A compound of Formula I wherein R 12 is selected from straight and branched-chain C 1 -C 8 alkyl; each R 10 is independently selected from hydrogen, R 12 and -OR 12; R 8 and R 9 are each independently selected from hydrogen and straight and branched-chain C 1 -C 8 alkyl, wherein each said alkyl for R 8 and R 9 is independently optionally substituted by -NH 2, -NHR 11, -NR 11 R 13, -OR 11, -OH, or -SR 11, wherein each R 11 and each R 13 are independently selected from straight and branched-chain C 1 -C 5 alkyl; r is an integer 0 or 1; G is oxygen or sulfur; Z 1 is H or straight or branched-chain C 1 -C 5 alkyl; Ar is 1,2-, 1,3-, or 1,4-phenylene optionally substituted with one, two or three groups independently selected from straight or branched-chain C 1 -C 6 alkyl, -OR 14, -SR 14, halogen, nitro, -COOR 14, -C(=O)NHR 14, -O(CH 2) n COOR 14, -S(CH 2) n COOR 14, -O(CH 2) n C(=O)NHR 14, and -S(CH 2) n C(=O)NHR 14, or Ar is a 1,2-, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 1,8-, 2,3-, 2,6-, or 2,7-naphthylidene optionally substituted with one, two, three, or four groups independently selected from straight or branched-chain C 1 -C 6 alkyl, -OR 14, -SR 14, halogen, nitro, -COOR 14, -C(=O)NHR 14, -O(CH 2) n COOR 14, -S(CH 2) n COOR 14, -O(CH 2) n C(=O)NHR 14, and -S(CH 2) n C(=O)NHR 14; wherein each R 14 is independently selected from (C 1 -C 5)alkyl and each R 14 is independently optionally substituted with one or two groups selected from -OH, -(C 1 -C 4)alkyl, and -S(C 1 -C 4)alkyl; each n is an integer independently selected from 0, 1, 2, 3, 4, and 5; W is selected from -O-, -S-, -C(=O)NH-, -NHC(=O)-, and -NR 15 -, wherein R 15 is a (C 1 -C 5)alkyl and R 15 is optionally substituted with one or two groups selected from -OH, -(C 1 -C 4)alkyl, and -S(C 1 -C 4)alkyl; and Y is a straight or branched-chain (C 1 -C 6)alkylene group or a straight or branched-chain (C 2 -C 6)alkenylene group. wherein R 12 is selected from straight and branched-chain C 1 -C 8 alkyl; each R 10 is independently selected from hydrogen, R 12 and -OR 12; R 8 and R 9 are each independently selected from hydrogen and straight and branched-chain C 1 -C 8 alkyl, wherein each said alkyl for R 8 and R 9 is independently optionally substituted by -NH 2, -NHR 11, -NR 11 R 13, -OR 11, -OH, or -SR 11, wherein each R 11 and each R 13 are independently selected from straight and branched-chain C 1 -C 5 alkyl; r is an integer 0 or 1; G is oxygen or sulfur; Z 1 is H or straight or branched-chain C 1 -C 5 alkyl; Ar is 1,2-, 1,3-, or 1,4-phenylene optionally substituted with one, two or three groups independently selected from straight or branched-chain C 1 -C 6 alkyl, -OR 14, -SR 14, halogen, nitro, -COOR 14, -C(=O)NHR 14, -O(CH 2) n COOR 14, -S(CH 2) n COOR 14, -O(CH 2) n C(=O)NHR 14, and -S(CH 2) n C(=O)NHR 14, or Ar is a 1,2-, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 1,8-, 2,3-, 2,6-, or 2,7-naphthylidene optionally substituted with one, two, three, or four groups independently selected from straight or branched-chain C 1 -C 6 alkyl, -OR 14, -SR 14, halogen, nitro, -COOR 14, -C(=O)NHR 14, -O(CH 2) n COOR 14, -S(CH 2) n COOR 14, -O(CH 2) n C(=O)NHR 14, and -S(CH 2) n C(=O)NHR 14; wherein each R 14 is independently selected from (C 1 -C 5)alkyl and each R 14 is independently optionally substituted with one or two groups selected from -OH, -(C 1 -C 4)alkyl, and -S(C 1 -C 4)alkyl; each n is an integer independently selected from 0, 1, 2, 3, 4, and 5; W is selected from -O-, -S-, -C(=O)NH-, -NHC(=O)-, and -NR 15 -, wherein R 15 is a (C 1 -C 5)alkyl and R 15 is optionally substituted with one or two groups selected from -OH, -(C 1 -C 4)alkyl, and -S(C 1 -C 4)alkyl; and Y is a straight or branched-chain (C 1 -C 6)alkylene group or a straight or branched-chain (C 2 -C 6)alkenylene group.