5140-98-7Relevant academic research and scientific papers
[C-H···O] interactions as a control element in supramolecular complexes: Experimental and theoretical evaluation of receptor affinities for the binding of bipyridinium-based guests by catenated hosts
Houk,Menzer, Stephan,Newton, Simon P.,Raymo, Fran?isco M.,Stoddart, J. Fraser,Williams, David J.
, p. 1479 - 1487 (1999)
Macrocyclic receptors incorporating two facing π-electron-rich aromatic surfaces, held at a distance of approximately 7 A? by polyether spacers, bind bipyridinium-based guests. This recognition motif, which is dictated by π- π stacking and [C-H···O] hydrogen-bonding interactions, has led to the development of efficient template-directed syntheses of mechanically interlocked molecules, such as catenanes and rotaxanes. By employing a supramolecularly assisted synthetic methodology based on these interactions, we have self-assembled two novel [3]catenanes, each incorporating two 1,5- dioxynaphtho-38-crown-10 components and one bipyridinium-based tetracationic cyclophane component. Single-crystal X-ray analyses of these [3]catenanes revealed that they possess internal cavities bounded on two opposite sites by π-electron-rich 1,5-dioxynaphthalene units separated by a distance of approximately 7-8 A?. Despite the presence of apparently ideal 'binding pockets', these mechanically interlocked compounds steadfastly refuse to bind bipyridinium-based guests in solution, as demonstrated by both 1H NMR and UV-vis spectroscopy. AMBER* and HF/321G calculations on appropriate models show that the absence of [C-H···O] hydrogen-bonding interactions is responsible for the instability of these geometrically ideal complexes. The [C-H···O] bond appears to be quantitatively much more important than π- π stacking interactions in these particular systems.
Twisting of Alkynes towards a Carbon Double Helix
Adam, Abdulselam,Haberhauer, Gebhard
supporting information, p. 12190 - 12197 (2017/09/13)
The carbon allotrope exhibiting only one-dimensional sp-hybridized carbon atoms is called carbyne. However, its existence is very controversial. Studies on model compounds for carbyne revealed that many oligoalkynes show not a straight, but a bent structu
Design, synthesis and characterization of self-assembled As 2L3 and Sb2L3 cryptands
Fontenot, Sean A.,Cangelosi, Virginia M.,Pitt, Melanie A. W.,Sather, Aaron C.,Zakharov, Lev N.,Berryman, Orion B.,Johnson, Darren W.
supporting information; experimental part, p. 12125 - 12131 (2012/03/11)
The syntheses and X-ray crystal structures of six new self-assembled supramolecular As and Sb-containing cryptands are described. Analysis in the context of previously reported As2L3 and Sb 2L3 cryptands reveals that small differences in ligand geometries result in significant differences in the helicity of the complexes and the stereochemistry of the metal coordination within the assembled complexes. Additionally, a new synthetic route is described which involves exposure of reactants to vacuum to help facilitate self-assembly.
Synthesis, molecular modeling, and K+ channel-blocking activity of dequalinium analogues having semirigid linkers
Rosa, Joaquin Campos,Galanakis, Dimitrios,Ganellin, C. Robin,Dunn, Philip M.
, p. 4247 - 4254 (2007/10/03)
Dequalinium [1,1'-(decane-l,10-diyl)bis(2-methyl-4-aminoquinolinium)] is an effective blocker of the small conductance Ca2+activated K+ channel. It has been shown that the number of methylene groups in the alkyl chain linking the two quinolinium rings of this type of molecule is not critical for activity. To further investigate the role of the linker, analogues of dequalinium have been synthesized, in which the alkyl chain has been replaced by CH2XCH2 where X is a rigid or semirigid group containing aromatic rings. The compounds have been tested for blockade of the slow after- hyperpolarization on rat sympathetic neurons. The most potent compounds have X = phenanthryl, fluorenyl, cis-stilbene, and C6H4(CH2)(n)C6H4 where n = 0-4. The conformational preferences of the compounds were investigated using the XED/COSMIC molecular modeling system. Although there is some dependence of the potency of the analogue on the conformational properties of the linker (X), overall, X groups having substantial structural differences are tolerated. It seems that X provides a support for the two quinolinium groups and does not interact with the channel directly. The intramolecular separation between the quinolinium rings, which is provided by rigid groups X, is not critical for activity; this may be attributed to the residual conformational mobility of the heterocycles and to the extensive delocalization of the positive charge. These two factors may permit favorable contacts between the quinolinium groups and the channel over a range of intramolecular separations.
6>Paracyclophanes - Large Ring Compounds with Extended ?-Systems
Raston, Ilona,Wennerstroem, Olof
, p. 655 - 660 (2007/10/02)
Two 6>paracyclophanes with unsaturated bridges, containing perimeters with 36 ?-electrons, have been prepared by fourfold Wittig reactions.Attempts to prepare cyclophanes with even larger ?-systems are reported.The reversible two-electron red
