850-23-7Relevant articles and documents
Charge-transfer probes for molecular recognition via steric hindrance in donor-acceptor pairs
Rathore,Lindeman,Kochi
, p. 9393 - 9404 (1997)
Molecular association of various aromatic hydrocarbons (D, including sterically hindered donors) with a representative group of diverse acceptors (A = quinone, trinitrobenzene, tetracyanoethylene, tropylium, tetranitromethane, and nitrosonium) is visually apparent in solution by the spontaneous appearance of distinctive colors. Spectral (UV-vis) analyses of the colored solutions reveal their charge-transfer origin (λ(CT)) and they provide quantitative information of the intermolecular association in the form of the K(DA) and ε(CT) values for the formation and visualization, respectively, of different [D,A] complexes. Importantly, such measurements establish charge-transfer absorption to be a sensitive analytical tool for evaluating the steric inhibition of donor-acceptor association. For example, the steric differences among various hindered aromatic donors in their association with quinone are readily dramatized in their distinctive charge-transfer (color) absorptions and verified by X-ray crystallography of the charge-transfer crystals and/or QUANTA molecular modeling calculations of optimum intermolecular separations allowed by van der Waals contacts.
