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This study was focused on the photochemistry of OAlOH and three possible pathways, which were studied with high-level multireference configuration interaction ab initio calculations. We computed cuts of the six-dimensional potential energy surfaces for the ground, the lowest singlet and triplet excited states, and probed the photodissociation mechanisms and the stabilities. The OAlOH electronic spectrum, with an energy reaching 7.15 eV, contained four prominent peaks. Photodissociation to AlO, OH, and AlOH constituted a plausible mechanism within the deep-UV range (λ = 250.4 nm). Our data indicated the photostability of OAlOH in the near-UV‒Vis region, so detection with laser-induced fluorescence is possible. Fluorescence and phosphorescence may occur upon excitation at 363.5 nm. The roles of OAlOH in the photochemical reactions of Al-bearing molecules in the upper atmosphere and VY Canis Majoris are discussed. [ABSTRACT FROM AUTHOR]

We investigate how electronic excitations and subsequent dissipative dynamics in the water soluble chlorophyll-binding protein (WSCP) are connected to features in two-dimensional (2D) electronic spectra, thereby comparing results from our theoretical approach with experimental data from the literature. Our calculations rely on third-order response functions, which we derived from a second-order cumulant expansion of the dissipative dynamics involving the partial ordering prescription, assuming a fast vibrational relaxation in the potential energy surfaces of excitons. Depending on whether the WSCP complex containing a tetrameric arrangement of pigments composed of two dimers with weak excitonic coupling between them binds the chlorophyll variant Chl a or Chl b, the resulting linear absorption and circular dichroism spectra and particularly the 2D spectra exhibit substantial differences in line shapes. These differences between Chl a WSCP and Chl b WSCP cannot be explained by the slightly modified excitonic couplings within the two variants. In the case of Chl a WSCP, the assumption of equivalent dimer subunits facilitates a reproduction of substantial features from the experiment by the calculations. In contrast, for Chl b WSCP, we have to assume that the sample, in addition to Chl b dimers, contains a small but distinct fraction of chemically modified Chl b pigments. The existence of such Chl b derivates has been proposed by Pieper et al. [J. Phys. Chem. B 115, 4042 (2011)] based on low-temperature absorption and hole-burning spectroscopy. Here, we provide independent evidence. [ABSTRACT FROM AUTHOR]

Identifying the oxidation structure of two-dimensional interfaces is crucial to improve surface chemistry and electronic properties. Beyond graphene with only phenyl rings, a novel carbon-nitrogen material, C3N, presents an intrinsic heterogeneous surface morphology where each phenyl ring is encircled by six nitrogen atoms, yet its atomistic oxidation structure remains unclear. Here, combining a series of density functional theory calculations and ab initio molecular dynamics simulations, we demonstrate that thermodynamically favorable oxidation loci are confined to the phenyl ring, and kinetic transformations of oxidation structures are feasible along the phenyl ring, whereas those toward nitrogen atoms are proven to be extremely difficult. These results are attributed to the lower barrier of oxygen atom migration along the phenyl ring, while the significantly high barriers toward nitrogen atoms are due to the heterogeneous potential energy surface for oxygen–C3N interaction. This work highlights the significance of surface morphology on the characteristics of oxidation structure, offering insights into tunable electronic properties via confined interfacial oxidation. [ABSTRACT FROM AUTHOR]

Wave packet interferometry with vacuum ultraviolet light has been used to probe a complex region of the electronic spectrum of molecular nitrogen, N2. Wave packets of Rydberg and valence states were excited by using double pulses of vacuum ultraviolet (VUV), free-electron-laser (FEL) light. These wave packets were composed of contributions from multiple electronic states with a moderate principal quantum number (n ∼ 4–9) and a range of vibrational and rotational quantum numbers. The phase relationship of the two FEL pulses varied in time, but as demonstrated previously, a shot-by-shot analysis allows the spectra to be sorted according to the phase between the two pulses. The wave packets were probed by angle-resolved photoionization using an infrared pulse with a variable delay after the pair of excitation pulses. The photoelectron branching fractions and angular distributions display oscillations that depend on both the time delays and the relative phases of the VUV pulses. The combination of frequency, time delay, and phase selection provides significant control over the ionization process and ultimately improves the ability to analyze and assign complex molecular spectra. [ABSTRACT FROM AUTHOR]

We present a numerically exact approach for evaluating vibrationally resolved electronic spectra at finite temperatures using the coherence thermofield dynamics. In this method, which avoids implementing an algorithm for solving the von Neumann equation for coherence, the thermal vibrational ensemble is first mapped to a pure-state wavepacket in an augmented space, and this wavepacket is then propagated by solving the standard, zero-temperature Schrödinger equation with the split-operator Fourier method. We show that the finite-temperature spectra obtained with the coherence thermofield dynamics in a Morse potential agree exactly with those computed by Boltzmann-averaging the spectra of individual vibrational levels. Because the split-operator thermofield dynamics on a full tensor-product grid is restricted to low-dimensional systems, we briefly discuss how the accessible dimensionality can be increased by various techniques developed for the zero-temperature split-operator Fourier method. [ABSTRACT FROM AUTHOR]

We present a detailed theoretical analysis of polarized absorption spectra and linear dichroism of cyanine dye aggregates whose unit cells contain two molecules. The studied threadlike ordered system with a molecular exciton delocalized along its axis can be treated as two chains of conventional molecular aggregates, rotated relative to each other at a certain angle around the aggregate axis. Our approach is based on the general formulas for the effective cross section of light absorption by a molecular aggregate and key points of the molecular exciton theory. We have developed a self-consistent theory for describing the orientational effects in the absorption and dichroic spectra of such supramolecular structures with nonplanar unit cell. It is shown that the spectral behavior of such systems exhibits considerable distinctions from that of conventional cyanine dye aggregates. They consist in the strong dependence of the relative intensities of the J- and H-type spectral bands of the aggregate with a nonplanar unit cell on the angles determining the mutual orientations of the transition dipole moments of constituting molecules and the aggregate axis as well as on the polarization direction of incident light. The derived formulas are reduced to the well-known analytical expressions in the particular case of aggregates with one molecule in the unit cell. The calculations performed within the framework of our excitonic theory combined with available vibronic theory allow us to quite reasonably explain the experimental data for the pseudoisocyanine bromide dye aggregate. [ABSTRACT FROM AUTHOR]

Doubly resonant sum frequency generation (DR-SFG) serves as a potent characteristic technique for probing the electronic spectra and vibronic coupling of molecules on surfaces. In this study, we successfully developed a novel infrared (IR)–white light (WL) DR-SFG spectroscopy based on narrowband IR and tunable broadband WL. This novel method was employed to explore the excitation spectrum and vibronic couplings of sub-monolayer Rhodamine 6G molecules. Our findings elucidate that the xanthene skeleton vibrational modes exhibit strong coupling with the S0–S1 electronic transition. Notably, we observed not only the 0–0 transition of the S0–S1 electronic continuum but also the 0–1 transition, a first time observation in the realm of DR-SFG spectroscopy. This advanced DR-SFG spectroscopy methodology facilitates a more sensitive examination of electronic spectra and the coupling between electronic transitions and vibrational modes, heralding a significant advancement in the understanding of molecular interactions on surfaces. [ABSTRACT FROM AUTHOR]

To spectroscopically qualify strength in the π-electron conjugation, the electronic spectra of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB) in the region of the transition to the lowest excited singlet (S1) 1B1u state are measured by the fluorescence excitation and the single-vibronic-level dispersed fluorescence methods. Strength is defined as the difference in potential energies between the planar and perpendicular conformations. BPEB possesses two large-amplitude torsional motions, out-of-phase 24 and in-phase 29 modes. The most stable is the planar conformation, and barrier heights at the perpendicular conformation are coincident in torsional potentials for the two modes. Torsional levels are successively observed up to 19± and 16− quantum levels in the ground state, respectively. Strength is determined to be 293 cm−1 (3.51 kJmol−1) with an accuracy of an error range smaller than 1 cm−1. In the excited state, strength is estimated to be 1549 ± 73 cm−1. Combination levels of two torsional modes are also measured up to high quantum levels. A systematic decrease in frequencies is observed with increasing the quantum number. Quantum-chemistry calculations of B3LYP, CAM-B3PLYP, WB97XD, and M062X with basis sets of aug-cc-pVDZ are performed, where B3LYP theories are carried out with the dispersion correlation. The calculated strength is 1.1–2.1 times larger than observed. [ABSTRACT FROM AUTHOR]

Ultraviolet and vacuum ultraviolet photo-absorption spectra of azido (–N3)-based energetic plasticizer, bis(1,3-diazido-prop-2-yl)-malonate (abbreviated as BDAzPM), in the gas phase is recorded at room temperature and in the photon energy range of 5.5–9.9 eV using a synchrotron radiation source. Complementary computational results obtained using the time-dependent density functional theory document the vertical transition energies and oscillator strengths. Comparison of the simulated spectra with the experimental absorption spectrum of BDAzPM reveals that the early part of the absorption spectrum of BDAzPM is of pure valence excitation character, whereas the later intense part of the absorption spectrum is dominated by mixed Rydberg and valence electronic excitations. [ABSTRACT FROM AUTHOR]

The spin‐orbit coupling corrected absorption spectra of osmium complexes, [Os(bpy) 3] 2+ and [Os(phen) 3] 2+, were calculated by using ab initio multireference perturbation method (NEVPT2) with relativistic effects taken into account throughout ZORA approximation and corresponding all‐electron basis sets. For the same purpose, the time‐dependent DFT techniques were used. A very good agreement between NEVPT2 and experimental spectra should be highlighted, especially for the MLCT transitions that occur in visible and near‐UV regions (16,000−33,000 cm −1). Moreover, the present study offers description of excited states of titled osmium complexes and their spectra interpretation using molecular orbitals. [ABSTRACT FROM AUTHOR]

The reaction of [Ru(dmso)4Cl2] with a potassium salt of four xanthate (RO–C(＝S)S−; R = Me, Et, iPr and tBu) ligands (depicted as Ln; n = 1–4) in hot methanol afforded a group of mixed-ligand complexes of type [Ru(Ln)2(dmso)2]. The crystal structures of all the four complexes have been determined, which show that the xanthate ligands are bound to the metal center forming four-membered chelates and dmso is coordinated through sulfur and they are mutually cis. The relative thermodynamic stability of this cis and the other possible trans-isomers of these complexes has been assessed with the help of DFT calculations, which have revealed that the cis-isomer is the more stable isomer. The coordinated dmso in the [Ru(Ln)2(dmso)2] complexes could be easily displaced by chelating bidentate ligands (depicted as L′) to furnish complexes of type [Ru(Ln)2(L′)], as demonstrated through isolation of two such complexes, viz. [Ru(L3)2(bpy)] and [Ru(L2)2(phen)] (bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline). The crystal structure of [Ru(L3)2(bpy)] has been determined and the structure of [Ru(L2)2(phen)] has been optimized by the DFT method. The electronic spectra of the four [Ru(Ln)2(dmso)2] complexes and the two derivatives ([Ru(Ln)2(L′)]; n = 3, L′ = bpy; n = 2, L′ = phen), recorded in dichloromethane solutions, show intense absorptions spanning the visible and ultraviolet regions, which have been analyzed by the TDDFT method. The [Ru(Ln)2(dmso)2] complexes are found to serve as efficient catalyst precursors for the acceptorless dehydrogenation of 2-propanol followed by crossed-aldol condensation with substituted benzaldehydes (and related aldehydes), using tert-butoxide as the co-catalyst, producing dibenzylideneacetone derivatives in good yields. [ABSTRACT FROM AUTHOR]

Quantum computational simulations based on density functional theory are employed to investigate the molecular structure of Retinol. Both geometrical parameters and electronic transitions for gas and green solvents are calculated. Characteristic frequencies were identified and band assignments were achieved through normal coordinate analysis. The calculated spectra and a comparative study of the vibrational spectra, which included a variety of vibration modes, were compared with the experimental spectra. A compound's strong reactivity may be indicated by the bandgap, which also indicates the possibility of further charge exchange through the molecule. Determination of relative electrophilicity/nucleophilicity indices of retinol was undertaken through the prediction of condensed Fukui functions, complemented by the generation of molecular electrostatic potential surface maps. This exploration was validated through meticulous correlation with reduced density gradient and isodensity surface plots. The docking analysis of retinol with different proteins was performed to confirm anti-inflammatory activity. To gain comprehensive insights into macromolecule pliability concerning protein–ligand interactions, an effective molecular dynamics simulation was conducted. [ABSTRACT FROM AUTHOR]

The paper discusses the results of the electrosynthesis of metal–polymer nanocomposites of silver and coatings on pure iron and steel electrodes by combining the process of electropolymerization of 1-vinyl-1,2,4-triazole (VT) with N-vinyl-caprolactam (VC) and cathodic precipitation of metals. During the electrolysis of aqueous and water–ethanol solutions of VT with VC at various ratios in the presence of AgNO3, metal nanocomposites and coatings are formed on purely iron and steel electrodes. The structure and composition of the synthesized metal nanocomposites were confirmed by various physicochemical methods, such as electron and IR spectroscopic, X-ray phase and thermogravimetric, elemental analyses, as well as by transmission electron microscopy. In the electronic spectra of nanocomposites, absorption bands appear with a maximum at 405–421 nm, which is typical for systems with zero-valent silver. The IR spectra show that the matrix structure hardly changes during the formation of nanocomposites and coatings. At high current densities (j ≥ 10 mA/sm2), nanocomposite films are formed on the electrode surface. The silver content in nanocomposites is 0–9%, which leads to an increase in the viscosity of nanocomposite solutions compared to solutions of the initial copolymers. Increasing the silver content above 8% will lead first to a partial and then to a complete loss of solubility. According to the data of transmission electron macroscopy, the synthesized polymer nanocomposites consist of isolated silver nanoparticles, predominantly spherical in shape, uniformly distributed in the bulk of the polymer matrix. The size dispersion of nanoparticles depends on the silver content in the nanoparticles. The thermal decomposition of metal nanocomposites occurs in stages. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the added value of spectral computed tomography (CT) parameters to conventional CT features for differentiating tuberculosis-associated fibrosing mediastinitis (TB-associated FM) from endobronchial lung cancer (EBLC). Chest spectral CT enhancement images from 109 patients with atelectasis were analyzed retrospectively. These patients were divided into two distinct categories: the TB-associated FM group (n = 77) and the EBLC group (n = 32), based on bronchoscopy and/or pathological findings. The selection of spectrum parameters was optimized with the least absolute shrinkage and selection operator regression analysis. The relationship between the spectrum parameters and conventional parameters was explored using Pearson's correlation. Multivariate logistic regression analysis was used to build spectrum model. The spectrum parameters in the spectrum model were replaced with their corresponding conventional parameters to build the conventional model. Diagnostic performances were evaluated using receiver operating characteristic curve analyses. There was a moderate correlation between the parameters ㏒(L-AEF NIC) - ㏒(L-AEF C) (r = 0.419; p < 0.0001), ㏒(O-AEF 40KeV) - ㏒(O-AEF C) (r = 0.475; p < 0.0001), [L-A-hydroxyapatite {HAP}(I)] - (L-U-CT) (r = 0.604; p < 0.0001), {arterial enhancement fraction (AEF) derived from normalized iodine concentration (NIC) of lymph node (L-AEF NIC), AEF derived from CT 40KeV of bronchial obstruction (O-AEF 40KeV), arterial-phase Hydroxyapatite (Iodine) concentration of lymph node [L-A-HAP(I)], AEF derived from conventional CT (AEF C), unenhanced CT value (U-CT)}. Spectrum model could improve diagnostic performances compared to conventional model (area under curve: 0.965 vs 0.916, p = 0.038). There was a moderate correlation between spectrum parameters and conventional parameters. Integrating conventional CT features with spectrum parameters could further improve the ability in differentiating TB-associated FM from EBLC. • Spectrum parameters correlated moderately with conventional parameters. • Spectrum parameters may be helpful for identifying atelectasis due to tuberculosis-associated fibrosing mediastinitis. • Integrating spectrum parameters with computed tomography features could further improve the differential ability. [ABSTRACT FROM AUTHOR]

Some novel FeIII, CuII, and PdII chelates incorporating N′‐(1‐methyl‐2‐oxoindolin‐3‐ylidene)benzohydrazide (MIBA) were fabricated. The tested compounds were investigated using thermogravimetric analysis (TGA), CHN, spectra analysis (IR, mass spectra, and NMR), melting point, magnetic moments, molar conductance, ultraviolet–visible spectroscopy, powder X‐ray diffraction, and computational studies. The conductance results showed that the tested FeIII, CuII, and PdII chelates are electrolytes. Magnetic and electronic spectra are applied to deduce the coordinating ability of the tested ligand, and the geometric structure of the studied chelates is found to be octahedral, distorted octahedral, and square planar for FeIII, CuII, and PdII chelates, respectively. The TGA study of these studied complexes displays that the hydrated H2O molecules, acetate, and nitrate are removed in the first and second degradation steps followed directly by degradation of the studied ligand leaving metal oxide as residue. The thermodynamic factors, like ΔS*, ΔH*, E*, A, and ΔG* are evaluated from the TGA curves and explained. The density functional theory (DFT)/B3LYP computation method was applied for the estimation of the molecular electrostatic potential (MEP; highest occupied molecular orbital [HOMO] and lowest unoccupied molecular orbital [LUMO]) energy for the studied compounds. In an in vitro study, the antimicrobial effects of the prepared compounds were screened on various strains of bacteria and fungi. It was found that tested compounds exposed a good biological efficacy through IC50 results close to reference drugs and antitumor potential against (MCF‐7, Hep‐G2, and HC‐T116) cell lines. The data obtained displayed that the studied chelates showed promising antitumor activity. The studied metal chelates were screened for in vitro antioxidant efficacy using DPPH assay. The studied compounds explained dynamic satisfying performance. Also, the crystal structures of breast cancer protein (PDB ID: 3HB5) and Escherichia coli (PDB ID: 2VF5) were performed by molecular docking simulation. Data of docking simulation suggestions are which tested compounds have biological behavior as well as have obvious benefit in the pharmaceutical business. [ABSTRACT FROM AUTHOR]

The need for photosensors and gas sensors arises from their pivotal roles in various technological applications, ensuring enhanced efficiency, safety, and functionality in diverse fields. In this paper, interlinked PbS/Sb2O5 thin film has been synthesized by a magnetron sputtering method. We control the temperature to form the nanocomposite by using their different nucleation temperature during the sulfonation process. A nanostructured PbS/Sb2O5 with cross-linked morphology was synthesized by using this fast and efficient method. This method has also been used to grow a uniform thin film of nanocomposite. The photo-sensing and gas-sensing properties related to the PbS/Sb2O5 compared with those of other nanomaterials have also been investigated. The experimental and theoretical calculations reveal that the PbS/Sb2O5 exhibits extraordinarily superior photo-sensing and gas-sensing properties in terms of providing a pathway for electron transport to the electrode. The attractive highly sensitive photo and gas sensing properties of PbS/Sb2O5 make them applicable for many different kinds of applications. The responsivity and detectivity of PbS/Sb2O5 are 0.28 S/mWcm−2 and 1.68 × 1011 Jones respectively. The sensor response towards NO2 gas was found to be 0.98 at 10 ppb with an limit of detection (LOD) of 0.083 ppb. The PbS/Sb2O5 exhibits high selectivity towards the NO2 gas. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to analyze the geometries, electronic structure, and electronic absorption spectra of a light sensor fabricated by PbS/Sb2O5. The results are very analogous to the experimental results. Both photosensors and gas sensors are indispensable tools that contribute significantly to the evolution of technology and the improvement of various aspects of modern life. [ABSTRACT FROM AUTHOR]

We show that the electronic spectrum in graphene, not unlike in other low-dimensional systems, can manifest a sharp impurity resonance near the Dirac point due to the presence of a single weakly coupled impurity described by the Fano model. It is demonstrated that, according to the established scenario, the electronic band structure of graphene undergoes a kind of transformation, specifically of the avoided crossing type, when the concentration of such short-range impurities increases. In this transformation process, main events unfold close to the impurity resonance energy, and, therefore, they relate to the most intriguing domain of the energy spectrum of graphene. The avoided crossing transformation develops in a threshold manner. Namely, it starts when the impurity concentration exceeds a critical value determined by the considerable spatial overlap of individual impurity states. Unlike former cases of such band structure transformations in low-dimensional systems, our findings unveil the formation of a new—impurity—Dirac point in the spectrum alongside the original shifted one, which doubles their number in the disordered system. The resulting electronic spectrum also features a single worthy of attention concentration broadening area or mobility gap of a substantially reduced width around the impurity resonance energy. Band edge smearing areas at old and newly formed Dirac points, where electronic states are also localized, are found to be negligibly narrow. Our analysis suggests that controlling the position of the Fermi level in the disordered system under study may allow observation of the re-entrant metal–insulator transition. The Fermi level entering and exiting the mobility gap causes the metal–insulator and insulator–metal transitions. [ABSTRACT FROM AUTHOR]

Pentagonal two-dimensional (2D) materials, distinguished by their unique pentagonal atomic configurations, have emerged as a new class of materials with remarkable physical and chemical properties. In this work, we investigate the effect of an external electric field and biaxial strain on the electronic and optical properties of two-dimensional Pentagonal PtX 2 (X= S, Se, Te) monolayers denoted by Penta-PtX 2 using the first-principles calculations. We found that Penta-PtX 2 monolayers are semiconductors with an indirect band gap of 1.92 eV, 1.51 eV, and 1.4 eV for Penta-PtS 2 , Penta-PtSe 2 , and Penta-PtTe 2 , respectively, that is larger than the 1T phase. External electric fields cause a slight decrease in the band gap of Penta-PtX 2 monolayers without changing the main feature of the electronic band structures. Tensile biaxial strain causes a continuous decrease in the band gap up to 12 % while compressive biaxial strain increases the band gap at first then it starts to decrease. However, phonon dispersion calculations showed that Penta-Ptx 2 are stable under tensile strain up to 12 % while they are unstable under compressive strain. The investigation of the optical properties revealed that monolayers Penta-PtX 2 have in-plane anisotropic optical properties with higher absorption spectra occurring along the y-direction for strained and unstrained structures. The maximum absorption occurs in the Ultraviolet (UV) region, therefore, they can harvest UV and visible photons more effectively. In contrast, the reflectivity is higher along the x-direction for both strained and unstrained monolayers where the maximum reflectivity occurs in the Infrared (IR) region. The combination of anisotropic properties and the unique characteristics of Pentagonal symmetry make Penta-PtX 2 monolayers attractive for fundamental scientific studies to better understand their behavior. They hold great promise for developing new technologies in the fields of optoelectronics and nanotechnology, potentially leading to innovative devices and applications. [ABSTRACT FROM AUTHOR]

This study was planned to prepare new mixed ligand chelates derived from N‐(4,6‐dimethylpyrimidin‐2‐yl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐benzimidazol‐2‐amine (BIP), and imidazole (I). They identified through CHN study, spectroscopic (NMR, FT‐IR, and UV–Vis), conductivity, magnetic susceptibility, mass analysis, and thermal analysis. Correlation between all results exposed that the BIP ligand performed as a bi‐dentate ligand through NN donation locations, where the co‐ligand shows as N–H monodentate. The optimization for the studied chelates led to the formation of distorted octahedral geometry for BIPICu and BIPIVO chelates, distorted (tetrahedral and square planar) geometry for BIPIAg and BIPIPd chelates, respectively, around the metal salt. The B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6–311G**‐LANL2DZ functional level for the solid chelates were used in density functional theory (DFT) calculations. The findings showed that DFT calculations produce conclusions that are consistent with those of the experiments. The resulting compounds' nonlinear optical properties were examined by calculating the hyperpolarizability (β) and molecular polarizability (α) parameters, which gave rise to several unexpected optical properties for the synthesized compounds. Using the agar well diffusion method, the antimicrobial activity of the produced compounds was experimentally confirmed against a subset of G+ and G− bacteria. To ascertain how these substances attach to the targeted protein binding sites, a molecular docking mechanism between the microbially resistant chelates and their suppressed microbial protein pocket receptors was investigated. Also, DNA binding estimated for studied structures was tested by electronic absorption spectrum, viscosity estimation, and gel electrophoresis. Data proposed that all tested compounds link with DNA using an intercalation, electrostatic, and covalent binding mechanism. Moreover, antioxidant performance for studied compounds was governed by radical scavenging techniques in vitro. In addition, an MTT assay has been worked out to explore in vitro cytotoxic impending. All the tested chelates assumed antimicrobial, antitumor, and antioxidant performances that cause them to suggest drugs. [ABSTRACT FROM AUTHOR]

Context: Xanthates are organic compounds of great interest in coordination chemistry due to their different basic sites, which allow them to form complexes with different coordination modes and geometries. These compounds are relevant in the environment and act as heavy metal collectors in aqueous environments. In this theoretical–experimental work, electronic spectroscopy studies of n-propyl xanthate complexes with group 12 metals were performed. This study verified structural differences in these systems, depending on the environment in which they are inserted. In addition, structural differences were observed when the solid was changed to an n-hexane solution. Thus, it was observed that the complexes assume a mononuclear structure in solution, while they present a polymeric form in the solid phase. The electronic spectra obtained through TD-DFT calculations were compared to those of the previously synthesized complexes. In the final theoretical analysis, the main orbitals involved in these transitions were assigned using population analysis calculations. The synthesis of the complexes was confirmed through infrared (MID and FAR), UV‒Vis, Raman, and NMR-1H spectroscopic analyses. Methods: The structures of the mononuclear and polymeric complexes were optimized in vacuum and n-hexane. Under vacuum, DFT levels M06L/6–311 + + G** + LANL2TZ and M06L/def2-TZVP were used for the mononuclear complexes, and M06L/LANL2DZ + LANL2 were used for the polymer complexes. For the calculations of the mononuclear complexes in n-hexane, the same level of theory was used for the solid state. TD-DFT calculations for 300 excited states were performed with the same levels of theory and used the optimized structures of the complexes. Furthermore, population analysis was carried out on all the systems studied. Gaussian 09 software was used for the structure optimization, TD-DFT, and population analysis calculations. GaussSum software was used to evaluate the molecular orbitals and electronic spectra. [ABSTRACT FROM AUTHOR]

This study focuses on the properties and intermolecular interactions of nitrosamine oligomers, which are important in both semiconductor manufacturing and nuclear waste management. The study explores various configurations of nitrosamine oligomers, ranging from monomers to pentamers in linear, ladder, and cyclic clusters, with the finding that dimer cyclic forms and hexamers and above are unstable. Many‐body analysis revealed that two‐body interaction energies made remarkable contributions to the binding energy, while the sum of 3‐, 4‐, and 5‐body energy contributed less, indicating the decrease in stability of nitrosamine from dimer to pentamer clusters. Using advanced computational techniques, such as dispersion‐corrected B3LYP‐D3 and TD‐DFT, the study investigates the vibrational modes and electronic absorption spectra of nitrosamine oligomers. The results reveal that different configurations can significantly affect the vibrational modes and electronic properties of nitrosamine oligomers. The NH2 symmetric and asymmetric modes were particularly intense in various forms of nitrosamine oligomers. The wavelengths of electronic transition, oscillator strength, and HOMO to LUMO gap were reported. Additionally, the study reports on nitrosamine oligomers' hydrogen‐bonded cooperativity and binding energy contributions. Overall, these findings offer valuable insights into the stability and properties of nitrosamine oligomers, with potential applications in materials science and chemical engineering. [ABSTRACT FROM AUTHOR]

Due to their high electronegativity and small atomic radius without undesirable steric hindrance, the incorporation of fluorine atoms onto a conjugated backbone has been proven to be a very effective way to tune the energy levels of organic semiconductors. In this paper, 5-fluorobenzo[c][1,2,5]thiadizole was adopted as the electron-deficient unit, thiophene and alkylthiophene as donor units, and further, thiophene and EDOT were taken as peripheral donor units, and one D–A–D and two D–π–A–π′–D fluorinated electrochromic polymer precursors were successfully synthesized via a Stille coupling reaction, namely F-BT, F-BT-Th, and F-BT-EDOT. Due to the elongation of the π-conjugated systems of precursors with the stronger electron-donating ability of the EDOT unit, the oxidation potential of the F-BT-EDOT precursor was further reduced to 0.56 V vs. Ag/AgCl accompanied by red-shifted electronic spectra. As-electropolymerized P(F-BT-EDOT) also showed favorable redox activity and excellent redox stability (<2.33% electroactivity loss after 1000 cycles). At the same time, the optical band gap of P(F-BT-EDOT) (1.37 eV) is much lower than that of P(F-BT-Th) and P(F-BT) (1.62 eV), and a stable reversible electrochromic change from dark green to dark blue was achieved with a fast response time. In the near-infrared region, P(F-BT-EDOT) shows intriguing overall electrochromic performance with a high optical contrast of up to 33% and a coloration efficiency of 196.3 cm2 C−1 at 1100 nm. It can be seen that the introduction of a strong electron-donor EDOT unit could bring about a new breakthrough in the electrochromic performance of 5-fluorobenzo[c][1,2,5]thiadizole-based fluorinated D–A polymers and enhancement in their stability, and it is expected to be applied in near-infrared electrochromic devices. [ABSTRACT FROM AUTHOR]

Flumequine ligand (FLQ) metal complexes of the [M(FLQ)2(Cl)(H2O)].nH2O type, where M are (La(III), Sm(III), and Tb(III)) and FLQ is flumequine have been synthesized. The FLQ metal complexes could be prepared using MCl3 : flumequine in stoichiometry of 1:2 in situ bidentate chelation. The characterization of FLQ complexes obtained have been done using elemental analyses (%C, %H and %N), molar conductivity (Λm), infrared spectroscopy (FTIR), electronic spectra (UV-Vis), thermal analysis (TGA), and physicochemical techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) measurements at room temperature. Accordingly, these complexes are indicative of an octahedral coordination structure. Flumequine ligand has a bidentate fashion through the oxygen atoms of carbonyl (quinolone) and carboxylic groups. The findings demonstrated the anti-cancer efficacy of these compounds against HepG-2 and MCF-7 cancer cell lines at extremely low doses of up to 58.2 · g/mL. The La(III) complex was shown to have the highest selectivity against cancer cells in comparable with both samarium and terbium(III) complexes. [ABSTRACT FROM AUTHOR]

Organometallic complexes, including copper atom, have attracted great interest as thermally activated delayed fluorescence (TADF) emitters for light emitting diode (LED) applications. This is ascribed to the potential low-cost, abundant availability of copper and most importantly to the ability of copper to enhance the spin–orbit couplings and, consequently, increase the reverse intersystem crossing rates. In this article, we use density functional theory (DFT) to investigate the excited state properties of six copper complexes based on N-heterocyclic carbene ligand, monoamido-amino carbene and diamido carbene, and carbazole ligand. The DFT calculations show that the lowest excited states consist of three groups, i.e., (i) local carbazole excitations, (ii) carbazole-to-carbene intramolecular charge transfer states, and (iii) metal-to-ligand charge transfer states. Only the latter states are characterized with large spin–orbit couplings. The DFT calculations show that the surrounding medium could have a major effect on electronic spectrum by reordering the states. Our results suggest that the TADF properties of the investigated complexes can be affected by the chemical structure of the ligands as well as by the dielectric properties of the LED device active layer. [ABSTRACT FROM AUTHOR]

The work aims to investigate the nonlinear optical (NLO) activity of piperazine‐1,4‐diium acetate (PAA) molecule utilizing computational techniques. The computational calculations are performed using density functional theory (DFT) to explore the vibrational modes, electronic and NLO properties of PAA by comparing them with piperazine and acetic acid molecules. The natural bond orbital analysis is performed to identify hydrogen bonding and charge transfer interaction. A vibrational analysis is carried out and the assignment of fundamental modes is done using the vibrational energy distribution analysis (VEDA) program. Molecular electrostatic potential, frontier molecular orbital, electron localization function, localized orbital locator and Fukui analysis are carried out to identify chemical reactivity and charge transfer interaction. The UV–visible analysis is performed to obtain the electronic absorption spectrum. The hole–electron analysis is performed for the first five excitations to identify the type of excitation. The atoms in molecules, reduced density gradient and independent gradient model are performed to identify the hydrogen bonding, steric and van der Waals interactions. Hirshfeld analysis is performed to explore the intermolecular interactions within the PAA molecule. The NLO calculation is performed to evaluate the NLO parameters. The obtained results show that the PAA molecule is suitable for NLO applications. [ABSTRACT FROM AUTHOR]

Context: The electronic properties and optical properties of Cr-doped monolayer WS2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1(ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. Methods: This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst–Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10−5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force. [ABSTRACT FROM AUTHOR]

Context: Push–pull compounds are model systems and have numerous applications. By changing their substituents, properties are modified and new molecules for different applications can be designed. The work investigates the gas-phase electronic absorption spectra of 15 derivatives of push–pull para–nitroaniline (pNA). This molecule has applications in pharmaceuticals, azo dyes, corrosion inhibitors, and optoelectronics. Both electron-donor and electron-withdrawing groups were investigated. Employing machine learning–derived Hammett's constants σm, σm0, σR, and σI, correlations between substituents and electronic properties were obtained. Overall, the σm0 constants presented the best correlation with HOMO and LUMO energies, whereas the σR constants best agreed with the transition energy of the first band and HOMO–LUMO energy gap. Electron-donors, which have lower σR values, redshift the absorption spectrum and reduce the HOMO–LUMO energy gap. Conversely, electron-withdrawing groups (higher σR's) blueshift the spectrum and increase the energy gap. The second band maximum energies, studied here for the first time, showed no correlation with σ but tended to increase with σ. A comprehensive charge transfer (CT) analysis of the main transition of all systems was also carried out. We found that donors (lower σ's) slightly enhance the CT character of the unsubstituted pNA, whereas acceptors (higher σ's) decrease it, leading to increased local excitations within the aromatic ring. The overall CT variation is not large, except for pNA–SO2H, which considerably decreases the total CT value. We found that the strong electron donors pNA–OH, pNA–OCH3, and pNA–NH2, which have the smallest HOMO–LUMO energy gaps and lowest σ's, have potential for optoelectronic applications. The results show that none of the studied molecules is fluorescent in the gas phase. However, pNA–NH2 and pNA–COOH in cyclohexane and water reveal fluorescence upon solvation. Methods: We investigated theoretically employing the second-order algebraic diagrammatic construction (ADC(2)) ab initio wave function and time-dependent density functional theory (TDDFT) the gas-phase electronic absorption spectra of 15 derivatives of p–nitroaniline (pNA). The investigated substituents include both electron-donor (C6H5, CCH, CH3, NH2, OCH3, and OH,) and electron-withdrawing (Br, CCl3, CF3, Cl, CN, COOH, F, NO2, and SO2H) substituents. [ABSTRACT FROM AUTHOR]

The computational predictions of transition-metal tri-chalcogenide (TMTCs) were performed using ab initio density functional theory (DFT) to investigate the electronic band structure, the partial density of states (PDOS), optical absorptions, dielectric functions, complex conductivity, reflectivity, refractive index, electron loss, the Poisson's ratio, Young's modulus, bulk-to-shear ratio, and phonon dispersion. The bandgap is measured from the valence band maximum (VBM) to the conduction band minimum (CBM) with the G–Z transitions. This suggests that the material is an indirect bandgap semiconductor. The electronic bandgap ( E g) is significantly improved with nonlocal hybrid functionals, especially in HSE0s, with E g of 1.0 eV, which is in excellent agreement with the experimental data. However, our data shows that the HF-LDA exchange correlations significantly overestimate the E g with 7.33 eV. Also, our optical absorption data indicates a high absorption coefficient of about 2. 9 × 1 0 5 cm − 1 . The absorption peak of 7.4 eV indicates TiS3 can be applied in vacuum ultra-violet (VUV) applications. The reflectivity is also shown to be high, with over 90% of light being reflected. The mechanical stability of the monoclinic system can be testified by our elastic coefficients and the phonon dispersions. [ABSTRACT FROM AUTHOR]

Investigations on binding strength differences of non-covalent protein complex components were performed by mass spectrometry. T4 fibritin foldon (T4Ff) is a well-studied miniprotein, which together with its biotinylated version served as model system to represent a compactly folded protein to which an Intrinsically Disordered Region (IDR) was attached. The apparent enthalpies of the gas phase dissociation reactions of the homo-trimeric foldon F-F-F and of the homo-trimeric triply biotinylated foldon bF-bF-bF have been determined to be rather similar (3.32 kJ/mol and 3.85 kJ/mol) but quite distinct from those of the singly and doubly biotinylated hetero-trimers F-F-bF and F-bF-bF (1.86 kJ/mol and 1.08 kJ/mol). Molecular dynamics simulations suggest that the ground states of the (biotinylated) T4Ff trimers are highly symmetric and well comparable to each other, indicating that the energy levels of all four (biotinylated) T4Ff trimer ground states are nearly indistinguishable. The experimentally determined differences and/or similarities in enthalpies of the complex dissociation reactions are explained by entropic spring effects, which are noticeable in the T4Ff hetero-trimers but not in the T4Ff homo-trimers. A lowering of the transition state energy levels of the T4Ff hetero-trimers seems likely because the biotin moieties, mimicking intrinsically disordered regions (IDRs), induced asymmetries in the transition states of the biotinylated T4Ff hetero-trimers. This transition state energy level lowering effect is absent in the T4Ff homo-trimer, as well as in the triply biotinylated T4Ff homo-trimer. In the latter, the IDR-associated entropic spring effects on complex stability cancel each other out. ITEM-FIVE enabled semi-quantitative determination of energy differences of complex dissociation reactions, whose differences were modulated by IDRs attached to compactly folded proteins. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) metal complexes of Mg(II), Ca(II), Cu(II), Cr(III), and Se(IV) were prepared and characterized using elemental analysis, molar conductance, IR, UV-spectra, 1H NMR, SEM, TEM, and X-ray diffraction. The very low values of molar conductance confirm that Cl-ions are absent inside or outside the chelation sphere confirming their non-electrolytic nature, while for Cr(III) Cur is high compared to other curcumin complexes, confirming that Cl-ions are inside the complexation sphere. Based on IR and electronic spectra, the Cur C=O group in enol form chelated to Mg(II), Ca(II), Cu(II), Cr(III), and tetravalent metal (Se). The surface morphology of the curcumin chelates showed an increase in particle size and irregular grains shaped with an elongated morphology. Transmission electron microscopy revealed that the Cur chelates have spherical black spots like shape with a particle size of 72.21-88.75 nm, 34.89-57.33 nm, and 80.71-100 nm for Cu(II), Zn(II), and Se(IV) Cur respectively. X-ray powder diffraction patterns for Cu(II) Cur complexes showed particle size within 70-90 nm; the antioxidant activities of Cur and its metal complexes were assessed. Results showed that the Cur complexes with Cr, Mg, Ca, Cu, or Se showed potent antioxidant activities. Further studies could evaluate the potency of these complexes to elevate the antioxidant defense system and enhance body functions against degenerative diseases, such as aging, Alzheimer's disease, and viral diseases. [ABSTRACT FROM AUTHOR]

The current research focused on the Schiff base ligand (S,E)-2-((2-hydroxy-3-methoxybenzylidene) amino)-3-(1H-imidazol-4-yl)propanoic acid which synthesis by reacting L-histidine and 2-hydroxy-3-methoxy-benzaldehyde. Its complexes with Ce(III) and Fe(III) both in bulk and nano size were also synthesized. The ligand and its metal complexes were characterized by various physicochemical methods such as FT-IR, 1H NMR, 13C NMR, electronic spectra, XRD, TGA, and SEM. The synthesized ligand and its metal complexes were screened against different fungi. It was found from the results that the cerium nano complex shows a potent antifungal activity for indoor uses as wallpapers. [ABSTRACT FROM AUTHOR]

In this study, the effect of polarity and hydrogen bonding ability of solvents on the absorption spectrum of Congo red was investigated. UV–Visible absorption spectra were recorded in eight neat solvents and four aqueous binary solutions of methanol, ethanol (as HBD solvents), and dimethylsulfoxide and dioxane (as HBA solvents). Congo red has two absorption maxima in the range (250–700 nm) that have been assigned to the azo and hydrazo systems. Molar transition energy (ET) values of Congo red in different solvents were correlated with the solvent parameters using linear solvation energy relationships. Multiparameter analysis shows the dependence of the electronic spectra of Congo red on the non-specific and specific interactions. Preferential solvation was observed in all binary mixtures when ET plotted as a function of mole fraction of organic solvents. The results showed that the Congo red was solvated by water–organic solvent complex species in all binary mixtures except in case of aqueous-ethanol mixtures, whose preferred solvation by ethanol in all mole fractions with f12/2 and f12/1 values less than unity. The dual-parameters model is a powerful tool for explaining binary mixture data with Kamlet–Taft parameters. The findings indicated that the HBD and HBA were responsible for the solvatochromism of the binary mixtures. [ABSTRACT FROM AUTHOR]

A new arsenato-polyoxovanadate with the composition {[Ni(dien)2]3[V6As8O26]}2+·2 Cl– has been crystallized under solvothermal conditions as turquoise block-like crystals. The central structural feature is the [V6IVAs8IIIO26]4– cluster anion, which is composed of two trinuclear {V3O11} groups consisting of three edge-sharing VO5 polyhedra. Pairs of pyramidal AsO3 moieties share a common corner forming As2O5 units, which interconnect the {V3O11} groups. One of the [Ni(dien)2]2+ complexes adopts the s-fac (Ni1) and the second complex the mer configuration (Ni2). The Cl− anion is involved in strong hydrogen bonding interactions and links the [Ni(dien)2]2+ complexes to form twelve-membered rings which host the [V6As8O26]4– cluster anions. The Hirshfeld surface analysis yields a detailed picture of the intermolecular interactions revealing clear differences for the two unique [Ni(dien)2]2+ complexes. Intermolecular contacts also include As⋯H, O⋯H and H⋯H interactions. In the electronic spectrum the bands of d–d transitions of the vanadyl group and of the Ni2+ cations overlap, preventing a detailed analysis. [ABSTRACT FROM AUTHOR]

Time-dependent density functional theory (TDDFT) offers a tractable means to predict electronic excitation spectra of ices if sufficient care is taken in selecting the DFT functional, basis sets, and the number of excited states. In this work 48 functionals in conjunction with various correlation consistent basis sets were benchmarked for predicting electronic spectra. A training set of important astromolecules was chosen: carbon monoxide, water, hydrogen cyanide, ammonia, methanol, and the hydroxyl radical. Vertical excitation energies between the ground and first excited state and some higher excited states were calculated using multireference configuration interaction calculations to serve as benchmarks for gas phase TDDFT calculations. When used in conjunction with aug-cc-pVDZ quality correlation consistent basis sets, two functionals, MPW1K and ωB97, emerged as very good choices to model electronic excitations for most of the molecules in the training set. Cluster calculation predictions for the UV spectra of amorphous ices of water and ammonia were performed at the TDDFT-MPW1K/AVDZ and TDDFT-ωB97/AVDZ levels and then compared against experimental data. The calculations qualitatively reproduce the shapes of the spectra for the most part and quantitatively predict the position of the critical first absorption peak. [ABSTRACT FROM AUTHOR]

Inclusion of one of the natural enantiomers of linalool ((R)-(-)-linalool, simply LIN) into cucurbit[n]urils (CB[n]s) was investigated by means of DFTB + and DFT computations with Grimme's dispersion correction and geometric counterpoise treatment. Among different cucurbit[n = 5 ~ 9]urils, some diastereoisomers of CB[7] can form relatively stable inclusion complexes (LIN@CB[n]s) with LIN in water. Hydrogen bonds and dispersion interaction between CB[n] and LIN play an important role in formation of the inclusion complexes. Molecular electrostatic potential, non-covalent interaction, and natural bond analysis were carried out for interpretation of stability of the relatively stable LIN@CB[7]s. Theoretical computations showed that LIN@i-CB[7] was the most stable and it can offer increased solubility to linalool in water than the normal CB[7]. The calculated electronic spectra of linalool, i-CB[7], and LIN@i-CB[7] showed that inclusion of linalool into i-CB[7] can be useful in protection of linalool from photo-degradation. [ABSTRACT FROM AUTHOR]

The aim of this work was to create new ligand complexes and evaluate their effectiveness against certain strains of bacteria. A Brucker Tensor 27co FTIR spectrophotometer was used to record the infrared spectra. Elemental analysis (C, H, N) was carried out on an AA670 atomic absorption spectrophotometer to determine mineral content, and the conductivity of PCM3 Jenway was measured to record electronic spectra. The ligand was prepared, that possessed physical constants and spectroscopic properties. The complexes [M(L)2Cl2] and [M(L)4Cl2] were also prepared, where M=Mn(II), Co(II), Ni(II), Cu(II), and Zn(II), which were synthesized by direct reaction of the above ligand with metal chlorides in (2:1) or (4:1) (Ligand : metal) molar ratio in the ethanol medium. The ligand compound 4-(2-(benzo-1,3-dioxol-5-yl)-4,5-diphenyl-2,5-dihydro1H-imidazol-1-yl)aniline (L) was obtained. The prepared complexes were shown by elemental analysis, spectroscopic studies (FTIR, UV/vis), 1H-NMR measurement, conductivity measurements, and electron spectrometry value, which indicate the presence of tetrahedral and octahedral geometry around the metal ions. The biological antibacterial activity of the compounds and complexes has been demonstrated against specific strains of G+ Staph. aureus and G− Bacillus. The bonding compound L coordinates the metal in a tetrahedral and octahedral N-M-N manner. The compound and its complexes had activity against specific strains of bacteria. The ligand (L1) and the complex (3) had a greater effect on different types of bacteria than the rest of the complexes, which had a lower efficiency rate. [ABSTRACT FROM AUTHOR]

In this work, we comparatively studied the electronic and optical properties of triangular-shaped nanoflakes of VX 2 with varying flake sizes and compositions. We calculated the electronic properties using the density functional theory (DFT) while employing the time-dependent density functional theory (TD-DFT) to explore the optical properties of nanoflakes. The density of states (DOS) of VX 2 triangular nanoflakes showed the existence of localized metallic states, primarily originating from the presence of edge atoms in the flake. The optical spectra of VX 2 triangular nanoflakes revealed that the discrete peaks at low energy levels show broadening as flake size increases while splitting in resonance peaks upon changing the composition of the nanoflake. To gain insights into the nature of photoabsorption peaks, we analyzed the induced density and transition contribution map (TCM), which revealed the presence of both single-particle excitations and collective excitations. The collective excitations are known as plasmons which arise from the localized metallic edge states of the nanoflakes. This study sheds light on how nanoflakes' electronic and optical characteristics depend heavily on their shape, size, and composition. Future experiments are necessary to validate these theoretical findings. [ABSTRACT FROM AUTHOR]

Research into and applications of phthalocyanines (Pc) are mostly connected to their intriguing electronic properties. Here, messenger‐type UV–vis spectroscopy of two metal‐free ions from the phthalocyanine family, cationic H2Pc+ and H2PcD+, along with their hydrates is performed. They show that the electronic properties of both ions can be traced to those in the conjugate base, Pc2–, however, they are affected by state splitting due to the reduced symmetry; in the H2Pc+ radical cation, a new band appears due to excitations into the singly‐occupied molecular orbital. Quantum chemical spectra modeling reproduces all important features of the measured spectra and provides insight into the nature of electronic transitions. Hydration of the ions has only a mild effect on the electronic spectra, showing the stability of the electronic structure with respect to solvation effects. [ABSTRACT FROM AUTHOR]

In this work, the four azo dyes (A1–A4) were synthesized using 5‐amino‐3‐methyl‐1‐phenyl pyrazole with four different coupling components by the conventional, simple diazo‐coupling method. These synthesized azo molecules were confirmed by various spectroscopic methods viz, FT‐IR spectra, HR‐MS spectra, 1H NMR spectra, and 13C NMR spectra. The electronic absorption and fluorescence spectra of synthesized azo compounds were recorded at room temperature, with different solvents. The DFT calculations were performed using 6‐311++G (d, p) basis set to evaluate the global reactive parameters of the synthesized azo dyes. The anti‐microbial activities were studied; the compound A1 exhibited a good antibacterial and anti‐fungal activities. The study of in silico molecular docking of the azo compounds revealed that all the compounds found to possess were extraordinary binding affinity as compared to the standards. The anti‐tuberculosis study was carried against mycobacterium tuberculosis and the results have shown that, the compound A2 showed good sensitivity to the studied azo compounds. [ABSTRACT FROM AUTHOR]

Anthraquinone derivatives are well recognized for their anticancer activities and pharmacological properties. In the present study, comprehensive theoretical and experimental FT-IR, FT-Raman, and UV-visible spectroscopic studies on the 1-Chloroanthraquinone (CAQ) molecule were carried out. The optimized molecular structure and harmonic vibrational frequencies was calculated using Gaussian 09 program. The experimental and calculated vibrational wavenumbers were assigned, which correlated well with the previous literature. The UV-visible absorption spectrum of the CAQ molecule was computed in the liquid phase (ethanol), which exhibits n–π* electronic transition, and the results were compared with the observed UV-visible spectrum. From the frontier molecular orbital analysis, the calculated energy gap value (4.03 eV) indicates that the CAQ molecule has a stable structure and the value was comparable with the band gap energy value of the reported bioactive molecules. The electron back donation from the carbonyl group oxygen atom to the benzene ring was identified using Mulliken atomic charge distribution analysis. Molecular electrostatic potential surface analysis confirms the reactive sites of the molecule. The natural bond orbital analysis validates electron back donation from the carbonyl group oxygen atom to the benzene ring of the CAQ molecule. The molecular docking analysis results that the CAQ molecule acts as a good inhibitor of histone deacetylase 6 (HDAC6) protein. HDAC6 protein is associated with oral squamous cell carcinoma. Thus, the present study paves the way for designing novel drugs for the treatment of oral squamous cell carcinoma. [ABSTRACT FROM AUTHOR]

The present study investigates the utilisation of density functional theory (DFT) to examine unmodified and amino acid-functionalised C4B32 borospherenes as potential carriers for drug transport. The recent and significant finding of borospherenes, which are composed of a cluster of four carbon atoms fused into a B364- structure (referred to as C4B32), has provided a valuable opportunity to explore the potential capabilities of unmodified and alanine-modified C4B32 clusters as efficient vehicles for medicinal substances. The main objective of this study was to utilise Density Functional Theory (DFT) to examine the interaction between unmodified and alanine-linked borospherenes and the medicinal substance Lamivudine (LV). The investigation results revealed that the incorporation of amino acids had a pivotal role in facilitating the distribution of bio-drugs, leading to an improvement in the binding capacity of the C4B32 cluster with the drug. In this study, the dispersion-corrected density functional theory (DFT) approach proposed by Grimme examined long-range interactions. The calculations were performed utilising the B3LYP functional, implemented with the 6–31 + G(d) basis set in the GAMMES software. The electronic spectra of the drug@cluster complexes were analyzed using UV-Vis calculations, revealing a noticeable shift towards longer wavelengths, commonly called redshift. The results above highlight the significant potential of alanine-modified C4B32 borospherenes in drug delivery applications. [ABSTRACT FROM AUTHOR]

Our understanding of quantum materials is commonly based on precise determinations of their electronic spectrum by spectroscopic means, most notably angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy. Both require atomically clean and flat crystal surfaces, which are traditionally prepared by in situ mechanical cleaving in ultrahigh vacuum chambers. We present a new approach that addresses three main issues of the current state-of-the-art methods: (1) Cleaving is a highly stochastic and, thus, inefficient process; (2) fracture processes are governed by the bonds in a bulk crystal, and many materials and surfaces simply do not cleave; and (3) the location of the cleave is random, preventing data collection at specified regions of interest. Our new workflow is based on focused ion beam machining of micro-strain lenses, in which shape (rather than crystalline) anisotropy dictates the plane of cleavage, which can be placed at a specific target layer. As proof-of-principle, we show ARPES results from micro-cleaves of Sr2RuO4 along the ac plane and from two surface orientations of SrTiO3, a notoriously difficult to cleave cubic perovskite. [ABSTRACT FROM AUTHOR]

Context: The study of molecular aggregation effects on the electronic spectrum is essential for the development of optoelectronic devices. However, investigating the entire valence absorption spectrum of aggregates using quantum mechanical methods is a challenging task. In this work, we perform systematic simulations of the absorption spectrum of benzene molecular clusters up to 35 eV applying two approaches based on time-dependent density functional theory. The results show that depending on the dimer packing, different energy shifts occur for the symmetry allowed π → π ∗ transition, in comparison to the monomer. The transition intensity increases for the band around 6 eV for larger aggregates from the monomer to dimers and tetramer, indicating the occurrence of the symmetry forbidden (in D 6 h point group) 1 A 1 g → 1 B 1 u transition. The benzene crystal exhibits a large redshift following the experimental spectrum. Also, the continuum regions of all spectra show a good agreement with the experiments both in gas and solid phases. Methods: Geometry optimization of the monomer was carried out with Gaussian 09 software using the PBE0/def2-TZVP level of theory. We used dimers and tetramer molecular geometries extracted from the experimental crystal structure. The absorption spectra were directly obtained by the Liouville-Lanczos TDDFT approach with plane waves basis set or indirectly by TDDFT pseudo-spectra calculated in a L 2 basis followed by analytic continuation procedure to obtain complex polarizability. The former is available at Quantum ESPRESSO, and the latter was calculated using Gaussian 09 with the post-processing performed with a code previously developed in our group. [ABSTRACT FROM AUTHOR]

Two-dimensional polymers (2DPs) are a class of 2D crystalline polymer materials with definite structures, which have outstanding physical–chemical and electronic properties. They cleverly link organic building units through strong covalent bonds and can construct functional 2DPs through reasonable design and selection of different monomer units to meet various application requirements. As promising energy materials, 2DPs have developed rapidly in recent years. This review first introduces the basic overview of 2DPs, such as their historical development, inherent 2D characteristics and diversified topological advantages, followed by the summary of the typical 2DP synthesis methods recently (including "top-down" and "bottom-up" methods). The latest research progress in assembly and processing of 2DPs and the energy-related applications in energy storage and conversion are also discussed. Finally, we summarize and prospect the current research status, existing challenges, and future research directions of 2DPs. [ABSTRACT FROM AUTHOR]

The magnetic structure of Fe5O6 is studied using a combination of the group-theoretical analysis and DFT + U calculations of the electronic spectrum. The calculations are performed for the magnetic k = (0, 0, 0) vector. The magnetic ground state corresponds to the orthogonal ordering of two magnetic subsystems: the magnetic moments of Fe2+/Fe3+ ions located at the octahedral sites (slabs of octahedra) are directed along the c axis and are antiferromagnetically ordered, whereas the magnetic moments of Fe2+ ions in trigonal prisms forming one-dimensional chains are directed along the b axis and are antiferromagnetically coupled along the c axis. The formation of a nonzero antiferromagnetic component of magnetic moments in the slabs of octahedra directed along the b axis is caused by the effect of magnetic chains on the three-dimensional magnetic structure. [ABSTRACT FROM AUTHOR]

Zinc(II) Schiff base complexes with different substituents at 5, 5' positions have been synthesized to study the effect of the electronic environment of the metal towards the cycloaddition reaction between CO2 and epoxide. The complexes have been characterized by FT‐IR, XPS, NMR, electronic spectroscopy, LC–MS, and TGA. We have used density functional theory to study the electronic structure of the Zn(II) complexes and modelled the electronic spectra and the mechanism of catalysis. Results obtained from DFT and LC–MS indicate the dimeric structures for all the complexes except ZnL4. The monomeric ZnL4 has the strongest electron withdrawing group, i. e. −NO2 at 5, 5' positions along with two labile water molecules attached to the Zn center. The dimeric complexes exhibit good to moderate yield for cycloaddition reaction to styrene carbonate under solvent‐free conditions and a relatively low reaction temperature of 80 °C, with CO2 pressure of ~1 atm. The best yield has been achieved by ZnL4. Different rate‐determining steps are captured by the DFT studies for dimeric and monomeric complexes. Without taking any preventing measure of dimerization by attaching the bulky tBu groups, relatively lesser catalytic amounts of all the complexes have shown yields of cyclic carbonate between 53–74 %, depending on the nature of the substituent present. [ABSTRACT FROM AUTHOR]

Valence tautomerism (VT) involves the stimulated reversible intramolecular electron transfer between a redox-active metal and ligand. Dinuclear cobalt complexes bridged by bis(dioxolene) ligands can undergo thermally-induced VT with access to {CoIII-cat-cat-CoIII}, {CoIII-cat-SQ-CoII} and {CoII-SQ-SQ-CoII} states (cat2− = catecholate, SQ˙− = semiquinonate, CoIII refers to low spin CoIII, CoII refers to high spin CoII). The resulting potential for two-step VT interconversions offers increased functionality over mononuclear examples. In this study, the bis(dioxolene) ligand 3,3′,4,4′-tetrahydroxy-5,5′-dimethoxy-benzaldazine (thMH4) was paired with Mentpa (tpa = tris(2-pyridylmethyl)amine, n = 0–3 corresponds to methylation at 6-position of the pyridine rings) to afford [{Co(Mentpa)}2(thM)](PF6)2 (1a, n = 0; 2a, n = 2; 3a, n = 3). Structural, magnetic susceptibility and spectroscopic data show that 1a and 3a remain in the temperature invariant {CoIII-cat-cat-CoIII} and {CoII-SQ-SQ-CoII} forms in the solid state, respectively. In contrast, 2a exhibits incomplete thermally-induced VT between these two tautomeric forms via the mixed {CoIII-cat-SQ-CoII} tautomer. In solution, room temperature electronic absorption spectra are consistent with the assignments from the solid-state, with VT observed only for 2a. From electrochemistry, the proximity of the two 1e−-processes for the thMn− ligand indicates weak electronic communication between the two dioxolene units, supporting the potential for a two-step VT interconversion in thMn− containing complexes. Comparison of the redox potentials of the Co and thMn− processes suggests that only 2a has these processes in sufficient proximity to afford the thermally-induced VT observed experimentally. Density functional theory calculations are consistent with the prerequisite energy ordering for a two-step transition for 2a, and temperature invariant {CoIII-cat-cat-CoIII} and {CoII-SQ-SQ-CoII} states for 1a and 3a, respectively. This work presents the third example, and the first formally conjugated example, of a bridging bis(dioxolene) ligand that can afford two-step VT in a Co complex, suggesting new possibilities towards applications based on multistep switching. [ABSTRACT FROM AUTHOR]

This study involves the synthesis of novel methoxyphenylthio-substituted phthalocyanines and their starting phthalonitriles as well as the characterization and investigation of their physical and spectral properties. Herein, although phthalocyanines were categorized as alpha and beta-substituted, the numbers of external substituent methoxy groups selected to obtain soluble phthalocyanines were also different. After their molecular structure was characterized using elemental analysis, FT-IR, NMR, and MALDI-TOF-MS techniques, the exhaustive electronic spectra of novel phthalocyanines were studied. During extensive UV-Vis spectroscopy studies, proton transfer complexes in basic coordinating solvents and protonated species in solvents containing acids as impurities occurred incidentally in some phthalocyanines. Then, it was investigated whether this incidentally encountered situation was related to the number of methoxy groups as external substituents. Consequently, it was revealed that the acidity of H atoms in the center of phenylthio-substituted phthalocyanines could be altered by outer groups in the substituents, and the wavelengths of the Q bands of the novel Pcs changed under the influence of these outer groups. Computational TD-DFT study at the ωB97XD/6-311G(d,p) level confirmed the redshift observed in electronic spectra upon inserting two additional OCH3 at outer groups, originating from small decreases in the HOMO–LUMO energy gap. The NBO charge distribution justified the electron donation from sulfur atoms to the phthalocyanine ring. [ABSTRACT FROM AUTHOR]

Photo‐induced charge transfer (CT) states are pivotal in many technological and biological processes. A deeper knowledge of such states is mandatory for modeling the charge migration dynamics. Real‐time time‐dependent density functional theory (RT‐TD‐DFT) electronic dynamics simulations are employed to explicitly observe the electronic density time‐evolution upon photo‐excitation. Asymmetrically substituted indenotetracene molecules, given their potential application as n‐type semiconductors in organic photovoltaic materials, are here investigated. Effects of substituents with different electron‐donating characters are analyzed in terms of the overall electronic energy spacing and resulting ultrafast CT dynamics through linear response (LR‐)TD‐DFT and RT‐TD‐DFT based approaches. The combination of the computational techniques here employed provided direct access to the electronic density reorganization in time and to its spatial and rational representation in terms of molecular orbital occupation time evolution. Such results can be exploited to design peculiar directional charge dynamics, crucial when photoactive materials are used for light‐harvesting applications. [ABSTRACT FROM AUTHOR]

This study successfully and cost-effectively synthesized a novel compound, 3-[(5-amino-1-phenyl-1H-pyrazol-4-yl)carbonyl]-1-ethyl-4-hydroxyquinolin-2(1H)-one (APPQ, 4), which displayed significant potential for various applications and yielded promising outcomes. Theoretical electronic absorption spectra in different media were acquired using the Coulomb-attenuating approach (CAM-B3LYP) and the Corrected Linear Response Polarizable Continuum Model (CLR) PCM. Employing CAM-B3LYP with the 6-311 + + G(d,p) level of DFT proved to be more accurate than alternative quantum chemical calculation methods, aligning well with the experimental data. Additionally, the CAM-B3LYP method using polarized split-valence 6-311 + + G(d,p) basis sets and CLR PCM in various solvents exhibited good agreement with the observed spectra. The high stability of APPQ, validated by the computed total energy and thermodynamic parameters at the same calculation level, surpassed that of anticipated structure 3. The theoretically calculated chemical shift values (1H and 13C) and vibrational wavenumbers were strongly correlated with the experimental data. The APPQ thin films demonstrated a band gap energy of 2.3 eV through distinctive absorption edge measurement. Photoluminescence spectra exhibited characteristic emission peaks at approximately 580 nm. Current–voltage measurements on n-Si heterojunction devices with APPQ thin films revealed typical diode behavior. These APPQ-based devices showed attractive photovoltaic properties, including an open-circuit voltage of 0.62 V, a short-circuit current of 5.1 × 10–4 A/cm2, and a maximum output power of 0.247 mW/cm2. Overall, the investigated heterojunctions display appealing photophysical characteristics, encouraging advancements in photovoltaics. [ABSTRACT FROM AUTHOR]