Organic polymers (molecules with very high molecular

QUESTION:

Organic polymers (molecules with very high molecular weight) can be designed with pores (cavities) that are specifically tailored to fit a particular guest molecule due to complementary size, shape, and functional group interactions (intermolecular forces). Such systems are often inspired by binding sites in natural enzymes, which display a high degree of specificity for a particular guest. Several porous polymers were designed to bind bisphenol A (compound 1), a compound that is of environmental concern due to its ability to mimic natural hor mones such as estrogen (J. Am. Chem. Soc. 2009, 131, 88338838). Schematics of the binding sites of two of these polymers are shown below. Polymer A was found to have only limited selectivity in that it binds 1 or 2 (a control guest molecule) to a similar degree. Polymer B is more selective in that it binds strongly to 1 and weakly to 2. Draw pictures showing how each guest (1, 2) may bind in the pores of each polymer (A, B), and propose an explanation for the differences in bind ing specificity described above. C C C CH3 CH3 C C C CC CC C C C C CC N C C C C C N CC C CC C C C C C C C C CC C C C C C C C CC CC C C C HO OH H2N NH2 1 2 Binding site in polymer A Binding site in polymer B H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H