The present invention is directed to compounds represented by the following structural formula, Formula I: wherein: (a) X is selected from the group consisting of a single bond, O, S, S(O)2 and N; (b) U is an aliphatic linker; (c) Y is selected from the group consisting of O, C, S, NH and a single bond; (d) E is C(R3)(R4)A or A and wherein (i) A is selected from the group consisting of carboxyl, tetrazole, C1-C6 alkylnitrile, carboxamide, sulfonamide and acylsulfonamide; (e) Z1 and Z2 are each independently selected from the group consisting of N, O, and C with the proviso that at least one of Z1 and Z2 is N; (f) Z3 is selected from the group consisting of N, O, and C. (g) R8 is selected from the group consisting of hydrogen, C1-C6 alkyl, C1-C4 alkylenyl and halo; (h) R9 is selected from the group consisting of hydrogen, C1-C4 alkyl, C1-C4 alkylenyl, halo, aryl- C0-C4 alkyl, heteroaryl, C1-C6 allyl, and OR29.