George Lem

First photosensitized enantiodifferentiating isomerization by optically active sensitizer immobilized in zeolite supercages.

Enantiodifferentiating photoisomerization of (Z)-cyclooctene sensitized by (R)- or (S)-1-methylheptyl benzoate immobilized in zeolite supercages afforded the respective enantiomer pair, (-)- and (+)-(E)-isomer (1E) in 5% enantiomeric excess, whilst racemic 1E was obtained upon homogeneous-phase photosensitization with the same antipodal sensitizer pair, thus demonstrating for the first time that chirally modified zeolites not only serve as supramolecular photosensitizing media but also enhance the original enantiodifferentiating ability of chiral photosensitizer.

Functionalization of C60 by Cycloaddition Reactions

Functionalization of C 60 has been achieved by [2+2] photocycloaddition reactions of enones and [2+4] cycloaddition reactions of dienes, the course of these reactions can be followed using electrospray mass spectrometry using a special tagging reagent. Using tagged C60 it was shown that cis and trans cycloadducts are formed from ketones such as 3-methylcyclohexenone. We have also employed the new technique of 3 He NMR spectrometry. 3 He is an NMR-active nucleus. Fullerenes containing an endohedral 3 He atom can be examined by NMR to obtain structural information and potentially determine isomer distributions. Examples, of helium spectra of fullerene hydrides are presented.