Kjeld J. C. van Bommel

Complexation and (templated) synthesis of rhenium complexes with cyclodextrins and cyclodextrin dimers in water

Several small, lipophilic rhenium complexes form inclusion complexes with native beta-cyclodextrin (beta-CD) and beta-CD dimers. Association constants larger than 10(9)M(-1) were obtained using dimers. The use of beta-CD also enabled the synthesis of these rhenium complexes in water, in excellent yields, through complexation of the otherwise insoluble corresponding ligands. The influence of the reaction time and temperature on the configuration of the reaction products has been investigated in depth for one of these complexes. Using a beta-CD dimer, it proved possible to specifically template the formation of one configuration. The strength of the complexes of the rhenium complexes in cyclodextrin dimers may allow radiolabeling of biomolecules.

Novel upper rim functionalizations of calix[4]arenes using the Tscherniac-Einhorn amidomethylation reaction

A variety of novel upper rim functionalized calix-[4]arenes have been synthesized, using the Tscherniac-Einhorn amidomethylation reaction. Partially or fully alkylated calix [4]arenes bearing propyl or ethoxyethyl substituents could be easily condensed with various N-methylol-amides and -imides under mild conditions. The resulting methyl-acetamido- (4a, 4b, 7a), methylchloroacetamido (4c, 4d,7b, 7c,9 methylphthalimido (4e, 4f, 4h)and methylchloroacetamido methylphthalimido functionalized calix[4]arenes (5) were obtained in yields varying from 30 till 97%. The amidomethylation reactions were proven to be independent of the conformation of the calix[4]arene.

More than just a catalyst: a novel role for benzylamine in the sol-gel transcription or organogels

Gelator-catalyst interactions allow the transcription of the organogel structure of methyl-4,6-O-(p-nitrobenzylidene)-alpha-D-glucopyranoside (1) into its silica analogue, even in the absence of positive charges or H-bonding sites on the gelator molecule which, until now, were considered indispensable.