Binding of 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane with tetramethylviologen calix[4]resorcin with a methyl radical in the resorcinol ring

The binding of the amphiphilic 1,5-bis(para-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane dianion (APCO^2?) with the octacation of the amphiphilic tetramethylviologen calix[4]resorcin having a methyl radical in the resorcinol ring (MVCA-C ₁ ⁸⁺ ) in 30% aqueous DMSO in a 0.1M NaCl supporting solution was studied by various methods. The dianion was bound at the upper rim of calixresorcin due to the donor-acceptor interactions between the viologen acceptor units and the nitrogen- and phosphorus-centered electron-donor fragments of APCO^2? and at the lower rim due to hydrophobic interactions. The composition of the complex depended on the MVCA-C ₁ ⁸⁺ : APCO^2? ratio. The complexes aggregated, forming insoluble precipitates. MVCA-C ₁ ⁸⁺ -APCO^2? is a system with reversibly electro-switchable aggregation. The starting MVCA- ₁ ⁸⁺ octacation partially bound APCO^2?, a certain quantity of both substrates remaining in a free state in solution. The MVCA-C ₁ ^4+· tetraradical tetracation formed as a result of the reduction of MVCA-C ₁ ⁸⁺ completely bound APCO^2? due to hydrophobic interactions when the MVCA-C ₁ ⁸⁺ : APCO^2? ratio was 1: 3. The reversible oxidation of MVCA-C ₁ ^4+· to the starting MVCA-C ₁ ⁸⁺ octacation brought the system back to its starting state     

Electrochemical switching of monomer—associate in the system tetraviologen calix[4]resorcinol—3,7-di(l-menthyl)-1,5-di(p-sulfonatophenyl)-1,5-diaza-3,7-diphosphacyclooctane

The possibility of controlling the association of tetraviologen calix[4]resorcinol (MVCA-C₅ ⁸⁺) with 3,7-di(l-menthyl)-1,5-di(p-sulfonatophenyl)-1,5-diaza-3,7-diphosphacyclooctane (APCO-2^2?) in the electrochemical cycle of reduction-reoxidation of viologen units was shown. Reduction to tetra(radical cation) MVCA-C₅ ^4+· transforms monomeric MVCA-C₅ ⁸⁺ and APCO-2^2- into the associate (π-polymer) (xAPCO-2^2?·yMVCA-C₅ ^4+·) _n , which is completely returned by reoxidation to the initial state.     

13,17,53,57-Tetraphenyl-13,17,53,57-tetrathio-3,7-dithia-1,5(1,5)-di(1,5-diaza-3,7-diphosphacyclooctana)-2,4,6,8(1,4)-tetrabenzenacyclooctaphane with an unusual conical-like conformation

1³,1⁷,5³,5⁷-tetraphenyl-1³,1⁷,5³,5⁷-tetrathio-3,7-dithia-1,5(1,5)-di(1,5-diaza-3,7-diphosphacyclooctana)-2,4,6,8(1,4)-tetrabenzenacyclooctaphane 2b was obtained by sulfurization of the corresponding macrocyclic tetraphosphine 1b. The structure of the inclusion complex of tetrasulfide 2b with DMF was investigated by the X-ray crystal structure analysis. A novel for this type of cyclophanes and relatively rare conical-like conformation of the macrocycle was found. A methyl group from one of the solvating DMF molecules penetrates the macrocyclic cavity of 2b from the side of the wider rim. According to quantum-chemical simulations, this may be the reason of the unusual conical conformation of 2b because the cavity of the macrocycles of this type is highly flexible. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The configuration and solid state conformation of 3,7-dihydroxy-1,5-bis(p-bromophenyl)octahydro-1,5-diazocine

The crystal structure of 3,7-dihydroxy-1,5-bis(p-brornophenyl)octahydro-1,5-diazocine ( 4 ) has been determined from the three dimensional x-ray diffraction data. This infers a similar structure for 3,7-dihydroxy-1,5-diphenyloetahydro-1,5-diazocine ( 1 ). The molecules are in a twist crown conformation and the configuration of the hydroxyl groups on the 3,7-positions is cis.     

Electrochemical synthesis of nanocomposite of palladium nanoparticles with polymer viologen-containing nanocapsule

An efficient mediated electrosynthesis of the spherical (85 nm) nanocomposite material Pd@p(MVCA⁸⁺-co-St) was carried out in an aqueous medium. Ultrasmall palladium nanoparticles (3—8 nm) are stabilized in nanocapsules of water-soluble nanoparticles of the copolymer p(MVCA⁸⁺-co-St) consisting of tetraviologen calix[4]resorcinol (MVCA⁸⁺) with styrene (St). The role of the mediator is played by viologen units of a polymer nanoparticle at potentials of the MV²⁺/MV^?+ redox couple. The high catalytic activity of the nanocomposite material in the reduction of nitrophenol with sodium borohydride is shown.     

A kinetic study of the Zn2+/Zn(Hg) system in dimethylsulfoxide and water + dimethylsulfoxide mixtures at various concentrations of NaClO4

The kinetics of the Zn²⁺/Zn(Hg) system have been studied at the hanging mercury drop electrode in dimethylsulfoxide (DMSO) and in H₂O + 50 % vol. DMSO mixtures at various concentrations of NaClO₄.The diffusion coefficients, the formal potentials, the standard rate constants and the parameters αn_α and βn_β have been determined.The influence of the concentration of electrolyte on Zn²⁺ reduction in DMSO has been explained by the Frumkin double-layer effect.The mechanism of the cathodic and anodic processes has been discussed.     

Electrochemical synthesis of metal nanoparticles using a polymeric mediator,whose reduced form is adsorbed (deposited) on an electrode

Efficient mediated electrosynthesis of nanocomposite Au@р(MVCA⁸⁺-co-St) (~6 nm), in which ultrasmall Au nanoparticles (Au-NP) were bound in nanocapsules of water-soluble nanoparticles of соpolymer р(MVCA⁸⁺-co-St) of tetraviologen calix[4]resorcinol (MVCA⁸⁺) with styrene (St), was accomplished by the reduction of Au^I in aqueous medium. The quanti- tative reduction of Au^I was carried out using the theoretically necessary amount of electricity and was not accompanied by the deposition of metal on the electrode. Radical cations of viologen units MV^?+ of the molecule р(MVCA^4?+-co-St) adsorbed on the electrode and π-dimers MV^?+···MV^?+ of π-polymers [р(MVCA^4?+-co-St)] _n deposited on the electrode act- ed as the reducing agents with respect to Au^I. During electrolysis, the nanoparticles agglo- merated to 37—50 nm. The nanocomposite particles dispersed in ethanol had sizes of 72±16 nm and also contained Au-NP with sizes of 51±8 and 19±3 nm. The catalytic activity of the nanocomposite in the reduction of p-nitrophenol with sodium borohydride was demon- strated. A similar reduction of AgCl nanoparticles (~250 nm) led to the formation of silver nanoparticles with crystallite sizes in the range of 7—11 nm, the process was inefficient, however, even when using 250% of electricity, an incomplete reduction of AgCl was still observed.     

Synthese,Kristallstruktur und thermischer Abbau von Cs1,5[Re3I3Cl7,5(H2O)1,5]

Synthesis, Crystal Structure and Thermal Behaviour of Cs_1,5[Re₃I₃Cl_7,5(H₂O)_1,5] Dark brown tetrahedra of Cs_1,5[Re₃I₃Cl_7,5(H₂O)_1,5] crystallize on slow cooling of a hot saturated solution of ReI₃ and CsCl in conc. hydrochlorid acid. The crystal structure (cubic, P4 3m (No. 215), a = 1241.06(3)pm, V_m = 287.8(1) cm³mol^?1, Z = 4, R = 0.067, R_w = 0.037) is built up from isolated building units [Re₃I₃Cl_7,5(H₂O)_1,5]^1,5? with statistical distribution of chloride ions and water molecules in the in plane, terminal positions. Consistent with the result based on the X-ray analysis, the IR-spectrum shows one band for the OH stretching frequencies of the water molecules coordinated to the Re₃ triangle at 3240 cm^?1. The anions are arranged in the fashion of a cubic closest packing with the cesium ions occupying all octahedral and one quarter of the tetrahedral interstices. Temperature-dependent Guinier-Simon photographs in connection with DTA/TG investigations reveal that Cs_1,5[Re₃I₃Cl_7,5(H₂O)_1,5] releases water at 190°C accompanied with a structural transition and the dehydration product decomposes at 370°C to Cs₂ReCl_6?xI_x, Re₃I_3+yCl_6?y and rhenium metal.     

Synthesis of 3,7-diacyl-1,5-dimethyl-3,7-diazabicyclo[3.3.1]nonane derivatives as promising lipid bilayer modifiers

Novel 3,7-bis(dialkylaminoacetyl)-1,5-dimethyl-3,7-diazabicyclo[3.3.1]nonanes were synthesized, which can undergo conformational reorganization under the change of solvent polarity, protonation (the change of pH) or complexation with LaCl₃. These compounds are capable of being embedded into the liposomal membranes and can serve as molecular switches for the development of stimulus-sensitive liposomal containers.     

Polarographic Behaviour and Determination of Kinetic Parameters of Lead-Pamoate Complex in Dimethyl Sulfoxide

The polarography of lead ion in dimethyl sulfoxide (DMSO) was investigated in the DMSO concentration range 0–80 vol.%. The complex species identified were Pb₂(DMSO)⁴⁺₃, Pb(DMSO)²⁺₃ and Pb(DMSO)²⁺₆ in [DMSO]<10 vol.%, 10< [DMSO]<43 vol.% and [DMSO]>43 vol.%, respectively. In the presence of pamoic acid, the reduction of lead ion in DMSO was two-electron reversible diffusion-controlled at pH≤6.0, but it became irreversible at pH>6.0. The complex species identified was Pb(D_m)₂(P_m)₃(OH)^6? at pH>6.0. The rate constants of electro-reduction and electro-oxidation, activation energies were determined. The hydrolysis constants of lead ion in dimethyl sulfoxide concentration 40–70 vol.% at pH 4.5–6.0 were found to be of the order of 10^?6. The stability constants of the Pb(DMSO)²⁺₃ and Pb(DMSO)²⁺₀ were also determined to be of the orders of 10¹ and 10⁵, respectively.     

The solid‐state 2:1 molecular complex of 1,5:3,7‐dimethano‐1,3,5,7‐benzotetrazonine with hydroquinone

The title compound, 1,5:3,7‐dimethano‐1,3,5,7‐benzotetrazonine–hydroquinone (2/1), 2C₁₁H₁₄N₄·C₆H₆O₂, crystallizes with the hydroquinone molecule located on a center of inversion. In contrast to other hydroquinone–adamanzane adducts, which form extended hydrogen‐bonded networks, in the present case, one hydroquinone molecule is linked to two 1,5:3,7‐dimethano‐1,3,5,7‐benzotetrazonine molecules, forming a 2:1 cluster through O—H...N hydrogen bonds.     

The oxidation of Cu(I) in electrolyte solutions

The rates of oxidation of Cu(I) in air saturated solutions was measured as a function of pH, temperature (5–45°C), and ionic strength (0.5 to 6m) in NaCl and NaCl–NaClO₄ solutions. In pure NaCl solutions, the effect of pH is independent of ionic strength and temperature. The overall rate constant is given by logk=12.32+0.12(pH)–2064/T–3.69I^1/2+ 0.73I The energy of activitation was 39±2 kJ-mol^–1 and is independent of ionic strength. At a constant ionic strength (I=1, 3 and 6m) in NaCl–NaClO₄ mixtures the Cl^– dependence of the rates is attributed to the oxidation of the various forms of Cu(I) in the solution. The rate constants for the oxidation of the various species are found to be functions of ionic strength. At a constant ionic strength (I=1) in NaCl–NaClO₄ solutions, the effect of temperature is independent of the chloride concentration. The effect of Mg²⁺ and HCO ₃ ^– on the oxidation rate was determined as a function of chloride concentration (1 to 6m) at 25°C and pH=8. The addition of Mg²⁺ causes the rate to decrease and the addition of HCO ₃ ^– causes the rate to increase. The possible causes of these effects are discussed. Empirical equations for the rate of oxidation of Cu(I) in Na-Mg-Cl-HCO₃ solutions as a function of composition are used to make reliable estimates of the oxidation in seawater and Red Sea waters.     

Complex formation of copper(II) and palladium(II) with L,L-3,7-bis[2-(4-hydroxyphenyl)-1-(methoxycarbonyl)ethyl]-1,5-di(ethoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one

Complexation of copper(II) chloride, copper(II) triflate, and palladium(II) chloride with optically active L,L-3,7-bis[2-(4-hydroxyphenyl)-1-(methoxycarbonyl)ethyl]-1,5-di(ethoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one was studied.     

A COMPARATIVE STUDY OF THE VISIBLE LIGHT PHOTOCHEMISTRY OF GILVOCARCINS V and M

Quantum yields for the formation of superoxide ions, O₂^?1, and singlet oxygen, ¹O₂, were determined during the photolyses of gilvocarcin M (GM) in air-saturated dry dimethylsulfoxide (DMSO) and in 45:55 (vol/vol) DMSO-water mixtures. The quantum yield for the photoreduction of methyl viologen by GM in nitrogen-saturated dry DMSO was also determined. These values are not different, within experimental error, from those corresponding to gilvocarcin V (GV). Because GV is a strong photocytotoxic agent and GM is not, these results imply that Type I and Type II mechanisms are not important pathways in the cytotoxicity of GV.     

Synthesis and separation of stereoisomeric 2,4,6,8-tetrasubstituted 3,7-dithia-1,5-diazabicyclo[3.3.0]octanes

Heterocyclization of hydrazine with aldehydes R-CHO (R = Me, Et, Prⁿ, Buⁿ, n-C₅H₁₁, Ph, 4-MeOC₆H₄, 3-Py) and H₂S leads to stereoisomeric 2,4,6,8-tetrasubstituted 3,7-dithia-1,5-diazabicyclo[3.3.0]octanes, which were separated by column chromatography. The trans-transoid-trans-configuration of tetramethyl(-ethyl,-propyl)-3,7-dithia-1,5-diazabicyclo-[3.3.0]octanes was inferred from the X-ray diffraction and ¹H and ¹³C NMR spectroscopic data.     

The synthesis of 1,5:3,7-dimethano-1,3,5,7-benzotetrazonine

A three-component condensation of formaldehyde, o-phenylenediamine, and ammonia gave a novel 1,5: 3,7-dimethano-1,3,5,7-benzotetrazonine. Its structure was determined by X-ray diffraction analysis. An analogous condensation of formaldehyde, ammonia, and 1,2-diamino-4-methylbenzene yielded 9-methyl-1,5:3,7-dimethano-1,3,5,7-benzotetrazonine. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 542—544, March, 2007.     

Evaluation of lead(II) and nickel(II) toxicity in NaCl and NaClO4 solutions by using MicrotoxR bioassay

The toxicity of nickel and lead compounds has been evaluated in NaCl and NaClO₄ solutions by using the Microtox^R bioassay. The aim of this work was to assess the toxicity of the different species in solution when varying the concentration of the medium. A modified Microtox protocol which enables the pH to be constant in all the cuvettes during analysis has been used. The positively charged species (Ni²⁺, Pb²⁺, PbCl⁺) were found to contribute more to the toxicity of Ni and Pb in NaCl while in NaClO₄ solutions free metal was the responsible species. In all media studied, Pb compounds were the most toxic and provoked a quick response of the bacteria. Received: 25 July 1997 / Revised: 9 September 1997 / Accepted: 20 September 1997     

Evaluation of lead(II) and nickel(II) toxicity in NaCl and NaClO4 solutions by using MicrotoxR bioassay

The toxicity of nickel and lead compounds has been evaluated in NaCl and NaClO₄ solutions by using the Microtox^R bioassay. The aim of this work was to assess the toxicity of the different species in solution when varying the concentration of the medium. A modified Microtox protocol which enables the pH to be constant in all the cuvettes during analysis has been used. The positively charged species (Ni²⁺, Pb²⁺, PbCl⁺) were found to contribute more to the toxicity of Ni and Pb in NaCl while in NaClO₄ solutions free metal was the responsible species. In all media studied, Pb compounds were the most toxic and provoked a quick response of the bacteria. Received: 25 July 1997 / Revised: 9 September 1997 / Accepted: 20 September 1997     

Structural studies on 3-acetyl-1,5-diaryl and 3-cyano-1,5-diaryl formazan chelates with cerium(III), thorium(IV) and uranium(VI)

Summary Solid complexes of 3-acetyl-1,5-diaryl and 3-cyano-1,5-diaryl formazans were prepared and characterized by elemental analysis, IR, NMR, TGA and DTA analyses. Based on these studies, the suggested general formula for the complexes is [M(HL) _m (OH^–) _n or (NO ₃ ^– or Cl^–) _x ·(H₂O) _y or (C₂H₅OH orDMSO) _z , where HL=formazanM=Ce³⁺, Th⁴⁺, and UO ₂ ²⁺ ,m=1–2,n=0–3,x=0–3,y=0–4 andz=0–3. The metal ions are expected to have coordination numbers 6–8.

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Strukturuntersuchungen an 3-Acetyl-1,5-diaryl- und 3-Cyan-1,5-diaryl-formazan-Chelaten mit Cer(III), Thorium(IV) und Uran(VI)

Zusammenfassung Die hergestellten Chelate wurden mittels Elementaranalyse, IR, NMR, TGA und DTA charakterisiert. Darauf basierend wird die generelle Formel [M(HL) _m (OH^–) _n bzw. (NO ₃ ^– oder Cl^–) _x ·(H₂O) _y oder (C₂H₅OH bzw.DMSO) _z ] vorgeschlagen, wobei HL=Formazan,M=Ce³⁺, Th⁴⁺ oder UO ₂ ²⁺ ,m=1–2,n=0–3,x=0–3,y=0–4 undz=0–3. Die Metallionen haben Koordinationszahlen von 6–8.

     

Dilute solutions of poly(vinyl alcohol) derived from vinyl trifluoroacetate

The dilute-solution behavior of poly(vinyl alcohol) (PVA_VTFA), derived from vinyl trifluoroacetate, in water-dimethylsulfoxide (DMSO) mixtures was investigated. With solvent mixtures ranging from 10 to 20 vol % DMSO, the relation between the reduced viscosity η_sp/C and the polymer concentration C was linear for polymer concentrations above 0.2 g/dL, whereas in solutions in mixed solvents of other compositions the dependence was linear for polymer concentrations above 0.1 g/dL. The relation between the intrinsic viscosity [η] obtained for aqueous solutions of PVA_VTFA and the molecular weight M estimated from viscosity measurements in solutions of poly(vinyl acetate) (PVA_VTFA), obtained by acetylation of PVA_VTFA, was given by [η] = 7.34 × 10^?4 M^0.63. The value of [η] was greatest for the solvent mixture with 10 vol % DMSO and smallest for about 50 vol % DMSO, and Huggins constants k were smallest and greatest for these two cases, respectively. The turbidity of the solutions of low-molecular-weight PVA_VTFA, was higher than that of high-molecular-weight PVA_VTFA up to 30 vol % DMSO, and the reverse relation held for 40-70 vol % DMSO.