DFT Study of the Molecular and Electronic Structure of Metal-Free Tetrabenzoporphyrin and Its Metal Complexes with Zn, Cd, Al, Ga, In

The electronic and molecular structures of metal-free tetrabenzoporphyrin (H2TBP) and its complexes with zinc, cadmium, aluminum, gallium and indium were investigated by density functional theory (DFT) calculations with a def2-TZVP basis set. A geometrical structure of ZnTBP and CdTBP was found to possess D4h symmetry; AlClTBP, GaClTBP and InClTBP were non-planar complexes with C4v symmetry. The molecular structure of H2TBP belonged to the point symmetry group of D2h. According to the results of the natural bond orbital (NBO) analysis, the M-N bonds had a substantial ionic character in the cases of the Zn(II) and Cd(II) complexes, with a noticeably increased covalent contribution for Al(III), Ga(III) and In(III) complexes with an axial –Cl ligand. The lowest excited states were computed with the use of time-dependent density functional theory (TDDFT) calculations. The model electronic absorption spectra indicated a weak influence of the nature of the metal on the Q-band position.

Synthesis, characterization and spectral studies of mononuclear and binuclear Fe(II), Co (II), Ni (II), Zn(II) complexes with 2,4-dinitrophenylhydrazine dithiocarbamate

New complexes of dithiocarbamate of the general formula [M(2,4-dinitrphenhydra - dtc)2], [MM’(2,4-dinithrphenhydra-dtc)4] where: M=Fe (II), Co(II), Ni(II), M’=Zn(II), 2,4- dinitrphenhydra-dtc=2,4- di nitro phenyl hydrazine dithiocarbamate and [M(l,10-phen)3][M’(2,4 – dinitrphenhydra-dtc)4], [M(1,10- phen)3][M’2(2,4-dinitrphenhydra - dtc)6] Where: M=Co(II), Ni(II), M’=Zn(II), (1,10-phen)= 1,10-phenanthroline monohydrate. Have been prepared and characterized by atomic absorption spectroscopy infrared, conductance measurements, electronic absorption spectra, nuclear magnetic resonance and magnetic susceptibility measurements. Magnetic moments and electronic spectra indicate that the complexes of the type [M(2,-dinitrphenhydra-dtc)2], [MM’(2,4-dinitrphenhydra - dtc)4] are of square planner geometry while the complexes of the type [M(1,10-phen)3][M’(2,4-dinitrphenhydra-dtc)4] and [M(1,10 phen)3][M’2(2,4-dinitrphenhydra-dtc)6] have octahedral geometry.

Some Aryl-1,2,4-triazol-1-ium Phenacylids in Binary Hydroxyl Solvent Mixtures. Computational and Spectral Study

Four carbanion monosubstituted p-aryl-1,2,4-triazol-1-ium methylids are subjected to a comparative study between their spectral and quantum-mechanical parameters in order to obtain more information about their structural features in hydroxyl solvents as water and ethanol and also on the nature of electronic absorption transitions from the visible range. The quantum mechanical analysis, made by the Spartan’14 program, established a series of molecular parameters of the studied ylids important for their reactivity and for intermolecular interactions with hydroxyl liquids. An extensive solvatochromic study of 1,2,4-triazol-1-ium ylids is impossible due to their limited solubility in liquids. Binary solvent mixtures of water and ethanol with known solvent parameters from the literature were used for this study. The electronic absorption spectra in binary solvents water and ethanol were used to establish the influence of intermolecular interactions on the spectral characteristics of the studied methylids and also on the composition of their first solvation shell in ternary solutions. The difference between the interaction energies in molecular pairs ylid–water and ylid–ethanol was determined based on the statistical cell model applied to the ternary solutions of the type of ylid + water + ethanol. The obtained values are very small due to the hydroxylic nature of the two solvents.

АССМОТРЕНИЕ ВЛИЯНИЯ САМОАГРЕГИРОВАНИЯ В НАНОРАЗМЕРНЫХ КЛАСТЕРАХ CDS

Quantum dots, such as cadmium sulfide (CdS), are semiconductor nanocrystals that possess unique optical properties, including wide­range excitation, size­tunable narrow emission spectra and high pho­tostability. The size and composition of quantum dots can be varied to obtain the desired emission prop­erties and make them suitable for various optical and biomedical applications. In this article, the effect of self­aggregation on the electronic absorption spectra and on the dipole moment in CdS nanoparticles is considered using computer modeling methods based on the density functional tight­binding (DFTB). The object of the study is four CdS structures and two models of an aggregated dimer for each cluster. The construction of dimers of cadmium sulfide clusters showed that a higher level of passivation can be achieved in comparison with the initial monomers. In this case, the construction of dimers should occur along the direction of the dipole moment of the monomer in order to minimize it. Therefore, it can be assumed that the dipole moment plays a key role in the formation of trap states in nanosized clusters of cadmium sulfide, and the problem of passivation is reduced to minimizing the dipole moment.

Standardization of the Pharmaceutical Substance of the Drug LCS-1208

Introduction. Indolocarbazole derivatives are of increasing scientific interest for practical oncology. A number of N-glycosides, indolo[2,3-a] carbazole under the laboratory code LCS, were synthesized in the laboratory of chemical synthesis of the National Medical Center of Oncology named after N.N. Blokhin. Currently, one of the most promising compounds in this class is LCS-1208, a representative of the arabinoside class of indolo [2,3-a]pyrrolo[3,4-c]carbazole-5,7-dione. According to the mechanism of biological action, LCS-1208 is a protein kinase C inhibitor and is of great interest for the treatment of malignant neoplasms.Aim. chemical and pharmaceutical standardization of the pharmaceutical substance LCS-1208.Materials and methods. Laboratory samples of pharmaceutical substance LCS-1208. Methods of investigation: gravimetry, spectrophotometry, polarimetry, high-performance liquid chromatography (HPLC), high-resolution nuclear magnetic resonance (NMR) spectroscopy and infrared (IR) spectroscopy.Results and discussion. The quality assessment of LCS-1208 was carried out according to the indicators adopted in the XIV edition of the State Pharmacopoeia of the Russian Federation for quality control of pharmaceutical substances. LCS-1208 - orange amorphous powder, odorless; soluble in dimethylsulfoxide (DMSO) and dimethylformamide (DMF); very slightly soluble in 95 % ethyl alcohol and practically insoluble in water. The authenticity of the substance is confirmed by NMR and IR spectra, as well as electronic absorption spectra. The values of the specific optical rotation of LCS-1208 (1 % solution in DMF) are placed in the range from +58° to +61°. All the studied samples of the substance were free of inorganic impurities, sulphate ash, heavy metals and contained no more than 1.0 % water, determined by the K. Fischer titration method. The content of possible related impurities in the substance LCS-1208 and the content of the main active substance were determined by HPLC. The studied laboratory series of the pharmaceutical substance LCS-1208 contained no more than 1.0 % of any single and no more than 3 % of the total unidentified impurities. The content of the main active substance was more than 97 %.Conclusion. As a result of the work carried out, quality criteria and parameters were selected and methods for their determination were developed, which allow to adequately assess the quality and standardness of the pharmaceutical substance LCS-1208.

Distinctly Different Morphologies of Bimetallic Au-Ag Nanostructures and Their Application in Submicromolar SERS-Detection of Free Base Porphyrin

Core-shell Au-Ag nanostructures (Au-AgNSs) are prepared by a seed-meditated growth, i.e., by a two-step process. The synthetic parameters greatly influence the morphologies of the final bimetallic Au-AgNSs, their stability and application potential as surface-enhanced Raman scattering (SERS) substrates. Direct comparison of several types of Au NPs possessing different surface species and serving as seeds in Au-AgNSs synthesis is the main objective of this paper. Borohydride-reduced (with varying stages of borohydride hydrolysis) and citrate-reduced Au NPs were prepared and used as seeds in Au-AgNSs generation. The order of reactants in seed-mediated growth procedure represents another key factor influencing the final Au-AgNSs characteristics. Electronic absorption spectra, dynamic light scattering, zeta potential measurements, energy dispersive spectroscopy and transmission electron microscopy were employed for Au-AgNSs characterization. Subsequently, possibilities and limitations of SERS-detection of unperturbed cationic porphyrin, 5,10,15,20-tetrakis(1-methyl-4-pyridyl)21H,23H-porphine (TMPyP), were investigated by using these Au-AgNSs. Only the free base (unperturbed) SERS spectral form of TMPyP is detected in all types of Au-AgNSs. It reports about a well-developed envelope of organic molecules around each Au-AgNSs which prevents metalation from occuring. TMPyP, attached via ionic interaction, was successfully detected in 10 nM concentration due to Au-AgNSs.

Solvatochromism and halochromism of some furo/pyrazole cyanine dyes

In this study, the electronic absorption spectra of some furo[2,3-b]pyrazole cyanine dyes was recorded and investigated in a number of 6 (six) pure solvents having different polarities [water (78.54), D.M.F (36.70), ethanol (24.3), chloroform (4.806), CC14 (2.238) and dioxane (2.209)], mixed solvents [DMF- H2O] and/or in a series of 8 (eight) aqueous universal buffer solutions having varied pH values [1.65, 2.32, 4.62, 5.85, 6.41, 7.82, 9.61 and 11.63 units] to evaluate their solvatochromic and/or halochromic properties, respectively. The study covers different types of cyanine dyes, it includes monomethine cyanine dyes (simple cyanine dyes), dimethine cyanine dyes and tetramethine cyanine dyes.

Synthesis and biological characterization of a new fluorescent probe for vesicular trafficking based on polyazamacrocycle derivative

The fluorescent probes represent an important tool in the biological study, in fact characterization of cellular structures and organelles are an important tool-target for understanding the mechanisms regulating most biological processes. Recently, a series of polyamino-macrocycles based on 1,4,7,10-tetraazacyclododecane was synthesized, bearing one or two NBD units (AJ2NBD·4HCl) useful as sensors for metal cations and halides able to target and to detect apolar environment, as lipid membranes. In this paper, we firstly illustrate the chemical synthesis of the AJ2NBD probe, its electronic absorption spectra and its behavior regarding pH of the environment. Lack of any cellular toxicity and an efficient labelling on fresh, living cells was demonstrated, allowing the use of AJ2NBD in biological studies. In particular, this green fluorescent probe may represent a potential dye for the compartments involved in the endosomal/autophagic pathway. This research’s field should benefit from the use of AJ2NBD as a vesicular tracer, however, to ensure the precise nature of vesicles/vacuoles traced by this new probe, other more specific tests are needed.