RESUMEN

A new three-dimensional (3D) coordination polymer, namely, poly[diaqua[µ5-2,2'-(1,3,5,7-tetraoxo-1,2,3,5,6,7-hexahydropyrrolo[3,4-f]isoindole-2,6-diyl)diacetato]barium(II)], [Ba(C14H6N2O8)(H2O)2]n, (I), has been synthesized by the microwave-irradiated reaction of Ba(NO3)2 with N,N'-bis(glycinyl)pyromellitic diimide {BGPD, namely, 2,2'-(1,3,5,7-tetraoxo-1,2,3,5,6,7-hexahydropyrrolo[3,4-f]isoindole-2,6-diyl)diacetatic acid, H2L}. The title compound was structurally characterized by single-crystal X-ray diffraction analysis and powder X-ray diffraction analysis, as well as IR spectroscopy. In the crystal structure of (I), the BaII ion is nine-coordinated by six carboxylate O atoms from five symmetry-related L2- dianions and one imide O atom, as well as two water O atoms. The coordination geometry of the central BaII ion can be described as a spherical capped square antiprism. One carboxylate group of the ligand serves as a µ3-bridge linking the BaII cations into a one-dimensional polynuclear secondary building unit (SBU). Another carboxylate group of the ligand acts as a µ2-bridge connecting the 1D SBUs, thereby forming a two-dimensional (2D) SBU. The resulting 2D SBUs are extended into a 3D framework via the pyromellitic diimide moiety of the ligand as a spacer. The 3D Ba framework can be simplified as a 5-connected hexagonal boron nitride net (bnn) topology. The intermolecular interactions in the 3D framework were further investigated by Hirshfeld surface analysis and the results show that the prominent interactions are H...O (45.1%), Ba...O (11.1%) and C...H (11.1%), as well as H...H (11.1%) contacts. The thermal stability, photoluminescence properties and UV-Vis absorption spectra of (I) were also investigated. The coordination polymer exhibits a fluorescence emission with a quantum yield of 0.071 and high thermal stability.

RESUMEN

Two new two-dimensional (2D) coordination polymers (CPs), namely, poly[diaqua[µ4-2,2'-(1,3,5,7-tetraoxo-1,2,3,5,6,7-hexahydropyrrolo[3,4-f]isoindole-2,6-diyl)diacetato-κ4O:O':O'':O''']cadmium(II)], [Cd(C14H6N2O8)(H2O)2]n (1), and poly[[tetraaqua[µ4-2,2'-(1,3,5,7-tetraoxo-1,2,3,5,6,7-hexahydropyrrolo[3,4-f]isoindole-2,6-diyl)diacetato-κ4O:O':O'':O'''][µ2-2,2'-(1,3,5,7-tetraoxo-1,2,3,5,6,7-hexahydropyrrolo[3,4-f]isoindole-2,6-diyl)diacetato-κ2O:O']dizinc(II)] dihydrate], {[Zn(C14H6N2O8(H2O)2]·H2O}n (2), have been synthesized by the microwave-irradiated reaction of Cd(CH3COO)2·2H2O and Zn(CH3COO)2·2H2O, respectively, with N,N'-bis(glycinyl)pyromellitic diimide {BGPD, namely, 2,2'-(1,3,5,7-tetraoxo-1,2,3,5,6,7-hexahydropyrrolo[3,4-f]isoindole-2,6-diyl)diacetic acid, H2L}. In the crystal structure of 1, the CdII ion is six-coordinated by four carboxylate O atoms from four symmetry-related L2- dianions and two coordinated water molecules, furnishing an octahedral coordination geometry. The bridging L2- dianion links four symmetry-related CdII cations into a 2D layer-like structure with a 3,4-connected bex topology. In the crystal structure of 2, the ZnII ion is five-coordinated by three carboxylate O atoms from three different L2- dianions and two coordination water molecules, furnishing a trigonal bipyramidal coordination geometry. Two crystallographically independent ligands serve as µ4- and µ2-bridges, respectively, to connect the ZnII ions, thereby forming a 2D layer with a 3,3-connected hcb topology. Crystal structure analysis reveals the presence of n→π* interactions between two carbonyl groups of the pyromellitic diimide moieties in 1 and 2. CP 1 exhibits an enhanced fluorescence emission compared with free H2L. The framework of 2 decomposes from 720 K, indicating its high thermal stability. A comparative analysis of a series of structures based on the BGPD ligand indicates that the metal-ion size has a great influence on the connection modes of the metal ions due to different steric effects, which, in turn, affects the structures of the SBUs (secondary building units) and frameworks.

RESUMEN

Among azobenzene derivatives, azothiophenes represent a relatively recent family of compounds that exhibit similar characteristics as dyes and photoreactive systems. Their technological applications are extensive thanks to the additional design flexibility conferred by the heteroaromatic ring. In this study, we present a comprehensive investigation of the structural and electronic properties of novel dyes derived from 3-thiophenamine, utilizing a multilevel approach. We thoroughly examined the potential energy surfaces of the E and Z isomers for three molecules, each bearing different substituents on the phenyl ring at the para position relative to the diazo group. This exploration was conducted through quantum chemistry calculations at various levels of theory, employing a continuum solvent model. Subsequently, we incorporated an explicit solvent (a dimethyl sulfoxide-water mixture) to simulate the most stable isomers using classical molecular dynamics, delivering a clear picture of the local solvation structure and intermolecular interactions. Finally, a hybrid quantum mechanics/molecular mechanics (QM/MM) approach was employed to accurately describe the evolution of the solutes' properties within their environment, accounting for finite temperature effects.

RESUMEN

Novel anticancer strategies reduce side effects on healthy tissues by elevating the lethal abilities of cancer cells. The development of effective particles with good bioavailability and selectivity remains problematic. For undesirable features, green chemistry is used to synthesize the best compounds, or natural-based particles are improved. Photodynamic therapy (PDT), modelled on phthalocyanines (Pcs), still delivers second-generation sensitizers which are complemented with metal ions, such as Zn2+, Al3+, or Ga3+. Gallium octacarboxyphthalocyanine hydroxide (Ga(OH)PcOC), was designed for skin cancer treatment, and was used as a pro-apoptotic and pro-oxidative agent on normal skin cell lines, fibroblasts (NHDF), and keratinocytes (HaCaT), with promising selectivity against melanoma cancer cells (Me45) in vitro. Compared to the previous reported findings, where the ZnPcOC acted on the skin cell lines at higher doses, the sensitivities to the Ga(OH)PcOC allows for an effective reduction of the sensitizer dose. The effective dose, for a novel Ga(OH)PcOC particle, was significantly reduced from 30 µM to 6 µM on Me45 cancer cells, tested using 24 h MTT viability, as well as cytometric pro-oxidative and pro-apoptotic assays. The promising photosensitizer did not reduce viability in normal fibroblasts and keratinocytes without reactive oxygen species (ROS) elevation or apoptosis induction. The improvement to the previous findings is better Ga-based photosensitizer selectivity against the cancer Me45 cells, then observed in Zn-based compounds.

Asunto(s)

Antineoplásicos , Apoptosis , Ensayos de Selección de Medicamentos Antitumorales , Galio , Indoles , Fármacos Fotosensibilizantes , Neoplasias Cutáneas , Humanos , Apoptosis/efectos de los fármacos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/síntesis química , Neoplasias Cutáneas/tratamiento farmacológico , Neoplasias Cutáneas/patología , Galio/química , Galio/farmacología , Estructura Molecular , Indoles/química , Indoles/farmacología , Indoles/síntesis química , Isoindoles/farmacología , Isoindoles/química , Isoindoles/síntesis química , Fotoquimioterapia , Relación Dosis-Respuesta a Droga , Supervivencia Celular/efectos de los fármacos , Relación Estructura-Actividad , Proliferación Celular/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Hidróxidos/química , Hidróxidos/farmacología

RESUMEN

CONTEXT: This work analyzes the isomerization effects and solvent contributions to the stability, electronic excitations, reactivity, and non-linear optical properties (NLO) of resveratrol molecules within the formalism of the Density Functional Theory. The findings suggest that resveratrol solvatochromism is significantly influenced by solvent polarization. The electronic and free energies (E and G) indicate that trans is the most stable conformer. The system is classified as a strong nucleophile. However, the analysis of the Fukui functions and the Mulliken charges indicate that cis-trans isomerization jointly affects the reactive indices of the carbon and hydrogen atoms. The results also suggest that solvent is relevant to solvatochromism and the NLO response. Both cis and trans conformers present strong π - π ∗ excitations that undergo a visible hypsochromic change when the polarity of the solvent increases. Once the absorption spectra are connected to the first hyperpolarization ( ß ) by the Oudar and Chemla relation, the hypsochromism of resveratrol is the reason for the drop in the generation of the second harmonic when the ambient polarity decreases. The CAM-B3LYP DFT results suggest that resveratrol is interesting for NLO applications. Depending on the choice of solvent, values ∼ 50 times those observed for urea ( ß = 0.34 × 10 - 34 esu), which is a standard NLO material. METHODS: The optimized geometries of cis and trans isomers of resveratrol in vacuum were obtained using Density Functional Theory (DFT) with the hybrid exchange-correlation function (CAM-B3LYP) and Pople basis set functions, specifically 6-311++G(d,p). The solvent effect on the geometries of both isomers was included using the polarizable continuum model (PCM) with the same level of QM calculation. Vibrational analysis was conducted to confirm that all optimized geometries correspond to the minimum energy. Various electronic properties, including dipole moments, molecular orbitals, transition energy, dipole polarizabilities, and global reactivity parameters, were calculated using both continuum and discrete solvation models based on the sequential QM/MM methodology. All QM calculations were performed with the Gaussian 09 program and the MC simulations with the DICE program. All NLO analysis was carried out using the Multiwfn code.

RESUMEN

Human cytochrome P450 CYP17A1 catalyzes the hydroxylation of pregnenolone and progesterone at the C17 position, with subsequent C17-C20 bond scission, to form dehydroepiandrosterone and androstenedione respectively. The first hydroxylation reaction is faster in H2O than in D2O, while the second carbon­carbon bond scission event demonstrates an inverse solvent isotope effect, which is more pronounced for 17-hydroxy pregnenolone. In order to better understand the cause of this difference, we compared the optical absorption spectra of oxygenated CYP17A1 with the four substrates (pregnenolone, progesterone, 17-hydroxy pregnenolone and 17-hydroxy progesterone) in both H2O and D2O. We also studied the temperature-dependent decay of the peroxo-ferric and hydroperoxo-ferric intermediates generated by cryoradiolysis of the corresponding oxygenated heme proteins at 77 K. For both pregnenolone and 17-hydroxypregnenolone, annealing of the peroxo-intermediates was observed at lower temperatures in H2O than in D2O. In contrast, no solvent isotope effect was detected when progesterone or 17-hydroxyprogesterone were used as substrates. These differences are attributed to their different positioning in the P450 active site with respect to the heme bound peroxo (Fe-OO-) moiety, which is in agreement with earlier structural and spectroscopic investigations. Analysis of the samples run in both H2O and in D2O, where 17-hydroxyprogesterone is the substrate, demonstrated significant (∼25%) yield of androstenedione product relative to the oxygenated starting material.

Asunto(s)

Pregnenolona , Esteroide 17-alfa-Hidroxilasa , Esteroide 17-alfa-Hidroxilasa/metabolismo , Esteroide 17-alfa-Hidroxilasa/química , Humanos , Pregnenolona/química , Pregnenolona/metabolismo , Progesterona/química , Progesterona/metabolismo , Óxido de Deuterio/química , Hidroxilación

RESUMEN

The UV-Vis spectrum of the solvated purine derivative Hypoxanthine (HYX) is investigated using the Quantum Mechanics/Fluctuating Charges (QM/FQ) multiscale approach combined with a sampling of configurations through atomistic Molecular Dynamics (MD) simulations. Keto 1H7H and 1H9H tautomeric forms of HYX are the most stable in aqueous solution and form different stable complexes with the surrounding water molecules, ultimately affecting the electronic absorption spectra. The final simulated spectrum resulting from the combination of the individual spectra of tautomers agrees very well with most of the characteristics in the measured spectrum. The importance of considering the effect of the solute tautomers and, in parallel, the contribution of the different solvent arrangements around the solute when modeling spectral properties, is highlighted. In addition, the high quality of the computed spectra leads to suggesting an alternative way for acquiring tautomeric populations from combined computational/experimental spectra.

RESUMEN

Pyridoxal and pyridoxal 5'-phosphate are aldehyde forms of B6 vitamin that can easily be transformed into each other in the living organism. The presence of a phosphate group, however, provides the related compounds (e.g., hydrazones) with better solubility in water. In addition, the phosphate group may sometimes act as a binding center for metal ions. In particular, a phosphate group can be a strong ligand for a gold(III) ion, which is of interest for researchers for the anti-tumor and antimicrobial potential of gold(III). This paper aims to answer whether the phosphate group is involved in the complex formation between gold(III) and hydrazones derived from pyridoxal 5'-phosphate. The answer is negative, since the comparison of the stability constants determined for the gold(III) complexes with pyridoxal- and pyridoxal 5'-phosphate-derived hydrazones showed a negligible difference. In addition, quantum chemical calculations confirmed that the preferential coordination of two series of phosphorylated and non-phosphorylated hydrazones to gold(III) ion is similar. The preferential protonation modes for the gold(III) complexes were also determined using experimental and calculated data.

Asunto(s)

Oro , Hidrazonas , Piridoxal , Hidrazonas/química , Oro/química , Piridoxal/química , Fosfato de Piridoxal/química , Complejos de Coordinación/química , Espectrofotometría Ultravioleta , Estructura Molecular

RESUMEN

The present study investigates the potential of a new compound containing sulfonamide and 4(3H)-quinazolinone to inhibit the hCA-IIX enzyme using in silico methods. Density functional theory-based calculations of electronic properties have been addressed through the analysis of frontier molecular orbitals, molecule electrostatic potential, and IR and UV-vis spectroscopy data. A molecular electrostatic potential analysis predicts that the target protein will be most inhibited by the sulfonamide groups since it has the highest potential spots for electrophile and nucleophile attack. The investigated compound exhibited good ADMET properties and satisfied the Lipinski rule of drug likeness. The hCA-IIX protein binding affinity with the proposed compound was determined by molecular docking analysis, which revealed a stable conformation with more negative binding energy (-12.19 kcal/mol) than the standard AZA drug (-7.36 kcal/mol). Moreover, a molecular dynamics study confirmed the docking results through trajectory analysis. The RMSD and RMSF both showed convergence and no significant fluctuations during the simulation time, which revealed a stable interaction within the active domain of the target protein. According to these findings, the proposed compound has a good pharmacological nature and could potentially be an efficient drug against hCAIX enzymes.

RESUMEN

Based on density functional theory (DFT) and wave function analysis, the ultraviolet and visible spectrophotometry (UV-Vis) spectra and Raman spectra of 1-meso and 1-rac obtained by the chiral separation of chiral nanographenes are theoretically investigated. The electron excitation properties of 1-meso and 1-rac are studied by means of transition density matrix (TDM) and charge density difference (CDD) diagrams. The intermolecular interaction is discussed based on an independent gradient model based on Hirshfeld partition (IGMH). The interaction of 1-meso and 1-rac with the external environment is studied using the electrostatic potential (ESP), and the electron delocalization degree of 1-meso and 1-rac is studied based on the magnetically induced current under the external magnetic field. Through the chiral separation of 1-rac, two enantiomers, 1-(P, P) and 1-(M, M), were obtained. The electrical-magnetic interaction of the molecule is revealed by analyzing the electron circular dichroism (ECD) spectra of 1-meso, 1-(P, P) and 1-(M, M), the transition electric dipole moment (TEDM) and the transition magnetic dipole moment (TMDM). It is found that 1-(P, P) and 1-(M, M) have opposite chiral properties due to the inversion of the structure.

RESUMEN

CONTEXT: Quantum mechanical calculations involving electron correlation, frequency dispersion, and solvent effects were carried out to examine the second-order nonlinear optical response of various acceptor, X (-CF3, -CN, -NO2) substituted in N,N-dimethylaniline (DMA) and julolidine(JLD). Here, both DMA and JLD acts as donor and the three substituted groups, X (-CF3, -CN and -NO2) at the para position of both the ring systems as acceptor. The NLO response (ßHRS) of -CF3 and -CN substituted DMA and JLD is relatively lower compared to DMA-NO2 and JLD-NO2. The charge distribution is found higher in case of -NO2 substituted DMA and JLD (±443 and ±449) compared to their -CF3 or -CN substitution. Electronic characteristics such as UV-Vis absorption spectra, crucial excited state parameters and charge transfer contribution to ßHRS have been used to explain the NLO parameter of DMA-X and JLD-X. Variation of the incident optical frequency of light shows fluctuation of ßHRS value and highest values of ßHRS are obtain at the λmax frequency of each compound. Solvent polarity variation study on ßHRS shows that ßHRS varies linearly with the Kirkwood-Onsagar dielectric factor (D). METHODS: All computational studies have been carried out using density functional theory (DFT) based method. Since CAM-B3LYP based hybrid functional improves the asymptotic behavior of the exchange interaction by dividing into short-range and long-range components, first hyperpolarizability values in the present study were computed using DFT/ CAM-B3LYP/ 6-31G+(d,p) level of theory.

RESUMEN

This paper studies the influence of B2O3 on the structure, properties and antibacterial abilities of sol-gel-derived TiO2/TeO2/B2O3 powders. Titanium(IV) butoxide, telluric(VI) acid and boric acid were used as precursors. Differences were observed in the degree of decomposition of Ti butoxide in the presence of H3BO3 and H6TeO6 acids. The phase transformations of the obtained gels in the temperature range of 200-700 °C were investigated by XRD. Composite materials containing an amorphous phase and different crystalline phases (metallic Te, α-TeO2, anatase, rutile and TiTe3O8) were prepared. Heating at 400 °C indicated a crystalline-to-amorphous-phase ratio of approximately 3:1. The scanning electron microscopy (SEM) analysis showed the preparation of plate-like TiO2 nanoparticles. The IR results showed that the short-range order of the amorphous phases that are part of the composite materials consists of TiO6, BO3, BO4 and TeO4 structural units. Free B2O3 was not detected in the investigated compositions which could be related to the better connectivity between the building units as compared to binary TiO2/B2O3 compositions. The UV-Vis spectra of the investigated gels exhibited a red shift of the cut-off due to the presence of boron and tellurium units. The binary sample achieved the maximum photodegradation efficiency (94%) toward Malachite green dye under UV irradiation, whereas the ternary sample photoactivity was very low. The compositions exhibited promising antibacterial activity against E. coli NBIMCC K12 407.

RESUMEN

Proteins in tears, including human lactoferrin (HLF), can be deposited and denatured on contact lenses, increasing the risk of microbial cell attachment to the lens and ocular complications. The surfactants currently used in commercial contact lens care solutions have low clearance ability for tear proteins. Chitosan oligosaccharide (COS) binds to a variety of proteins and has potential for use in protein removal, especially in contact lens care solutions. Here, we analyzed the interaction mechanism of COSs hydrolyzed from chitosan from different resources with HLF. The molecular weights (MWs) and concentrations of COSs were key factors for the formation of COS-HLF complexes. Lower MWs of COSs could form more stable COS-HLF complexes. COS from Aspergillus ochraceus had a superior effect on HLF compared with COS from shrimp and crab shell with the same MWs. In conclusion, COSs could bind to and cause a conformational change in HLF. Therefore, COSs, especially those with low MWs, have potential as deproteinizing agents in contact lens care solution.

Asunto(s)

Quitosano , Lactoferrina , Humanos , Lactoferrina/metabolismo , Quitosano/metabolismo , Peso Molecular , Oligosacáridos

RESUMEN

Structural, conformational, and spectroscopic investigations of methyl-eugenol were made theoretically at the B3LYP-6-311++G**level. Experimental IR, Raman, and UV-vis spectra were investigated and analyzed in light of the computed quantities. Conformational analysis was carried out with the help of total energy vs. dihedral angle curves for different tops, yielding 21 stable conformers, out of which only two have energies below the room temperature relative to the lowest energy conformer. The effect of the solvent on different molecular characteristics was investigated theoretically. MEP and HOMO-LUMO analysis were carried out and barrier heights and bioactivity scores were determined. The present investigation suggests that the molecule has three active sites with moderate bioactivity. The solvent-solute interaction is found to be dominant in the vicinity of the methoxy moieties.

RESUMEN

Water-insoluble organic UV filters like tris-biphenyl-triazine (TBPT) can be prepared as aqueous dispersions of nanoparticles. The particles consist of the respective UV absorber molecules and show strong UV absorbance. Since there is a certain solubility of such UV absorbers in organic solvents, it is possible to measure the absorbance spectrum also in solution, for instance in ethanol or dioxane. The UV spectrum of the aqueous dispersion shows a slight hypsochromic shift of the original band with an additional shoulder at longer wavelengths. For the understanding of the observed changes of UV-Vis spectra of this UV absorber, either dissolved in an organic solvent or dispersed as nanoparticles in water, DFT calculations were carried out with the respective monomer and aggregates of TBPT molecules in the different media. The calculated UV-Vis spectra of isolated, that means dissolved, TBPT molecules in ethanol and in dioxane agree well with experimentally observed ones. The observed changes in the shape of experimental UV-Vis spectra in aqueous dispersion cannot be explained with a solvent effect only. It was found that the studied molecules could form stable energetically favorable π-stacked aggregates, which show UV-Vis spectra in reasonable agreement with those experimentally observed in aqueous dispersion. Such aggregates of TBPT are most likely the reason for the observed additional shoulder in the UV/vis absorbance spectrum. In addition, the mechanism of the photochemical deactivation of excited TBPT molecules was studied in detail with TD DFT in dioxane and in water.

RESUMEN

Gold(III) complexes with different ligands can provide researchers with a measure against pathogenic microorganisms with antibiotic resistance. We reported in our previous paper that the UV-Vis spectra of different protonated species of complexes formed by gold(III) and five hydrazones derived from pyridoxal 5'-phosphate are similar to each other and to the spectra of free protonated hydrazones. The present paper focuses on the reasons of the noted similarity in electron absorption spectra. The geometry of different protonated species of complexes of gold(III) and hydrazones (15 structures in total) was optimized using the density functional theory (DFT). The coordination polyhedron of gold(III) bond critical points were further studied to identify the symmetry of the gold coordination sphere and the type of interactions that hold the complex together. The UV-Vis spectra were calculated using TD DFT methods. The molecular orbitals were analyzed to interpret the calculated spectra.

Asunto(s)

Oro , Hidrazonas , Hidrazonas/química , Fosfatos , Piridoxal

RESUMEN

Benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) (isoBBT) is a new electron-withdrawing building block that can be used to obtain potentially interesting compounds for the synthesis of OLEDs and organic solar cells components. The electronic structure and delocalization in benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole), 4-bromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole), and 4,8-dibromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) were studied using X-ray diffraction analysis and ab initio calculations by EDDB and GIMIC methods and were compared to the corresponding properties of benzo[1,2-c:4,5-c']bis[1,2,5]thiadiazole (BBT). Calculations at a high level of theory showed that the electron affinity, which determines electron deficiency, of isoBBT was significantly smaller than that of BBT (1.09 vs. 1.90 eV). Incorporation of bromine atoms improves the electrical deficiency of bromobenzo-bis-thiadiazoles nearly without affecting aromaticity, which increases the reactivity of these compounds in aromatic nucleophilic substitution reactions and, on the other hand, does not reduce the ability to undergo cross-coupling reactions. 4-Bromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) is an attractive object for the synthesis of monosubstituted isoBBT compounds. The goal to find conditions for the selective substitution of hydrogen or bromine atoms at position 4 in order to obtain compounds containing a (het)aryl group in this position and to use the remaining unsubstituted hydrogen or bromine atoms to obtain unsymmetrically substituted isoBBT derivatives, potentially interesting compounds for organic photovoltaic components, was not set before. Nucleophilic aromatic and cross-coupling reactions, along with palladium-catalyzed C-H direct arylation reactions for 4-bromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole), were studied and selective conditions for the synthesis of monoarylated derivatives were found. The observed features of the structure and reactivity of isoBBT derivatives may be useful for building organic semiconductor-based devices.

Asunto(s)

Tiadiazoles , Estructura Molecular , Tiadiazoles/química , Bromo , Cristalografía por Rayos X , Hidrógeno

RESUMEN

New high-level ab initio quartic force field (QFF) methods are explored which provide spectroscopic data for the electronically excited states of the carbon monoxide, water, and formaldehyde cations, sentinel species for expanded, recent cometary spectral analysis. QFFs based on equation-of-motion ionization potential (EOM-IP) with a complete basis set extrapolation and core correlation corrections provide assignment for the fundamental vibrational frequencies of the A˜2B1 and B˜2A1 states of the formaldehyde cation; only three of these frequencies have experimental assignment available. Rotational constants corresponding to these vibrational excitations are also provided for the first time for all electronically excited states of both of these molecules. EOM-IP-CCSDT/CcC computations support tentative re-assignment of the ν1 and ν3 frequencies of the B˜2B2 state of the water cation to approximately 2409.3 cm-1 and 1785.7 cm-1, respectively, due to significant disagreement between experimental assignment and all levels of theory computed herein, as well as work by previous authors. The EOM-IP-CCSDT/CcC QFF achieves agreement to within 12 cm-1 for the fundamental vibrational frequencies of the electronic ground state of the water cation compared to experimental values and to the high-level theoretical benchmarks for variationally-accessible states. Less costly EOM-IP based approaches are also explored using approximate triples coupled cluster methods, as well as electronically excited state QFFs based on EOM-CC3 and the previous (T)+EOM approach. The novel data, including vibrationally corrected rotational constants for all states studied herein, provided by these computations should be useful in clarifying comet evolution or other remote sensing applications in addition to fundamental spectroscopy.

Asunto(s)

Monóxido de Carbono , Agua , Teoría Cuántica , Formaldehído , Cationes/química

RESUMEN

The degradation process of diclofenac (DCF) by hematoprotein myeloperoxidase (MPO) and iron octacarboxyphthalocyanine (FePcOC) in the presence of hydrogen peroxide was compared. During the oxidation of diclofenac, in the presence of iron octacarboxyphthalocyanine (FePcOC) and hydroxyl radicals (HO•) (from H2O2), an intermediate product (dimer with an m/z value of 587) with the characteristic yellow colouration and an intense band at λmax = 451 nm is formed. Iron octacarboxyphthalocyanine oxidises in the presence of hydrogen peroxide, following the first-order reaction kinetics for FePcOC and H2O2. The concentration of diclofenac does not affect the initial reaction rate. For comparison, the oxidation of DCF in the presence of myeloperoxidase and hydrogen peroxide also provided yellow-coloured solutions with an absorption maximum at λmax = 451 nm. However, LC-MS/MS analysis indicates the presence of at least seven main products of the diclofenac oxidation process in the final reaction mixture, including two dimers with the ion mass [M-H]¯ = 587.01. The mechanism of the diclofenac degradation with hematoprotein myeloperoxidase is more complex than with iron octacarboxyphthalocyanine. Furthermore, the biological activity of diclofenac and DCF dimer (iron octacarboxyphthalocyanine and hydroxyl radicals degradation product) was tested. In this case, the long-term assayed in vitro against E. coli, colorectal HCT116 and melanoma Me45 cancer cells were performed.

Asunto(s)

Diclofenaco , Peroxidasa , Cromatografía Liquida , Escherichia coli , Peróxido de Hidrógeno , Radical Hidroxilo , Hierro , Polímeros , Espectrometría de Masas en Tándem

RESUMEN

This study presents the degradation of rhodamine B (RhB) by photo Fenton-like (PF-like) process under visible light irradiation (λ > 380 nm) using cobalt phosphate microparticles (CoP-MPs). The effects of the initial concentration of RhB, pH value, CoP-MPs dosage, hydrogen peroxide (H2O2) concentration, and salts found in textile wastewater (such as NaNO3, Na2SO4, and NaCl) were investigated in detail. It was found that CoP-MPs can maintain high catalytic activity with wide pH values varying from 4 to 8. This indicated that the use of CoP-MPs overcame the low efficiency of Fenton-like reaction at neutral and even weakly alkaline pH. The PF-like degradation of RhB followed pseudo-first order kinetics in various conditions. Moreover, a comparison of experimental results showed that the PF-like system has good degradation ability for RhB and methyl blue (MB) solution, but is poor for methyl orange (MO) solution. The repeat experiments indicated that the chemical structures of CoP-MPs were stable. Furthermore, the Co2+ ions leaching to the solutions were measured by an inductively coupled plasma mass spectrometer (ICP-MS). Analysis of UV-vis spectra suggested that RhB was degraded by the formation of a series of N-de-ethylated intermediates followed by cleavage of the whole conjugate chromophore structure.HighlightsRhB can be effectively degraded in the PF-like process under visible light irradiation by CoP-MPs.The PF-like process can maintain high catalytic activity at neutral and even weakly alkaline pH.Degradation kinetics exhibited pseudo-first-order kinetics and were influenced by the key parameters.The variation in the UV-vis spectra of RhB was analyzed in detail to infer a possible degradation pathway.

Asunto(s)

Peróxido de Hidrógeno , Hierro , Peróxido de Hidrógeno/química , Hierro/química , Cinética , Rodaminas/química , Cobalto