The chameleon-like nature of zwitterionic micelles: the intrinsic relationship of anion and cation binding in sulfobetaine micelles

The rate of specific hydrogen ion-catalyzed hydrolysis of 2-( p-heptoxyphenyl)-1,3-dioxolane and acid-base equilibrium of 4-carboxy-1-n-dodecylpyridinium in zwitterionic micelles of SB3-14, C14H29NMe2+(CH2)3SO3(-) are controlled by NaClO4, which induces anionic character and uptake of H3O+ in the micelles. Other salts, e.g., NaF, NaCl, NaBr, NaNO3, NaI, NaBF4, have similar, but smaller, effects on the uptake of H3O+. Salt effects upon zeta potentials of SB3-14 micelles, estimated by capillary electrophoresis, are anion specific, and the anion order is similar to that of the rates of acid hydrolysis and of acid-base equilibria. Fluorescence quenching shows that the micellar aggregation number is not very sensitive to added salts, consistent with electrophoretic evidence. These specific anion effects follow the Hofmeister series and are related to anion hydration free energies.     

Reactivity and models for anion distribution: specific iodide binding to sulfobetaine micelles

The reaction of I (-) with methyl naphthalene-2-sulfonate (MeONs) is accelerated by the micellized sulfobetaine surfactants N-decyl, N-dodecyl, N-tetradecyl, and N-hexadecyl- N, N-dimethylammonio-1-propanesulfonate. Concentrations of micellar-bound I (-) were determined by using ion-selective electrodes (ISE), and capillary electrophoresis. At low concentrations, I (-) incorporation fits Langmuir isotherms and is related to changes in micellar surface potentials. Rate effects of dilute KI are fitted quantitatively by a pseudophase model that describes I (-) binding in terms of a sorption isotherm, but at higher [KI], where the simple model predicts saturation, rates increase due to electrolyte invasion. This model considers transfer equilibria of both reactants between water and micelles and second-order rate constants in each pseudophase. Estimated second-order rate constants for reaction of MeONs with I (-) in the micellar pseudophase are 3.2- to 3.5-fold higher than the second-order rate constant, k 2w, in water, depending on surfactant structure and assumptions in the treatment.     

In Silico Mining of Conserved miRNAs of Indian Catfish <Emphasis Type="Italic">Clarias batrachus</Emphasis> (Linnaeus, 1758) from the Contigs,ESTs, and BAC End Sequences

MicroRNAs are small non-coding RNAs which play significant role in RNA interference. The present work deals with mining of the conserved miRNA and their target genes from the contigs, ESTs, and BAC end sequences of commercially important catfish, Clarias batrachus, from India. A total of 138, 1 and 1 conserved pre-miRNA sequences, were mined from the contigs, ESTs, and BAC end sequences, respectively. The analysis of families of the conserved pre-miRNA revealed conservation of the fish-specific family mir-430 and other important families, such as mir-455, let-7, mir-133, and mir-137. The mir-455 is involved in hypoxia signaling, let-7 family represents potential anti-tumor molecules involved in human cancer therapy, whereas mir-133 and mir-137 have high therapeutic potentials. Using an alternate computational in silico approach, mining of mature miRNAs resulted in identification of 210 mature miRNAs from contigs, 1 from EST, and 2 each from forward as well as reverse BAC end sequences. Target prediction of these putative miRNAs resulted in the identification of 66,758 and 18,747 target genes in C. batrachus and Danio rerio, respectively. Functional annotation of these miRNAs indicated their involvement in diverse biological functions. The findings of the present study can serve as a valuable resource for further functional genomics studies in C. batrachus.     

Cobalt‐Catalyzed C−H Nitration of Indoles by Employing a Removable Directing Group

A mild and efficient C(sp²)?H nitration of 3‐substituted indoles, by using the economical and non‐toxic cobalt nitrate hexahydrate [Co(NO₃)₂ ? 6 H₂O] as a catalyst and tert‐butyl nitrite (TBN) as the nitro source, is reported. This approach provides a unique methodology involving a site‐selective C?N bond formation for preparation of C‐2 substituted nitro indoles. Utilization of the tBoc as the removable directing group enhances the synthetic utility of the method.     

Chemoselective Oxidation of Benzylic Alcohols with Solid Supported CrO3/TBHP Under Microwave Irradiation

The efficient use of microwave energy coupled with dry media technique for the oxidation of benzylic alcohols using catalytic CrO₃ and TBHP has been effectively projected     

Dephosphorylation of paraoxon by hydroxamate ions in micellar media

The rate-surfactant concentration profiles for the reaction of the insecticide paraoxon with hydroxamate ions (R(CO)·NHO⁻, R = CH₃, R = C₆H₅, R = 2-HOC₆H₄) in aqueous solutions of cetyltrimethylammonium salts, CTAX (X⁻ = Br⁻, Cl⁻, SO₃H⁻) have been measured at pH 11.0 at 30 °C. All these profiles are typical of micelle-assisted bimolecular reactions involving interfacial ion exchanges. The salicylhydroxymic acid-CTACl combination is most reactive.     

Non-iterative bi-directional wave propagation method for treating reflections

We describe a bi-directional wave propagation method based on the split-step non-paraxial collocation method. The method is non-iterative and does not require any matrix inversion or diagonalization. The method is applied to reflections from waveguide discontinuities, terminations as well as multilayer reflecting structures. The results obtained compare very well with those obtained using computationally intensive methods such as the finite element method (FEM) and the finite-difference time-domain (FDTD) method.     

Synthesis of Ferrocene 1,3-Derivatives by Distal C−H Activation**

The third position of cyclopentadienyl ring of a monosubstituted ferrocene has remained as an inaccessible chemical space for direct functionalization. Until recently, functionalizing the C(3)-position while bypassing the predominantly active C(2)-position is the most challenging task. Herein, we report a distal C−H functionalization of monosubstituted ferrocenes using an easily removable directing group with precise site-selectivity, under a Pd^II/ mono-N-protected amino-acid ligand catalytic system. The robust synthetic protocol leads to the synthesis of ferrocene 1,3-derivatives with broad scope in olefins while functionalizing ferrocenyl methylamine in moderate to good yields via a highly strained ferrocene appended 12-membered palladacycle intermediate.