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81.
Sign Reversal of a Large Circularly Polarized Luminescence Signal by the Twisting Motion of a Bidentate Ligand 下载免费PDF全文
Dr. Junpei Yuasa Hiroshi Ueno Prof. Dr. Tsuyoshi Kawai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8621-8627
This work demonstrates sign reversal of large circularly polarized luminescence (CPL) signal based on the hinge‐like twisting motion of a bidentate ligand, 3,3‐bis(diphenylphosphoryl)‐2,2‐bipyridine (BIPYPO), in a cis–trans isomerization of chiral europium(III) complexes. X‐ray diffraction analysis revealed that twisting motion of BIPYPO provides s‐cis and s‐trans geometries of a chiral EuIII complex containing either tris[3‐(trifluoromethylhydroxymethylene)‐(+)‐camphorate] (D ‐ 1 ) or tris[3‐(heptafluoropropylhydroxymethylene)‐(+)‐camphorate] (D ‐ 2 ). The s‐cis EuIII complexes show eight‐coordinate geometry around the EuIII ion, in which the chelate between the phosphoryl oxygen and the EuIII ion forces the s‐cis geometry of BIPYPO. In contrast, the phosphorus–nitrogen interaction provides a conformational lock for the s‐trans geometry of the BIPYPO ligand, inducing a quasi‐seven‐coordinate EuIII complex. The difference in coordination geometry causes the sign change of the CPL signals between the s‐cis and s‐trans isomers, whereby the s‐cis and s‐trans isomers of EuIII complexes exhibit the positive and negative CPL signals, respectively, for the 5D0→7F1 transition. The proportion of the s‐trans‐D ‐ 1 against s‐cis‐D ‐ 1 increases upon changing the solvent from [D3]acetonitrile to [D6]acetone, inducing a sign change of the CPL signals. The complexes D ‐ 1 and D ‐ 2 show a biexponential decay with two different lifetimes, suggesting two emitting species, that is, the s‐cis and s‐trans isomers of EuIII complexes. In both cases, the proportions of the longer lifetime components (τ1) decrease and instead the shorter lifetime components (τ2) increase upon changing the solvent from [D3]acetonitrile to [D6]acetone. 相似文献
82.
M. V. Ladoshkin 《Mathematical Notes》2006,79(5-6):664-674
For each left graded module M over a graded algebra A, a Hochschild cochain complex S*(A, M) whose homology is responsible for the existence of nontrivial structures of A ∞-modules over A ∞-algebras on the given module is constructed. 相似文献
83.
A new class of steroid-based liquid crystals was synthesized and characterized with regard to their mesogenic and chiroptical properties. The β-selective formation of the cholestanyl difluoromethyl ether bridge was achieved by an oxidative fluorodesulfuration procedure. 相似文献
84.
《Liquid crystals》2012,39(15):2181-2189
ABSTRACTSignificant attention has been paid to improve the helical twisting power (β) and Δβ between the two different isomers of axially chiral azobenzene dopants in cholesteric liquid crystals (CLCs); however, the correlations between the vales (β and Δβ) with the molecular structures as well as photoisomerisation kinetics are far from clear. In this study, a series of binaphthyl-azobenzene cyclic dopants R1–R3 with different lengths of alkoxy chain was synthesised, which exhibited photochemically reversible trans–cis isomerisation in both organic solvents and liquid crystal hosts. When doping into a nematic liquid crystal, dopant R2 with one linking alkoxy group showed the highest values of β and Δβ. The results revealed that the β value was related to the dihedral angle between two naphthyl planes and the miscibility between the dopants and the host molecule. Moreover, Δβ was also depended on the photoisomerisation quantum yields. With increasing length of alkoxyl chain, the photoisomerisation rate constant of dopants increased upon ultraviolet irradiation and decreased for the reverse process upon visible light irradiation either in isotropic acetonitrile or in CLCs. These results enable the precise tuning of the pitch and selective reflection wavelength of CLCs. 相似文献
85.
Qun-xing Pan 《代数通讯》2013,41(10):3955-3973
Let H be a Hopf algebra and A an H-bimodule algebra. This article investigates homological dimensions and Gorenstein dimensions of L-R smash products A?H. Several well-known results are generalized. Moreover, we explore the stability of Gorenstein projective (flat) precovers and Gorenstein injective preenvelopes between the category of left A-modules and the category of left A?H-modules. 相似文献
86.
Toshiyuki Itoh Manabu Kanbara Shino Nakajima Yusuke Sakuta Shuichi Hayase Motoi Kawatsura Takashi Kato Kazutoshi Miyazawa Hidemitsu Uno 《Journal of fluorine chemistry》2009,130(12):1157-1163
The synthesis of a novel spiro type gem-difluorocyclopropane building block, 1,1,7,7-tetrafluoro-2,8-bis(hydroxymethyl)dispiro[2.2.2.2]decane (1), has been accomplished in optically pure form using chemo-enzymatic reaction protocol. Various types of diesters or dialkyl ether were prepared from diol (+)-1 or (−)-1 in optically active form and their helical twisting power (HTP) was evaluated by addition of 1.0 wt% to a non-chiral nematic liquid crystal host. Although their HTP values were not significant, all compounds showed liquid crystal property with SmC* phase when they were dissolved (20 wt%) in achiral nematic host liquid crystal. 相似文献
87.
Alexander N. Semenenko Nikolay L. Babak Stepan S. Popov Svitlana V. Shishkina Alexander V. Mazepa 《合成通讯》2018,48(9):1008-1015
New ylidene and spirocyclopropyl derivatives of cholestanone and dehydroepiandrosterone series were synthesized and their structure was determined by X-ray analysis. These compounds may be used as chiral dopants for cholesteric liquid crystal compositions which are applied in bistable displays with low power consumption. The ability of the synthesized substances to induce cholesteric mesophase in 4′-pentyl-1,1′-biphenyl-4-carbоnitrile nematic solvent was examined. The highest values of the helical twisting power |β| (190.0?±?2.3) and (165.5?±?1.9) µm?1 mol pats?1 were showed by (E)-2-{[3-(1,1′-biphenyl-4-yl)-1-phenyl-1H-pyrazol-4-yl]methyldene}-cholestanon and (1S,2S)-1-(1-phenyl-3-(4-methoxyphenyl)-1H-pyrazole-4-yl)-2,16′-spirocyclopropyldehydroepiandrosterone, correspondingly. 相似文献
88.
L. A. Kutulya L. D. Patsenker V. V. Vashchenko V. P. Kuznetsov V. I. Kulishov Yu. N. Surov V. V. Kravets 《Russian Chemical Bulletin》1995,44(7):1200-1209
It has been established by X-ray structural analysis that 2-(1-biphenyl-4-yl-1-hydroxy)methyl-p-menthan-3-one, one of the products of the reaction of (–)-menthone triisopropyloxytitanium enolate with 4-phenylbenzaldehyde, has a 1R,2S,4S,1S configuration. In crystals, this -hydroxyketone adopts a chair conformation with equatorial methyl and isopropyl groups and an axial 2-(1-biphenyl-4-yl-1-hydroxy)methyl substituent. Unlike the stereoisomeric compound with the 1R,2S,4S,1S configuration, the exocyclic fragment of which has an intramolecular >C=O...H-O- hydrogen bond in crystals and solutions, in the crystals of the 1R,2S,4S,1S ketol under study, molecules are linked by a network of cooperative -O-H...O-H...O-H... hydrogen bonds. Based on the results of molecular mechanics calculations and experimental data of1H NMR and IR spectroscopy, conformations of molecules of this compound, which are in equilibrium in solution, have been characterized. Based on data on spatial structures of stereoisomeric -hydroxyketones and the character of H-bonds formed by these compounds, the characteristic features of the effect of these chiral alloying additives on the supramolecular structure and macroscopic properties of liquid crystalline systems have been interpreted.The results of a study of stereoselectivity of the reactions of different (–)-menthone enolates with aromatic aldehydes will be published later.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1247–1255, July, 1995.The work was supported by the Foundation for Basic Research of the State Science and Engineering Committee of Ukraine (Project No. 93-3.2/75). 相似文献
89.
Hochschild Homology of Twisted Tensor Products 总被引:1,自引:1,他引:0
We compute the Hochschild homology of some twisted tensor products of algebras, which are a natural generalization of the Ore extensions. We apply our result to the ring D
Q,P(X,/X) of differential operators of the multiparametric affine space, the ring
of coordinates of the quantum symplectic 2v-dimensional space and the ring
of coordinates of the quantum 2v-dimensional Euclidean space. 相似文献
90.
Let k be an arbitrary field, H a kbialgebra and A a kalgebra. In Comm.Algebra 23 (7) (1995), pp. 2719–2744, the first author defined, in the case that A is an (H,H*)bicomodule algebra, a new product in A called the twist of the original multiplication. We generalize these considerations and define the twist with respect to more general twisting data that need not come from a bicomodule algebra structure. This general setting enlarges the range of applications of the concept of twisting, in particular it is shown that most known examples of twisting, e.g. the twist by cocycles and the concept of biproduct as introduced by Radford and Majid appear as particular cases of our construction. 相似文献