The Katz Research Group
Department of Chemistry
Colby College

Complete list of Katz Group Publications and Funding

Rings, rings, and more rings...

The Katz group is focused on the synthesis of macrocyclic scaffolds for molecular and supramolecular applications. We are currently exploring the synthesis of oxacalixarenes by nucleophilic aromatic substitution reactions. We have developed a general, single-step synthesis of oxacalix[4]arenes and bicyclooxacalixarenes by condensation of meta-diphenols with 1,5-difluoro-2,4-dinitrobenzene. The method is selective for the tetrameric cyclooligomer, and tolerates a wide range of functional groups on the nucleophilic component (alkyl groups, esters, ketones, aldehydes, nitriles, nitro-groups, phenols).  Azaheterocyclic electrophiles such as pyridines, pyrazines, pyrimidines, and naphthyridines also participate in oxacalix[4]arene formation, producing good yields of the corresponding oxacalix[2]arene[2]hetarenes.  Electrophiles bearing strong electron withdrawing groups react at room tempterature, while less activated systems require elevated temperatures.

The bigger the better...

Large-ring oxacalix[n]arenes (n>4) can be isolated directly from cyclization of certain aromatic monomers under conditions of kinetic product control.  We are continuing to optimize the formation of these large-ring products, explore their scope with respect to both nucleophile and electrophile, and investigate their conformational properties.

What do we do with these things?

Oxacalix[2]arene[2]naphthyridines, readily accessible by condensation of 2,7-dichloronaphthyridine with diphenols, are particularly good substrates for molecular recognition. The naphthydridine rings create a spacing of approximately 7.0 Å between the nucleophilic component rings, creating a new class of "molecular tweezers". These substrates have shown selectivity for host-guest binding of certain aromatic compounds in organic solution.

The Katz group is also exploring potential applications of other accessible oxacalixarenes. We are investigating their molecular recognition properties, use as chemical sensors and catalysts, as well as ability to form supramolecular architectures.