A compound represented by the formula: wherein each R 1 and R 2 in (R 1) 2 and (R 2) 2 independently represents hydrogen, optionally substituted C 1 -C 4 alkyl, halogen, hydroxyl, amino, nitro, or thiol; Y 1a represents O, S, NR 4a, wherein R 4a represents optionally substituted C 1 -C 4 alkyl; or Si(R 4b) 2, wherein each R 4b in (R 4b) 2 independently represents optionally substituted C 1 -C 4 alkyl; n is an integer 0 or 1; Y 1b, when present, represents O, S, NR 5a, wherein R 5a represents optionally substituted C 1 -C 4 alkyl; Si(R 5b) 2, wherein each R 5b in (R 5b) 2 independently represents optionally substituted C 1 -C 4 alkyl; or C(R 5c) 2, wherein each R 5c in (R 5c) 2 represents hydrogen or optionally substituted C 1 -C 4 alkyl; each of Y 2a, Y 2b, Y 2c, and Y 2d independently represents N, NR 6a, or CR 6b, wherein each of R 6a and R 6b independently represents hydrogen, halogen, hydroxyl, amino, nitro, thiol, or optionally substituted C 1 -C 4 alkyl; each of Y 3a, Y 3b, Y 3c, Y 3d, Y 3e, Y 4a, Y 4b, Y 4c, and Y 4d independently represents N, O, S, NR 6a, C, or CR 6b, wherein each of R 6a and R 6b independently represents hydrogen or optionally substituted C 1 -C 4 alkyl; or Z(R 6c) 2, wherein Z is C or Si, and wherein each R 6c in (R 6c) 2 independently represents hydrogen or optionally substituted C 1 -C 4 alkyl; m is 1 or 2; the open dotted circle indicates partial or full unsaturation of the ring with which it is associated; and the optional substituents for each C 1 -C 4 alkyl are selected from the group consisting of alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxyl, nitro, silyl, sulfo-oxo, and thiol; provided that if m is 1, each of Y 2a and Y 2d is CH and each of Y 2b and Y 2c is N, then at least one of Y 4a, Y 4b, Y 3a, or Y 3d is not N; and provided that if n is 0, m is 2, each of Y 2a and Y 2d is CH, and each of Y 2b and Y 2c is N, then at least one of Y 3b or Y 3c is not N. wherein each R 1 and R 2 in (R 1) 2 and (R 2) 2 independently represents hydrogen, optionally substituted C 1 -C 4 alkyl, halogen, hydroxyl, amino, nitro, or thiol; Y 1a represents O, S, NR 4a, wherein R 4a represents optionally substituted C 1 -C 4 alkyl; or Si(R 4b) 2, wherein each R 4b in (R 4b) 2 independently represents optionally substituted C 1 -C 4 alkyl; n is an integer 0 or 1; Y 1b, when present, represents O, S, NR 5a, wherein R 5a represents optionally substituted C 1 -C 4 alkyl; Si(R 5b) 2, wherein each R 5b in (R 5b) 2 independently represents optionally substituted C 1 -C 4 alkyl; or C(R 5c) 2, wherein each R 5c in (R 5c) 2 represents hydrogen or optionally substituted C 1 -C 4 alkyl; each of Y 2a, Y 2b, Y 2c, and Y 2d independently represents N, NR 6a, or CR 6b, wherein each of R 6a and R 6b independently represents hydrogen, halogen, hydroxyl, amino, nitro, thiol, or optionally substituted C 1 -C 4 alkyl; each of Y 3a, Y 3b, Y 3c, Y 3d, Y 3e, Y 4a, Y 4b, Y 4c, and Y 4d independently represents N, O, S, NR 6a, C, or CR 6b, wherein each of R 6a and R 6b independently represents hydrogen or optionally substituted C 1 -C 4 alkyl; or Z(R 6c) 2, wherein Z is C or Si, and wherein each R 6c in (R 6c) 2 independently represents hydrogen or optionally substituted C 1 -C 4 alkyl; m is 1 or 2; the open dotted circle indicates partial or full unsaturation of the ring with which it is associated; and the optional substituents for each C 1 -C 4 alkyl are selected from the group consisting of alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxyl, nitro, silyl, sulfo-oxo, and thiol; provided that if m is 1, each of Y 2a and Y 2d is CH and each of Y 2b and Y 2c is N, then at least one of Y 4a, Y 4b, Y 3a, or Y 3d is not N; and provided that if n is 0, m is 2, each of Y 2a and Y 2d is CH, and each of Y 2b and Y 2c is N, then at least one of Y 3b or Y 3c is not N.