Cyclodextrin covalent capping

The research group of Abelt has been seeking to construct photochemically active derivatives of p-cyclodextrin by capping the molecule with sulfonate derivatives of benzophenone and anthraquinone [27,28]. Under certain reaction conditions (irradiation in water or acetonitrile) the cyclodextrin itself is photo-oxidized to the aldehyde at one of the primary hydroxyls. Abelt and coworkers have used MMX [29] calculations to demonstrate the feasibility of, and perhaps even some selectivity in, the intramolecular hydrogen abstraction from this position by the covalently bound, photochemically induced radical. 

The hydrolysis of esters by the nickel derivative (271) provided an early example of the use of a metal-capped cyclodextrin as a catalyst (shown here as its p-nitrophenyl acetate inclusion complex) (Breslow Overman, 1970 Breslow, 1971). The synthesis of this host involves the following steps (i) covalent binding of the pyridine dicarboxylic acid moiety to cyclodextrin, (ii) coordination of Ni(n) to this species, and (iii)... 

Fig. 20 a The polyrotaxane formed by a-CD and PEO with 2,4-dinitro-phenyl end caps, b The figure-of-eight cross-link covalently cross-linked cyclodextrins. c Schematic diagram of the polyrotaxane gel prepared from the sparse polyrotaxane by covalently cross-linking cyclodextrins using cyanuric chloride as crosslinking agent [89]... 

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