16144-65-3Relevant articles and documents
Polar self-assembly: Steric effects leading to polar mixed-ligand coordination cages
Zhang, Jianyong,Miller, Philip W.,Nieuwenhuyzen, Mark,James, Stuart L.
, p. 2448 - 2453 (2006)
We present a highly unusual example of self-assembly, specifically a polar, mixed-ligand cage which forms in preference to symmetrical homoligand products, and which suggests that steric effects can be exploited to obtain novel non-uniform polyhedral cage
Synthesis and anion-selective complexation of homobenzylic tripodal thiourea derivatives
Hisaki, Ichiro,Sasaki, Shin-Ichi,Hirose, Keiji,Tobe, Yoshito
, p. 607 - 615 (2007/10/03)
Cryptand- and tripod-type thiourea derivatives 4b and 5a-d, which have binding functionalities at the homobenzylic positions, were synthesized as possible neutral receptors toward anions with an expectation that the three binding sites work cooperatively to bind an anion selectively. 1H NMR spectroscopic monitoring of the titration of cryptand 4b with CH 3CO2-, Cl-, and F- in CDCl2CDCl2 at 100°C showed that the binding constants were considerably smaller than those of tripodal thiourea 5a, presumably owing to the presence of strong intramolecular hydrogen bonding in 4b. Complexation constants of tripodal receptors 5a-d with H2PO4 -, CH3CO2-, Cl-, and Br- anions were evaluated by 1H NMR and/or UV/Vis spectroscopic analysis of the titration in DMSO. Though tripodal receptors 5a,b undergo complexation with phosphate anion in a 1:1 stoichiometry, their association constants were not as large as simple reference compound 14 probably because of the steric hindrance around the binding sites and the large entropy cost for cooperative binding. Receptor 5c exhibits complexation in a 1:2 stoichiometry with H2PO4- and CH 3CO2-, whereas it forms 1:1 complexes with chloride and bromide anions because of the subtle balance between the steric hindrance and the binding ability. However, by increasing the acidity of the thiourea functionality, receptor 5d exhibited remarkably enhanced binding ability and selectivity toward H2PO4- compared to those of reference compound 15 presumably through cooperative complexation of the three binding sites to the guest anion. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
OXIDATION OF HEXAMETHYLBENZENE AND 2,3,4,5,6-PENTAMETHYLBENZYL CATION IN FLUOROSULFONIC ACID
Rudenko, A. P.,Zarubin, M. Ya.,Fedorova, E. M.
, p. 1609 - 1618 (2007/10/02)
The oxidation of hexamethylbenzene in HSO3F-PbO2 takes place with the participation of the 1-H+-1,2,3,4,5,6-hexamethylbenzenonium ion and the intermediate formation of the 2,3,4,5,6-pentamethylbenzyl cation, which is capable of entering into further oxidative transformations leading to substitution of the hydrogen atom in two and three methyl groups.The structure of the final products from the observed transformations were established, and a mechanism is proposed for their formation.