Nonlinear dynamics of confined polymer melts with attractive walls

A scaling model is presented to analyze the reversible strain-hardening phenomenon in end-tethered polymer clay nanocomposites (Krishnamoorti, R.; Giannelis, E. P. Langmuir 2001, 17, 1448). It is assumed that for attractive clay-polymer interactions a fraction of the polymer chains that span the space between opposite clay plates get adsorbed on them, thereby bridging the plates. Under large amplitude oscillatory shear, such bridges are stretched, and this results in the strain-hardening behavior. The onset of strain hardening is predicted to be dependent only on the average distance separating the two plates and is independent of the frequency of the oscillations and the polymer molecular weight.     

Synthesis of 2'-O-methoxyethylguanosine using a novel silicon-based protecting group

A short and efficient synthesis of 2'-O-methoxyethylguanosine (8) is described. Central to this strategy is the development of a novel silicon-based protecting group (MDPSCl(2), 2) used to protect the 3',5'-hydroxyl groups of the ribose. Silylation of guanosine with 2 proceeded with excellent regioselectivity and in 79% yield. Alkylation of the 2'-hydroxyl group of 6 proceeded with methoxyethyl bromide and NaHMDS and afforded compound 7 in 85% yield, without any noticeable cleavage of the silyl protecting group and without the need to protect the guanine base moiety. Finally, deprotection of 7 was achieved using TBAF and produced 8 in 97% yield.     

Solution-processed electrochemical synthesis of ZnFe2O4 photoanode for photoelectrochemical water splitting

Journal of Solid State Electrochemistry - Herein, we report the synthesis of ZnO nanorod films onto FTO (fluorine-doped tin oxide) substrates using the solution-processed electrodeposition method....     

Chiral Interlocked Corrole Dimers Directly Linked at Inner Carbon Atoms of Confused Pyrrole Rings

A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face-to-face intramolecularly interlocked corrole dimers were formed by the oxidative C−C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials.     

Tetraphenylethene‐Based Conjugated Fluoranthene: A Potential Fluorescent Probe for Detection of Nitroaromatic Compounds

This study reports the synthesis and photophysical properties of a star‐shaped, novel, fluoranthene–tetraphenylethene (TFPE) conjugated luminogen, which exhibits aggregation‐induced blue‐shifted emission (AIBSE). The bulky fluoranthene units at the periphery prevent intramolecular rotation (IMR) of phenyl rings and induces a blueshift with enhanced emission. The AIBSE phenomenon was investigated by solvatochromic and temperature‐dependent emission studies. Nanoaggregates of TFPE, formed by varying the water/THF ratio, were investigated by SEM and TEM and correlated with optical properties. The TFPE conjugate was found to be a promising fluorescent probe towards the detection of nitroaromatic compounds (NACs), especially for 2,4,6‐trinitrophenol (PA) with high sensitivity and a high Stern–Volmer quenching constant. The study reveals that nanoaggregates of TFPE formed at 30 and 70 % water in THF showed unprecedented sensitivity with detection limits of 0.8 and 0.5 ppb, respectively. The nanoaggregates formed at water fractions of 30 and 70 % exhibit high Stern–Volmer constants (K_sv=79 998 and 51 120 m ^?1, respectively) towards PA. Fluorescence quenching is ascribed to photoinduced electron transfer between TFPE and NACs with a static quenching mechanism. Test strips coated with TFPE luminogen demonstrate fast and ultra‐low‐level detection of PA for real‐time field analysis.     

Electrochemical studies of novel olivine-layered (LiFePO4-Li2MnO3) dual composite as an alternative cathode material for lithium-ion batteries

Journal of Solid State Electrochemistry - In the present work, olivine-layered composites, i.e., LiFePO4-Li2MnO3, are successfully synthesized in the form of a single monolithic electrode and layer...     

Structure and dynamics of biological liquid crystals

A review of thermodynamic and flow liquid crystal models is presented and applied to a wide range of biological liquid crystals (BLCs), including helicoidal plywoods, biopolymer solutions and in vivo liquid crystals. The key characteristics of liquid crystals (self-assembly, packing, defects, functionalities, processability) are discussed in relation to biological materials and the strong correspondence between different synthetic and biological materials is discussed. Viscoelastic models for nematic and chiral nematics are reviewed and discussed in terms of key parameters that facilitate understanding and quantitative information from experimental measurements. The range and consistency of the predictions demonstrates that the use of mesoscopic liquid crystal models is an efficient tool to develop the science and biomimetic applications of mesogenic biological materials.     

Novel betaines/mesoionic compounds via a simple and convenient MCR in aqueous micellar system: synthesis of thiazolo[2,3-a]isoquinolin-4-ium derivatives

An inexpensive one-pot green methodology has been developed for the synthesis of thiazolo[2,3-a]isoquinolin-4-ium derivatives by the reaction of different derivatives of isoquinoline and 2-bromoacetophenone/bromoacetonitrile with benzoyl isothiocyanate in aqueous micellar medium.