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151.
Wang E Ma Z Zhang Z Vandewal K Henriksson P Inganäs O Zhang F Andersson MR 《Journal of the American Chemical Society》2011,133(36):14244-14247
A new, low-band-gap alternating copolymer consisting of terthiophene and isoindigo has been designed and synthesized. Solar cells based on this polymer and PC(71)BM show a power conversion efficiency of 6.3%, which is a record for polymer solar cells based on a polymer with an optical band gap below 1.5 eV. This work demonstrates the great potential of isoindigo moieties as electron-deficient units for building donor-acceptor-type polymers for high-performance polymer solar cells. 相似文献
152.
Garcia Y Robert F Naik AD Zhou G Tinant B Robeyns K Michotte S Piraux L 《Journal of the American Chemical Society》2011,133(40):15850-15853
The first crystal structures of a dinuclear iron(II) complex with three N1,N2-1,2,4-triazole bridges in the high-spin and low-spin states are reported. Its sharp spin transition, which was probed using X-ray, calorimetric, magnetic, and (57)Fe Mossbauer analyses, is also delineated in the crystalline state by variable-temperature fluorimetry for the first time. 相似文献
153.
Jurgen Sleven Thomas Cardinaels Koen Binnemans Daniel Guillon Bertrand Donnio 《Liquid crystals》2013,40(11):1425-1433
This paper deals with the synthesis of vanadyl phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions. The alkoxy chain length was varied, and octa-octyloxy (C8H17O), octa-dodecyloxy (C12H25O) and octa-hexadecyloxy (C16H33O) substituted vanadyl phthalocyanine complexes were prepared. Studies by polarizing optical microscopy and small angle X-ray diffraction (XRD) revealed that all the complexes are liquid crystalline and that these metallomesogens exhibit a columnar phase. The symmetry of the 2D lattice is rectangular, with a c 2 mm space group, as determined by the indexation of the XRD reflections; hence a rectangular columnar phase (Colr) was assigned. A double periodicity, although weak, along the axis of the columns was found, which indicates some degree of pairing or dimerization. A tentative explanation based on an antiferroelectric stacking is given. Transition enthalpies were determined by differential scanning calorimetry. The compounds start to decompose above 250°C before reaching the clearing temperatures. A significant bathochromic shift of the Q-band in the UV/Vis spectra of the vanadyl complexes compared with the metal-free ligands and other metallophthalocyanines (M=CoII, NiII, CuII, ZnII) was also observed. 相似文献
154.
Jurgen Sleven Thomas Cardinaels Koen Binnemans Daniël Nelis Jules Mullens Dirk Hinz-Hübner 《Liquid crystals》2013,40(2):143-148
Cobalt (II) phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions were prepared. The alkoxy chain length was varied between n-butyloxy (C4H9O) and n-octadecyloxy (C18H37O). Studies by polarizing optical microscopy and high temperature X-ray diffraction revealed that all the complexes are liquid crystalline and that they exhibit a hexagonal columnar mesophase (Colh). Transition enthalpies were determined by differential scanning calorimetry. The clearing point could only be observed for compounds with a chain length longer than C13H27O. Both the melting and clearing points decrease with increasing chain length. The transition temperatures of these discotic metallomesogens are higher than those of the corresponding metal-free phthalocyanines, but are comparable with those of the corresponding copper (II) compounds. The thermal decomposition of the compounds was studied by thermogravimetry. 相似文献
155.
Adducts were formed between a mesomorphic Ni(salen) complex [salen=2,2′-N,N′-bis(salicylidene)ethylenediamine] with six terminal alkoxy chains and a lanthanide nitrate (Ln=La, Gd). Different alkoxy chain lengths were used: OC12H25, OC14H29, OC16H33 and OC18H37. Trinuclear nickel–lanthanum and nickel–gadolinium complexes [Ln(NO3)3{Ni(salen)}2] were obtained. The compounds exhibit a wide-temperature-range hexagonal columnar mesophase (ColH) with rather low melting points. The mesophase stability ranges of both the parent nickel complexes and the nickel–lanthanide complexes decrease with increasing chain length. A decrease in the mesophase stability range over the lanthanide series was also observed. The results are compared with those of similar copper–lanthanide complexes. A marked difference is the higher thermal stability of the nickel–lanthanide complexes in comparison with the copper–lanthanide complexes. 相似文献
156.
Dr. Jan Vanbuel Dr. Estefanía Germán Guillaume Libeert Koen Veys Janni Moens Prof. Dr. Julio A. Alonso Prof. Dr. María J. López Prof. Dr. Ewald Janssens 《Chemphyschem》2020,21(10):1012-1018
The adsorption of molecular deuterium (D2) onto charged cobalt-fullerene-complexes ConC60+ (n=1–8) is measured experimentally in a few-collision reaction cell. The reactivity is strongly size-dependent, hinting at clustering of the transition metal atoms on the fullerenes. Formation and desorption rate constants are obtained from the pressure-dependent deuterogenation curves. DFT calculations indeed find that this transition metal clustering is energetically more favorable than decorating the fullerene. For n=1, D2 is predicted to bind molecularly and for n=2 dissociative and molecular configurations are quasi-isoenergetic. For n=3–8, dissociation of D2 is thermodynamically preferred. However, reaching the ground state configuration with dissociated deuterium on the timescale of the experiment may be hindered by dissociation barriers. 相似文献
157.
We investigate the suggestion of R.L. Dobrushin, that for many examples of non-Gibbsian measures, a well-defined interaction
potential can still be derived.
Such an interaction cannot be absolutely summable, uniformly in all configurations. Rather there will exist a typical set
of configurations on which the interaction decays sufficiently fast. We show how to construct an interaction, using quite
elementary methods, for example of the restriction of the Ising pure phases to one layer of the lattice.
We sketch a general setup, showing that there is an intimate relation between the problem treated here and the decay of correlations
in certain disordered systems.
Received: 27 March 1996 / Accepted: 29 July 1996 相似文献
158.
Artur Adamski Kristiaan Neyts Koen D'hav Per Rudquist Roman D browski 《Liquid crystals》2005,32(6):707-715
We have systematically studied the quality of bookshelf alignment and electro-optic characteristics of two antiferroelectric liquid crystal materials in cells with various boundary conditions. The electro-optic characteristics of the materials studied depend strongly on both the liquid crystal materials and the boundary conditions at the supporting substrates. We have compared a number of observations in these cells: the tendency to form AFLC domains in the virgin state and after switching; the surface electroclinic effect (SEC effect); the transmission-voltage characteristics (TV) when driven with triangular- and square-wave voltages at various frequencies; the threshold field and the conditions for relaxation to the AFLC state. The set of samples includes specially designed and manufactured test cells with different polyimides as alignment layers, treated with varying rubbing strengths. We discuss the significance of various factors and show the importance of simultaneously optimizing both materials and cell parameters for AFLC applications. 相似文献
159.
160.
Koen Thas Hendrik Van Maldeghem 《Transactions of the American Mathematical Society》2008,360(5):2327-2357
Finite Moufang generalized quadrangles were classified in 1974 as a corollary to the classification of finite groups with a split BN-pair of rank , by P. Fong and G. M. Seitz (1973), (1974). Later on, work of S. E. Payne and J. A. Thas culminated in an almost complete, elementary proof of that classification; see Finite Generalized Quadrangles, 1984. Using slightly more group theory, first W. M. Kantor (1991), then the first author (2001), and finally, essentially without group theory, J. A. Thas (preprint), completed this geometric approach. Recently, J. Tits and R. Weiss classified all (finite and infinite) Moufang polygons (2002), and this provides a third independent proof for the classification of finite Moufang quadrangles.
In the present paper, we start with a much weaker condition on a BN-pair of Type and show that it must correspond to a Moufang quadrangle, proving that the BN-pair arises from a finite Chevalley group of (relative) Type . Our methods consist of a mixture of combinatorial, geometric and group theoretic arguments, but we do not use the classification of finite simple groups. The condition on the BN-pair translates to the generalized quadrangle as follows: for each point , the stabilizer of all lines through that point acts transitively on the points opposite .