A compound of Formula I: or a pharmaceutically acceptable salt thereof, wherein: W represents: R a represents: (CH 2) n R aa, or R aa; Raa represents: J represents N or CR 1; K represents O, S, or NR 1; Het represents a 5-6 membered nitrogen containing heterocycle substituted with 0 to 4 groups of R 2; T represents hydrogen, halogen, OR 1, or C 1-6 alkyl; R 1 independently represents hydrogen, or C 1-6 alkyl; M is a negative charge, H, or a pharmaceutically acceptable metal or ammonium salt, and provided that when W contains a moiety with multiple positive charges, there is an appropriate number of L ⊖ present to provide overall neutrality; R 2 and R 5 independently represent hydrogen, halogen, cyano, -OR 1, or C 1-6 alkyl; R 3 and R 4 independently represent cyano, C 1-6 alkyl, -X m -Y m -Z* m -R 8, or -X m -Y m -Z* m -Q +; R 7 represent hydrogen, halogen, cyano, -OR 1, C 1-6 alkyl, -X m -Y m -Z* m -R 8, or -X m -Y m -Z* m -Q +; provided at least one of R 3, R 4, and R 7 is -X m -Y m -Z* m -Q +; X and Y independently are O, NR x, (C=O), SO 2, (CH 2) n, -(CH 2) n NR 1 C -, -(CH 2) n S-, or -(CH 2) n N(R x) 2 -; Z* is (CH 2) n which may be substituted with one to four R b, R 6 represents C 6-10 aryl, or C 5-10 heteroaryl, said aryl and heteroaryl optionally substituted; R 8 represents halo, N(R c) 2, -C R 5, NR c C NH 2, NR c C H, (CH 2) n C 5-10 heterocyclyl, said heterocyclyl optionally substituted; Q is selected from the group consisting of: wherein Z represents N + or carbon; and A is O, CH 2, S 0-2, NR x, or N + (R x) 2; + represents a positive charged ion; L ⊖ represents a pharmaceutically acceptable counterion that is present as needed to provide charge balance on the molecule; a and b are 1,2 or 3; α represents O, S or NR s; β, δ, λ, μ and σ represent CR t, N or N ⊕ R s, provided that no more than one of β, δ, λ, μ and σ is N ⊕ R s; each R b independently represents halo; -CN; -NO 2; phenyl; -NHSO 2 R c; -OR c, -SR c; - N(R c) 2; -N + (R c) 3; -C N(R c) 2; -SO 2 N(R c) 2; heteroaryl; heteroarylium; formamidinyl, -CO 2 R c;-C R c; -OC R c; -NHC R c; -NHC 2 R c; guanidinyl; carbamimidoyl or ureido, said phenyl and heteroaryl optionally substituted; each R c independently represents hydrogen, a -C 1-6 straight or branched-chain alkyl group, a -C 3 -C 6 cycloalkyl group or C 6-10 aryl, said aryl optionally substituted with one to four groups of halogen; -CN; -NO 2; phenyl; -NHSO 2 R j; -OR 1, -SR j; -N(R j) 2; -N + (R j) 3; -C N(R j) 2; -SO 2 N(R j) 2; heteroaryl; heteroarylium; formamidinyl, -CO 2 R j; -C R j; -OC R j; -NHC R j; -NHC 2 R j; guanidinyl; carbamimidoyl or ureido, said phenyl and heteroaryl optionally substituted, wherein Rj is selected from the group consisting of hydrogen, a -C 1-6 straight or branched-chain alkyl group, a -C 3 -C 6 cycloalkyl group or C 6-10 aryl. each R s independently represents hydrogen; phenyl or -C 1-6 straight- or branched-chain alkyl, unsubstituted or substituted with one to four R b groups; each R 1 independently represents hydrogen; halo; phenyl; -CN; -NO 2; -NR u R v;-OR u; -SR u; -C NR u R v; -COOR c; -SOR u; -SO 2 R u; -SO 2 NR u R v; -NR u SO 2 R v; -C R u; - NR u C R v; -OC R u; -OC NR u R v; -NR u CO 2 R v; -NR u C NR v R w; -OCO 2 R v; -C 1-6 straight- or branched-chain alkyl, unsubstituted or substituted with one to four R b groups; R u and R v represent hydrogen or -C 1-6 straight- or branched-chain alkyl, unsubstituted or substituted with one to four R b groups; each R w independently represents hydrogen; -C 1-6 straight- or branched-chain alkyl, unsubstituted or substituted with one to four R b groups; C 3-6 cycloalkyl optionally substituted with one to four R b groups; phenyl optionally substituted with one to four R b groups, or heteroaryl optionally substituted with one to four R b groups; R x represents hydrogen or a C 1-8 straight- or branched- alkyl chain, optionally interrupted by one or two of O, S, SO, SO 2, NR w, N + R c R w, or -C -, said alkyl chain being unsubstituted or substituted with one to four of halo, CN, NO 2, -N 3, OR w, SR w, SOR w, SO 2 R w, NR c R w, N + (R c) 2 R w, Q, -C -R w, C NR c R w, SO 2 NR c R w, CO 2 R w, OC R w, OC NR c R w, NR c C R w, NR c C NH 2, NR c C H, NR c C NR c R w, phenyl, napthyl, heteroaryl, or heterocyclic group said phenyl, heteroaryl, and heterocyclic group optionally substituted with from one to four R b groups or with one to two C 1-3 straight- or branched- chain alkyl groups, said alkyl groups being unsubstituted or substituted with one to four R b groups; R y and R z represent hydrogen; phenyl; -C 1-6 straight or branched chain alkyl, unsubstituted or substituted with one to four R b groups, and optionally interrupted by O, S, NR w, N + R c R w or -C -; m represents 0 to 1; n represents 0 to 6; wherein it is understood that when a value is zero, a bond exists; and wherein alkyl is defined as a straight or branched chain aliphatic group having from 1 to 12 carbon atoms, optionally substituted with one, two or three substituents; and wherein cycloalkyl is defined as a saturated or partially unsaturated cyclic hydrocarbon group having 3 to 12 carbon atoms, wherein the cycloalkyl group is optionally substituted. W represents: