Liquid crystalline phase transitions in hexakis(4-(4′-heptyloxy)biphenoxy)cyclotriphosphazene

Abstract

Hexakis(4-(4′-heptyloxy)biphenoxy)cyclotriphosphazene (HHCP) was synthesized from hexachlorocyclotriphosphazene and 4-heptyloxy-4′-hydroxybiphenyl. The mesogenicity of HHCP was studied by DSC, FTIR spectroscopy and polarizing microscopy. Enantiotropic smectic C and nematic phases were observed between 450 and 455 K and 455 and 456 K, respectively, on heating, and between 456 and 455 K (nematic) and 455 and 440 K (smectic C) on cooling from the isotropic liquid phase. The introduction of the heptyloxybiphenoxy groups as side chains into cyclotriphosphazene has generated the liquid crystalline phase. FTIR spectroscopy showed that the P=N and P-O-(C) stretching vibrations converted to lower frequencies from 1224 to 1210 cm^?1 and from 920 to 910cm^?1, respectively, at the crystalline (C)-S_c phase transition. This result suggests that the state of the cyclotriphosphazene ring dramatically changes near the C-S_c phase transition.     

q-Painlevé Systems Arising from q-KP Hierarchy

A system of q-Painlevé type equations with multi-time variables t ₁,...,t _M is obtained as a similarity reduction of the N-reduced q-KP hierarchy. This system has affine Weyl group symmetry of type . Its rational solutions are constructed in terms of q-Schur functions.     

Ferroelectric liquid crystalline phase transition of (S)-hexakis(4-(4'-(6-methyl)octyloxy)biphenoxy) cyclotriphosphazene

(S)-Hexakis(4-(4'-(6-methyl)octyloxy)biphenoxy)cyclotriphosphazene (SMOCP) was synthesized in a search for new ferroelectric liquid crystalline compounds. We found an enantiotropic ferroelectric smectic C* phase between 419 and 441 K in SMOCP by using polarizing microscopy and DSC measurements. The spontaneous polarization was estimated to be -130.5 μCm^-2 at 437.6 K, several times larger than that of DOBAMBC ((S)-2-methylbutyl 4-(4'-decyloxybenzylidene)aminocinnamate.     

The polarized reflection and absorption spectra of perylene crystals in monomeric and dimeric forms

The electronic absorption spectra of perylene crystals in the α- and β-forms were measured by the normal incidence reflection method in the spectral region from 20 000 to 60 000 cm^?1. From the absorption spectrum polarized perpendicular to [1$\text{1}$0] axis of the α-form crystal, the bands around 24 000 cm^?1 were determined to be polarized along the long molecular axis. Two strong bands with different polarizations were observed around 50 000 cm^?1 for each of the α- and β-perylene crystals and were assigned to the transitions to the ¹B_2u and ¹B_3u states. The observed polarized absorption spectra as a whole were consistent with the theoretical results by Hummel and Ruedenberg and the reflection method was found to be suitable to the polarized absorption measurement of strong bands of crystals. The observed factor-group splittings were compared with the theoretical values, the oriented gas model being found to be applicable to the β-form crystal.     

A simplified measurement of hydrated crystal densities of low melting points (low transition points) by solidifications of aqueous solutions

A volume change method for measuring crystal densities is described. It allows the densities of unstable hydrated crystals at room temperature to be determined, by measurements of volume changes during the solidification of aqueous solutions. NaCl x 2H2O, KCl, MgSO4 x 12H2O and K2HPO4 x 6H2O were measured by the method and their densities (SE) are 1.61+/-0.02, 1.99+/-0.05, 1.45+/-0.01 and 1.75+/-0.02 g ml(-1) respectively. Data of NaCl x 2H2O and KCl are in good agreement with the previously reported values.     

Laser-driven vehicles – from inner-space to outer-space

Laser-supported propulsion of a micro-airplane with a water-covered ablator is demonstrated. The repetitive use of an overlay structure is experimentally demonstrated with a specially designed water supply. Various transparent overlays are investigated by the CIP-based hydrodynamic code and by experiments using a pendulum and using a semi-conductor load cell. A momentum-coupling efficiency of ∼10⁴ N s/MJ is achieved by water–exotic-target experiments, in agreement with the simulation code, which predicts a maximum efficiency of ∼10⁵ N s/MJ. The concept of laser-supported propulsion can also be used for driving a Mach 5 airplane in the stratosphere, a micro-ship inside the human body, and a robot in a nuclear power reactor accident, during which large numbers of neutrons make electronic devices useless. Received: 7 October 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003 RID="*" ID="*"Corresponding author. Fax: +81-3/5734-2165, E-mail: yabe@mech.titech.ac.jp     

Total synthesis of cladocorans A and B: a structural revision

Cladocorans A and B, isolated from the Mediterranean coral Cladocora cespitosa, are novel sesterterpenoids whose structures were initially proposed as 1 and 2, respectively. These designations, however, subsequently came under doubt. In the present study, the synthesis of compounds 5 and 6 was undertaken. The physical properties of 5 and 6 were found to be identical to those of natural cladocorans A and B, whose structures were thus concluded to be 5 and 6, respectively. Cladocoran B is thus clearly shown to be an olefinic regioisomer of dysidiolide and cladocoran A as its acetate.     

Insulinomimetic Zn(II) complexes as evaluated by both glucose-uptake activity and inhibition of free fatty acids release in isolated rat adipocytes

We prepared 4 new Zn(II) complexes with Zn(O4), Zn(N(2)O(2)), and Zn(S2O2) coordination modes and evaluated their insulinomimetic activities in an in vitro study. The insulinomimetic activities of bis(pyrrole-2-carboxylato)zinc (Zn(pc)2), bis(alpha-furonic acidato)zinc (Zn(fa)2), bis(thiophene-2-carboxylato)zinc (Zn(tc)2), and bis(thiophene-2-acetato)zinc (Zn(ta)2) complexes were found to be higher than that of zinc sulfate (ZnSO4). Zn(ta)2 showed the highest insulinomimetic activity among the Zn(II) complexes because of its high lipophilicity.