Synthesis of isomeric indolobenzo[b]thiophenes

Indolo[6,5-d]benzo[b]thiophene, indolo[4,5-d]benzo[b]thiophene, indolo[5,6-d]benzo-[b]thiophene, and indolo[5,4-d]benzo[b]thiophene were obtained from the 2- and 3-dibenzothienylhydrazones by means of the Fischer reaction. The structures of the compounds obtained were proved by their PMR, IR, UV, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 203–208, February, 1980.     

Local dense structural heterogeneities in liquid water from ambient to 300 MPa pressure: evidence for multiple liquid-liquid transitions.

Difference and double-difference near-infrared DO-D and HO-H stretching overtone (2nuOD and 2nuOH) spectroscopy and a rigorous (physically substantiated) band deconvolution technique were applied to reveal three different kinds of inherent (interstitial) structures of liquid water, which determine its high density (compared to ice lh under ambient conditions), its compressibility (under hydrostatic pressure, up to 300MPa), and its high fragility (manifested under temperature variation). Our data processing allowed the rigorous discrimination of up to six vibrational components. On the basis of an extensive comparative analysis combined with available structural data (X-ray and neutron scattering) and molecular dynamics (MD) simulations for liquid water, as well as with experimental and computed data for small non-tetrahedrally arranged water clusters, the major four components could be ascribed to: i) The basic lh icelike substructure; ii) the temperature-dependent remote interstitial "defects" due to tetrahedral displacements (primarily responsible for transport properties); iii) the interstitial "defects" most probably arranged in quasiplanar noncyclic tetramers (totally absent in the ice structure); and iv) the interstitial "defects" formed with increasing pressure, probably arranged in cubic water octamers and composed of two pairs of noncyclic and cyclic tetramer fragments. The latter structures include, essentially, bent hydrogen bonds stabilized by resonance effects.     

Synthesis and Characteristics of Tetracyclic Systems of Benzo[b]furoindoles and Their Derivatives. (Review)

Published data on the nomenclature, structure, synthesis, and chemical characteristics of benzo[b]furoindoles with a pyrrole ring fused at various positions in relation to initial tricyclic system of dibenzofuran are reviewed.     

Charge-transfer mechanism for cytochrome c adsorbed on nanometer thick films. Distinguishing frictional control from conformational gating

Using nanometer thick tunneling barriers with specifically attached cytochrome c, the electron-transfer rate constant was studied as a function of the SAM composition (alkane versus terthiophene), the omega-terminating group type (pyridine, imidazole, nitrile), and the solution viscosity. At large electrode-reactant separations, the pyridine terminated alkanethiols exhibit an exponential decline of the rate constant with increasing electron-transfer distance. At short separations, a plateau behavior, analogous to systems involving -COOH terminal groups to which cytochrome c can be attached electrostatically, is observed. The dependence of the rate constant in the plateau region on system properties is investigated. The rate constant is insensitive to the mode of attachment to the surface but displays a significant viscosity dependence, change with spacer composition (alkane versus terthiophene), and nature of the solvent (H(2)O versus D(2)O). Based on these findings and others, the conclusion is drawn that the charge-transfer rate constant at short distance is determined by polarization relaxation processes in the structure, rather than the electron tunneling probability or large-amplitude conformational rearrangement (gating). The transition in reaction mechanism with distance reflects a gradual transition between the tunneling and frictional mechanisms. This conclusion is consistent with data from a number of other sources as well.     

Pyrrolocarbazoles. 1. Synthesis and some properties of 3h-pyrrolo[2,3-c]carbazole

3H-Pyrrolo[2,3-c]carbazole was synthesized from 3-aminocarbazole by means of the Japp-Klingemann reaction. The structure of this heterocycle was proved by a study of the absorption, fluorescence, IR, PMR, and mass spectra. A great analogy between 3H-pyrrolo[2,3-c]carbazole and carbazole as compared with indole in the case of formation of hydrogen bonds was observed; this was indicated by the shift of the absorption band of the NH group in the IR spectra of the investigated compound in the presence of various proton-acceptors.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 790–793, June, 1979.     

Synthesis and reductive reactions of 2,3-dioxo-2,3-dihydrobenzo[<Emphasis Type="Italic">b</Emphasis>]furo[2,3-<Emphasis Type="Italic">f</Emphasis>]-, -[2,3-<Emphasis Type="Italic">g</Emphasis>]-, and -[3,2-<Emphasis Type="Italic">e</Emphasis>]indoles

The Sandmeyer reaction was used to prepare 2,3-dioxo-2,3-dihydrobenzo[b]furoindoles which could be reduced with diborane or with complex hydrides to give the corresponding unsubstituted as well as the 3-hydroxybenzo[b]furoindoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 11, pp. 1683–1689, November, 2004.     

Two-electron transfer for Tl(aq)(3+)/Tl(aq)(+) revisited. Common virtual [Tl(II)-Tl(II)](4+) intermediate for homogeneous (superexchange) and electrode (sequential) mechanisms

Homogeneous and electrochemical two-electron transfers within the Tl(aq)(3+)/Tl(aq)(+) couple are considered on a common conceptual basis. For the 2 equiv electrochemical reduction of Tl(aq)(3+) to Tl(aq)(+), the intermediate state with a formal reduction potential, E(1) = 1.04 +/- 0.10 V vs the normal hydrogen electrode, was detected, different from the established value of 0.33 V for a Tl(3+)/Tl(2+) couple. Examination of obtained electrochemical (cyclic voltammetry (CV) and rotating disk electrode techniques, along with the CV-curve computer simulation procedure) and literature data indicate that the detected formal potential cannot be the property of electrode-adsorbed species, but rather of the covalently interacting dithallium intermediate [Tl(II)-Tl(II)](4+) located at the outer Helmholtz plane. The analysis of microscopic mechanisms, based on the recent hypothesis of H. Taube and the Marcus-Hush theory extended by Zusman and Beratan, and Koper and Schmickler, revealed that the homogeneous process most probably takes place through the superexchange inner-sphere two-electron-transfer mechanism, via an essentially virtual (undetectable) dithallium intermediate. In contrast, the electrochemical process occurs through a sequential mechanism, via the rate-determining step of Tl(aq)(2+) ion formation immediately followed by activationless formation of the metastable (CV-active) dithallium state. The second electrochemical electron-transfer step is fast, and shows up only in the peak height (but not in the shape) of the observed CV cathodic wave. The anodic wave for a microscopically reverse process of the oxidation of Tl(aq)(+) to Tl(aq)(3+) cannot be observed within the considered potential range due to the blocking of through-space electron transfer by the competitor process of ion transfer to the electrode.     

New method for the synthesis of indole-and benzothiophene-containing condensed systems

A new method is described for the synthesis of the heterocyclic systems of benzo[b]thiophenoindoles from the respective isomeric amino acids with amino groups at positions 2 and 3. The method makes it possible to produce the tetracyclic systems with both angular and linear structure. The classical Fischer reaction served as model for such transformations. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 361–367, March, 2007.