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Tali Menahem Yitzhak Mastai 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):3009-3017
A series of chiral polymers based on poly(N‐acryl) amino acids was synthesized using a convergent synthetic approach. These chiral polymers have been used as chiral additives to induce enantioselective crystallization of racemic or conglomerate amino acids in solutions. These polymeric additives showed strong capabilities to enhance highly enantioselective resolution during the crystallization of amino acids. In addition, these polymers caused unusual modifications of amino acid crystal morphologies. Furthermore, spherical microparticles of those same chiral polymers were also shown active in similar chiral discriminations during amino acid crystallizations occurring on microparticle surfaces. Our study demonstrates the high potential of chiral polymers and microparticles to resolve amino acids throughout crystallization processes. High enantiomeric excesses in one targeted enantiomer of amino acids can also be maximized via time‐dependent kinetic control of crystallizations. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3009–3017, 2006 相似文献
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The crystal structures of the 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, TCNQF(4), electron transfer salts of meso-tetraphenylporphinatomagnesium(II), [MgTPP][TCNQF(4)].PhMe and [MgTPP][TCNQF(4)].3(1,2-C(6)H(4)Cl(2)), and meso-tetrakis(3,4,5-trimethoxyphenyl)porphinatomagnesium(II), [MgT(3,4,5-OMe)PP][TCNQF(4)].3(1,2-C(6)H(4)Cl(2)), provide the first structurally characterized examples of 1-D metal-radical chains involving [Mg(II)(porphyrin(*))](+). These salts possess [TCNQF(4)](*-) stabilized by trans-mu-coordination to Mg(II) and exhibit nu(CN) at 2199 and 2177, 2212 and 2187, and 2194 and 2172 cm(-1), respectively. The [TCNQF(4)](*-) species is planar and bridges two cations with MgN distances of 2.266(16), 2.221(2), and 2.276(3) A, respectively, which are shorter than the MnN 2.321(3) A distance observed for [MnT(3,4,5-OMe)PP][TCNQF(4)].3(1,2-C(6)H(4)Cl(2)). The room-temperature effective moments for [MgTPP][TCNQF(4)].xS (S = PhMe and 1,2-C(6)H(4)Cl(2)) and [MgTPP][C(4)(CN)(6)].PhMe are consistent with the calculated spin only value of 2.45 micro(B) with weak antiferromagnetic coupling (J(intra)/k(B) approximately -2.9 K; H = -2JSa.Sb) for these [TCNQF(4)](*-) salts and for this [C(4)(CN)(6)](*-) salt (J(intra)/k(B) approximately -0.8 K) on the basis of fits to several models. The coupling is significantly reduced with respect to that of the Mn analogues due to lack of spin on the metal site for [Mg(II)(por(*))](+). The antiferromagnetic coupling is enhanced for [MgT(3,4,5-OMe)PP][TCNQF(4)] with respect to [MgTPP][TCNQF(4)] as [TCNQF(4)](*-) gets closer to the [Mg(II)(por(*))](+) plane, which leads to greater interactions and coupling. 相似文献
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Natalia Fridman Moshe Kapon Yana Sheynin Menahem Kaftory 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):153-157
1,3-Benzenediamine,N,N′-bis(4,6-dichloro-1,3,5-triazine-2-yl) and 1,3,5-Triazine,2,2′-[2-methyl-1,3-phenylenebis(oxy)] bis(4,6-dichloro) were synthesized as host molecules. The inclusion compound of 1,3-Benzenediamine,N,N′-bis(4,6-dichloro-1,3,5-triazine-2-yl) crystallizes in the monoclinic crystal system in space group C2/c. The host molecule occupies the space group 2-fold special position and packed in the crystal lattice in such a manner as to leave channels running along the c axis of a rectangular cross-section. It crystallizes with two molecules of acetone that are hydrogen bonded to the amino nitrogen atoms. Molecules of 1,3,5-Triazine,2,2′-[2-methyl-1,3-phenylene bis(oxy)]bis(4,6-dichloro) are packed in the crystal in such a manner as to leave channels of a trapezoid cross-section that are running along the a axis. Guest molecules such as metanol, ethanol, and ethyl acetate can be used to fill the channels. The crystal structures of two inclusion compounds are described. 相似文献
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Hellena Taycher Mark Botoshansky Vitaly Shteiman Menahem Kaftory 《Supramolecular chemistry》2013,25(1):181-192
Abstract 2-Anilino-4,6-dimethoxy-1,3,5-triazine (13), 2-anilino-4,6-diethoxy-1,3,5-triazine (14), 2-(2′-nitoanilino) 4,6-dimethoxy-1,3,5-triazine (15) undergo alkyl rearrangement in the liquid-state, while 2-(4′-nito-anilino) 4,6-dimethoxy-1,3,5-triazine (16) undergoes methyl rearrangement in the solid-state. The crystal structure and thermal behavior of these compounds are described. 13 crystallizes in monoclinic P21/c space group, a = 11.030(4), b = 6.345(4), c = 16.315(4) Å, β = 90.76(3)°. The calculated density for Z = 4 is 1.351 Mg/m3. The number of unique reflections collected is 2092, and the final R = 0.0643 [I > 2σ(I)]. 14 crystallizes in triclinic P-1 space group, a = 7.700(2), b = 9.723(3), c = 10.154(3) Å, α = 78.78(3), β = 70.32(3), γ = 73.67(3)°. The calculated density for Z = 2 is 1.266 Mg/m3. The number of unique reflections collected is 2401, and the final R = 0.0561 [I > 2σ(I)]. 15 crystallizes in monoclinic P21/m space group, a = 11.020(3), b = 6.600(2), c = 8.409(3) Å, β = 99.72(3)°. The calculated density for Z = 2 is 1.527 Mg/m3. The number of unique reflections collected is 1153, and the final R = 0.0502 [I > 2σ(I)]. 16 crystallizes in monoclinic P21/c space group, a = 7.499(3), b = 21.846(5), c = 7.895(3) Å, β = 115.42(3)°. The calculated density for Z = 4 is 1.576 Mg/m3. The number of unique reflections collected is 2036, and the final R = 0.0757 [I > 2σ(I)]. 相似文献
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Seri N Simaan S Botoshansky M Kaftory M Biali SE 《The Journal of organic chemistry》2003,68(18):7140-7142
The use of a chiral solvating agent enabled the determination of the NMR-silent ring-inversion process of the ketocalixarene 3. Spectroscopic and crystal data indicate that 3 adopts the unusual 1,3-alternate conformation. 相似文献
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David Levanony Menahem Baruch 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1987,38(6):874-882
The behaviour of a non-uniform beam loaded by a parallel or tangential compressive force respectively is analyzed by exploiting a two-degree-of-freedom dynamic model. The same system has been analyzed previously by Lee and Reissner from a static point of view and by Neer and Baruch by a dynamic approach using a one-degree-of-freedom model. The previous analyses revealed only part of the phenomena by the present approach.Here, for the tangential force a classical flutter instability is obtained and for the parallel force only static instability is possible. 相似文献
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Natalya Fridman Moshe Kapon Menahem Kaftory 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o47-o49
5‐Methylsulfanyl‐1H‐tetrazole, C2H4N4S, crystallizes in dimorphic forms; the α‐form crystallizes at room temperature in the monoclinic crystal system, space group P21/m, and the β‐form crystallizes by sublimation at 423 K in the orthorhombic crystal system, space group Pbcm. In both forms, the molecules occupy crystallographic mirror planes and are connected to one another via N—H⋯N hydrogen bonds, the amino H atoms being disordered. The two forms differ from one another in their packing; there are polar layers in the α‐form and non‐polar layers in the β‐form. 相似文献
8.
Mark Botoshansky Menahem Kaftory Brian O. Patrick Keyan Wang 《Tetrahedron letters》2005,46(7):1141-1144
Based on molecular mechanics, Yang photocyclization of α-1-norbornylacetophenone derivatives in the crystalline state was engineered through methylation adjacent to the carbonyl group, thus changing the conformation in the crystal and leading to enhanced diastereo- and enantioselectivity. 相似文献
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