Abstract Azide modification of synthetic oligonucleotides is a versatile tool for obtaining bioconjugates for a wide range of applications from analytics to therapeutics. However, each new synthetic modification designed for bioconjugation requires a new set of data to show how it would affect the native structure and functionality of the biomolecule. In the present work, we have investigated the impact of single and multiple non‐nucleoside L‐hydroxyprolinol‐based azide modifications on the stability of oligonucleotide duplexes. Overall, the data obtained with different methods – secondary structure simulation, UV–vis melting, fluorescence melting with intercalating dye, and circular dichroism – correlated well.

The present study examines reaction products in the solution of antibiotic cefotaxime with succinic anhydride, maleic anhydride copolymer, and dialdehyde wheat starch. The reaction of cefotaxime with succinic anhydride is shown to produce succinamide; to maleic anhydride copolymer, cefotaxime is likely to bind via noncovalent intermolecular interactions. An azomethine derivative of oxidized polysaccharide with cefotaxime was found to form; the molar ratio of initial glucosidic units in starch, unreacted dialdehyde units, and those bonded to cefotaxime through the azomethine linkage is 0.204:0.606:0.19. Drug release from the obtained matrix form was studied in different biorelevant media (saline, phosphate buffer, and Tris-HCl buffer). The amount of cefotaxime released in ten hours was found to approach 100%. Its release proceeds in two phases. In the first phase (1–2 h), 35 (pH 7.14) to 70% (pH 7.4–8.0) of the drug substance is released into the solution, followed by a significant decrease in the release rate. The processing of kinetic data using the first-order and Higuchi equations revealed consistency with both models. The obtained rate constants increase in proportion to the solution pH. It is assumed that first, the azomethine bond hydrolysis occurs with the release of cefotaxime molecules from the polymer matrix; then, the macromolecules of oxidized starch residing on the surface are dissolved; due to an increase in the viscosity of the solution layer surrounding the conjugate particle, the hydrolysis rate decreases. In general, cefotaxime release from the conjugate proceeds as a pseudo-first-order reaction accompanied by diffusion processes.

Abstract The study reports results from the quantum chemical assessment of the spontaneous monolayer formation of fatty alcohols CnH2n+1ОН (n = 6 − 14) at the graphene-like surface modeled by polyaromatic hydrocarbon (PAH) within the PM6-DH2 method. Unlike monolayers of alkanes, lamellae of alcohols on graphene form a herringbone pattern due to the presence of hydrogen O∙∙∙H–O bonds between the hydroxyl groups of two interacting surfactant molecules belonging to neighboring lamellae. Calculations of the thermodynamic parameters of binding for alcohol monomers and dimers with tricircumcoronene have shown that the intermolecular interactions of the terminal fragments of surfactants make a destabilizing contribution to the Gibbs energy of the alcohol association during the formation of a monolayer on a graphene surface. However, C–H∙∙∙π interactions between CH2 fragments of the alcohol chain and condensed PAH rings are stabilizing, contributing − 4.77 kJ/mol. Their significant advantage is partially countervailed by the formation of energetically unfavorable CH∙∙∙HC interactions of the “e” type between the hydrocarbon chains of interacting alcohol molecules. It results in existence of a threshold length of the alcohol chain, starting from which these compounds are capable of crystalline monolayer formation on graphene-like surfaces. Spontaneous film formation of n-alcohols on graphene at 298 K is possible for surfactants possessing no less that10 carbon atoms in the chain. An increase in the chain length of alcohols by one methylene fragment is equivalent to an increase in the temperature of the film formation in the range from 6 to 22 ° C for alcohols from pentanol to octadecanol, following experimental data.

New coordination compounds of copper(I), copper(II), cobalt(II), and nickel(II) with 2,4-dimethylpyrazolo[1,5-а]benzimidazole (L) were synthesized and studied. The complexes [CuLCl] (I), [CuLBr] (II), [CuL2Cl2] (III), [CuL2(NO3)2] · H2O (IV), [CoL2Cl2] · 0,5H2O (V), [CoL2(NO3)2] · · 0,5H2O (VI), and [NiL2(NO3)2] · 0,5H2O (VII) were studied by IR spectroscopy and powder and single crystal X-ray diffraction (CCDC nos. 2321779 ([CuL2Cl2]), 2321780 ([CoL2(NO3)2])). The results indicate that the coordination polyhedron in 2,4-dimethylpyrazolo[1,5-a]benzimidazole complexes is formed by the nitrogen atoms of the monodentate ligand and the coordinated anion. The cytotoxic and cytostatic properties of L and complexes I–III were studied in relation to the HepG2 hepatocellular carcinoma cells.

The molecular structures and relative energies of trans- and cis-isomers of bis(chelate) complexes of Pd(II) and Pt(II) salicylal-, thiosalicylal-, and selenosalicylaldiiminates are calculated using the density functional theory. The role of the kinetic factor in the formation of the trans- and cis-isomers of the PdL2 and PtL2 complexes is studied in the framework of the model of the step-by-step formation of the bis(ligand) metal complexes ML2 (M++ + (L)– → (ML)+, (ML)+ + (L)–→ ML2). The competition of the trans- and cis-isomers of the PdL2 and PtL2 bis(chelate) azomethine complexes with the coordination nodes MN2O2, MN2S2, and MN2Se2 is shown to be determined by both the energy preference of one of possible configurations and activation barriers of the isomerization of the products formed in the first step of the interaction of the initial reagents.

Synthesis and structural characterization of a family of germanium-dioxolene complexes with ditopic N-donor ligands (L1-L5) (L1=1,2-bis(pyridin-2-ylmethylene)hydrazine L2=1,6-bis-(pyridin-2-yl)-2,5-diaza-1,5-hexadiene, L3=N,N-bis(pyridin-2-ylmethylene)-1,4-benzenediamine, L4=N,N-bis(pyridin-2-ylmethylene)-(biphenyl)-4,4-diamine, L5=2,2'-azopyridine) is reported. The reaction of germanium bis-catecholate with bridging ligands L1 - L4, differing by the nature of the linker between pyridine sites gives rise to dinuclear digermanium complexes (36Cat2Ge)2L1-4 (36Cat=dianion of 3,6-di-tert-butylcatechol) 1-4 of DMAMD type (donor-metal-acceptor-metal-donor) with a charge transfer in the UV-Vis region. In opposite, the interaction of the 36Cat2Ge with 2,2'-azopyridine (L5) results in the two-electron transfer from the donor 36Cat2- ligands to the azopyridine bridge forming stable open-shell complex 5 [(36SQ)(36CatGe)]2(L5)2- (36SQ=radical-anionic semiquinonate ligand). Molecular structures of compounds 3 and 5 were determined by single crystal X-ray diffraction analysis. Electronic structures of complexes 1-5 were studied by means of DFT calculations.

ObjectivesThe study aimed to investigate heavy metal contamination (copper, arsenic, manganese) in Georgian rivers affected by mining and develop a two-stage water purification technology using Spirulina (Arthrospira platensis) and trehalose lipid (TRL). This technology offers a sustainable and efficient solution to mitigate environmental and health hazards from mining-related pollution, improving river ecosystems and public health.Data DescriptionThis study examines the current state of the Kvirila, Lukhuni, Kazretula, and Mashavera rivers in terms of heavy metal pollution. Data were collected from field application of a two-stage purification process. Initial assessments showed heavy metal concentrations exceeding local regulatory limits (საქართველოს საკანონმდებლო მაცნე. გარემოსდაცვითი ტექნიკური რეგლამენტების დამტკიცების თაობაზე. Environmental Technical Regulations Approval. www.matsne.gov.ge/en/document/view/2196792?publication=0&scroll=0. Accessed 22 Aug 2024.). The purification process involved a 72-h incubation in a primary tank, followed by membrane filtration and the addition of biomass with trehalose lipid (TRL) in a secondary tank. Post-treatment data revealed significant reductions in manganese and copper concentrations, bringing them below permissible thresholds. These data highlight the effectiveness of the two-stage purification technology in removing heavy metal contaminants from water sources impacted by industrial pollution. The findings demonstrate the potential of this technology to improve sustainable water management practices and provide scalable solutions for communities facing similar water quality challenges.

New cadmium 2,3,4,5-tetrafluorobenzoate (6HTfb) and 2,3,5,6-tetrafluorobenzoate (4Htfb) complexes, [Cd(6HTfb)(H2O)3]n·(6HTfb)·2nH2O (I), [Cd3(Phen)2(6HTfb)6] (II, Phen = 1,10-phenanthroline), [Cd2(Phen)2(4Htfb)4]n·2nH2O (III), and [Cd(Phen)2(4Htfb)2] (IV), were synthesized. Analysis of the obtained results and published data demonstrated that a decrease in the number of fluorine substituents is unfavorable for the formation of coordination polymers comprising stacked alternating fluorinated and nonfluorinated aromatic moieties. In the case of 2,4,5-trifluorobenzoate complex, a typical trivial structure of the binuclear cadmium complex with ligand-shielded metal core is formed. The synthesis of 2,3,4,5- and 2,3,5,6-tetrafluorobenzoate complexes produced an intermediate situation and demonstrated that the structure of complex formation products is affected by not only the number, but also the positions of fluorine substituents. Using quantum chemical calculations, it was shown that the formation of coordination polymers requires a molecular precursor with a Chinese lantern structure stable in solutions, while the formation of unusual flattened binuclear complexes with additionally coordinated water molecules requires doubly bridged binuclear complexes able to switch to a conformation with exposed coordinatively unsaturated metal centers.