Fabrication of polyindene and polyindole nanostructures

One-dimensional (1D) nanostructures of fused ring polymeric systems: polyindene (PIn) and polyindole (PInd) were fabricated onto glass substrates using a chemical vapor deposition (CVD) method. Morphology of fabricated PIn and PInd structures studied using Olympus microscope reveals formation of 1D straight tubular, smooth and fluorescent nanostructures. The results obtained were further correlated with scanning electron microscopic (SEM) studies of PIn and PInd nanostructures, indicating appearance of fine nanothread entangled network (having diameter ∼ 50 nm) for PIn, and well-defined, straight and aligned nanotubes (having diameter ∼ 60 nm) for PInd. A comparative study on the morphology/dimensions of fabricated PIn and PInd nanostructures with the nanosized PIn and PInd structures obtained by oxidative synthetic routes is also discussed. The structural composition of fabricated PIn and PInd nanostructures is confirmed by Fourier transform infrared (FTIR) spectroscopy, thereby indicating existence of all infrared markers corresponding to the characteristic bands present in PIn and PInd. The study suggests that the fabricated PIn and PInd nanodimensional structures may find potential applications in the field of nanotechnology.     

Effect of Electrolyte Concentration on the Stern Layer Thickness at a Charged Interface

The chemistry and physics of charged interfaces is regulated by the structure of the electrical double layer (EDL). Herein we quantify the average thickness of the Stern layer at the silica (SiO₂) nanoparticle/aqueous electrolyte interface as a function of NaCl concentration following direct measurement of the nanoparticles’ surface potential by X‐ray photoelectron spectroscopy (XPS). We find the Stern layer compresses (becomes thinner) as the electrolyte concentration is increased. This finding provides a simple and intuitive picture of the EDL that explains the concurrent increase in surface charge density, but decrease in surface and zeta potentials, as the electrolyte concentration is increased.     

Cycloaddition of CS2 to N‐benzylaziridine to synthesize N‐benzylthiazolidine‐2‐thione: a novel reaction route proposed by DFT Study

N‐Benzylthiazolidine‐2‐thione is the key intermediate for the synthesis of pharmaceutically important compounds. A novel route for the synthesis of N‐benzylthiazolidine‐2‐thione through cycloaddition of CS₂ with N‐benzylaziridine in the presence of 1,3‐di‐tert‐butylimidazolium‐2‐dithocarboxylate ( catalyst I ) has been proposed by reliable computations performed within the formalism of density functional theory. The mechanism of the proposed reaction is similar to the cycloaddition of tertiary aziridines and carbon dioxide using a recyclable catalyst that is reported to provide access to 3‐substituted 2‐oxazolidones with excellent yield. Because the rate determining step needs to surmount a high energy barrier, the reaction route has been deciphered in high boiling solvent (1, 2‐ethanediol). The highlight of the mechanistic route detailed here is that the proposed pathway is a cyclic process that is exothermic in nature with the regeneration of the catalyst and involves simple reagents. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of anionic hypervalent cyclic selenenate esters: relevance to the hypervalent intermediates in nucleophilic substitution reactions at the selenium(II) center

The synthesis of a diaryl diselenide that contains 2,6‐dicarboxylic acid groups, 2,2′‐diselanediylbis(5‐tert‐butylisophthalic acid) ( 10 ), is described. Diselenide 10 undergoes intramolecular cyclization in methanol to form a cyclic selenenate ester, 5‐tert‐butyl‐3‐oxo‐3H‐benzo[c][1,2]oxaselenole‐7‐carboxylic acid ( 11 ). The cyclization reaction proceeds more rapidly in the presence of organic bases, such as pyridine, adenine, and 4,4′‐bipyridine, to form pyridinium 5‐tert‐butyl‐3‐oxo‐3H‐benzo[c][1,2]oxaselenole‐7‐carboxylate ( 14 ), adeninium 5‐tert‐butyl‐3‐oxo‐3H‐benzo[c][1,2]oxaselenole‐7‐carboxylate ( 15 ), and 4,4′‐bipyridiniumbis(5‐tert‐butyl‐3‐oxo‐3H‐benzo[c][1,2]oxaselenole‐7‐carboxylate) ( 16 ), respectively. However, 2,2′‐diselanediyldibenzoic acid ( 22 ) does not undergo cyclization under similar conditions. Structural studies on cyclic selenenate esters 14 – 16 revealed that the Se???O (COO^?) secondary distances (2.170, 2.075, and 2.176 Å) were significantly shorter than the corresponding Se???O distances (2.465, 2.472, and 2.435 Å) observed for the selenenate esters stabilized by the neutral donors (CHO, COOH, and COOEt). ¹H, ¹³C, and ⁷⁷Se NMR spectroscopy of compounds 11 and 14 – 16 reveal that the aryl protons of compound 11 and the organic cations of compounds 14 – 16 exchange between the two carboxylate groups via a hypercoordinate intermediate. The corresponding hypercoordinate intermediate ( 14 b , pyridinium selenuranide) for compound 14 was detected at low temperatures using ⁷⁷Se NMR spectroscopy. The presumed hypercoordinate intermediates in the carboxylate‐exchange reactions at the selenium(II) center for a set of model reactions were optimized using DFT‐B3LYP/6–311+g(d) calculations and their structural features compared with the X‐ray structure of anionic selenenate esters 14 – 16 .     

Crystallization kinetics of compatibilized blends of polypropylene and polyethylenimine

Journal of Thermal Analysis and Calorimetry - In this paper, isothermal and non-isothermal crystallization behaviour of neat polypropylene (PP), blends of PP/maleic anhydride grafted polypropylene...     

Room-Temperature Dialkylamination of Chloroheteroarenes Using a Cu(II)/PTABS Catalytic System

The dimethylamino functionality has significant importance in industrially relevant molecules and methodologies to install these efficiently are highly desirable. We report herein a highly efficient, room-temperature dimethylamination of chloroheteroarenes performed via the in-situ generation of dimethylamine using N,N-dimethylformamide (DMF) as precursor wiith a large substrate scope that includes various heteroarenes, purines as well as commercially relevant drugs such as altretamine, ampyzine and puromycin precursor.     

Vapor-phase processable novel nonplanar donor-acceptor quateraryls for blue OLEDs(#)

A novel series of thermally stable blue light emitting quateraryls with a piperidine donor and a nitrile acceptor was prepared from a ketene- S, S-acetal under mild conditions without using an organometal catalyst. The performance of a blue quateraryl 6e was investigated by fabricating a multilayer OLED with a configuration of ITO/PEDOT:PSS (40 nm)/quateraryl (60 nm)/BCP (6 nm)/Alq(3) (20 nm)/LiF (0.5 nm)/Al (200 nm), which exhibited blue emission with a low turn on voltage of 4 V at a brightness of 0.22 cd/m(2).     

Emerging trends in miniaturized and microfluidic electrochemical sensing platforms

Electrochemical sensing has established a strong presence in diverse areas. The conventional electrochemical sensing approach consumes large sample volumes and reagents and requires bulky potentiostat, macro-electrodes, and other equipment. The synergistic integration of electrochemical sensing systems with miniaturized or microfluidic electrochemical devices and microelectrodes in a single platform provides rapid analysis with a disposable, reusable, and cost-effective platform for multiplexed point-of-care detections. Such microdevices have created scope for using several materials as electrodes and sensing platforms by using appropriate fabrication techniques. One of the most recent advancements in miniaturized devices includes the integration of automation and Internet of Things to realize fully automated and robust electrochemical microdevices. The review summarizes the emerging trends in fabrication methods of miniaturized and microfluidic devices, their multiple applications in real-time, integration of Internet of Things, automation, identifying research gaps with strategies for bridging these gaps, future outlook, and recent approaches to intelligent electrochemical sensing.