Formation of ordered arrays of oriented polyaniline nanoparticle nanorods

We report the preparation of ordered polyaniline (PANI) nanorod arrays in an aqueous medium. The oriented PANI nanorods (80-400 nm in diameter and 8-15 mum in length) were synthesized in the presence of hydrophilic Allura Red AC (ARAC) as the structure-directing agent and ammonium persulfate as an oxidant in HCl solution. The morphologies of the oriented PANI nanoparticle nanorods were confirmed by scanning electron microscopy (SEM) and transmission electron microscopy images, and the effect of reaction conditions on the morphology of PANI nanostructures was also studied. On the basis of the result obtained from small-angle X-ray scattering, we propose that rodlike micelle arrays of ARAC-aniline are responsible for directing the formation of oriented PANI nanoparticle nanorods. SEM images and the data analysis of static and dynamic light scattering give supportive evidence to the formation of the PANI nanoparticle nanorods by an elongation process. The chemical and electronic structures of the PANI nanorods were also studied by Fourier transform IR and UV-vis spectrometries, respectively.     

Asymmetric Reduction of Acetophenones with NaBH4 in the Presence of Mono-6-(1-methyl-3-imidazolium)-6-deoxy-β-cyclodextrin Tosylate

The asymmetric reduction of acetophenone and its derivatives was achieved with sodium borohydride utilizing a novel chiral ionic liquid of β-cylclodextrin (CD), mono-6-(1-methyl-3-imidazolium)-6-deoxy-β-cyclodextrin tosylate (MIM-β-CDOTs). It was found that this chiral β-CD-based ionic liquid could provide higher enantioselectivity for the product alcohols. Moreover, the enantioselectivity of the product alcohols was highly dependent on the structure of prochiral ketones, structure of CD and reduction temperature. An erratum to this article can be found at     

Micellization phenomena of biodegradable amphiphilic triblock copolymers consisting of poly(beta-hydroxyalkanoic acid) and poly(ethylene oxide)

This paper reports the studies on micelle formation of new biodegradable amphiphilic poly(ethylene oxide)-poly[(R)-3-hydroxybutyrate]-poly(ethylene oxide) (PEO-PHB-PEO) triblock copolymer with various PHB and PEO block lengths in aqueous solution. Transmission electron microscopy showed that the micelles took an approximately spherical shape with the surrounding diffuse outer shell formed by hydrophilic PEO blocks. The size distribution of the micelles formed by one triblock copolymer was demonstrated by dynamic light scattering technique. The critical micellization phenomena of the copolymers were extensively studied using the pyrene fluorescence dye absorption technique, and the (0,0) band changes of pyrene excitation spectra were used as a probe for the studies. For the copolymers studied in this report, the critical micelle concentrations ranged from 1.3 x 10(-5) to 1.1 x 10(-3) g/mL. For the same PEO block length of 5000, the critical micelle concentrations decreased with an increase in PHB block length, and the change was more significant in the short PHB range. It was found that the micelle formation of the biodegradable amphiphilic triblock copolymers consisting of poly(beta-hydroxyalkanoic acid) and PEO was relatively temperature-insensitive, which is quite different from their counterparts consisting of poly(alpha-hydroxyalkanoic acid) and PEO.     

The Reaction of SnCl2 with the Complexes cis-PtCl2 (phosphorus ligand)2 as studied by 31P and 195Pt NMR

The reactions of SnCl₂ with the complexes cis-PtCl₂P₂, P=trialkyl and triaryl phosphines and phosphites, in CDCl₃ and CD₂Cl₂ have been studied using ³¹P and ¹⁹⁵Pt NMR. methods. For equimolar amounts of Sn and Pt, products of the type PtCl(SnCl₃)P₂ are formed with the complex geometry depending on the nature of P. For P?PEt₃ and P(OPh)₃, further addition of SnCl₂ produces trans-Pt(SnCl₃)₂ complexes. The syntheses of trans-PtCl(SnCl₃) (PEt₃)₂ and trans-Pt(SnCl₃)₂ (OPh₃)₂ are described.     

Top down characterization of secreted proteins from Mycobacterium tuberculosis by electron capture dissociation mass spectrometry

Secreted proteins of Mycobacterium tuberculosis are implicated in its disease pathogenesis and so are considered as potential diagnostic and vaccine candidates. The search for these has been slow, even though the entire genome sequence of M. tuberculosis is now available; of the 620 protein spots resolved by 2-D gel electrophoresis, 114 secreted proteins have been identified, but for only 13 has the primary structure been partly characterized. For comparison, in this top down mass spectrometry (MS) approach the secreted proteins were precipitated from cell culture filtrate, resuspended, and examined directly by electrospray ionization (ESI) Fourier transform MS. The ESI spectra of three precipitates showed 93, 535, and 369 molecular weight (M(r)) values, for a total of 689 different values. However, only approximately 10% of these values matched (+/-1 Da) the DNA predicted M(r) values, but these identifications were unreliable. Of nine molecular ions characterized by MS/MS, only one protein match was confirmed, and its isotopic molecular ions were overlapped by those of another protein. MS/MS identified a total of ten proteins by sequence tag search, of which three were unidentified previously. The low success of M(r) matching was due to unusually extensive posttranslational modifications, including loss of a signal sequence, loss of the N-terminal residue, proteolytic degradation, oxidation, and glycosylation. Although in eubacteria the latter is relatively rare, a 9 kDa protein showed 7 hexose attachments and two 20 kDa proteins each had 20 attachments. For MS/MS, electron capture dissociation was especially effective.     

Heterotapes: A Persistent,Dual‐Synthon Hydrogen‐Bonding Motif

The small dinitrile anion carbamoyldicyanomethanide, [C(CN)₂‐(CONH₂)]^? (cdm), reproducibly forms a hydrogen‐bonded tape containing two different supramolecular synthons: a “heterotape”. The tape incorporates both an amide dimer and a nitrile‐containing ring. The robustness of the motif is confirmed by its persistence from an isolated tape in a separated ion‐pair structure, [K(15c5)₂](cdm)? H₂O, to its incorporation into coordination complexes of octahedral metals, thus facilitating the formation of 2D sheets. Complexes containing coligands that occupy the equatorial coordination sites, [Cu(2,2′‐py₂NH)₂(cdm)₂]? 2MeOH, [Ni(cyclam)(cdm)₂], and [Cu(cyclam)(cdm)₂]?2MeOH (cyclam=1,4,8,11‐tetraazacyclotetradecane, 2,2′‐py₂NH=di(2‐pyridyl)amine), show retention of the heterotape motif, whilst the ethylene diamine complex [Cu‐(en)₂(cdm)₂] (en=ethylene diamine) displays an alternative hydrogen‐bonding motif due to interference from the diamine ligands.