Pyrrole syntheses based on titanium-catalyzed hydroamination of diynes

Titanium-catalyzed hydroamination of 1,4- and 1,5-diynes by primary amines leads to imino-alkynes that undergo in situ 5-endo dig and 5-exo dig cyclization reactions, respectively. The products are 1,2,5-trisubsituted pyrroles accessed directly from readily available diyne starting materials.     

Imaging the long-range dipolar field in structured liquid state samples

We describe imaging experiments in which the pattern of the dipolar field generated by spatially modulated nuclear magnetization is directly visualized in simply structured phantoms. Two types of experiment have been carried out at 11.7 T using (1)H NMR signals. In the first, the field from a single spin species is imaged via its own NMR signal. In the second, the NMR signal from one spin species is used to image the field generated by a second species. The field patterns measured in these experiments correspond well with those calculated using simple theoretical expressions for the dipolar field. The results also directly demonstrate the spatial sensitivity of the signal generated using dipolar field effects, indicating that the range of the field depends upon the inverse of the spatial frequency with which the magnetization is modulated.     

Mechanistic analysis of anodic dissolution of cobalt in alkaline glycine solution

Journal of Solid State Electrochemistry - The kinetics of dissolution of Co in alkaline glycine solution under anodic conditions was investigated. Potentiodynamic polarization and electrochemical...     

Gradient echo single scan inversion recovery: application to proton and fluorine relaxation studies

Single scan longitudinal relaxation measurement experiments enable rapid estimation of the spin‐lattice relaxation time (T₁) as the time series of spin relaxation is encoded spatially in the sample at different slices resulting in an order of magnitude saving in time. We consider here a single scan inversion recovery pulse sequence that incorporates a gradient echo sequence. The proposed pulse sequence provides spectra with significantly enhanced signal to noise ratio leading to an accurate estimation of T₁ values. The method is applicable for measuring a range of T₁ values, thus indicating the possibility of routine use of the method for several systems. A comparative study of different single scan methods currently available is presented, and the advantage of the proposed sequence is highlighted. The possibility of the use of the method for the study of cross‐correlation effects for the case of fluorine in a single shot is also demonstrated. Copyright © 2015 John Wiley & Sons, Ltd.     

Hydrogenation of nitroarenes catalyzed by a dipalladium complex

A dipalladium complex [Pd₂( L )Cl₂](PF₆)₂ ( 2 ), via the substitution of (PhCN)₂PdCl₂ with 5‐phenyl‐2,8‐bis(6′‐bipyridinyl)‐1,9,10‐anthyridine ( L ) followed by the anion exchange, was found to be a good pre‐catalyst for the reduction of nitroarenes to yield the corresponding anilines under atmospheric pressure of hydrogen in methanol. This method provides a straightforward access to a diverse array of functionalized anilines, exhibiting a possible application in synthetic chemistry. The catalytic activity of this complex is enhanced by the di‐metallic system via the synergistic effect.     

Electrochemical impedance spectroscopic studies on niobium anodic dissolution in HF

Journal of Solid State Electrochemistry - The dissolution of niobium electrode in anodic regime in hydrofluoric acid was studied using electrochemical techniques. In the active region, complex...     

Structural,Electronic and Charge Transfer Studies of Highly Sensitive Fluorescent Probe 2-((E)-2-(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)phenol: Quantum Chemical Investigations

This article presents a facile synthesis of novel class of bluish-green fluorescent 2-((E)-2-(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)phenol [PPIVP] and their optical, electrochemical and thermal properties. Detailed photophysical and quantum chemical studies have been performed to elucidate the origin of the dual emission shifts. PPIVP undergo excited state intramolecular proton transfer (ESIPT) reaction leading a large Stoke’s shifted fluorescence emission from the phototautomer. The results of quantum chemical investigations not only confirmed the intramolecular charge transfer characteristics of the ESIPT tautomers but also provided a rational for the observed high fluorescence quantum efficiency in the solid state. The high photoluminescence quantum yield in the solid state is ascribed to twisted chromophores due to phenyl substituents at 1,2-position of the phenanthroimidazole ring which restricted intramolecular motion, leading to an optically allowed lowest optical transition without self quenching.     

First Total Synthesis of N‐(3‐Guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide

The first total synthesis of the α‐oxo amide‐based natural product, N‐(3‐guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide ( 3 ), isolated from aqueous extracts of hydroid Campanularia sp., has been achieved. The α‐oxo amide 12 , prepared via the oxidative amidation of 1‐[4‐(benzyloxy)phenyl]‐2,2‐dibromoethanone ( 9a ) with 4‐{[(tert‐butyl)(dimethyl)silyl]oxy}butan‐1‐amine ( 10a ), has been used as the key intermediate in the total synthesis of 3 as HBr salt. On the way, an expeditious total synthesis of polyandrocarpamide C ( 2c ), isolated from marine ascidian Polyandrocarpa sp., was carried out in four steps.