‐8), cyclic selenazinium selenocyanates (9‐10) and the acyclic benzimidazolium analogs having two different types of selenocyanate units (11‐12). The final organoselenium compounds were synthesized from benzimidazole in several steps in reasonably good yields. The single crystal X‐ray structures of the compounds revealed that both the N atom and Se atom of the negatively charged SeCN unit act as ChB acceptors in building the Se···N or Se···Se ChB interactions along with the additional hydrogen bonding (HB) interactions. Moreover, the structural optimization and natural bond orbital (NBO) analyses were carried out using density functional theory (DFT) to calculate the natural charges on different Se centers and the strength of second‐order perturbation energy (E2) for the ChB interactions. Finally, electrostatic potential surface (SEP) of the compounds was developed to visualize the formation of σ‐holes.

Synthesis, spectroscopic characterization techniques of aromatic iminoaniline derived compound, along with the evaluation of its LNO properties using quantum chemistry

In this research work, we synthesized a Schiff base derivative, N,N-dimethyl-4-{[(4-nitrophenyl)imino]-methyl}aniline, denoted as (n1). The molecule (n1) was characterized using spectroscopic analyses, including FT-IR, NMR 1H, and 13C. Our compound (n1) is an unsaturated molecule, consisting of two benzylic rings connected by a methylimine bridge. The resulting system comprises seven alternating π bonds. At both ends of (n1) and in the para position, there are the N(CH3)2 group with a strong electron-donating effect and the NO2 group with a strong electron-accepting effect. The molecular structure of our compound prompted us to evaluate and study its properties in the field of NLO. The assessment of NLO properties is conducted by determining the Egap and employing density functional theory (DFT) quantum chemistry studies. The optical gap of (n1), measured using the Tauc method, is found to be 2.7 eV, serving as a reference value for the choice of the DFT functional in theoretical calculations. Quantum chemistry studies were carried out using Gaussian09 software, and the results were visualized with GaussView05. CAM-B3lyp functional was chosen for theoretical calculations due to its close agreement with experimental values. The studies confirm that (n1) exhibits significant NLO properties. Additionally, NBO (Natural Bond Orbital) analyses provide insight into the mechanism and trajectory of intramolecular charge transfer in (n1).

Stereoselective Ring-Opening Reaction of α-Fluorinated Oxetanes: A Practical and Theoretical Investigation.

The ring-opening reaction of fluorinated oxetanes by halides, including alkylidene oxetanes and spirocyclic oxetanes, was highly stereoselective and directed by the presence of a fluorine atom. This reaction allowed a stereoselective preparation of tetrasubstituted alkenes and substituted pyrrolidines containing all-carbon quaternary centers. Theoretical calculations were performed to shed light on experimentally observed regioselectivity in the opening of oxetane derivatives. Transition state calculations were carried out to compare the energy of transition states responsible for forming different diastereoisomers. These calculations were performed using several DFT functionals and benchmarked to DLPNO-CCSD(T)/def2-TZVP calculations. Intrinsic reaction coordinated (IRC) calculations were run to confirm if the found transition states connect reactants and products. The IRC paths were then decomposed into the electrostatic, steric hyperconjugative contributions to reaction barriers by using the natural bond orbital (NBO) analysis. The destabilizing Fδ-···Br- electrostatic interaction directs the reaction pathway.

Electrical and work function-based chemical gas sensors utilizing NC3 and graphene combination

Research has been conducted on the potential practical uses of heterostructures made of graphene and carbon nitride (NC3) following their successful synthesis. The remarkable gas sensing properties of these 2D nanosheets have captured significant interest, attributed to distinctive electronic characteristics and exceptional surface-to-volume ratio that are resulted from combination of NC3 and graphene. In this study, we present a detailed analysis of electronic and structural features of pristine NC3 and graphene (PG), and their in-plane heterostructures using first-principles density functional theory. Our investigation utilizes the B3LYP and dispersion-corrected van der Waals (vdW) functional WB97XD, along with 6-311G (d, p) basis set. Our findings indicate that the nanosheets we anticipated exhibit robust structural stability, characterized by a desirable cohesive energy. Furthermore, we observed a gradual increase in the bandgap as the concentration of N–C in the nanosheets increases. Additionally, we investigated the adsorption characteristics of these heterostructures towards toxic gas molecules such as SO2 and CO. Among the studied heterostructures, GNC3I demonstrated higher adsorption energy (Eads), with values of approximately −0.283 and −0.491 eV when exposed to SO2 and carbon monoxide gas molecules respectively. Electronic characteristics, including LUMO and HOMO energy values, energy gap (Eg) between HOMO and LUMO, work function, Fermi level, and conductivity, underwent notable modifications upon SO2 gas adsorption over nanosheets, except for PG. However, these parameters remained relatively unchanged following carbon monoxide adsorption. Natural bond orbital (NBO) and Mulliken charge analysis demonstrates that there is a transfer of charge from gas molecules to nanosheets. Although nanosheets exhibit slightly higher adsorption energy (Eads) values for CO gas compared to SO2 gas, various assessments, including molecular electrostatic potential (MEP) mapping, electronic properties, and charge transfer (CT) analysis, suggest that these nanosheets are superior sensors for detecting SO2 gas rather than carbon monoxide gas molecules.

Theoretical investigation of Diels–Alder reaction mechanism and regioselectivity with functionalized fullerene derivatives

AbstractDensity functional theory (DFT) was used to study the mechanism of Diels–Alder (DA) reaction between 2‐Methyl‐ 1,3 Butadiene (MBD) with B12N12, B6N6C12 and B6C12N6 fullerens in the gas phase. In this mechanism, B‐N bonds of four‐membered and six‐membered rings of nanocages were chosen to react with MBD. Due to the existence of two types of B‐N bonds, two competitive pathways (a and b) were investigated. The effect of the substitution of carbon atoms instead of boron and nitrogen atoms on the stability of the structures and the regioselectivity of the DA reaction was examined. The potential energy of all structures and the activation barrier for all reaction pathways was evaluated. The chemical reactivity of fullerens using the molecular quantum descriptors was assessed. To evaluate the global electron density transfer in transition states (TS) structures, the natural bond orbital (NBO) analysis was performed.

A theoretical investigation into the impact of solvents (alkanolic and non-alkanolic), structural and spectroscopic properties, donor-acceptor insights, Hirshfeld surface, and molecular docking of the anti-tumor compound (2E)-3-[4-(dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one

In this study, computational methods were employed to analyze the molecular structure of (2E)-3-[4-(Dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one (DMAPNP), investigating its structural and spectroscopic properties along with its biological activity. In particular, the Frontier Molecular Orbital (FMO) and Molecular Electrostatic Potential (MEP) surfaces in alkanolic solvents (ethanediol, ethanol, and methanol) and non-alkanolic solvents (DMSO, toluene, and water) were generated to analyze the solvent-solute interactions. The H→L transition shows low oscillator strengths (0.0002 in toluene to 0.0013 in ethanediol, DMSO, and water), indicating limited significance in the absorption spectrum. In contrast, the H→L+1 transition has much higher oscillator strengths, around 0.9412 for ethanediol and 0.9385 for DMSO and toluene, suggesting a greater likelihood of absorption at these wavelengths. The simulated vibrational wavenumbers revealed the presence of CH, NO2, CN, CC, CH3, and C=O groups in DMAPNP. The calculated chemical shifts confirmed the molecular structure of DMAPNP and aligned with standard values. In Hirshfeld surface analysis, the crystal packing of DMAPNP was primarily stabilized by H…H interactions, contributing 41.3%, followed by O…H / H…O interactions at 30.9%. In Natural Bond Orbital (NBO) analysis, the interaction between C20-H38 and C15-H33 shows a stabilization energy of 1102.89 kJ/mol, highlighting σ-σ* transitions. In contrast, the C12-C16 and C15-H33 interactions exhibit a stabilization energy of 2542.16 kJ/mol, indicating substantial π-σ* contributions. In the Mulliken charge distribution, the carbon atoms C18 (-1.33704e) and C13 (1.776064e), located in the para and meta positions concerning the nitro group (NO2), exhibit the highest positive and negative potentials, respectively. Molecular docking assessed DMAPNP as a potential anti-tumor agent by inhibiting the key regulatory enzyme fructose-2,6-bisphosphatase, with a binding energy of -8.13 kcal/mol.

Synthesis, Theoretical Gaussian Quantum Chemical Calculations, and Spectroscopic Elucidation of N‐(4‐bromophenyl)‐10H‐phenothiazine‐10‐carboxamide

AbstractPhenothiazine derivative N‐(4‐bromophenyl)‐10H‐phenothiazine‐10‐carboxamide (BPC), a novel compound is selected for the present study based on the reported effectiveness of phenothiazine towards neurodegenerative diseases. Synthesis and characterization of BPC are carried out in the present work. To comprehend the electronic and structural aspects of BPC, quantum chemical studies are performed. Computational aspects using the density functional theory method using B3LYP/6–31 G ++(d,p) as a basis set are studied for the geometry optimization of the molecule. To analyze the reactivity, stability, and intramolecular interactions of the compound frontier orbital molecular analysis, molecular electrostatic potential distribution, and Fukui function are implemented. Calculations have been made to determine the electrophilic and nucleophilic descriptors of the title compounds by Fukui function evaluations on atomic charges. To visualize and quantify the localization of electrons and molecular orbitals in the molecule, electron localization function, localized orbital locator analysis and orbital localization analysis are carried out for a better understanding of chemical bonding. Basin Analysis is used for analysis of the nature of chemical bonds and interactions. To understand bond strengths, hyperconjugation, and reactivity natural bond orbital analysis is performed.

Positional isomers and non-covalent interactions of acrylonitrile-methylpyridinium iodide salts: Combined experimental and quantum chemical calculations investigations

Quaternary salts d-π-A+X- having a large π-conjugated system (I) 2-((Z)-1-cyano-2-[4-(dimethylaminophenyl]ethenyl)-1-methylpyridin-1-ium iodide, (II) 3-((Z)-1-cyano-2-[4-(dimethylaminophenyl]ethenyl)-1-methylpyridin-1-ium iodide, and (III) 4-((Z)-1-cyano-2 iodide -[4-(dimethylaminophenyl]ethenyl)-1-methylpyridin-1-ium iodide, were synthesized straightforwardly and easily and characterized by single-crystal X-ray diffraction, IR, UV–Vis, 1HNMR spectroscopy, DSC, and TGA. Quantum chemical calculations were performed to obtain electronic structure by using DFT. The salts I-III exhibited a hyperchromic shift and a strong bathochromic effect of 100 nm compared to the precursors, which indicates charge transfer (CT) due to ionic interactions. The Hirshfeld, MEPS, QTAIM, and NCI-RDG analyses showed that the -CN group and the counterion I(-) atom play major roles in the intermolecular interaction for crystal packing. The significance of non-covalent interactions for the stability of the molecules in their solid state is also revealed by natural bond orbital analysis.

The Gauche‐Effect in 1,2‐Bis(arylsulfonate)ethanes

AbstractWith an aim of obtaining a fundamental understanding of C−C bond conformation theory, the molecular structure of an ethane with electron‐withdrawing groups, 1,2‐bis(4‐methoxybenzene‐sulfonate)ethane, was elucidated. According to the general conformation rule for alkanes, which states that molecules adopt a stabilized structure to avoid steric repulsion, ethanes typically adopt anti‐conformation. However, the title compound exhibited gauche‐conformation, as revealed by a single crystal diffraction study. Theoretical studies also support this behavior. Natural Bond Orbital (NBO) analysis suggests that the orbital interaction between the σ*CO orbital, attributable to the sulfonate groups, and the adjacent σCH orbital stabilizes the gauche‐conformation. The authors conclude that the sulfonate group acts as a gauche‐effect synthon, which is widely applicable in organic chemistry.

Quantum Chemical Analysis of the Molecular and Fragment Ion Formation of Butyrophenone by High-Electric Field Tunnel Ionization at Atmospheric Pressure.

The molecular ion M+· was observed when the liquid sample of butyrophenone was supplied using atmospheric pressure corona discharge (APCD). In contrast, the vapor supply resulted in the formation of the protonated molecule [M+H]+. The mass spectrum obtained with the liquid supply showed two distinctive fragment ions at m/z 105 and 120, resulting from α-cleavage and McLafferty rearrangement (McLR), respectively. The APCD spectrum showed peaks of M+· and the characteristic two fragment ions that were the same as the field ionization mass spectra of butyrophenone as reported by Chait et al. and Beckey et al. The formation of the molecular and fragment ions strongly indicated that high-electric field tunnel ionization (HEFTI) occurs by the HEF strength exceeding 108 V/m at the tip of the corona needle in APCD. The charge and spin density distributions of the molecular and fragment ions were analyzed by quantum chemical calculations using time-dependent density functional theory (TDDFT) and natural bond orbital (NBO) analysis.

DFT study of electronic and nonlinear optical properties of alkaline earth metals and superalkalis doped all-cis-1, 2, 3, 4, 5, 6-hexafluorocyclohexane as an efficient excess electron system

Continual advancements are being pursued to discover innovative strategies for developing materials with remarkable nonlinear optical (NLO) response. Herein, electronic, geometric, thermodynamic and NLO properties of excess electron systems based on stacked Janus dimer, all-cis-1,2,3,4,5,6-hexafluorocyclohexane (C6H6F6)2 are thoroughly investigated. The excess electron systems are designed by doping alkaline earth metals (AEMs) on fluorine face and superalkalis on hydrogen face of Janus dimer. The higher values of vertical ionization energies (VIE) and interaction energies (Eint), confirm the electronic and thermodynamic stabilities of the designed complexes, respectively. Natural bond orbital (NBO) analysis is performed, and the excess electron character of the complexes is confirmed through frontier molecular orbital (FMO) analysis by highest occupied molecular orbital (HOMO) iso-densities. FMO shows a significant decrease in energy gaps (Egap) of the complexes (i.e., Eg = 1.80–3.12 eV), compared to the stacked Janus dimer (i.e., Eg = 9.41 eV). The transparency of the complexes to UV region is confirmed through UV–vis analyses, revealing their maximum absorption in visible and near-IR regions. The higher NLO response of the designed excess electron systems is further proved by the greater values of first hyperpolarizability (β o ) i.e., up to 1.70 × 106 au. Moreover, the time dependent-density functional theory (TD-DFT) computations and two-level model are employed to investigate the controlling factors of hyperpolarizability, illustrating the contribution of transition energy (∆E3), change in dipole moment (∆μ) and oscillator strength (f o ) in controlling the β o . Ab-initio molecular dynamics (AIMD) simulation further confirm that the designed superalkalide complexes are kinetically and thermally stable. The thorough investigation of these excess electron systems proves them an appropriate candidate for NLO applications.

Skeletal Editing of Aromatic N-Heterocycles via Hydroborative Cleavage of C-N Bonds-Scope, Mechanism, and Property.

Skeletal editing of the core structure of heterocycles offers new opportunities for chemical construction and is a promising yet challenging research topic that has recently gained increasing interest. However, several limitations of the reported systems remain to be addressed. For example, the reagents employed are generally in high-energy, such as chlorocarbene precursors, nitrene species, and metal carbenes, which are also associated with low atomic efficiencies. Thus, the development of simple systems for the skeletal editing of heterocycles is still desired. Herein, a straightforward and facile BH3-mediated skeletal editing of readily available indoles, benzimidazoles, and several other aromatic heterocycles is reported. Structurally diverse products were readily obtained, including tetrahydrobenzo azaborinines, diazaboroles, O-anilinophenylethyl alcohols, benzene-1,2-diamines, and more. Density functional theory (DFT) calculations and natural bond orbital (NBO) analysis revealed a BH3-induced C-N bond cleavage reaction pathway. An exciting and counterintuitive indole hydroboration phenomenon of -BH2 shift from C3-position to C2-position was disclosed. Moreover, the photophysical properties of the synthesized diazaboroles were studied, and an interestingly and pronounced aggregation-induced emission (AIE) behavior was disclosed.

In-Depth Theoretical Investigations of Borazine’s Aromaticity: Tailoring Electron Delocalization through Substituent Effects

The current study investigates the influence of several R substituents (e.g., Me, SiH3, F, Cl, Br, OH, NH2, etc.) on the aromaticity of borazine, also known as the “inorganic benzene”. By performing hybrid DFT methods, blended with several computational techniques, e.g., Natural Bond Orbital (NBO), Quantum Theory of Atoms in Molecules (QTAIM), Gauge-Including Magnetically Induced Current (GIMIC), Nucleus-Independent Chemical Shift (NICS), and following a simultaneous evaluation of four different aromaticity indices (para-delocalization index (PDI), multi-centre bond order (MCBO), ring current strength (RCS), and NICS parameters), it is emphasized that the aromatic character of B-substituted (B3R3N3H3) and N-substituted (B3H3N3R3) borazine derivatives can be tailored by modulating the electronic effects of R groups. It is also highlighted that the position of R substituents on the ring structure is crucial in tuning the aromaticity. Systematic comparisons of calculated aromaticity index values (i.e., via regression analyses and correlation matrices) ensure that the reported trends in aromaticity variation are accurately described, while the influence of different R groups on electron delocalization and related aromaticity phenomena is quantitatively assessed based on NBO analyses. The most relevant interactions impacting the aromatic character of investigated systems are (i) the electron conjugations occurring between the p lone pair electrons (LP) on the F, Cl, Br, O or N atoms, of R groups, and the π*(B=N) orbitals on the borazine ring (i.e., LP(R)→π*(B=N) donations), and (ii) the steric-exchange (Pauli) interactions between the same LP and the π(B=N) bonds (i.e., LP(R)↔π(B=N) repulsions), while inductive/field effects influence the aromaticity of the investigated trisubstituted borazine systems to a much lesser extent. This work highlights that although the aromatic character of borazine can be enhanced by grafting electron-donor substituents (F, OH, NH2, O−, NH−) on the N atoms, the stabilization due to aromaticity has only a moderate impact on these systems. By replacing the H substituents on the B atoms with similar R groups, the aromatic character of borazine is decreased due to strong exocyclic LP(R)→π*(B=N) donations affecting the delocalization of π-electrons on the borazine ring.

Assessing the Noncovalent Interaction of Deucravacitinib and Ethanol with Special Reference to an Independent Gradient Model Based on Hirshfeld Partition.

The current study begins by optimizing the deucravacitinib molecule in the gas phase at the ωB97XD/cc-pVDZ level of theory using density functional theory and proceeds to study its intramolecular interactions. Further, a molecule of EtOH was introduced at different locations on the deucravacitinib molecule, and the noncovalent interactions arising from them were also investigated using several computational tools. In this way, eight deucravacitinib-EtOH systems (1-8) were identified and their electronic environment was studied after evaluating their binding energy. Using natural bond orbital analysis, the localization of charges between the donor and acceptor fragments in these interacting systems was examined. The nature of interactions was analyzed using the reduced gradient approach (NCI analysis), and few hydrogen bonding interactions (intermolecular and intramolecular) were found in each system. The strength of these hydrogen bonding interactions was further investigated by using theoretical tools such as atoms in molecules analysis and independent gradient model based on Hirshfeld partition analysis. The binding energy of deucravacitinib with EtOH was decomposed into energy components based on the domain-based local pair natural orbital coupled cluster technique using LED analysis. The results from the hydrogen bonding interaction analysis using different computational tools were found to be consistent with the calculated order of binding energy of systems 1-8 and they also pointed toward the higher stability of system 3.

Deciphering the Two-Step Hydride Mechanism of Monoamine Oxidase Flavoenzymes.

The complete two-step hydride transfer mechanism of amine oxidation involved in the metabolism of monoamine neurotransmitters was scrutinized by DFT calculations. In living organisms, this process is catalyzed by monoamine oxidase enzymes. Herein, we focus on some intriguing aspects of the reaction that may have been previously noticed but have not been clarified to date. The first step of the reaction includes the C-H bond cleavage on the methylene group vicinal to the amino group of the monoamine substrate and the subsequent transfer of hydrogen to the N5 atom of the flavin prosthetic group of the enzyme. We confirmed the nature of this step to be hydride transfer by evaluation of the pertinent HOMO-LUMO gap together with analysis of orbital contours alongside the intrinsic reaction coordinate profile. Next, we investigated the rather peculiar intermediate adduct that may form between the amine substrate and the flavin molecule, featuring an unusually long C-N bond of ∼1.62 Å. Although this bond is quite stable in the gas phase, the presence of just a few explicit water molecules facilitates its dissociation almost without energy input so that the amine-flavin intermediate can form an ionic pair instead. We attribute the existence of the unusual C-N bond to a fragile balance between opposing electronic structure effects, as evaluated by the natural bond orbital analysis. In line with this, the intermediate in the solution or in the enzyme active site can exist in two energetically almost equivalent forms, namely, as a covalently bound complex or as an ion pair, as suggested by previous studies. Finally, we characterized the transformation of the intermediate to the fully reduced flavin and imine products via proton transfer from the amino group to the flavin N1 atom, completing the reductive part of the catalytic cycle. Although we found that explicit solvation substantially boosts the kinetics of this step, the corresponding barrier is significantly lower than that in the hydride transfer step, confirming hydrogen abstraction as the rate-limiting step of amine oxidation and validating the two-step hydride transfer mechanism of monoamine oxidases.

Synthesis, photophysical properties, and in-silico nonlinear optics of 3-hydroxy-N-phenyl-2-naphthamide and its acetate, acrylate, and benzoate derivative

In this study, we report the successful growth of single crystals of 3-hydroxynaphthalene-2-carboxanilides (NAS) with a monoclinic structure in the P21/c space group and space group number of 14 for the first time. We have developed a yield and time-effective modified synthetic procedure using a synthetic reactor by replacing the traditional microwave method. Additionally, acylated derivatives of NAS, including novel acryloyl derivative (NAS AC), are synthesized with a modified procedure, replacing pyridine with triethylamine.We investigate the structural, photophysical, and quantum chemical properties of N-(4-acetylphenyl)-2-oxo-2H-chromene-3-carboxamide (NAS) and its acylated derivatives (NAS AC, NAS ACT, NAS BZ). Photophysical studies reveal significant Stokes shifts observed in different solvents, including time-enhanced fluorescence in DMSO, attributed to solvent relaxation processes. Natural bond orbital (NBO) analysis, molecular electrostatic potential (MEP) maps, and frontier molecular orbital (FMO) provide insights into electronic interactions and asymmetric charge distribution. Low-lying LUMO values of these compounds (-2.31 eV to -1.95 eV) support candidature for the electron acceptor applications. Nonlinear optical properties were thoroughly investigated, with NAS displaying the highest static first-order hyperpolarizability (17.89 × 10−30 esu) and NAS BZ exhibiting the highest second-order hyperpolarizability (113.09 × 10−36 esu), indicating significant nonlinear optical responses. Thermal stability (TGA and DTA) highlights the significant range of temperatures for the NLO applications.

Role of Intermolecular Interactions in Deep Eutectic Solvents for CO2 Capture: Vibrational Spectroscopy and Quantum Chemical Studies.

Recent research and reviews on CO2 capture methods, along with advancements in industry, have highlighted high costs and energy-intensive nature as the primary limitations of conventional direct air capture and storage (DACS) methods. In response to these challenges, deep eutectic solvents (DESs) have emerged as promising absorbents due to their scalability, selectivity, and lower environmental impact compared to other absorbents. However, the molecular origins of their enhanced thermal stability and selectivity for DAC applications have not been explored before. Therefore, the current study focuses on a comprehensive investigation into the molecular interactions within an alkaline DES composed of potassium hydroxide (KOH) and ethylene glycol (EG). Combining Fourier transform infrared (FT-IR) and quantum chemical calculations, the study reports structural changes and intermolecular interactions induced in EG upon addition of KOH and its implications on CO2 capture. Experimental and computational spectroscopic studies confirm the presence of noncovalent interactions (hydrogen bonds) within both EG and the KOH-EG system and point to the aggregation of ions at higher KOH concentrations. Additionally, molecular electrostatic potential (MESP) surface analysis, natural bond orbital (NBO) analysis, quantum theory of atoms-in-molecules (QTAIM) analysis, and reduced density gradient-noncovalent interaction (RDG-NCI) plot analysis elucidate changes in polarizability, charge distribution, hydrogen bond types, noncovalent interactions, and interaction strengths, respectively. Evaluation of explicit and hybrid models assesses their effectiveness in representing intermolecular interactions. This research enhances our understanding of molecular interactions in the KOH-EG system, which are essential for both the absorption and desorption of CO2. The study also aids in predicting and selecting DES components, optimizing their ratios with salts, and fine-tuning the properties of similar solvents and salts for enhanced CO2 capture efficiency.

Exploring Through-Space Charge Transfer-Mediated Optoelectrochemical Properties of Dual-State Luminescent Aliphatic Polymers and Optoelectronic Responses toward Metal Ions.

Herein, natural-synthetic hybrid dual-state luminescent conducting polymers (DLCPs/DLCP1-DLCP8) possessing significant optoelectrochemical properties are strategically developed by the polymerization of prop-2-enamide, cis-butenedioic acid, 2-acrylamido-2-methylpropane-1-sulfonic acid, and in situ-generated 2-(3-acrylamidopropanamido)-2-methylpropane-1-sulfonic acid alongside the grafting of gum tragacanth. The spectroscopic data of aliphatic DLCPs affirm DLCP7 as the most stable supramolecular assembly endowing optoelectronic properties. Computational calculations identified -C(═O)NH-, -C(═O)OH, -OH, and -SO3H as subluminophores. The absorption spectra, excitation wavelength-/solvent-polarity-/concentration-dependent luminescence, solid state luminescence, aggregation-induced enhanced luminescence, and time-correlated single photon count (TCSPC) studies confirm the occurrence of aggregation-mediated intramolecular through-space charge transfer (ITSCT) in the excited state of DLCP7. Mulliken charge, natural bond orbital, dipole moments, and electronic potential surface analyses confirm the charge donor-acceptor system in DLCP7. Furthermore, the selective optoelectronic response of DLCP7 toward Ca2+/Cu(II) at 438/574 nm is explored using ultraviolet-visible spectra, TCSPC analyses, a dynamic light scattering study, and computational investigations. The chelation-enhanced luminescence and ITSCT inhibition are responsible for turn-on and turn-off detections of Ca2+ and Cu(II), respectively. Cu(II) → Cu(I) reduction in a DLCP7 solution is inferred from electrochemical and spectroscopic analyses. The conductivities of 9.65 × 10-5 S cm-1 (solid state) and 44.35 × 10-5 S cm-1 (solution) in DLCP7 are validated by current-voltage and electrochemical impedance measurements. Again, strong electronic conductivities of 43.89 × 10-5 S cm-1 (solid state)/53.34 × 10-5 S cm-1 (solution) and 45.42 × 10-5 S cm-1 (solid state)/64.81 × 10-5 S cm-1 (solution) are observed in Ca2+-DLCP7 and Cu(II)-DLCP7, respectively.

Growth, characterization and cognition of 2-cyanopyridinium perchlorate single crystals for nonlinear optical applications.

The fascinating electronic applications attracted researchers to explore the field of nonlinear optical (NLO) materials. The slow evaporation of solvent technique (SEST) was employed to grow the 2-cyanopyridinium perchlorate (2-CPPC) NLO single crystals. The cell parameters of the grown 2-CPPC crystal are confirmed by the single crystal X-ray diffraction (SCXRD) study. The powder X-ray diffraction studies confirm the crystallinity of 2-CPPC crystals, and the peaks were indexed. The computation for the geometry optimization, HOMO-LUMO energy gap, global reactivity parameters, natural bond orbital (NBO) analysis, polarizability, and hyperpolarizability of the 2-CPPC molecule was done using B3LYP (6-311G basis set) functional of DFT method. The experimental FTIR and UV-Vis results of the 2-CPPC compound were compared with the simulated results. The second harmonic generation (SHG) study for the 2-CPPC crystal was employed using Kurtz-Perry powder technique. Single beam Z-scan technique using He-Ne laser is used to study the third-order NLO properties.

Study of the Torquoselectivity of a Set of Unusual Ring‐Opening Electrocyclic Reactions: Determination of the Electronic Bonding Structure Through the Methodologies of Natural Bond Orbital Analysis and Quantum Theory of Atoms in Molecules, and Analysis of the Electronic Reaction Mechanism Through Bond Reactivity Descriptors

ABSTRACTIn this work, we have studied the torquoselectivity of a set of unusual ring‐opening electrocyclic reactions that have not been successfully rationalized using models based on orbital symmetry nor have they been explained by steric hindrance. Firstly, the corresponding transition states have been obtained, and it has been verified that the intrinsic reaction coordinates associated with these transition states are consistent with the reactants and products of the reactions studied. This has allowed us to theoretically calculate the reaction barriers (with their corresponding thermal corrections) and compare them with the corresponding experimental values. In a second step, we have analyzed the electronic bonding structure using the methodologies of Natural Bond Orbital Analysis and Quantum Theory of Atoms in Molecules, searching for interactions that may significantly stabilize the transition states. Finally, we have analyzed the reactivity using a recent model that has allowed us to calculate the corresponding bond reactivity descriptors.