End-to-end azide-bridged manganese(III) chain compounds: field-induced magnetic phase transitions and variation of T(C) to 38 K depending on the side groups of the Schiff bases

Three one-dimensional coordination polymers [Mn(L)(N(3))](n) [L = L1 (1), L2 (2), L3 (3); L1H(2) = N,N'-bis(5-chlorosalicylideneiminato)-1,3-diaminopentane, L2H(2) = N,N'-bis(5-bromosalicylideneiminato)-1,3-diaminopentane, L3H(2) = N,N'-bis(5-bromosalicylideneiminato)-1,3-diamino-2-dimethylpropane] bridged by end-to-end azides were prepared. The crystal systems differ according to the Schiff bases used. Each Mn atom adopts a typical Jahn-Teller distortion. The helicity of the chains occurs in a racemic manner only for 2. No noncovalent forces are relevant in 2, while π-π contacts are visible in 1 and 3. Magnetic measurements show the presence of apparent spin canting. Complexes 1 and 3 exhibit a field-induced metamagnetic transition from an antiferromagnetic state to a weak ferromagnetic phase, whereas 2 embraces a field-induced two-step magnetic phase transition. The critical temperature is observed at 38 K for 2, which is relatively higher than those for 1 (11 K) and 3 (10 K). The pronounced long-range order may contribute from intrachain exchange couplings and through-space dipolar interactions between adjacent chains.     

Helical silica nanotubes: Nanofabrication architecture,transfer of helix and chirality to silica nanotubes

A series of neutral gelators and cationic amphiphiles derived from 1,2 diphenylethylenediamine (I) and 1,2-cyclohexanediamine (II) was synthesised. Helical silica nanotubes were prepared utilising these organic gelators through sol-gel polycondensation of tetraethoxy silane, (TEOS-silica source). Right- and left-handed helical nanotubes respectively were obtained from a 1: 1 mass mixture of optically active, (1S,2S)-III-(1S,2S)-V neutral gelator and (1S,2S)-IV-(1S,2S)-VI cationic amphiphile and a 1: 1 mass mixture of optically active, (1R,2R)-III-(1R,2R)-V neutral gelator and (1R,2R)-IV-(1R,2R)-VI cationic amphiphile, indicating that the handedness of the helical nanotubes varied with the change in the neutral gelator precursors used. The nanotubes were characterised by SEM images.     

Carbon nanofibers extracted from soot as a sorbent for the determination of aromatic amines from wastewater effluent samples

The isolation and characterization of carbon nanofibers from soot obtained by burning natural oil is reported. The fibers were extracted from the soot with tetrahydrofuran followed by sonication. The carbon nanofibers were mixed with poly(vinyl alcohol) and electrospun to get the nanofiber mat. The extraction ability of electrospun nanofibers for the separation and preconcentration of aromatic compounds such as 3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline were tested and efficiently evaluated using high performance liquid chromatography. Under optimized conditions, the method showed good linearity in a range of 0.5–50 μg L⁻¹ with correlation coefficient ranging from 0.989 to 0.998. High precision of the extraction with RSD values of 4.5–5.8% and low LOD value in a range of 0.009–0.081 μg L⁻¹ for all aniline compounds were achieved. The proposed microextraction method offers advantages such as easy operation, high recovery, fast extraction, minimal use of organic solvent and elimination of tedious solvent evaporation and reconstitution steps.     

Multiscale fabrication of multiple proteins and topographical structures by combining capillary force lithography and microscope projection photolithography

We present new methods that enable the fabrication of multiscale, multicomponent protein-patterned surfaces and multiscale topologically structured surfaces by exploiting the merits of two well-established techniques: capillary force lithography (CFL) and microscope projection photolithography (MPP) based on a protein-friendly photoresist. We further demonstrate that, when hierarchically organized micro- and nanostructures were used as a cell culture platform, human colon cancer cells (cell line SW480) preferentially adhere and migrate onto the area with nanoscale topography over the one with microscale topography. These methods will provide many exciting opportunities for the study of cellular responses to multiscale physicochemical cues.     

Syntheses and characterization of carbazole based new low‐band gap copolymers containing highly soluble benzimidazole derivatives for solar cell application

Newly designed 2H‐benzimidazole derivatives which have solubility groups at 2‐position have been synthesized and incorporated into two highly soluble carbazole based alternating copolymers, poly[2,7‐(9‐(1′‐octylnonyl)‐9H‐carbazole)‐alt‐5,5‐(4′,7′‐di(thien‐2‐yl)‐2H‐benzimidazole‐2′‐spirocyclohexane)] (PCDTCHBI) and poly[2,7‐(9‐(1′‐octylnonyl)‐9H‐carbazole)‐alt‐5,5‐(4′,7′‐di(thien‐2‐yl)‐2H‐benzimidazole‐2′‐spiro‐4′′‐((2′′′‐ethylhexyl)oxy)‐cyclohexane)] (PCDTEHOCHBI) for photovoltaic application. These alternating copolymers show low‐band gap properties caused by internal charge transfer from an electron‐rich unit to an electron‐deficient moiety. HOMO and LUMO levels are –5.53 and –3.86 eV for PCDTCHBI, and –5.49 and –3.84 eV for PCDTEHOCHBI, respectively. Optical band gaps of PCDTCHBI and PCDTEHOCHBI are 1.67 and 1.65 eV, respectively. The new carbazole based the 2H‐benzimidazole polymers show 0.11–0.13 eV lower values of band gaps as compared to that of carbazole based benzothiadiazole polymer, poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT), while keeping nearly the same deep HOMO levels. The power conversion efficiencies of PCDTCHBI and PCDTEHOCHBI blended with [6,6]phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) are 1.03 and 1.15%, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Novel Calix[4]arene Azacrown Ether

1,3-diproyloxycalix[4]arene azacrown ether was successfully synthesized in the fixed 1,3-alternate conformation which was confirmed by a solid state structure.