نتایج جستجو برای: crown symmetry

تعداد نتایج: 104166  

2010
Hien Ngoc Phan Hans-Wolfram Lerner Michael Bolte

The title compound, [Na(CF(3)O(3)S)(C(12)H(24)O(6))], features a sodium cation that is coordinated by eight O atoms in an irregular hexa-gonal bipyramidal environment. The equatorial positions are occupied by the six O atoms of an 18-crown-6 ether ring. In the axial positions, there is one O atom of a trifluoro-methane-sulfonate anion and an ether O atom of a symmetry-equivalent crown ether rin...

2004
VIRPI HARILA Lassi Alvesalo Tuomo Heikkinen Anna-Liisa Järvenpää

The aim of this study was to examine the effect of preterm birth on the development of the dentition. The spesific aims were to examine the effect on deciduous and permanent tooth crown dimensions, the eruption of permanent teeth and the sagittal occlusal relationships within the dentition. The subjects consisted of 328 prematurely born (< 37 gestational weeks ) white and black children and 180...

Journal: :Dalton transactions 2006
De-Liang Long Oliver Brücher Carsten Streb Leroy Cronin

A range of complexes based on the high-nuclearity [W36] isopolyoxotungstate cluster, [H12W36O120]12-, with a triangular topology has been isolated by using the organic cation, protonated triethanolamine. In analogy to an 18-crown-6 crown ether with six oxygen donors on a ring, the cluster can form alkali and alkaline earth metal complexes [M within W36] (M = K+, Rb+, Cs+, NH4+, Sr2+ and Ba2+, 1...

2013
Zouhour Denden Leila Bel Haj Hassen Mohamed Salah Belkhiria Jean-Claude Daran Habib Nasri

In the title compound, [Zn(C44H28N4)]·C12H24O6, the Zn(II) ion lies on an inversion center and the asymmetric unit contains one half of a Zn(TPP) complex (TPP = 5,10,15,20-tetra-phenyl-porphyrin dianion) and one half of a centrosymmetric 18-crown-6 mol-ecule. The Zn(TPP) complex exhibits a nearly planar conformation of the porphyrin core [maximum deviation = 0.106 (2) Å] with an average Zn-N di...

2014
Yi Qi Chang Yuan Zhang Huo Lin Lian

In the title compound, 2C11H18N(+)·2PF6 (-)·C12H24O6, the 18-crown-6 mol-ecule has crystallographically imposed inversion symmetry. In the crystal, it inter-acts with the cation through weak C-H⋯O hydrogen bonds. The cations and anions are further linked via N-H⋯F and C-H⋯F hydrogen bonds, leading to a sandwich structure .

Journal: :Physical chemistry chemical physics : PCCP 2015
Yoshiya Inokuchi Takeharu Haino Ryo Sekiya Fumiya Morishima Claude Dedonder Géraldine Féraud Christophe Jouvet Takayuki Ebata

The geometric and electronic structures of cold host-guest complex ions of crown ethers (CEs) in the gas phase have been investigated by ultraviolet (UV) fragmentation spectroscopy. As host CEs, we chose 15-crown-5 (15C5), 18-crown-6 (18C6), 24-crown-8 (24C8), and dibenzo-24-crown-8 (DB24C8), and as guests protonated-aniline (aniline·H(+)) and protonated-dibenzylamine (dBAM·H(+)) were chosen. T...

2008
Xing-Min Song Xian-Qiang Huang Jian-Min Dou Da-Cheng Li

The title complex, bis-(μ-benzene-18-crown-6)-3κ(6)O:4κO;4κ(6)O:3κO-bis-(benzene-18-crown-6)-1κ(6)O,6κ(6)O-tetra-μ-thiocyanato-1:2κ(2)S:N;2:3κ(2)N:S;4:5κ(2)S:N;5:6κ(2)N:S-dithio-cyanato-2κN,5κN-2,5-dicopper(I)-1,3,4,6-tetra-potassium(I), [K(4)Cu(2)(NCS)(6)(C(16)H(24)O(6))(4)] or {[K(C(16)H(24)O(6))](4)[Cu(NCS)(3)](2)}, consists of four [K(benzene-18-crown-6)](+) cations and two [Cu(NCS)(3)](2-)...

Journal: :Langmuir : the ACS journal of surfaces and colloids 2014
Tea Mihelj Vlasta Tomašić Nikola Biliškov

18-Crown-6, one of the most relevant crown ethers, and sodium cholate, a steroidal surfactant classified as a natural bile salt, are components of a novel, synthesized coordination complex: 18-crown-6-sodium cholate (18C6·NaCh). Like crown ethers, bile salts act as building blocks in supramolecular chemistry to design new functionalized materials with a desired structure and properties. In orde...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده علوم پایه 1389

در قسمت اول رساله واکنش تشکیل کمپلکس یون تالیم با calix[4]crown-6 و سه مشتق دیگر آن با روشهای 203tl , 1h nmr مورد بررسی قرار گرفتند. همچنین کمپلکس یک هسته ای tlclo4 و 1,3-calix[4]bis-o-benzo-crown-6 در حالت جامد تهیه شد و ساختار بلوری x-ray آن تعیین گردید. سینتیک و مکانیسم تفکیک و تغییرات پیکربندی کمپلکس تالیم و calix[4]crown-6 با دینامیک 1h nmr مورد مطالعه قرار گرفت. یک منحنی محدب آرنیوس برای ...

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