Mass-spectrometric distinction of linear and angular 2,2'-dimethyl-3'-oxo-dihydropyranocoumarins

Summary A chromatospectrophotometric method for determining ferutinin and teferin + ferutin in a preparation has been developed.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 616–618, September–October, 1976.     

Mass-spectrometric distinction of linear and angular 3′,4′-dihydroxy-substituted dihydropyranocoumarins and their derivatives

Summary The dissociative ionization of four linear dihydropyranocoumarins and three of their deuterium analogs has been studied. It has been shown that by means of the mass-spectrometric method it is possible to determine the type of linkage of the dihydropyrane ring with the coumarin ring for each pair of linear and angular isomers in this series of substances, to determine the presence of hydroxy or methoxy groups in position 4 of their molecules, and to distinguish the presence of the acyl residue of senecioic acid from that of angelic acid in the products of the partial hydrolysis and methanolysis of 3,4-diacyloxydihydropyranocoumarins.M. V. Lomonosov Moscow State University. Patrice Lumumba University of Peoples' Friendship, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 38–44, January–February, 1977.     

Experimental and computational studies of nuclear substituted 1,1'-dimethyl-2,2'-bipyridinium tetrafluoroborates

The synthesis and spectral properties of a new 2,2'-bipyridinium ion, 1,1'-dimethyl-4,4'-(dimethylamino)-2,2'-bipyridinium bis(tetrafluoroborate) are reported. Rotation of the dimethylamino group is slow at room temperature on the 400 MHz 1H and 100 MHz 13C NMR time scales. Complete line shape fit of the dynamically broadened NMR spectra was used to determine the activation barriers for this process. The first complete set of UV-vis spectra for a 2,2'-bipyridinium dication and its one- and two-electron reduced products was reported. TD-DFT calculations were used to help assign the origin of the long wavelength absorptions in these species. The effect of substituents on the energies and conformational potential energy surfaces of all three species were also examined using the B3LYP/6-31G(d) computational method.     

Synthesis of novel nematic liquid crystals containing 3,3'-dimethyl-2,2'-bipyridyl

Liquid-crystalline 3,3′-dimethyl-2,2′-bipyridyl derivatives with long 4-(alkoxyphenyl)ethynyl (-C≡C-C₆H₄-OR) groups in the 5,5′-positions were synthesized by palladium-catalysed crosscoupling reactions. The compounds exhibit exclusively nematic behaviour; for example, the hexyl derivative showed a nematic phase over the temperature range 145.2–205.0°C. On increasing the length of the terminal chain, the transition temperatures were lowered; for example, the hexadecyl derivative was nematic in the range 117.0–126.8°C.     

Synthesis of novel nematic liquid crystals containing 3,3'-dimethyl-2,2'-bipyridyl

Liquid-crystalline 3,3'-dimethyl-2,2'-bipyridyl derivatives with long 4-(alkoxyphenyl)ethynyl (-C=C-C₆H₄-OR) groups in the 5,5'-positions were synthesized by palladium-catalysed crosscoupling reactions. The compounds exhibit exclusively nematic behaviour; for example, the hexyl derivative showed a nematic phase over the temperature range 145.2-205.0°C. On increasing the length of the terminal chain, the transition temperatures were lowered; for example, the hexadecyl derivative was nematic in the range 117.0-126.8°C.     

Crystal chemistry of the 4,4'-dimethyl-2,2'bipyridine/copper bromide system

The reaction of 4,4'-dimethyl-2,2-bipyridine (henceforth dmbp) with copper(I) and/or copper(II) bromide under a wide variety of conditions has led to the isolation of 10 different crystalline materials. These include one Cu(I) salt, [Cu(dmbp)(2)]Br (a distorted tetrahedral Cu species and a lattice Br(-) ion); two mixed valence Cu(I,II) compounds, [Cu(dmbp)(2)Br][CuBr(2)] (discrete 5-coordinated Cu(II) and linear Cu(I) species) and Cu(dmbp)(2)BrCu(2)Br(3) (linked 5-coordinate Cu(II) and trigonal planar Cu(I) species); and seven Cu(II) compounds, (dmbp)CuBr(2) (stacked planar monomers), [(dmbp)CuBr(2)](2)(five coordinate bibridged dimers), (dmbp)Cu(2)Br(4) (stacked planar bibridged dimers), (dmbp)CuBr(2)(DMSO) (five coordinate monomers), [Cu(dmbp)(2)Br]OH.5(1)/(2)H(2)O and [Cu(dmbp)(2)Br](Br/OH).5(1)/(2)H(2)O (five coordinate monomers), and (dmbpH(2))CuBr(4).H(2)O (distorted tetrahedral monomers). The crystal structure determinations of these materials are reported. A common thread in their structural chemistry is the supramolecular architecture developed through interdigitation of the dmbp rings on neighboring molecular species. The interdigitation leads to layer structures in many of the materials. The distances between the interdigitated dmbp rings are in the range 3.4-3.7 A. The Cu(dmbp)(2)Br(+) species exhibits an exceptionally large distortion from tetrahedral geometry due to deviation of the dihedral angle between the mean planes of the Cu(dmbp) fragments from 90 degrees. The Cu(dmbp)(2)Br(+) cations have distorted trigonal bipyramidal geometry, the Br(-) ion occupying an equatorial position. The length of the Cu-Br bond in the Cu(dmbp)(2)Br(+) species is correlated with the change in dihedral angle between the planes of the two dmbp ligands. The mono-dmbp complexes show a greater variation in coordination geometry for the Cu(II) species, including distorted trigonal bipyramidal and augmented square planar 4 + 1 and 4 + 2 coordination.     

Syntheses, characterizations, and properties of electronically perturbed 1,1'-dimethyl-2,2'-bipyridinium tetrafluoroborates

[reaction: see text] The syntheses of three new 2,2'-bipyridinium tetrafluoroborate sensitizers are reported. Their preliminary electrochemical and photophysical properties are compared to the properties of the more widely used pyrylium cation sensitizers. In addition, the first examples of triplet-triplet absorption spectra of 2,2'-bipyridinium ions are presented.     

六氟磷酸二(2,2'-联吡啶)·(4,4'-二甲基-2,2'-联吡啶) 合钌(Ⅱ)的二维核磁共振谱分析

用一维NMR方法研究了电化学发光物质六氟磷酸二(2,2'-联吡啶)·(4,4'-二甲基-2,2'-联吡啶)合钌(Ⅱ)的立体结构,借助二维1H-1H COSY和1H-13C COSY实验技术对其氢谱和碳谱进行了完全的归属,并给出了其氢谱和碳谱的化学位移值.     

Synthesis of linear and angular anthraquinonoisothiazol-3-ones,their S-oxides,and S,S-dioxides

2-Methyltetrahydroanthra[2,3-d]isothiazole-3,5,10-trione and 2-R-tetrahydroanthra[2,1-d]isothiazole-3,6,11-triones were synthesized by the reactions of 3-chloro-9,10-dioxo-9,10-dihydroanthracene-2-carboxamide and 1-nitro-9,10-dioxo-9,10-dihydroanthracene-2-carboxamide with alkanethiols followed by cyclization of the resulting alkylthioamides into isothiazolones under the action of SO₂Cl₂. The products were oxidized to give the corresponding S-oxides and S,S-dioxides.     

Chiral distinction in square planar Pt and Pd complexes of 2,2′-bipyridine derivatives

A computational study of square planar organometallic complexes formed by the ligand 2,2′-bipyridine and all its possible difluoro derivatives in analogous position of the aromatic rings (n,n′-difluoro-2,2′-bipyridine, where n = n′ = 3, 4, 5, and 6) and two M–X₂ (M = Pd and Pt and X = F, Cl, Br, and I) fragments has been carried out amounting to a total of 80 complexes. Relationships have been found between the chiral distinction energy and the different chemical moieties present. Using the statistical Free-Wilson method, the relative energies between the diastereomeric complexes have been correlated with the position of the substituent, the counter anion, and the central metal cation.     

Large dielectric susceptibility associated with proton transfer in a supramolecular structure of chloranilic acid and 5,5'-dimethyl-2,2'-bipyridine

A 1:1 adduct of chloranilic acid with 5,5'-dimethyl-2,2'-bipyridine, in which two kinds of molecules are connected by infinite hydrogen bond chains, exhibits a distinct dielectric phase transition when cooled. Below T(c)(=318 K) the hydrogen atoms participating in hydrogen bonding undergo long-range ordering and form an antiferroelectric-like state, taking a single minimum potential in the high-temperature phase (T>T(c)) due to the bifurcate hydrogen bond system. The proton-transfer phenomenon was clearly observed by electron density distribution analysis using a maximum entropy method of synchrotron x-ray diffraction data.     

Mass-spectrometric behavior of N-substituted 2-methyl-3-acetyl pyrroles

In the dissociation of N-substituted derivatives of 2-methyl-3-acetylpyrroles by the action of electron impact, the methyl group splits off from the acetyl substituent, and then the exocyclic N-C bond is ruptured due to the preferential localization of the charge on the C₍₂₎-C₍₃₎ bond in the pyrrole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 776–778, June, 1987.     

Isomerization of linear to angular [3]phenylene and PAHs under flash vacuum pyrolysis conditions

[structure: see text]. Flash vacuum pyrolysis (FVP) of linear [3]phenylene affords its angular counterpart and the same mixture of polycyclic aromatic hydrocarbon isomers as that observed on FVP of angular [3]phenylene. A mechanism, supported by a 13C labeling study, is proposed to explain these results.     

Object-oriented synthetic approach toward angular and linear fused pyrazoloquinolines of biological importance with InCl3 catalyst

A simple and short approach for the synthesis of pyrazolo[3,4-b]quinoline (3a–3p) and pyrazolo[4,3-c]quinoline (6a–6 h) using various Lewis acid catalysts was developed. InCl₃ was found to be more effective in providing greater yield of products compared to Yb(OTf)₃, Sc(OTf)₃, SnCl₄, AlCl₃, TiCl₄, ZnCl₂, FeCl₃, and BF₃ · Et₂O. Moreover, a comparison of conventional and microwave methods has revealed that the latter method is more efficient compared to former one. Structures were confirmed by Fourier transform infrared, mass spectrometry, ¹H and ¹³C NMR, X-ray crystallography, and elemental analyses. All of the synthesized compounds were evaluated for α-glucosidase inhibitory activity. Compounds 3a, 3p, 3i, 3 h, 3k, 3o, and 3 g exhibited anti α-glucosidase inhibitory activity with IC₅₀ values of 57.5, 60.3, 65.9, 71.9, 80.8, 123.7, and 126.4 µM, respectively, which is quite comparable to the standard drug acarbose (IC₅₀ = 115.8 µM).