作者:Riccardo F. Carina、Christiane Dietrich-Buchecker、Jean-Pierre Sauvage
DOI:10.1021/ja961459p
日期:1996.1.1
Molecular composite knots have been prepared from transition metal-assembled precursors via a Glaser acetylenic coupling reaction. The templating metal is copper(I), and the coordinating fragments incorporated into the final structure are 1,10-phenanthroline-type chelates. The compounds are composite knots as opposed to prime knots such as the classical trefoilknot. By combining two tied open-chain
A molecular trefoil knot, constructed around two copper(I) centres used as a template, has been synthesized in 29% yield (cyclization step) by the use of 1,3-phenylene spacers between the 1.10-phenanthroline subunits; the double stranded helical precursor complex is formed quantitatively. This latest improvement allowed us to prepare this topologically chiral molecule on a large scale and hence to undertake the resolution of its enantiomers. The resolution technique is based on crystallization of diastereomers with an enantiomerically pure chiral counterion, (S)-(+)-1,1'-binaphtyl-2,2'-diyl phosphate [(+)BNP-]. After anion exchange, several tens of milligrams of each enantiomer were isolated, with an excellent enantiomeric excess (ee > 98%). The optical purity was determined by H-1 NMR and circular dichroism (CD) spectroscopy. The absolute configuration was established on the basis of an X-ray diffraction study, the dextrorotatory knot corresponding to the left-handed knot. Demetallation with excess KCN yielded the free ligand, which could subsequently be, remetallated with silver(I) or copper(I). The chiroptical properties of each species are reported.
Rings-and-String Approach to the Construction of Porphyrin Arrays by Transition-Metal-Directed Threading
作者:David B. Amabilino、Christiane O. Dietrich-Buchecker、Jean-Pierre Sauvage