A composition comprising a compound covalently bound to a silica gel substrate, said compound having a structure according to Formula wherein n is an integer selected from 0 and 1; X 1 is O or S; X 2 is O or S, with the proviso that at least one of X 1 or X 2 is O; R 20 is selected from the group consisting of H, substituted or unsubstituted phenyl, and linear or branched alkyl optionally substituted with hydroxyl or alkoxy substituted with hydroxy; R 21 is selected from the group consisting of H, substituted or unsubstituted phenyl, and unsubstituted linear or branched alkyl when X 2 is O, and R 21 is selected from the group consisting of substituted or unsubstituted phenyl, and unsubstituted linear or branched alkyl of C 1 or C 4 -C 14 alkyl, optionally unsubstituted linear or branched C 5 -C 14 alkyl such as C 12 alkyl when X 2 is S, with the proviso that both R 20 and R 21 cannot both be H; R 1, R 2 and R 3 are independently selected from the group consisting of halogen, OR 10, NR 10 R 11, OC R 12, OS 2 R 12, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl and a bond to said substrate wherein each R 10 and each R 11 is selected independently from the group consisting of H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl and a bond to said silica gel substrate; each R 12 is independently selected from the group consisting of substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and substituted or unsubstituted heterocycloalkyl, with the proviso that at least one of R 1, R 2 and R 3 is covalently bound to said substrate, and with the proviso that at least one of R 1, R 2 and R 3 is unsubstituted C 1 -C 3 alkyl or OH; L 1 and L 2 are linker groups independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl; and Y is O. n is an integer selected from 0 and 1; X 1 is O or S; X 2 is O or S, with the proviso that at least one of X 1 or X 2 is O; R 20 is selected from the group consisting of H, substituted or unsubstituted phenyl, and linear or branched alkyl optionally substituted with hydroxyl or alkoxy substituted with hydroxy; R 21 is selected from the group consisting of H, substituted or unsubstituted phenyl, and unsubstituted linear or branched alkyl when X 2 is O, and R 21 is selected from the group consisting of substituted or unsubstituted phenyl, and unsubstituted linear or branched alkyl of C 1 or C 4 -C 14 alkyl, optionally unsubstituted linear or branched C 5 -C 14 alkyl such as C 12 alkyl when X 2 is S, with the proviso that both R 20 and R 21 cannot both be H; R 1, R 2 and R 3 are independently selected from the group consisting of halogen, OR 10, NR 10 R 11, OC R 12, OS 2 R 12, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl and a bond to said substrate wherein each R 10 and each R 11 is selected independently from the group consisting of H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl and a bond to said silica gel substrate; each R 12 is independently selected from the group consisting of substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and substituted or unsubstituted heterocycloalkyl, with the proviso that at least one of R 1, R 2 and R 3 is covalently bound to said substrate, and with the proviso that at least one of R 1, R 2 and R 3 is unsubstituted C 1 -C 3 alkyl or OH; L 1 and L 2 are linker groups independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl and substituted or unsubstituted heterocycloalkyl; and Y is O.