Synthesis of a series of ethylene glycol modified water-soluble tetrameric TPE-amphiphiles with pyridinium polar heads: Towards applications as light-up bioprobes in protein and DNA assay,and wash-free imaging of bacteria

Available online Development of water soluble AIE-active “light-up” bioprobes for the detection of biomacromolecules has drawn huge research interests in recent past. In this study, a series of ethylene glycol modified water soluble tetrameric tetraphenylethylene amphiphiles with pyridinium polar heads (TPE-xEG-Py, x = 3, 4, 6 or 1a-c) have been synthesized by varying the ethylene glycol spacer. Their unique structure allows them to form vesicles and other nanoaggregates in aqueous solutions. These amphiphiles were successfully utilized for fluorimetric detection and quantitation of BSA and DNA based on the electrostatic interactions to trigger AIE-emission from the TPE moiety. The electrostatic interaction was also proved very effective in wash-free imaging of both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria with up to 92 folds increase in fluorescence response within bacterial concentration 0–12 × 10⁸ CFU mL^?1. The strategy is advantageous due to cost-effective and easy synthesis, high water solubility, and fast response.     

Desorption of carboxylates and phosphonates from galvanized steel: Towards greener lubricants

This paper studies the removal of chemisorbed carboxylates and phosphonates from TiO₂-coated galvanized steel using NaOH_(aq). XPS and FTIR data show that NaOH_(aq) is effective at desorbing these species and so is an alternative to gas phase processes (eg, plasma cleaning). Tribological investigations show that NaOH_(aq)-treated surfaces show reduced friction and wear, relative to the “as-received” galvanized steel. This is ascribed to carbonate (present as an impurity in NaOH) that adsorbs to the surface of the substrate during NaOH_(aq) immersion. Carbonate removal through sonication in water generates surfaces that show friction similar to “as-received” galvanized steel. This work is useful in areas (eg, automotive manufacturing), where the effective removal of lubricants following tribological contact is key to subsequent paint adhesion.     

Aromatic polyesters containing cardo perhydrocumyl cyclohexylidene groups: Synthesis,characterization and gas permeation study

Three bisphenols containing cardo perhydrocumyl cyclohexylidene group, namely; 1,1-bis(4-hydroxyphenyl)-4-perhydrocumylcyclohexane, 1,1-bis(4-hydroxy-3-methylphenyl)-4-perhydrocumylcyclohexane and 1,1-bis(4-hydroxy-3,5-dimethylphenyl)-4-perhydrocumylcyclohexane were synthesized starting from p-cumyl phenol. Each of these bisphenols was polycondensed with both terephthaloyl chloride and isophthaloyl chloride by phase transfer-catalyzed interfacial polymerization to obtain a series of new aromatic polyesters. Inherent viscosities and number average molecular weights of polyesters were in the range 0.51-0.64 dL/g and 17390-41430?g/mol, respectively which indicated the formation of reasonably high molecular weight polymers. The detailed NMR studies revealed that axial and equatorial identity of the phenyl rings of bisphenols was retained in polyesters resulting in constitutional isomerism. Polyesters containing perhydrocumyl cyclohexylidene groups showed excellent solubility in organic solvents viz, chloroform, dichloromethane, 1,1,2,2-tetrachloroethane and tetrahydrofuran. The self-standing films of polyesters could be cast from their chloroform solution. The 10% weight loss temperatures and glass transition temperatures of polyesters were in the range 453–485?°C and 201–267?°C, respectively demonstrating their excellent thermal characteristics. The gas permeability study of polyesters was carried out for He, H₂ and N₂ by variable-volume method. An improvement in permeability and decrease in selectivity was observed due to symmetric methyl substituents while reverse trend was observed in case of polyesters with asymmetric methyl substituents.     

Observation of carbon‐facilitated phase transformation of titanium dioxide forming mixed‐phase titania by confocal Raman microscopy

Confocal Raman microscopy, a relatively new and advanced technique, is found to be suitable for imaging the chemical morphology below the submicrometer scale. It has been employed to probe the phase transformation of carbon‐containing titania (TiO₂) nanopowder and titania thin film subjected to laser annealing. The observation of phase transformation from the anatase phase to the rutile phase at high laser power annealing is attributed to carbon inclusion inside or on the surface of titania. Upon annealing, carbon could react with the oxygen of titania and create oxygen vacancies favoring the transformation from the anatase to the rutile phase. This study provides evidence for the carbon‐assisted phase transformation for creating carbon‐containing mixed‐phase titanium dioxide by laser annealing. We explicitly focus on the presence of carbon in the phase transformation of TiO₂ using confocal Raman microscopy. In all of the investigated samples, mixed anatase/rutile phases with carbon specifically was found at the rutile site. X‐ray diffraction (XRD), scanning electron microscopy (SEM) and energy‐dispersive spectroscopy (EDS) studies have been performed in addition to Raman mapping to verify the mixed‐phase titania formation. Copyright © 2010 John Wiley & Sons, Ltd.     

Mild and Efficient Tf2O-Mediated Synthesis of 3-Amino-1-benzofurans

Russian Journal of Organic Chemistry - A mild and efficient procedure has been developed for the synthesis of 3-amino-1-benzofurans by intramolecular cyclization of the corresponding...     

Ionic Assembly,Anion–π, Magnetic,and Electronic Attributes of Ambient Stable Naphthalenediimide Radical Ions

Organic spin-based molecular materials are considered to be attractive for the generation of functional materials with emergent optoelectronic, magnetic, or magneto-conductive properties. However, the major limitations to the utilization of organic spin-based systems are their high reactivity, instability, and propensity for dimerization. Herein, we report the synthesis, characterization, and magnetic and electronic studies of three ambient stable radical ions ( 1 a^.+ , 1 b^.+ , and 1 c^.+ ). The radical ions 1 b^.+ and 1 c^.+ with BPh₄⁻ and BF₄⁻ counter anions, respectively, were synthesized in excellent yields by means of anion metathesis of 1 a^.+ with Br⁻ as its counter anion. Notably, synthesis of 1 a^.+ was achieved in an ecofriendly, solvent-free protocol. The radical ions were characterized by means of single-crystal X-ray diffraction studies, which revealed the discrete nature of the radical ions and extensive hydrogen-bonding interactions within the radical ions and with the counter anions. Thus, radical ions can be organized to form infinite supramolecular arrays using weak noncovalent interactions. In addition, the Br⁻, BF₄⁻, and BPh₄⁻ anions formed diverse types of anion–π interactions with the naphthalene and imide rings of the radical ions. The radical ions were characterized by means of X-band electron paramagnetic resonance (EPR) spectroscopy in solution and in the solid state. Magnetic studies revealed their paramagnetic nature in the range of 10 to 300 K. The radical ions exhibited high resistivity approaching the gigaohm (GΩ) scale. In addition, the radical ions exhibited panchromism.     

Reversible Ultra-Slow Crystal Growth of Mixed Lead Bismuth Perovskite Nanocrystals: The Presence of Dynamic Capping

An ultra-slow crystal growth over a period of 24 h of a newly synthesized CH₃NH₃Pb_1/2Bi_1/3I₃ perovskite (MPBI) nanocrystal in non-polar toluene medium is reported here. From several spectroscopic techniques as well as from TEM analysis we found that the size of nanocrystals changes continuously with time, in spite of being capped by the ligands. Using a single molecular spectroscopic technique, we also found that this size change is not due to the stacking of nanocrystals but due to crystal growth. The notable temperature dependence and reversible nature of the nanocrystals growth is explained by the dynamic nature of the capping. The observed temperature-dependent ultra-slow growth is believed to be a pragmatic step towards controlling the size of perovskite NC in a systematic manner.     

An approach toward the syntheses of triazolo benzoxazines,triazolo quinoxalines,triazolo benzodiazepines,triazolo benzoxazepines,and triazolo benzothiazines via a simple and convenient protocol using basic alumina as solid support

A microwave assisted green protocol for the syntheses of triazole fused benzoxazines, benzoxazepines, quinoxalines, and benzothiazines was investigated using basic alumina as solid support. The one-pot reaction was carried out using Cu(phen)(PPh₃)Br as a catalyst. The protocol did not require the use of any additional ligands, base or the use of expensive and toxic palladiums.