Theoretical prediction on vibrational spectra of [Ar...Ar-H]<Superscript>+</Superscript>

Centrosymmetric linear [Ar-H-Ar]⁺ and asymmetric linear [Ar---Ar-H]⁺ are two stable configurations of [Ar₂H]⁺. Based on the global potential energy surface of [Ar₂H]⁺ provided by our group recently, we calculated the vibrational spectra of [Ar---Ar-H]⁺ with total angular momentum J = 0 by time-dependent quantum mechanical method, and the influence of quantum tunneling effect on vibrational spectra was found. With the help of the observation on the eigenstate functions and the modified potential energy surface, assignments were made to the spectra. The strong coupling between the excited bending mode of [Ar-H-Ar]⁺ and the vibrational states of [Ar---Ar-H]⁺ was discussed.     

Multicomponent heterocyclization of hydrazine,hydrogen sulfide,and formaldehyde

Multicomponent heterocyclization of hydrazine, hydrogen sulfide, and formaldehyde gave previously unknown bi-, tri-, and tetracyclic nitrogen- and sulfur-containing heterocycles. 3,7-Dithia-1,5-diazabicyclo[3.3.0]octane, 4,9-dithia-1,2,6,7-tetraazatricyclo[5.3.1.1^2,6]dodecane, and 4,9,14-trithia-1,2,6,7,11,12-hexaazatetracyclo[10.3.1.1^2,6.1^7,11]octadecane were obtained selectively, depending on the reaction temperature (0–60 °C).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1652–1656, August, 2004.     

Molecular and crystal structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.017,18.013,14.08,9.05,10]tetracos-3-yl acetate

The molecular structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.0^17,18.0^13,14.0^8,9.0^5,10]tetracos-3-yl acetate III. Compound III C₃₂H₅₂O₃ crystallizes in the monoclinic crystal system with the unit cell parameters a = 13.265(15) ?, b = 6.481(7) ?, c = 32.274(4) ?, β = 99.333(2)°, space group C2, Z = 4, d = 1.176 g/cm³. Original Russian Text Copyright ? 2009 by N. I. Medvedeva, O. B. Flechter, and A. A. Korlyukov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 399–401, March–April, 2009.     

An efficient synthesis of pentacyclo[4.2.0.02,5.03,8.04,7]octane-1,4-dicarboxylates

Dialkyl pentacyclo[4.2.0.0^2,5.0^3,8.0^4,7]octane-1,4-dicarboxylates (where alkyl is methyl,iso-propyl, 2-fluoro-2,2-dinitroethyl, or 2,2,2-trinitroethyl) were prepared in high yields by O-alkylation of 1,4-cubanedicarboxylic acid with the corresponding monoalkyl sulfates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 801–802, April, 1993.     

The formation of tetracyclo[7.2.1.02,5.02,8]dodeca-6,10-dienes under conditions of thermal isomerization of spiro[2.4]hepta-4,6-diene into bicyclo[3.2.0]hepta-1,3-diene

The formation of the novel hydrocarbons, tetracyclo[7.2.1.0^2,5.0^2,8]dodecadienes, as a result of thermal isomerization of spiro[2.4]hepta-4,6-diene into bicyclo[3.2.0]hepta-1,3-diene and its capture by 1,3-dienes is demonstrated. The conditions of thermal isomerization and dimerization of the spiroheptadiene are studied. Cyclopropanation of the polycyclic dienes formed by diazomethane in the presence of Pd-catalysts was accomplished, and occured solely through the norbornene double bond.For preliminary communication see ref.¹ Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 132–137, January, 1993.     

Complex compounds of tetracycline with WO 4 2− and MoO 4 2− ions. Investigation by pH-metric and conductometric methods

By using pH-metric and conductometric methods it has been found that tetracycline (H₃TC) forms with WO ₄ ^2– and MoO ₄ ^2– ions the following complex compounds: [WO₃HTC]^2–, [WO₃(H₂TC)₂]^2– and [MoO₃(H₂TC)₂]^2–. Stability constants log/gb ₁ ^k =7.86 and log ₁ ^k =7.80 for [WO₃HTC]^2– and [MoO₃HTC]^2–, respectively, have been calculated from pH-metric measurements.     

Thionation of the monoacetal of pentacyclo[5.4.0.0.0.0]undecane-8,11-dione

As part of a programme to synthesize thione derivatives with pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane moieties it was decided to sulfurize the monoacetal 6 of pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane-8,11-dione 2. Unexpectedly the diol 9 was isolated as the product.     

The Synthesis of Dibenzo[3n]crown-n by Novel Methods and their Cation Binding Studied by Fluorescence Spectroscopy. Part IV

The dibenzo[3n]crown-n were synthesised from1,2-bis(o-hydroxyphenoxy)ethane obtained from 1,2-bis(o-formylphenoxy)ethane via Bayer-Willigeroxidations with H₂O₂/CH₃COOH in good yields. The cyclic condensation of 1,2-bis(o-hydroxyphenoxy)ethanewith dichlorides, and ditosylates of polyethylene glycols in DMF/Me₂CO₃ gave the macrocyclesdibenzo[15]crown-5, dibenzo[18]crown-6, dibenzo[21]crown-7 anddibenzo[24]crown-8. The structures were identified using IR, mass, ¹H and ¹³C NMR spectroscopy. Therecognition of the molecules for the cations, Li⁺, Na⁺, K⁺, Rb⁺ and Zn²⁺were conducted quantitatively with steady state fluorescencespectroscopy. The 1:1 association constants in acetonitrileshowed a good relation of the appropriate size of the macrocyclic ether towards the fitting cationradii. Namely, dibenzo[15]crown-5 was the best for Li⁺ binding and more than 100 times better thanNa⁺ and K⁺. Dibenzo[21]crown-7 was excellent for Rb⁺ binding while K⁺ is 100 timesless preferred. The largest crown ether studied, dibenzo[24]crown-8, exhibited the order of binding power,Rb⁺ > K⁺ > Na⁺. Zn²⁺ displayed, however, a marked binding with only dibenzo[18]crown-6.p>     

Novel Methods of Synthesis of Dibenzo[3n]crown-n and Their Cation Binding Studied by Fluorescence Spectroscopy. Part V

The dibenzo[3n]crown-n were synthesised starting from bis[2-(o-hydroxyphenoxy)ethyl]ether obtained from bis[2-(o-formylphenoxy)ethyl]ether via Baeyer-Villiger oxidation in H₂O₂/CH₃COOH in a good yield. The cyclic condensation ofbis[2-(o-hydroxyphenoxy)ethyl]etherwith tri- and tetraethylene glycol bisdichlorides andthe bisditosylate of pentaethylene glycol in DMF/Me₂CO₃ afforded the large cyclic ethers of dibenzo[21]crown-7, dibenzo[24]crown-8 and dibenzo[27]crown-9. The structures were analysed with IR, ¹H NMR, ¹³C NMR and low-resolution mass spectroscopy methods. The Na⁺, K⁺, Rb⁺ and Cs⁺ cations' recognition of the molecules were conducted withsteady-state fluorescence spectroscopy. The 1:1 association constants, K_a, in acetonitrile were estimated. Dibenzo[21]crown-7 was the best both for K⁺ and Rb⁺ binding but showed too small an effect on Cs⁺. Dibenzo[24]crown-8 exhibited the binding power in the order of Rb⁺ > K⁺ > Na⁺ > Cs⁺. However, dibenzo[27]crown-9 displayed marked binding with only K⁺ but not with Rb⁺ or with Cs⁺ cations probably due to the heavy atom effect of fluorescence quenching.     

Nitropyrazoles

The structures of substitutedN-aminonitropyrazoles and 1- and 2-amino-4-nitro-1,2,3-triazoles as well as the site of protonation of 1-aminopyrazole were determined based on the¹H,¹³C, and¹⁵N (¹⁴N) NMR spectra. The¹³C NMR spectra were recorded under conditions of¹³C-{¹H,¹⁴N} triple resonance. Effects of substituents in the pyrazole ring on the¹³C and¹⁴N chemical shifts were studied. The¹³C,¹H and¹⁵N,¹H spin-spin coupling constants, obtained using techniques of [¹H]¹³C and [¹H]¹⁵N polarization transfer (SPT, INEPT), were measured, fully assigned, and discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2181–2186, November, 1995.For Part 8, see Ref. 1.     

Tandem regio- and stereospecific cyclization of ethyl isonicotinate with cyanoacetylenic alcohols to provide novel polycondensed heterocyclic systems

Ethyl isonicotinate reacts with tertiary cyanoacetylenic alcohols under exceptionally mild conditions (room temperature, without catalyst or solvent) to afford novel polycondensed heterocyclic systems, 4,15-dioxa-7,12-diazapentacyclo[9.5.2.0^2,10.0^3,7.0^12,16]octadeca-8,17-dienes, in 30-68% yields. This tandem cyclization is regio- and stereospecific. Despite several asymmetric carbons (up to six) being present in the molecules, only one diastereomer is formed and both cyanomethylidene fragments possess exclusively Z-configuration. The tandem sequence includes the formation of 1,3-oxazolidino-1,2-dihydropyridines which undergo Diels-Alder cyclodimerization to give the final products.     

Molecular and crystal structure of a new compound methyl-18R-13-isopropyl-10a,7-dimethyl-4-oxo-1-oxahexacyclo×[12.4.0.05a,4a.013,1201,1a.010a,6a]heneicosane-7-carboxylate

Synthesis is performed and the molecular structure is analyzed of methyl-18R-13-isopropyl-10a,7-dimethyl-4-oxo-1-oxahexacyclo[12.4.0.0^5a,4a.0^13,12.0^1,1a.0^10a,6a]heneicosane-7-carboxylate II. Compound II C₂₇H₄₀O₄ crystallizes in orthorhombic symmetry with cell parameters: a = 11.9915(15) ?, b = 12.1674(16) ?, c = 15.8094(17) ?, P2₁2₁2₁, Z = 4, d = 1.234 g/cm³. Original Russian Text Copyright ? 2009 by I. E. Smirnova, E. V. Tret’yakova, O. B. Kazakova, Z. A. Starikova, and I. V. Fedyanin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 391–392, March–April, 2009.     

Molecular design of calixarene-based ion-selective electrodes

In order to obtain insights into relationships between the calix[4]arene structure and the ion selectivity in the electrode system, 20 ionophoric calix[4]arenes were synthesized and their ion selectivity (with Na⁺ as a standard) estimated. Among these ionophoric calix[4]arenes, 25,26,27,28-tetrakis[(ethoxycarbonyl)methoxy]-p-t-octylcalix[4]arene afforded the highest logK _NA,M ^pot value (–3.1) in the presence of 2-fluorophenyl-2-nitrophenylether (10) as the best of 13 plasticizers. This is the first example in which the Na⁺/K⁺ selectivity exceeds a factor of 10³ in the electrode system based on the neutral carrier. The high Na⁺ selectivity is attributed to modification of the upper rim which ostensibly has no relation with the component of the cavity. This paper demonstrates the potential relationships between the unique structure of the calix[4]arene-based ligands and selectivity performance for the design of ion-selective electrodes.     

多吡啶钴(Ⅲ)配合物与Zn2+形成的新型“关-开”荧光探针

近十几年来,对小分子过渡金属配合物与大分子DNA键合与识别机理的研究一直是国际上生物无机化学领域十分活跃的研究课题[1￣3],已发展了一系列具有特定功能的配合物,如DNA结构探针和DNA荧光探针等。与其他类型的金属配合物相比,八面体过渡金属多吡啶配合物具有丰富的光化学和光物理信息,当这些配合物与DNA相互作用时,由于结构匹配或微环境的差异,配合物的光谱特征会出现不同程度的改变,从而达到对DNA的检测。传统的DNA荧光探针有[Ru(bpy)2dppz]2 和[Ru(phen)2dppz]2 (bpy=2,2′-联吡啶,phen=1,10-菲咯啉,dppz=二吡啶[3,2-a∶2′,3′…     

Water-soluble para-Sulfonated 1,2;3,4-Calix[4]arene-biscrowns in the 1,2-Alternate Conformation

The preparation of a series of p-sulfonated 1,2;3,4-calix[4]arene-biscrowns in the 1,2-alternate conformation is reported. These compounds are of two types:symmetrical p-sulfonated 1,2;3,4-calix[4]arene-biscrowns in which the two crown loops are the same and unsymmetrical p-sulfonated1,2;3,4-calix[4]arene-biscrowns in which the two crown loops are different. The X-ray structures of two synthetic intermediates are given. Preliminary complexation studies showed the ligands to present pronounced Cs⁺/Na⁺ selectivities.     

Preparation of the novel fluorine-18-labeled VIP analog for PET imaging studies using two different synthesis methods

Vasoactive intestinal peptide (VIP) receptors are expressed on various tumor cells in much higher density than somatostatin receptors, which provides the basis for radiolabeling VIP as tumor diagnostic agent. However, fast proteolytic degradation of VIP in vivo limits its clinical application. With the aim to develop and evaluate new ligands for depicting the VIP receptors with positron emission tomography (PET), the structure modified [R^8,15,21, L¹⁷]-VIP analog was radiolabeled with ¹⁸F using two different methods. With the first method, N-4-[¹⁸F]fluorobenzoyl-[R^8,15,21, L¹⁷]-VIP ([¹⁸F]FB-[R^8,15,21, L¹⁷]-VIP 7) was produced in a decay-corrected radiochemical yield (RCY) of 33.6 ± 3%, a specific radioactivity of 255 GBq/μmol (n = 5) within 100 min in four steps. Similarly, N-4-[¹⁸F](fluoromethyl)-benzoyl-[R^8,15,21, L¹⁷]-VIP ([¹⁸F]FMB-[R^8,15,21, L¹⁷]-VIP 8) was synthesized in a RCY of 34.85 ± 5%, a specific radioactivity of 180 GBq/μmol (n = 5) within 60 min in only one step. The two products 7 and 8 were both shown good stability in HSA. Moreover, the low bone uptakes of 7 and 8 in vivo of mice showed good defluorination stability.     

Kinetic and Mechanistic Studies on [Zn(II)-Gly-Phe]+–Ninhydrin Reaction in Aqueous and Cationic CTAB Surfactant Micelles

The rates of reaction between metal-dipeptide complex ([Zn(II)-Gly-Phe]⁺) and ninhydrin have been determined in aqueous and aqueous–cationic micelles of cetyltrimethylammonium bromide (CTAB) at 70°C and pH 5.0. The rate data indicate that the reaction follows the template reaction mechanism in both the media. The reaction followed a first-order and fractional-order kinetics with respect to [Zn(II)-Gly-Phe]⁺ and [ninhydrin], respectively, in the excess of ninhydrin over [Zn(II)-Gly-Phe]⁺. The rate constant is affected by [CTAB] changes and maximum rate enhancement is approximately three-fold. CTAB micelles decrease the activation enthalpy and make the activation entropy less negative. Quantitative kinetic analysis of rate constant (k _ψ)–[CTAB] data was performed on the basis of pseudophase model of the micelles (proposed by Menger and Portnoy and developed by Bunton). The values of binding constants K _S for [Zn(II)-Gly-Phe]⁺ and K _N for ninhydrin with micelles are calculated with the help of observed kinetic data. The results obtained in micellar medium are treated quantitatively on the basis of pseudophase model.     

The dimerization and photochemical rearrangement of pentacyclo-[5.4.0.0.0.0]undecane-8-thione

Pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecan-8-one 1 is readily sulfurated into pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane-8-thione 2 with Lawesson’s reagent in dry THF. Upon standing at ambient temperature the thione 2 formed the corresponding thio-dimer 3 within 10 days. When the thio-dimer 3 was exposed to oxygen and ultraviolet light an unexpected photochemical oxidation and rearrangement took place to form the stable disulfenate 5.     

Synthesis of [F]xenon difluoride as a radiolabeling reagent from [F]fluoride ion in a micro-reactor and at production scale

[¹⁸F]Xenon difluoride ([¹⁸F]XeF₂), was produced by treating xenon difluoride with cyclotron-produced [¹⁸F]fluoride ion to provide a potentially useful agent for labeling novel radiotracers with fluorine-18 (t_1/2 = 109.7 min) for imaging applications with positron emission tomography. Firstly, the effects of various reaction parameters, for example, vessel material, solvent, cation and base on this process were studied at room temperature. Glass vials facilitated the reaction more readily than polypropylene vials. The reaction was less efficient in acetonitrile than in dichloromethane. Cs⁺ or K⁺ with or without the cryptand, K 2.2.2, was acceptable as counter cation. The production of [¹⁸F]XeF₂ was retarded by K₂CO₃, suggesting that generation of hydrogen fluoride in the reaction milieu promoted the incorporation of fluorine-18 into xenon difluoride. Secondly, the effect of temperature was studied using a microfluidic platform in which [¹⁸F]XeF₂ was produced in acetonitrile at elevated temperature (≥85 °C) over 94 s. These results enabled us to develop a method for obtaining [¹⁸F]XeF₂ on a production scale (up to 25 mCi) through reaction of [¹⁸F]fluoride ion with xenon difluoride in acetonitrile at 90 °C for 10 min. [¹⁸F]XeF₂ was separated from the reaction mixture by distillation at 110 °C. Furthermore, [¹⁸F]XeF₂ was shown to be reactive towards substrates, such as 1-((trimethylsilyl)oxy)cyclohexene and fluorene.     

Functionalization of one or two methyl groups in the [Cp*<Subscript>2</Subscript>RuBr]<Superscript>+</Superscript>Br<Superscript>−</Superscript> complex in the reaction with bromine

The reaction of [Cp*₂RuBr]⁺Br⁻ with bromine in CH₂Cl₂ (CD₂Cl₂) in an inert atmosphere at room temperature produces the complexes [Cp*Ru(Br)C₅Me₄CH₂Br]⁺Br₃ ⁻ (syn conformer), [Cp*Ru(Br)C₅Me₃(CH₂Br)₂]⁺ (syn and anti conformers), and [Ru(Br)(C₅Me₄CH₂Br)₂]⁺ (syn conformer). All complexes were characterized by ¹H and ¹³C NMR spectroscopy; the former complex, by elemental analysis. These complexes were also prepared by the reaction of [Cp*RuC₅Me₄CH₂]⁺BF₄ ⁻ with bromine in CH₂Cl₂. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2712–2718, December, 2005.