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561.
Manuela Müller Hans‐Wolfram Lerner Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(8):796-800
2,5‐[(Diphenylphosphanyl)methyl]‐1,1,2,4,4,5‐hexaphenyl‐1,4‐diphospha‐2,5‐diboracyclohexane shows polymorphism as two tetrahydrofuran (THF) disolvates [C64H58B2P4·2C4H8O, (Ia) and (Ib)] and pseudo‐polymorphism as its toluene monosolvate [C64H58B2P4·C7H8, (Ic)]. In each of polymorphs (Ia) and (Ib), the diphosphadiboracyclohexane molecule is located on a centre of inversion. The THF molecule of (Ib) is disordered over two sites, with a site‐occupation factor of 0.612 (8) for the major‐occupied site. Both structures crystallize in the same space group (P21/n), but they display a different crystal packing. For pseudo‐polymorph (Ic), although the space group is P21/c, which is just a different setting of the P21/n space group of (Ia) and (Ib), the crystal packing is completely different. Although the crystal packing in these three structures is significantly different, their molecular conformations are surprisingly the same. 相似文献
562.
Use of solvent mapping, based on multiple-copy minimization (MCM) techniques, is common in structure-based drug discovery. The minima of small-molecule probes define locations for complementary interactions within a binding pocket. Here, we present improved methods for MCM. In particular, a Jarvis-Patrick (JP) method is outlined for grouping the final locations of minimized probes into physical clusters. This algorithm has been tested through a study of protein-protein interfaces, showing the process to be robust, deterministic, and fast in the mapping of protein "hot spots." Improvements in the initial placement of probe molecules are also described. A final application to HIV-1 protease shows how our automated technique can be used to partition data too complicated to analyze by hand. These new automated methods may be easily and quickly extended to other protein systems, and our clustering methodology may be readily incorporated into other clustering packages. 相似文献
563.
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565.
Sänger I Kückmann TI Dornhaus F Bolte M Wagner M Lerner HW 《Dalton transactions (Cambridge, England : 2003)》2012,41(22):6671-6676
The dimeric iron carbonyl [CpFe(CO)(2)](2) and the iodosilanes tBu(2)RSiI were obtained from the reaction of [CpFe(CO)(2)]I with the silanides Na[SiRtBu(2)] (R = Me, tBu) in THF. By the reactions of [CpFe(CO)(2)]I and Na[SiRtBu(2)] (R = Me, tBu) the disilanes tBu(2)RSiSiRtBu(2) (R = Me, tBu) were additionally formed using more than one equivalent of the silanide. In this context it should be noted that reduction of [CpFe(CO)(2)](2) with Na[SitBu(3)] gives the disilanes tBu(3)SiSitBu(3) along with the sodium ferrate [(Na(18-crown-6))(2)Cp][CpFe(CO)(2)]. The potassium analogue [(K(18-crown-6))(2)Cp][CpFe(CO)(2)] (orthorhombic, space group Pmc2(1)), however, could be isolated as a minor product from the reaction of [CpFe(CO)(2)]I with [K(18-crown-6)][PtBu(2)BH(3)]. The reaction of [CpFe(CO)(2)](2) with the potassium benzophenone ketyl radical and subsequent treatment with 18-crown-6 yielded the ferrate [K(18-crown-6)][CpFe(CO)(2)] in THF at room temperature. The crown ether complex [K(18-crown-6)][CpFe(CO)(2)] was analyzed using X-ray crystallography (orthorhombic, space group Pna2(1)) and its thermal behaviour was investigated. 相似文献
566.
Inge Sänger Frauke Schödel Michael Bolte Hans-Wolfram Lerner 《Journal of chemical crystallography》2012,42(5):472-474
Abstract
When a benzene solution of tBu2PHO·BCl3 was exposed to air at room temperature, the phosphonium chloride [tBu2PH2]Cl was formed together with di-tert-butylphosphinic acid, tBu2PO(OH). X-ray quality crystals of the hydrochloride [tBu2PH2]Cl·HCl were obtained from the reaction solution at room temperature. The hydrochloride [tBu2PH2]Cl·HCl crystallizes in the monoclinic space group P21 /m, a = 6.3012(7) ?, b = 6.8970(10) ?, c = 14.5011(15) ?, β = 99.376(9)°, V = 621.79(13) ?3, Z = 2, d calcd = g cm−3 1.165; R1 = 0.0510, wR2 = 0.1503 for 1,129 reflections with I > 2σ(I). The crystal was a non-merohedral twin with a contribution of 0.353(7) of the minor component. The structure is composed of discrete di-t-butylphosphonium cations and Cl anions. Both are located on a crystallographic mirror plane and are connected by P–H···Cl hydrogen bonds. 相似文献567.
Sänger I Heilmann JB Bolte M Lerner HW Wagner M 《Chemical communications (Cambridge, England)》2006,(19):2027-2029
Reaction of [(fc)3(Li)6.(TMEDA)2] with FeCl2 gives the pentanuclear iron complex [(fc)3(Fe)2(Li)2.(TMEDA)2] featuring two ferra[1]ferrocenophane moieties bridged by a 1,1'-ferrocenediyl unit; the non-ferrocene Fe(II) ions are tetra-coordinate and adopt a high-spin state. 相似文献
568.
Lerner RA 《Angewandte Chemie (International ed. in English)》2006,45(48):8106-8125
Although it took over one hundred years, Ehrlich's concept of the magic bullet is now a reality. Today, therapeutic antibodies are, arguably, the most important class of new drugs for the treatment of illnesses ranging from Alzheimer's disease to cancer. The emergence of therapeutic antibodies had to wait for advances in immunochemistry that allowed construction of antibodies in vitro. The centerpiece of the new technology is the combinatorial antibody library, which essentially allows one to synthesize an artificial immune system with a diversity that exceeds that of the natural repertoire. The construction of such libraries was perceived to be difficult because, if the natural immune system was to be used as the starting material, construction of the libraries would entail protocols that are the opposite of usual cloning. In gene cloning one starts with complexity and reduces it to a singularity. In the generation of diversity by construction of combinatorial antibody libraries, one starts with a collection of clones, randomly expands their complexity, and then returns them to recoverable singularities. The methods developed to accomplish this seemingly formidable task now allow construction of antibodies in a test tube to any antigen. These synthetic antibodies may be qualitatively and quantitatively superior to those of nature. 相似文献
569.
Jan W. Bats Tonia Kretz Hans‐Wolfram Lerner 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):m94-m96
A P212121 polymorph of the title compound, [Cu(CH3CN)4]BF4, is reported. The crystal structure is very similar to the structure of the Pna21 polymorph reported by Jones & Crespo [Acta Cryst. (1998), C 54 , 18–20]. The anions and one of the three independent cations occupy similar positions in both polymorphs. Two of the four symmetry‐related positions of the other two cations are also identical in the two polymorphs, and the other two positions are related by mirror symmetry. The crystal used for the structure determination contained a volume fraction of 0.088 (7) of the Pna21 polymorph. 相似文献
570.
1869年,门捷列夫在第一张元素周期表中的锆元素后留出原子量为180的元素位置,预测铪与锆同族。1913年,原子序数和莫斯莱定律的提出揭示了铪元素在周期表中位置排列的实质,为铪元素的发现提供理论基础。20世纪20年代,玻尔理论的发展证实铪与锆同族,指导科学家从锆矿石中寻找铪元素。1923年,赫维西和科斯特借助X射线光谱技术发现铪元素,彰显了X射线光谱技术的独特价值。20世纪30年代以后,同位素理论和质谱技术促成了铪同位素的发现,使人们对铪元素有了新的认识。总之,铪元素及其同位素的发现是技术进步和思想发展的共同结晶。 相似文献