Poly(vinyl chloride)/Nanocarbon Composites for Advanced Potentiometric Membrane Sensor Design.

Polymer nanocomposites filled with carbon nanoparticles (CNPs) are a hot topic in materials science. This article discusses the current research on the use of these materials as interfacial electron transfer films for solid contact potentiometric membrane sensors (SC-PMSs). The results of a comparative study of plasticized poly (vinyl chloride) (pPVC) matrices modified with single-walled carbon nanotubes (SWCNTs), fullerenes-C60, and their hybrid ensemble (SWCNTs-C60) are reported. The morphological characteristics and electrical conductivity of the prepared nanostructured composite films are reported. It was found that the specific electrical conductivity of the pPVC/SWCNTs-C60 polymer film was higher than that of pPVC filled with individual nanocomponents. The effectiveness of this composite material as an electron transfer film in a new potentiometric membrane sensor for detecting phenylpyruvic acid (in anionic form) was demonstrated. Screening for this metabolic product of phenylalanine in body fluids is of significant diagnostic interest in phenylketonuria (dementia), viral hepatitis, and alcoholism. The developed sensor showed a stable and fast Nernstian response for phenylpyruvate ions in aqueous solutions over the wide linear concentration range of 5 × 10-7-1 × 10-3 M, with a detection limit of 10-7.2 M.

Synthesis and Structures of Lead(II) Complexes with Substituted Derivatives of the Closo-Decaborate Anion with a Pendant N3 Group.

In this work, we studied lead(II) and cobalt(II) complexation of derivatives [2-B10H9O(CH2)2O(CH2)2N3]2- and [2-B10H9O(CH2)5N3]2- of the closo-decaborate anion containing pendant azido groups in the presence of 1,10-phenanthroline and 2,2'-bipyridyl. Mononuclear [PbL2{An}] and binuclear [Pb2L4(NO3)2{An}] lead complexes (where {An} is the N3-substituted boron cluster) were isolated and studied by IR spectroscopy and elemental analysis. The mononuclear lead(II) complex [Pb(phen)2[B10H9O(CH2)2O(CH2)2N3] and the binuclear lead(II) complex [Pb2(phen)4(NO3)2[B10H9O(CH2)5)N3] were determined by single-crystal X-ray diffraction. In complex [Pb2(phen)4(NO3)2[B10H9O(CH2)5)N3], the boron cluster is coordinated by the metal atom only via the 3c2e MHB bonds. In complex [Pb(phen)2[B10H9O(CH2)2O(CH2)2N3], the coordination environment of the metal includes BH groups of the boron cluster and the oxygen atom of the exo-polyhedral substituent. When the reaction was performed in a CH3CN/water mixture, the binuclear lead(II) complex [(Pb(bipy)NO3)(Pb(bipy)2NO3)(B10H9O(CH2)2O(CH2)2N3)]·CH3CN·H2O was isolated, where the boron cluster acts as a bridging ligand between lead atoms coordinated by the boron cage via the O atoms of the substituent and/or the BH groups. In the course of cobalt(II) complexation, the starting compound (Ph4P)2[B10H9O(CH2)5N3] was isolated and its structure was also determined by X-ray diffraction. Although a number of lead(II) complexes with coordinated N3 are known from the literature, no complexes with the boron cluster coordinated by the pendant N3 group involved in the metal coordination have been isolated.

Synthesis of Disubstituted Carboxonium Derivatives of Closo-Decaborate Anion [2,6-B10H8O2CC6H5]-: Theoretical and Experimental Study.

A comprehensive study focused on the preparation of disubstituted carboxonium derivatives of closo-decaborate anion [2,6-B10H8O2CC6H5]- was carried out. The proposed synthesis of the target product was based on the interaction between the anion [B10H11]- and benzoic acid C6H5COOH. It was shown that the formation of this product proceeds stepwise through the formation of a mono-substituted product [B10H9OC(OH)C6H5]-. In addition, an alternative one-step approach for obtaining the target derivative is postulated. The structure of tetrabutylammonium salts of carboxonium derivative ((C4H9)4N)[2,6-B10H8O2CC6H5] was established with the help of X-ray structure analysis. The reaction pathway for the formation of [2,6-B10H8O2CC6H5]- was investigated with the help of density functional theory (DFT) calculations. This process has an electrophile induced nucleophilic substitution (EINS) mechanism, and intermediate anionic species play a key role. Such intermediates have a structure in which one boron atom coordinates two hydrogen atoms. The regioselectivity for the process of formation for the 2,6-isomer was also proved by theoretical calculations. Generally, in the experimental part, the simple and available approach for producing disubstituted carboxonium derivative was introduced, and the mechanism of this process was investigated with the help of theoretical calculations. The proposed approach can be applicable for the preparation of a wide range of disubstituted derivatives of closo-borate anions.

A New Approach to the Synthesis of Nanocrystalline Cobalt Boride in the Course of the Thermal Decomposition of Cobalt Complexes [Co(DMF)6]2+ with Boron Cluster Anions.

In the course of the study, nanocrystalline cobalt monoboride was prepared by thermal decomposition of precursors [Co(DMF)6][An], where [An] = [B12H12]2- (1), [trans-B20H18]2- (2) or [B10Cl10]2- (3) in an argon atmosphere. Three new salt-like compounds 1-3 were prepared when Co(NO3)2 was allowed to react with (Et3NH)2[An]. Compound 1 is new; the structures of compounds 2 and 3 have been previously reported. Samples 1-3 were annealed at 900 °C in argon to form samples 1a-3a, which were characterized by single crystal XRD for 1 and powder XRD for 1-3. Powder XRD on the products showed the formation of BN and CoB for 1a in a 1:1 ratio; 2a gave a higher CoB:BN ratio but an overall decreased crystallinity. For 3a, only CoB was found. IR spectra of samples 1a-3a as well as X-ray spectral fluorescence analysis for 3a confirmed these results. The nanoparticular character of the decomposition products 1a-3a was shown using TEM; quite small particle sizes of about 10-15 nm and a quite normal size distribution were found for 1a and 2a, while the decomposition of 3 gave large particles with 200-350 nm and a broad distribution.

Non-Covalent Interactions in the Crystal Structures of Perbrominated Sulfonium Derivatives of the closo-Decaborate Anion.

A new series of compounds based on perbrominated disubstituted sulfonium derivatives of the closo-decaborate anion (n-Bu4N)[2-B10Br9SR2] (R = n-Pr, i-Pr, n-Bu, n-C8H17, n-C12H25, n-C18H37) was obtained, characterised by modern physicochemical methods of analysis. According to the results of an X-ray diffraction study, some of the anions and solvate molecules were disordered. The cations (n-Bu4N)+ and anions [2-B10Br9SR2]- were associated via C-H…Br and H…H contacts. In addition, Br…Br interactions between anions were revealed. The role of these contacts was analysed in terms of Hirshfeld surface analysis, QTAIM theory and the NCI method using quantum chemical calculations. An increase in the size of the alkyl R moiety led to significant strengthening of the total energy of H…H interactions. In the case of R = -n-C18H37, a parallel mutual orientation of alkyl moieties was established that was similar to the packing of salts of fatty acids. The nature of C-H…Br and Br…Br interionic interactions was found to be attractive, in contrast to the repulsive nature of intermolecular Br…Br interactions.

High-Temperature Spin Crossover in Iron(II) Complexes with 2,6-Bis(1H-imidazol-2-yl)pyridine.

Novel iron(II) coordination compounds containing a ligand 2,6-bis(1H-imidazol-2-yl)pyridine (L), having such a composition as [FeL2]SO4·0.5H2O, [FeL2]Br2·H2O, [FeL2](ReO4)2, [FeL2]B10H10∙H2O, [FeL2]B12H12∙1.5H2O had been synthesized and studied using UV-Vis (diffuse reflectance), infrared, extended X-ray absorption fine structure (EXAFS), and Mössbauer spectroscopy methods, as well as X-ray diffraction and static magnetic susceptibility methods. The analysis of the µeff(T) dependence in the temperature range of 80-600 K have shown that all the obtained complexes exhibit a high-temperature spin crossover 1A1 ↔ 5T2.

Protonation of Borylated Carboxonium Derivative [2,6-B10H8O2CCH3]-: Theoretical and Experimental Investigation.

The process of protonation of [2,6-B10H8O2CCH3]- was investigated both theoretically and experimentally. The most suitable conditions for protonation of the derivative [2,6-B10H8O2CCH3]- were found. The process of protonation was carried out in the presence of an excess of trifluoromethanesulfonic acid CF3SO3H at room temperature in dichloromethane solution. The structure of the resulting complex [2,6-B10H8O2CCH3*Hfac]0 was established using NMR data and the results of DFT calculations. An additional proton atom Hfac was found to be localized on one of the facets that was opposite the boron atom in a substituted position, and which bonded mainly with one apical boron atom. The main descriptors of the B-Hfac bond were established theoretically using QTAIM and NBO approaches. In addition, the mechanism of [2,6-B10H8O2CCH3]- protonation was investigated.

New type of RNA virus replication inhibitor based on decahydro-closo-decaborate anion containing amino acid ester pendant group.

In this work, a synthetic approach to prepare an example of new class of the derivatives of the closo-decaborate anion with amino acids detached from the boron cluster by pendant group has been proposed and implemented. Compound Na2[B10H9-O(CH2)4C(O)-His-OMe] was isolated and characterized. This compound has an inorganic hydrophobic core which is the 10-vertex boron cage and the -O(CH2)4C(O)-His-OMe organic substituent. It has been shown to possess strong antiviral activity in vitro against modern strains of A/H1N1 virus at 10 and 5 µg/mL. The compound has been found to be non-cytotoxic up to 160 µg/mL. At the same time, the compound has been found to be inactive against SARS-CoV-2, indicating specific activity against RNA virus replication. Molecular docking of the target derivative of the closo-decaborate anion with a model of the transmembrane region of the M2 protein has been performed and the mechanism of its antiviral action is discussed.

Primary Amine Nucleophilic Addition to Nitrilium Closo-Dodecaborate [B12H11NCCH3]-: A Simple and Effective Route to the New BNCT Drug Design.

In the present work, a convenient and straightforward approach to the preparation of borylated amidines based on the closo-dodecaborate anion [B12H11NCCH3NHR]-, R=H, Alk, Ar was developed. This method has two stages. A nitrile derivative of the general form [B12H11NCCH3]- was obtained, using a modified technique, in the first stage. On the second stage the resulting molecular system interacted with primary amines to form the target amidine products. This approach is characterised by a simple chemical apparatus, mild conditions and high yields of the final products. The mechanism of the addition of amine to the nitrile derivative of the closo-dodecaborate anion was studied, using quantum-chemical methods. The interaction between NH3 and [B12H11NCCH3]- ammonia was chosen as an example. It was found that the structure of the transition state determines the stereo-selectivity of the process. A study of the biological properties of borylated amidine sodium salts indicated that the substances had low toxicity and could accumulate in cancer cells in significant amounts.

Synthesis of Hafnium(IV) Polyaminoacetates.

The interaction of hafnium(IV) salts (oxide-dichloride, chloride, and bromide) with nitrilotriacetic acid (NTA), diethylenetriamminepentaacetic acid (DTPA), 1,2-diaminocyclohexanetetraacetic acid (CDTA), 1,3-dipropylmino-2-hydroxy N,N,N',N'-tetraacetic acid (dpta), and N-(2-hydroxyethyl)ethylenediamine triacetic acid (HEDTA) has been studied. The corresponding complexes Na2[Hf(NTA)2]·3H2O (1), Na[HfDTPA]·3H2O (2), [HfCDTA(H2O)2] (3), and Na[Hf2(dpta)2]·7.5H2O·0.5C2H5OH (4) have been isolated and characterized and their structures have been determined by single crystal X-ray diffraction. Biological studies of [HfCDTA(H2O)2] have shown that in 5% glucose solution this complex has low toxicity and good contrasting ability.

Synthesis of Perchlorinated Sulfonium Derivatives of closo-Decaborate Anion [2-B10Cl9SR2]- (R = i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, n-C18H37, CH2Ph, and cyclo-S(CH2)4).

A method for obtaining perchlorinated di-S,S-substituted derivatives of the closo-decaborate anion with various alkyl groups has been developed: [B10Cl9SR2]- (R= i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, n-C18H37, CH2Ph, and cyclo-S(CH2)4). The method is based on the preparation of the sulfonium-substituted anion [B10H9SR2]- by alkylation of the anion [B10H9SH]2- with bromoalkanes (i-C3H7Br, n-C3H7Br, n-C4H9Br, n-C8H17Br, n-C12H25Br, n-C18H37Br, PhCH2Br, and BrCH2(CH2)2CH2Br) followed by the cluster chlorination with sulfuryl chloride SO2Cl2 in acetonitrile. The process proceeds until the hydrogen atoms in the boron cluster are completely replaced with chlorine and completes within 60 h. It has been found that the melting point of salts ((C4H9)4N)[B10Cl9SR2] (R= i-C3H7, n-C3H7, n-C4H9, n-C8H17, n-C12H25, and n-C18H37) strongly depends on the length of the hydrocarbon chain of the substituent R.

Novel Cationic Meso-Arylporphyrins and Their Antiviral Activity against HSV-1.

This work is devoted to the search for new antiherpes simplex virus type 1 (HSV-1) drugs among synthetic tetrapyrroles and to an investigation of their antiviral properties under nonphotodynamic conditions. In this study, novel amphiphilic 5,10,15,20-tetrakis(4-(3-pyridyl-n-propanoyl)oxyphenyl)porphyrin tetrabromide (3a), 5,10,15,20-tetrakis(4-(6-pyridyl-n-hexanoyl)oxyphenyl)porphyrin tetrabromide (3b) and known 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetraiodide (TMePyP) were synthesized, and their dark antiviral activity in vitro against HSV-1 was studied. The influence of porphyrin's nanosized delivery vehicles based on Pluronic F127 on anti-HSV-1 activity was estimated. All the received compounds 3a, 3b and TMePyP showed virucidal efficiency and had an effect on viral replication stages. The new compound 3b showed the highest antiviral activity, close to 100%, with the lowest concentration, while the maximum TMePyP activity was observed with a high concentration; porphyrin 3a was the least active. The inclusion of the synthesized compounds in Pluronic F-127 polymeric micelles had a noticeable effect on antiviral activity only at higher porphyrin concentrations. Action of the received compounds differs by influence on the early or later reproduction stages. While 3a and TMePyP acted on all stages of the viral replication cycle, porphyrin 3b inhibited viral replication during the early stages of infection. The resulting compounds are promising for the development of utilitarian antiviral agents and, possibly, medical antiviral drugs.

Fused 1,2-Diboraoxazoles Based on closo-Decaborate Anion-Novel Members of Diboroheterocycle Class.

The novel members of the 1,2-diboraoxazoles family have been obtained. In the present work, we have carried out the intramolecular ring-closure reaction of borylated iminols of general type [B10H9N=C(OH)R]- (R = Me, Et, nPr, iPr, tBu, Ph, 4-Cl-Ph). This process is conducted in mild conditions with 83-87% yields. The solid-state structures of two salts of 1,2-diboraoxazoles were additionally investigated by X-ray crystallography. In addition, the phenomena of bonding interactions in the 1,2-diboraoxazole cycles have been theoretically studied by the Quantum Theory of Atoms in Molecules analysis. Several local and integral topological properties of the electron density involved in these interactions have been computed.

Solvent-Induced Encapsulation of Cobalt(II) Ion by a Boron-Capped tris-Pyrazoloximate.

Boron-cross-linked cobalt(II) pseudoclathrochelate was obtained by the template reaction of 2-acetylpyrazoloxime, phenylboronic acid, and a new DMF cobalt(II) solvato complex with a decachloro-closo-decaborate dianion. As confirmed by single-crystal X-ray diffraction, this complex crystallizes with two symmetry-independent cobalt(II) pseudoclathrochelate cations, one decachloro-closo-decaborate dianion, one benzene, one dichloromethane solvent molecule, and two molecules of DMF. The latter act as pseudocapping fragments to the monocapped tris-pyrazoloximate ligands by forming N-H···O hydrogen bonds with their pyrazole groups. The CoIIN6-coordination polyhedra adopt a nearly ideal TP geometry with distortion angles φ equal to 1.22(16) and 2.58(17)° for two symmetry-independent pseudoclathrochelate cations, both containing the encapsulated cobalt(II) ion in its high-spin state (Co-N 2.115(4)-2.198(3) Å). Magnetic properties of this complex were studied both by dc-magnetometry and by solution-state NMR spectroscopy to reveal a high magnetic anisotropy, thus suggesting a large magnetic susceptibility tensor anisotropy (25.8 × 10-32 m3 at 298 K) and a large negative zero-field splitting energy (-85 cm-1). The results of magnetometry studies in the ac magnetic field suggest a single molecule magnet behavior of this TP complex with an effective magnetization reversal barrier of approximately 130 cm-1. Its pseudocapping DMF molecules that form H-bonds with tris-pyrazoloximate fragments are easy to substitute by strong H-bond acceptors, such as chloride ions and di- and tetramethylureas, thus affecting the magnetic properties of a whole pseudomacrobicyclic paramagnetic system.

closo-Dodecaborate Intercalated Yttrium Hydroxide as a First Example of Boron Cluster Anion-Containing Layered Inorganic Substances.

The first member, Y2(OH)5.46(B12H12)0.23Cl0.08·4.98H2O, of a new family of boron-containing substances, closo-dodecaborate intercalated layered rare-earth hydroxides, was synthesized using a microwave-assisted hydrothermal method. The structure and composition of this compound were studied by X-ray diffraction, transmission and scanning electron microscopy, thermal analysis, inductively coupled plasma mass spectrometry, IR spectroscopy, and X-ray photoelectron spectroscopy. The title compound had the composition Y2(OH)5.46(B12H12)0.23Cl0.08·4.98H2O and crystallized in a form of plate-like, aggregated particles less than 10 nm thick. The coordination of closo-dodecaborate anions with yttrium hydroxide host layers was demonstrated.

Tetra-butyl-ammonium 2-[2,5-dimethyl-3-(4-nitro-phen-yl)-2,3-dihydro-1,2,4-oxadiazo-lium-4-yl]nona-hydro-closo-deca-borate.

The title ionic compound, C16H36N(+)·C10H20B10N3O3(-), consists of a tetra-butyl-ammonium cation and a closo-deca-borate cluster anion, which is bound to the substituted 2,3-dihydro-1,2,4-oxadiazole ring through a B-N bond [1.540 (2) Å]. The distances between connected B atoms in the deca-borate cluster range from 1.689 (2) to 1.844 (2) Å. The 2,3-dihydro-1,2,4-oxadiazole ring adopts an envelope conformation with the N atom as the flap atom.