Conductive liquid crystalline compounds having a piperazine structure

New conductive thermotropic liquid crystalline materials having a piperazine ring in the central core: 1-[4-(9-decenyloxy)phenyl]-4-alkylpiperazines (6) were synthesized. The mesomorphic behaviours of these compounds and their conductivity in the liquid crystal phase were measured. The principal features of these compounds are to exhibit a smectic B phase around room temperature (for example 6: Cr 50 SmB 81 I, °C) and to exhibit a large dark current (6d: 430 μA cm^?2, applied voltage 20 V, at 70°C) in the smectic B phase.     

Catalytic Enantioselective Reaction of α‐Phenylthioacetonitriles with Imines Using Chiral Bis(imidazoline)–Palladium Catalysts

The catalytic enantioselective reaction of α‐phenylthioacetonitriles with imines has been developed. The reaction of various imines proceeds in good yields and diastereo‐ and enantioselectivities in the presence of chiral bis(imidazoline)–palladium catalysts. The obtained products can be converted into β‐aminonitrile or β‐aminoamide compounds without loss of enantiopurity.     

Synthesis and isolation of a monoamine having a thermodynamically stabilized pseudo-chirotopic nitrogen

We have synthesized a tricyclic monoamine, (1S,4R)-(E)-7,3′-heptenylene-2,3:5,6-dibenzo-7-azabicyclo[2.2.1]heptane (1), by applying a ring-closing metathesis reaction in the key step of the synthetic route and by using preparative chiral HPLC for the separation. The X-ray crystallographic analysis of its salt with (1R)-camphor-10-sulfonic acid showed that the geometry and absolute configuration are (E) and (1S,4R), respectively. The theoretical calculations revealed that the inversion of the nitrogen atom at the 7-position of (1S,4R)-(E)-1 thus isolated takes place through a very slow process and that the configuration of the N(7) is highly biased to (R), indicating that (1S,4R)-(E)-1 is a thermodynamically controlled N-pseudo-chirotopic compound ((1S,4R,7R): (1S,4R,7S) = 99.68:0.32 at 120 °C).     

Side chain liquid crystal poly(fumarate)s bearing tolane‐based mesogens

Cyanotolane or fluorotolane mesogens were for the first time introduced into the fumarate monomer under basic conditions. All fumarate monomers undergo radical polymerization in benzene in the presence of dimethyl 2,2′‐azobis(isobutyrate) as an initiator at 60 °C, affording the corresponding poly(fumarate)s with a molecular weight (M_n) of ～ 10⁴ and an exceptionally narrow polydispersity. The phase behaviors of the fumarate monomers and the correspoding poly(fumarate)s were comprehensively investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X‐ray diffraction (XRD) analysis. For the fumarate monomers, fluorotolane derivatives were prone to form higher‐order liquid crystal phases such as a smectic phase, while cyanotolane derivatives tended to show a wide mesophase temperature range, depending on the alkyl chain spacer length. Very surprisingly, these features dramatically weakened when they were polymerized. The mesophase temperature ranges became narrow and completely disappeared for the poly(fumarate)s with a shorter alkyl chain spacer. A nematic phase representing lower‐order arrangements became a predominant liquid crystal phase for the poly(fumarate) carrying cyanotolane mesogens. Only the poly(fumarate) carrying fluorotolane mesogens with a longer alkyl chain spacer displayed the characteristic XRD patterns of the smectic B phase. The transient photocurrent measurements of the fumarate monomer with cyanotolane mesogens displayed a hole mobility of the order of 10^?4–10^?5 cm² V^?1 s^?1 at room temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5101–5114, 2008     

A coumarin-based fluorescent probe for Hg2+ and Ag+ with an N'-acetylthioureido group as a fluorescence switch

For detection of Hg(2+) and Ag(+), we have developed a coumarin-based probe with an N'-acetylthioureido group as a novel fluorescence switch, in which the hydrogen bond formation between the N-hydrogen and the acetyl O atom markedly increases the susceptibility of the probe toward desulfurization by Hg(2+) and Ag(+).     

Inexact rational Krylov method for evolution equations

BIT Numerical Mathematics - Linear and nonlinear evolution equations have been formulated to address problems in various fields of science and technology. Recently, methods using an exponential...     

Conductive liquid crystalline compounds having a piperazine structure

New conductive thermotropic liquid crystalline materials having a piperazine ring in the central core: 1-[4-(9-decenyloxy)phenyl]-4-alkylpiperazines ( 6 ) were synthesized. The mesomorphic behaviours of these compounds and their conductivity in the liquid crystal phase were measured. The principal features of these compounds are to exhibit a smectic B phase around room temperature (for example 6 : Cr 50 SmB 81 I, °C) and to exhibit a large dark current (6d: 430 μA cm^-2, applied voltage 20 V, at 70°C) in the smectic B phase.     

A new synthetic method for α-ketosilanes employing methoxy(phenylthio)trialkylsilylmethane as an α-silylacyl anion equivalent

Development of a new synthetic method for α-ketosilanes can be achieved by a sequence of alkylation of methoxy(phenylthio)trialkylsilylmethane and oxidation with NaIO₄.