- On the parity in helical twisting power of Ru(III) 1,3-diketonates of C2 symmetry in nematic liquid crystals
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It is demonstrated that the sign of helical twisting power (HTP) of an enantiomeric Ru(III) complex of type [Ru(acac)2L] can be switched by choosing L from either Lper or Lpara, which is elongated either perpendicular or p
- Yoshida, Jun,Sato, Hisako,Yamagishi, Akihiko,Hoshino, Naomi
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p. 8453 - 8456
(2007/10/03)
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- Chemistry of Rh(I) complexes based on mesogenic 3,5-disubstituted pyrazole ligands. X-ray crystal structures of 3,5-di(4-n-butoxyphenyl)pyrazole (Hpzbp2) and [Rh(μ-pzR2)(CO)2]2 (R = C6H4OCnH2n+1, n = 10, 12) compounds. Part II
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Four new 3,5-disubstituted pyrazoles HpzR2 containing long-chain 4-n-alkyloxyphenyl substituents [R = C6H4OCnH2n+1; n=4 (1), 6 (2), 12 (5), 14 (6)] have been prepared and characterised. All of them showed mesomorphic behaviour,the stability and the range of the mesophases increasing with the length of the chain on the pyrazole. The X-ray structure of Hpzbp2 (1) showed a highly linear molecular shape. Related results were deduced for the remained HpzR2 and the structural consequences agree with the observed mesomorphic properties. The mesogenic pyrazoles HpzR2 (1-6) were used as ligands towards [RhCl(CO)2] and [Rh(CO)2] fragments. [RhCl(CO)2(HpzR2)] complexes (7-12) showed some physical properties dependant on the long-chained pyrazoles, and related to different molecular arrays in the solid state. In all cases these compounds evolved to [Rh(μ-pzR2)(CO)2]2 in solution. The pyrazolate Rh(I) complexes [Rh(μ-pzR2)(CO)2]2 (3-18) had the usual boat conformation, as deduced by the crystal structure of two of these derivatives [n =10 (16), 12 (17)]. The packing arrangement has both layer and columnar characteristics. No mesophases have been detected for any of the Rh(I) complexes.
- Torralba,Cano,Campo,Heras,Pinilla,Torres
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p. 150 - 161
(2007/10/03)
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- First Examples Exhibiting both Double Melting Behavior and Mesomorphism in a Series of Long Chain Substituted Compounds: 1,3-Di(p-n-alkoxyphenyl)propane-1,3-dione
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A new series of β-diketones substituted by the same kind of chains, (alkoxy groups) having different lengths (CnO-Diketone, n = 1-12), has been synthesized.It was found that CnO-Diketone shows triple melting behavior for n = 1, double melting behavior for n = 2-7, and smectic mesomorphism for n = 8-12.It is the first example exhibiting both double (triple) melting behavior and mesomorphism in a series of long chain substituted compounds, so far as we know.Furthermore, it is noteworthy that the critical change from double melting behavior to mesomorphism occurs between n = 7 and n = 8, which is also the first example in the long chain substituted compounds, so far as we know.Keywords: double melting behavior, smectic mesomorphism, long chain substituted compounds, β-diketone
- Ohta, Kazuchika,Muroki, Hiromitsu,Hatada, Koh-Ichi,Takagi, Akira,Ema, Hiroshi,et al.
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p. 163 - 178
(2007/10/02)
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- Discotic Liquid Crystals of Transition Metal Complexes, 3: the First-Established Discotic Lamellar Phase in Biscopper(II)
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A new series of disk-like complexes, biscopper(II) (abbreviated as CnO-Cu, n = 1-12), has been synthesized.It was found that each of the complexes from C3O-Cu to C12O-Cu is a discogen, and that each of them has only one discotic mesophase.C3O-Cu is the first compound substituted by the shortest side chains in the discogen, so far as we know.The mesomorphic textures could be observed as mosaic textures for C3O-Cu ca.C5O-Cu and a big broken fan-like textures for C6O-Cu ca.C12O-Cu.The eutectic point calculated from Le Chatelier-Schroeder relations agrees well with the found eutectic point in the binary phase diagram between C8O-Cu and C8-Cu.This is the first example of such agreement in the discogens of the organic transition metal complexes.It has been established for the first time from X-ray diffraction measurements that each of the discotic mesophases in the complexes from C6O-Cu to C12O-Cu is a discotic lamellar phase.It becomes clear that this discotic mesophase is truly a new discotic lamellar phase (DL) different from the mesophase in C10-Cu, and that the DL phase has a structure in which the molecules tilt to the layers.Keywords: discotic liquid crystal, transition metal complex, bis(β-diketonato)copper(II), discotic lamellar phase
- Ohta, Kazuchika,Muroki, Hiromitsu,Takagi, Akira,Hatada, Koh-Ichi,Ema, Hiroshi,et al.
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p. 131 - 152
(2007/10/02)
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