Electronic Absorption Spectra Research Articles

Assessing the antimicrobial and cytotoxic activities of VO(IV), Cr(III), Cu(II)-metformin-schiff-base's complexes enhanced by gold nanoparticles

A new series of VO(IV), Cr(III), and Cu(II) complexes have been synthesized by condensation of metformin with β-diketones (acetylacetone, benzoylacetone, dibenzoylmethane) in the presence of metal salts. The elemental analysis, magnetic susceptibility, conductivity assessments, Infra-Red, UV–visible spectroscopy measurements, SEM, XRD, ESR, GCMS–, DTA, and DTG were used to characterize the novel compounds. The results show that every complex has a metal: ligand ratio of 1:1. The complexes exhibit distorted tetrahedral structural geometry for Cu(II), square pyramidal and octahedral geometry for VO(IV), and octahedral geometry for Cr(III), according to their electronic absorption spectra and magnetic susceptibility studies. Using the computer program Expo2014, crystallographic parameters were estimated for the complexes. The outcomes show that every complex has triclinic crystal structures with the space group P-1, apart from complex [VOL1OSO3], which has a monoclinic structure with the P 1 2 1 space group. In contrast to the complex [VOL1OSO3], which includes monodentate sulfate, conductivity data, XRD, EDX, and GC–MS verified the purity and composition of the compounds being studied. IR data showed that the complexes Na.[VOL2O2SO2] and Na.[VOL3O2SO2] has bidentate chelating sulfate ion. TG, DTG, and DTA have all been used to investigate the complexes' thermal stabilities. Some Schiff-base metformin complexes under investigation had their biological activity evaluated both with and without the addition of AuNPs. Various bacteria and harmful fungi strains have been used to screen the antimicrobial activity. The findings indicate that only copper-loaded Schiff base complexes on AuNPs gave promising results versus Staphylococcus aureus, Escherichia coli, Salmonella, and Candida albicans. On human cell lines of breast cancer (MCF7) and cancer of the human liver (HEPG2), in vitro cytotoxic activity was tested. Results showed that vanadium benzoylacetone doped with gold nanoparticles, with an IC50 value of 7 µg/ml against the HEPG2 cell line and 9.8 against MCF7 has the most effective cytotoxic effect.

Study on An Interaction between Titan Yellow and Orange S Indicators in Water and Ethanol by using Spectroscopy Technique

Charge transfer complex (CTC) of Orange S (donor) and Titan Yellow (acceptor) has been studied in ethanol, and water solvents at room temperature (20°C) using absorption spectrophotometer. The results indicate that formation of CTC in high polar solvent is high. The stoichiometry of the complex was found to be 1:1 ratio by straight-line method between donor and acceptor with maximum absorption bands and present of isosbestic point suggest this fact. The data are discussed in terms of formation constant (KCT), molar extinction coefficient (εCT), standard free energy (ΔGo), transition energy (ECT), and ionization potential (IP). The formation constant (KCT) for the complex was shown to be dependent upon the polarity of solvents that were used. Electronic absorption spectra, which indicate the CT interaction, associated with proton migration from the acceptor to the donor followed by hydrogen bonding.

DFT and TD‐DFT Study of Many‐Body and Hydrogen Bonding Interactions: Nitrosamine Oligomers

AbstractThis 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.

Preparation and characterization of MnIIMnIII complexes with relevance to class Ib ribonucleotide reductases

The Mn2 complex [MnII2(TPDP)(O2CPh)2](BPh4) (1, TPDP = 1,3-bis(bis(pyridin-2-ylmethyl)amino)propan-2-ol, Ph =phenyl) was prepared and subsequently characterized via single-crystal X-ray diffraction, X-ray absorption, electronic absorption, and infrared spectroscopies, and mass spectrometry. 1 was prepared in order to explore its properties as a structural and functional mimic of class Ib ribonucleotide reductases (RNRs). 1 reacted with superoxide anion (O2•–) to generate a peroxido-MnIIMnIII complex, 2. The electronic absorption and electron paramagnetic resonance (EPR) spectra of 2 were similar to previously published peroxido-MnIIMnIII species. Furthermore, X-ray near edge absorption structure (XANES) studies indicated the conversion of a MnII2 core in 1 to a MnIIMnIII state in 2. Treatment of 2 with para-toluenesulfonic acid (p-TsOH) resulted in the conversion to a new MnIIMnIII species, 3, rather than causing O—O bond scission, as previously encountered. 3 was characterized using electronic absorption, EPR, and X-ray absorption spectroscopies. Unlike other reported peroxido-MnIIMnIII species, 3 was capable of oxidative O—H activation, mirroring the generation of tyrosyl radical in class Ib RNRs, however without accessing the MnIIIMnIV state.

DETERMINATION OF CHAMAZULENE BY REVERSED PHASE HPLC

A method for the determination of hamazulene in essential oils using reverse-phase high-performance liquid chromatography with diode-matrix detection has been developed. The possibility of qualitative determination of hamazulene from the electronic absorption spectra recorded in the detector cell and quantitative determination of this substance during detection at several different wavelengths is shown. To obtain chromatograms, it is proposed to use C18 stationary phase with a mobile phase containing 20 vol. % water in acetonitrile. Samples for the study were prepared by dissolving essential oils in acetonitrile. The chromatographic determination of hamazulene is not hindered by the accompanying components of the studied essential oils of four plants: Matricaria chamomilla, Achillea millefolium, Tanacetum annuum and Artemisia absinthium; the concentration of hamazulene in them was 0.184, 0.311, 0.299 and 0.0025 mol/l, respectively. The wavelength of 603 nm provides the most selective detection of hamazulene along a complex electron-vibrational band for a solution in the mobile phase. When the detection wavelength changes from 603 to 350 and up to 280 nm, the sensitivity of hamazulene detection increases by 15.5 and 187 times. The chromatographic method has a linear response of the detector despite the known features of the electronic absorption spectra of azulene derivatives. It was found that when a blue-colored spot of hamazulene is isolated from TLC plates, other nonpolar components of oils that are detected when recording a chromatogram under HPLC conditions at a detector wavelength of 210 nm also enter the extract. It was also found that when recording chromatograms at 200 nm, differentiation of oils is possible, since most of the components of these oils have at least one isolated double C=C bond in the structure, which allows detecting compounds at 190-200 nm. For citation: Deineka V.I., Salasina Ya.Yu. Determination of chamazulene by reversed phase HPLC. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 6-20. DOI: 10.6060/ivkkt.20246706.6989.

INTERACTION OF 7,7´-DIOXO-7H, 7´ H-3, 3´ -BENZIMIDAZO[2,1-a]BENZO[de]ISOQUINOLINE-4, 4´ -DICARBOXYLIC ACID WITH SODIUM DITHIONITE IN WATER-ALKALINE SOLUTION

Using the spectrophotometric method, the interaction of 7,7´-dioxo-7H, 7´ H-3, 3´ -benzimidazo[2,1-a]benzo[de]isoquinoline-4, 4´ -dicarboxylic acid with sodium dithionite in an aqueous-alkaline solution in aerobic and anaerobic conditions has been studied. It is found, that in the initial stage of process very rapidly formation of a tetraanion is observed due to the addition of two electrons. In the future, depending on the conditions of the reaction (aerobic, anaerobic atmosphere, small or large concentrations of the reducing agent), the tetraanion transition to the initial compound is observed due to its oxidation with air oxygen or sulfite anion formed from dithionite anions, as well as at sufficiently high concentrations of the reducing agent. A subsequent chemical stage of cyclization is possible with the cleavage of two carboxyl groups from the reduced form of the initial compound. It has also been established that the cyclization product is N,N'-di(benzimidazole)diimides of perilen-tetracarboxylic acid, which is isolated from a solution in a solid state. Its elemental composition is analyzed, IR- and electronic absorption spectra were obtained. The reversible nature of the initial stage of the interaction of 7, 7´-dioxo-7H, 7' H-3, 3´-benzimidazo[2,1-a]benzo[de]isoquinoline-4,4´-dicarboxylic acid with sodium dithionite is indicated by the fact that under aerobic conditions the concentration of the intermediate product present in the form of tetraanion decreases faster than the anaerobic atmosphere. The transition of the reduced form of the initial compound to the original, non-restored one is also observed during bubbling of air through the reaction mixture. It has been established by cyclic voltammetry that reversible reduction of the initial compound is also possible due to an electrochemical reaction occurring on a carbon-metal electrode in an aqueous-alkaline solution. The analysis of the voltage dependences showed that two electrons participate in the electrode reaction. For citation: Polenov Yu.V., Egorova E.V. Interaction of 7,7´-dioxo-7H, 7´ H-3, 3´ -benzimidazo[2,1-a]benzo[de]isoquinoline-4, 4´ -dicarboxylic acid with sodium dithionite in water-alkaline solution. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 80-87. DOI: 10.6060/ivkkt.20246706.7056.

Investigation of the Dyeing Ability of Some Reactive Triazine Azo Dyes Containing Pyrazole Fragment.

The IR, 1H NMR, and DFT studies indicated that the prepared reactive disperse dyes predominately exist as hydrazone tautomers. The electronic absorption spectra in methanol were observed and compared to those computed using B3LYP/6-311G(d,p). The dyeing efficiency of the produced dispersed reactive dyes was examined on polyester, cotton, and polyester/cotton blended fabrics. The degree of exhaustion and the quick properties of the dyed samples in terms of perspiration, washing, scorch and light fastness were assessed. It was found that reactive disperse dyes under investigation have a higher affinity for dyeing polyester textiles than cotton textiles. Moreover, the reflectance and color strength of the synthesized dyes were measured and discussed.

Investigation of the structural and optoelectronic characteristics in coumarin-based dye-sensitized solar cells, both in isolation and with TiO2 adsorption

In this study, six novel organic dyes derived from coumarin have been formulated by limiting the rotation of bithiophene through the introduction of substituents, namely NCH3, Si(CH3)2, C(CH3)2, C=C(CH3)2, and C=O. Their structural, electronic, photovoltaic, and spectral properties were investigated using density functional theory at the B3LYP/6-31G(d,p) level. Furthermore, the time-dependent DFT (TD-DFT) at TD-BHandH/6-31G(d,p) level method was chosen to calculate the electronic absorption spectra and charge transfer characteristics of the investigated dyes in the chloroform solvent, as well as molecular properties such as geometries parameters, optoelectronic properties, and frontier molecular orbitals. With our studies, we reveal that all the studied dyes show significance in the range of 340.97–610.89 nm, with a band gap in the range of 1.90–2.26 eV, as well as high light capture efficiency (LHE) and significant intramolecular charge transfer (ICT) properties. In addition, we were interested in the energetic, electronic, and absorption studies of dyes linked to the TiO2 semiconductor (Dye@TiO2). All designed dyes exhibit better geometric and optoelectronic properties except for D3, which has the lowest gap energy and extends towards the red. The results reveal that these compounds would be used as potential sensitizers for DSSC applications.

High-performance optoelectronic and thermoelectric properties of transparent conductors based on Tl2O3 under pressure

In this work, the full-potential linearized augmented plane wave method (FP- LAPW) and the modified Becke-Johnson (mBJ) functional with spin–orbit (SO) coupling are used the obtain the structural, optoelectronic and thermoelectric properties of Tl2O3 under pressure. The results show that Tl2O3, as transparent conducting oxide (TCO), is a direct bandgap semiconductor with a band gap of 1.23 eV. The band gap value and the effective mass of electrons increases by increasing pressure. Density of state spectra reveal that the nature of electrons in Tl-6s state in the bottom of conduction band, like free electrons in s state, is responsible for the conducting behavior of Tl2O3. A blue shift is observed in optical spectra such as electron energy loss and absorption spectra with an increase in pressure. Obtained dielectric constants under pressure are inversely proportional to the band gap value according to Penn model. The effects of pressure on thermometric properties are also explored. The hydrostatic pressure increases Seebeck coefficient, while it decreases thermal conductivity that is an effective way to the enhancement of the thermoelectric efficiency of TCOs. A figure of merit (ZT) of 0.98 in p-type Tl2O3 is achieved that is desirable for using in thermoelectric devices.

Synthesis of new [6]helicene derivatives for OLED applications. Experimental photophysical and chiroptical properties and theoretical investigation

Six-membered helicenes with specific functionalities were synthesized in good overall yields (40 %-73 %) through a concise photochemical method, allowing for their comprehensive characterization. The racemic mixtures were effectively resolved into their P- and M-enantiomers with high optical purity (97.56 %-100 % ee) by using chiral HPLC. This separation showcased remarkable optical activity, revealing substantial optical rotations (e.g., +2500–3000 for the (P)-enantiomer at λ = 589 nm) and notable electronic circular dichroism (ECD) signals. The organic helical species showed a strong absorption in the UV region and exhibited a red shifted emission, resulting in a quantum yield of 0.12–0.21. Moreover, they demonstrated irreversible one-electron oxidation and reduction processes, and their HOMO and LUMO energy levels were estimated via electrochemical methods. Utilizing DFT and TD–DFT computational approaches, we accurately predicted the electronic absorption and ECD spectra, as well as the frontier molecular orbitals (FMOs), aligning closely with experimental observations. Furthermore, in-depth analyses of absorption and ECD spectra, molecular electrostatic potential (MEP), and reduced density gradient (RDG) through quantum chemical calculations offered insights into the fundamental characteristics of these materials. The collective properties strongly indicate the potential application of these helicenes in electroluminescent and OLED devices, underscoring their promise as candidates in optoelectronic applications.

Comparison study (experimental and theoretical), hydrogen bond interaction through water, donor acceptor investigation and molecular docking study of 3,3-((1,2-phenylenebis (azaneylylidene)) bis (methaneylylidene)) diphenol

The novel Schiff’s base (CS6) was synthesized and confirmed by various studies. The B3LYP/cc-pVDZ basis set was used for theoretical study and the results indicated that both the theoretical and experimental studies correlated well. The interaction energy of CS6-water complex calculated by using the local energy decomposition analysis was found to be −7.28 kcal/mol. The TD-TFT method was used for the calculation of electronic absorption spectrum. This study confirmed that the observed wavelength and the simulated wavelength in the electronic spectra were almost similar. The electrophilic and nucleophilic attacking sites of the titled compound were identified by using FMO and MEP studies. The highest stabilization energy (30.19 kcal/mol) formed by LP (2) O24 to anti-bonding σ*(C18-C19) was confirmed by the NBO study. The localized and delocalized electrons were confirmed by ELF and LOL studies. The hydrogen bond interaction as well as the physical and chemical properties of CS6 indicated that it showed a moderate similarity to the drugs. The docking study confirmed that the dehydro-L-gulonate decarboxylase inhibitor (1Q6O) could interact with CS6 compound with the binding energy of −5.26 kcal/mol. Communicated by Ramaswamy H. Sarma

Determining flavonoids in the skin of Citrus reticulata

n this work we studied the flavonoid composition of tangerine skins using 10 kinds of tangerines from various producers. The tangerine skins were peeled from fruit purchased from the market in Belgorod and dried at room temperature outside direct sunlight. The compositions of “green” ethanol-based extraction solutions and the “weighed portion of plant material: volume of extraction solution” ratios were chosen for extraction to ensure a high yield of flavonoids. For separation, reverse-phase HPLC on the Kromasil 100-5C18 stationary phase was used in environmentally friendly mobile phase compositions that contained ethanol as an organic modifier. In gradient elution mode all mobile phases contained 0.2 vol. % orthophosphoric acid. To assign extract components, we used samples of a number of substances and parameters of electronic absorption spectra in comparison with published data. It was found that the chromatographic profiles of the extracts of the studied samples were noticeably different. A number of the least lipophilic compounds, derivatives of cinnamic acids, were found in all extracts. After that, we discovered two flavanone glycosides, the main of which was hesperidin (hesperitin-7-rutinoside) with a content of is 26.0-39.9 mg per 1 g of dried raw material, and naringin (naringenin-7-neohesperidiside) in significantly smaller quantities, from 0 to 1.15 mg per 1 g. But of greatest interest were polymethoxylated flavones, among which the main component was nobiletin (5,6,7,8,3′,4′-hexamethoxyflavone) with a content from 0.03 to almost 11 mg/g in dried peel and tangeretin (5,6,7,8,4′-pentamethoxyflavone), found in slightly smaller quantities, 0.1-5.4 mg/g. It was established that nobiletin and tangeretin were mostly accumulated in the skins of small tangerines. On the whole, tangerine skin is a great source of highly biologically active flavonoids, so its processing is an important task for the food industry.

New nanometric metal complexes based on thiazole derivative as potential antitumor and antimicrobial agents: Full structural elucidation, docking simulation and biological activity studies

Novel Mn(II), Ni(II), Zr(IV) and Cd(II) nanosized complexes of thiazole Schiff base derivative (HL) were synthesized for further medicinal applications. The inspected complexes were fully characterized using elemental and thermal analyses in addition to infrared spectroscopy (IR) and nuclear magnetic resonance (1HNMR). Electronic absorption spectra, X-ray powder diffraction (XRD), transmittance electron microscopy (TEM), molar conductance and magnetic moment were also measured and explained. The brought about data revealed that the ligand–metal chelation happened through the N atom of N = N group, and the ortho-dehydrogenated phenolic O atom to form the chelates where the metal binds with one molecule of the parent ligand. All applied spectroscopic and analytical techniques confirmed tetrahedral geometry in Mn(II) and Ni(II) complexes and octahedral geometry for Cd(II) and Zr(IV) complexes. The ligand, Mn(II), Ni(II), and Zr(IV) chelates' XRD patterns indicated an amorphous character where the Cd(II) complex's nature is crystalline. Transmission electron microscopy (TEM) images of the prepared compounds showed that the surface morphology is uniform and homogeneous. Also, the metal ions distribute through the complexes' surface in a nanosized nature. The metal complexes have been simulated by docking in the co-crystal structures of the liver cancer and breast cancer proteins with PDB IDs, 2JW2 and 3S7S, successively. Antibacterial, antifungal and anticancer activities for the ligand that has been produced and its complexes were achieved. The most encouraging antitumor results were acquired by Ni(II) chelate which exhibited an IC50 of 23.52 µg/ml contra MCF-7 cells (human breast cancer) which is lower than the reference 5-Fluorouracil (5-FU, IC50 = 28.00 µg/ml).

Lanthanide furoate complexes as promising systems with double effects – From suppression of mycobacteria to potential bioimaging

Several ternary complexes of rare earth ions (Gd3+, Eu3+, Sm3+) with 3-furoic (H3fur) / 5-nitro-2-furoic (Hnfur) acids and 1,10-phenanthroline (phen) have been synthesized. According to the X-ray data the resulting complexes can be divided into two groups − heterocarboxylate [Ln2(3fur)4(OAc)2(phen)2]·L and homocarboxylate complexes [Ln2(nfur)6(phen)2]·L (LnIII = Gd (1, 2), Eu (3, 4), Sm (5, 6, 7); L = 4EtOH (1–4), 4MeOH (5), H2O (7)). The stability of the complexes 1–6 in solutions was studied by recording electronic absorption spectra for two days. Optical properties of the complexes 1–6 were studied by recording absorption, excitation and luminescence spectra. The study of antibacterial properties 1–7 showed high activity of complexes in vitro against non-pathogenic Mycolicibacterium smegmatis. For the most active 3, antibacterial activity against the reference strain Mycobacterium tuberculosis H37Rv was determined (minimum inhibitory concentration (MIC) up to 12.5 μg/mL)..

Exploring the weak visible-near-infrared and NO2 detection capabilities of PbS/Sb2O5 heterostructures with DFT interpretations

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.

Design, synthesize, physicochemical characterization, nonlinear optical properties structural elucidation, biomedical studies, and DNA interaction of some new mixed ligand complexes incorporating 4,6‐dimethylpyrimidine derivative and imidazole ligand

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.

Absorption spectra of p-nitroaniline derivatives: charge transfer effects and the role of substituents.

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. 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.

A new class of hexadentate thioether-containing ligands and their complexes with nickel(II)

A new series of hexadentate thioether-containing ligands was designed. Five nickel(II) dicationic pseudo-octahedral complexes synthesised with them revealed different degrees of deviation from ideal geometry. The electronic absorption spectra confirm the formation of high-spin octahedral [NiN4S2]2+chromophores with a large covalency typical for Ni(II) thioether complexes. DFT calculations help assign the chelating agent transitions, and support the Ni(II) high-spin ground state assignments, while suggesting that the SOMOs have mainly ligand character. The electrochemical behaviour of the complexes is consistent with irreversible n = 1 redox processes around −1.0 V, formally assignable to the Ni(II)/Ni(I) couple. Ligand reduction and large current augmentation due to catalytic H2production are also observed in this region.

The influence of reed nanocellulose on the quality indicators of paper-basis for wallpapers

Improving the production technology of products with improved quality indicators and with less impact on the environment remains an urgent scientific and practical problem of paper industry enterprises. This refers to the technology for the production of paper-bases for wallpaper using environmentally safe chemical additives, in particular nanocellulose (NC), which was obtained by acid hydrolysis from reed cellulose. The production of cellulose was carried out in two stages - extraction from reed stalks with a solution of alkali and an organosolvent method of cooking in a solution of peracetic acid. The obtained organosolvent cellulose contained the remains of lignin and mineral substances, which allows it to be used for the preparation of NC. As a result of the hydrolysis of organosolvent cellulose, a time-stable NC suspension was extracted, the properties of which were investigated by scanning electron microscopy (morphological changes in the structure of reed cellulose-containing materials), atomic force microscopy (determination of topographic characteristics of NC), analysis of electronic absorption spectra (transparency of NC films). It was established that reed NC films had nanoparticles with a cross-sectional size of 5-25 nm, density up to 1.52 g/cm3, transparency up to 81.6 %, tensile strength up to 65 MPa. For the production of castings of paper-bases for wallpaper samples, sulfated pine bleached cellulose and polyester synthetic fiber were used, to the fibrous mass of which were added the following chemical additives: alkyl ketene dimer, reed NC, binder, and optical brightener. It has been shown that the use of nanocellulose at a rate of 0.35 % to 1.0 % of the paper mass leads to a significant improvement in the physical and mechanical quality indicators of the paper base for wallpaper. It was established that the replacement of 50 % of the synthetic chemical auxiliary substance alkyl ketene dimer with nanocellulose or additional application of nanocellulose at a rate of 0.5 g/m2 on the surface of the casting with 0.7 % alkyl ketene dimer allows to obtain paper that meets the requirements of the standard. The obtained results indicate the prospects of using reed nanocellulose for the production of other mass types of paper and cardboard.

Enhanced reactivity and selective adsorption: Unveiling the potential of metal-decorated graphene membranes for biosensing

This study investigates the structural, stability, electronic, and optical properties of finite graphene membranes through a comprehensive computational analysis. The 2D membranes are constructed from hexagonal graphene quantum dots and are decorated with Co, Mn, and Ni. Stability assessments, based on binding energies, affirm the stable formation of the 2D membrane and its derivatives. Electronic investigations reveal a reduction in the energy gap upon metal decoration, indicating enhanced reactivity. Membrane studies demonstrate effective adsorption of creatinine and uric acid on both edge and surface sites, supported by negative adsorption energies. Electronic transitions and absorption spectra shifts indicate dynamic interactions, emphasizing the materials' potential for selective molecular separation. Non-covalent interaction analysis confirmed the role of van der Waals interactions in creatinine and uric acid adsorption. Overall, the findings suggest that the graphene membrane and its decorated derivatives hold promise for selective adsorption applications, especially in the context of biosensing.