- Black hybrid iodobismuthate containing linear anionic chains
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Three hybrid 1,1′-(1,n-alkanediyl)bis(4-methylpyridinium) iodobismuthates 1-3 were prepared by a facile solution route and showed thermal stability in air up to 230 °C. The structures of solids 1 and 3 contain zero-dimensional anions, and the structure of 2 contains one-dimensional linear anionic chains [BiI5]n2n-. Photoluminescence (PL) in the spectral range between 600 and 750 nm was observed for 1 and 2. DFT calculations and optical studies confirmed that compounds 1-3 are semiconductors with band gaps of 1.73-2.10 eV, which correspond with their intense black (for 2) or red (for 1 and 3) colors. The optical absorption of 2 in the red spectral range is primarily due to charge transfer from the I5p orbitals at the top of the valence band to the Bi6p orbitals at the bottom of the conduction band.
- Kotov, Vitalii Yu.,Ilyukhin, Andrey B.,Korlyukov, Alexander A.,Smol'Yakov, Alexander F.,Kozyukhin, Sergey A.
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- Crystal structure and Hirshfeld surface analysis of 1,2-ethylene-bis (para-methyl pyridinium) dichromate as a new selective and mild agent in oxidation of alcohols
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1,2-Ethylene-bis(para-methyl pyridinium) dichromate, (C 14 H 18 N 2) [Cr 2 O 7 ], is used as a new oxidizing agent in conversion of some alcohols to their corresponding carbonyl compounds in CH 3 CN solvent and also under solvent-free conditions. In both procedures, high conversion percentages are observed. However, a much shorter reaction time is achieved in solvent-free conditions. For allylic alcohols, the C = C bond is not oxidized and the examined saturated alcohol in this work (i.e. cyclo-hexanol) remains intact, which illustrates the mild nature of reagent used. The structure of the reagent is investigated by single-crystal X-ray diffraction analysis. The C–H · · · O and O · · · π interactions are the most important features of crystal packing, which are visualized by the Hirshfeld surface map.
- Gholizadeh, Mostafa,Pourayoubi, Mehrdad,Housaindokht, Mohammad Reza,Amiri Rudbari, Hadi,Farimaneh, Masoumeh,Saneei, Anahid,Bruno, Giuseppe
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p. 555 - 567
(2019/05/16)
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- Synthesis, thermal stability, crystal structure and optical properties of 1,1′-(1,n-alkanediyl)bis(4-methylpyridinium) bromobismuthates
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Four hybrid 1,1′-(1,n-alkanediyl)bis(4-methylpyridinium) bromobismuthates, namely (PiC2)2Bi2Br10 (1), PiC4(H5O2)BiBr6·2H2O (2), (PiC5)2Bi2Br10 (3) and (PiC6)2(H5O2)Bi2Br11 (4), were prepared by a facile solution method. The crystal structures of 1 and 3 contain zero-dimensional Bi2Br10 anion units. A 2-D network structure consisting of {H5O2}[BiBr6]·2H2O interconnected by hydrogen bonds was found in 2 and a 1-D network structure consisting of {H5O2}[Bi2Br11] was observed in 4.
- Kotov, Vitalii Yu.,Ilyukhin, Andrey B.,Simonenko, Nikolai P.,Kozyukhin, Sergey A.
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p. 122 - 126
(2017/09/11)
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- A versatile template for the formation of [2]pseudorotaxanes. 1,2-Bis(pyridinium)ethane axles and 24-crown-8 ether wheels
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Linear 1,2-bis(pyridinium)ethane 'axles' and macrocyclic 24-membered crown ether 'wheels' (24C8, DB24C8 and DN24C8) combine to form [2]pseudorotaxanes. These interpenetrated adducts are held together by N+...O ion-dipole interactions, a series
- Loeb, Stephen J.,Tiburcio, Jorge,Vella, Sarah J.,Wisner, James A.
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p. 667 - 680
(2007/10/03)
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- Kinetics and mechanism of the formation of N-vinyl pyridinium cations in elimination reactions in aqueous base
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The rates of the elimination reactions of N-(2-bromoethyl) pyridinium cations (1) and N,N'-ethylene bispyridinium dications (3) to give the corresponding N-vinyl pyridinium cations (2) have been measured spectrophotometrically in basic aqueous solutions (ionic strength 0.1, 25 deg C) for a variety of substituents in the pyridine rings of each of these classes of pyridinium cation.The reaction kinetics are first order in 1 or 3 and first order in hydroxide ion.Bronsted-type plots of the second-order rate constants (kOH) as a function of the basicity (as pKBH) of the corresponding substituted pyridine are nonlinear for each of 1 and 3 and can be interpreted in terms of E1cb reaction mechanism.For 1, the Bronsted-type plot displays two distinct ''concave down'' linear regions; rate-determining deprotonation for pKBH > 5.16 (slope = -0.30), and a change in rate-determining step to bromide ion departure for pKBH > 5.16 (slope -0.58).For 3, the Bronsted-type plot appears to be smoothly curved for symmetrically disubstituted bispyridinium dications, as a consequence of the multiple substituent effects upon each step of the E1cb reactions of these dications.However, log kOH for 3 is a smooth linear function of the previously reported log kOH for the E1cb reactions of N-(2-cyanoethyl) pyridinium cations over a range in which a change in rate-determining step has been directly demonstrated for these latter cations.Thus a change in rate-determining step as a function of pyridine basicity is also required within the E1cb mechanism for 3.The E1cb reactions of 1 are approximately 104-fold faster than the corresponding hydroxide ion catalyzed E2 eliminations from 2-phenylethyl bromides that are isoelectronic with 1.
- Bunting, John W.,Toth, Andrea,Kanter, James P.
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p. 1195 - 1203
(2007/10/02)
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- Synthesis of some bischromophoric dyes containing nonabsorbing flexible bridge
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Bis-chromophoric dyes (9-68) having nonabsorbing flexible bridges have been synthesised by the condensation of 1,1'-alkylenebis (α/γ picolinium bromides) (1-8) with aromatic aldehydes.
- Mishra, J K,Behera, P K,Parida, S K,Mishra, B K
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p. 118 - 122
(2007/10/02)
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- Photosensitive Cyclomer Formation of 1,1'-(1,2-Ethanediyl)bis(pyridinyl) Diradical and Its Derivatives
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Two-electron reduction of 1,1'-(1,1-ethanediyl)bis(pyridinium) dibromide (1a) with sodium amalgam affords the meso and dl cyclomers formed by intramolecular cyclization of the diradical (3a).The meso cyclomer (4a) is thermally converted into the dl cyclomer (5a), while inversely 5a is photolytically converted into 4a.Reduction of the 4,4'-dimethyl and 4,4'-di-tert-butyl derivatives (1b and 1c, respectively) of 1a similarly affords the corresponding meso (4b and 4c) and dl (5b and 5c) cyclomers, which are convertible to each other.One-electron reduction products (2band 2c) of 1b and 1c are detected at room temperature as shown by the ESR spectra in acetonitrile, which exhibited intramolecular rapid spin exchange between the two pyridine rings in the cation radical.The activation energy for the meso to dl conversion was obtained by NMR spectroscopy to be 22.4, 26.9, and 28.8 kcal*mol-1 for 4a-c, respectively.Photodissociation of the cyclomers gives the diradicals, which were characterized by the ESR triplet spectra at -196 deg C with the zero-field parameters: D = 0.0222 and E = 0.0012 cm-1 for 3a, D = 0.0210 and E = 0.0008 cm-1 for 3b, and D = 0.0219 and E = 0.0016 cm-1 for 3c.Calculations of the D value suggest that the dihedral angle of the NCH2CH2N group of the diradical ina rigid glass is about 950 for these three diradicals.
- Ikegami, Yusaku,Muramatsu, Takashi,Hanaya, Kaoru
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p. 5782 - 5787
(2007/10/02)
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- Properties of Conducting 7,7,8,8-Tetracyano-p-quinodimethane Salts with 1,n-Bisalkane Dication Homologues
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1,n-Bisalkane-(TCNQ)m salts are nonstoichiometric with m varying from 3.4 to 4.7 for n=2-7.The conductivity (compressed pellet, four-probe method, in the temperature range 230-310 K) varies with the alkyl chain length of the dications, the highest being 2 S cm-1, for n=4 and m=4.6, with the lowest activation energy (0.033 eV).FT-IR and electronic absorption spectra are presented and discussed.On the basis of the results observed, a possible structure is proposed for these homologous salts.
- Yu, L. J.,Lang, F. C.,Lee, J. S.
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p. 4543 - 4546
(2007/10/02)
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