Supramolecular Photochemistry: Guest-Host Complexes and Supermolecules

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9313102 Turro The photochemical behavior of supramolecular systems will be studied, in particular guest-host complexes and supermolecules. The guest systems include precursor ketones which produce triplet geminate radical pairs and metal complexes that serve as electron donor acceptor transfer pairs. The host systems include colloidal micellar aggregates, double helical DNA and porous molecular crystalline zeolites. The supermolecules include biradicals produced by photolysis of large ring cyclic ketones and donor-acceptor complexes separated in space at fixed distances by a DNA spacer. The objectives of the proposed research include the discovery of new knowledge which will allow the control of the chemistry of supramolecular systems that involve highly reactive species such as biradicals and micellized radical pairs, and the photoinduced electron transfer processes between metal complexes. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Nicholas J. Turro at Columbia University. Supramolecular chemistry has been defined as the chemistry beyond the molecule. Two important classes of supramolecules will be studied: guest-host complexes and supermolecules. Guest-host complexes consist of two or more molecules that are held together by attractive forces, rather than chemical bonds. The supermolecules to be studied can be viewed as a consisting of two or more subunits, connected by spacer units. The structure and dynamics of these supramolecules as well as reactive intermediates that will generated by photolysis will be studied. The results of this study will find applications to technological activities involving chemistry at interfaces, the characterization of materials possessing unusual properties, and to an understanding of the binding of small guest molecules to biomolecules. ***