A compound of Formula, or salts, mesomeric forms thereof: wherein R 1 is each R 2, R 3, R 4, and R 5 is independently selected from the group consisting of H, alkyl, substituted alkyl, alkoxy, alkenyl, alkynyl, haloalkyl, haloalkoxy, alkoxyalkyl, amino, aminoalkyl, halo, cyano, hydroxy, hydroxyalkyl, heteroalkyl, C-carboxy, O-carboxy, C-amido, N-amido, nitro, sulfonyl, sulfo, sulfino, sulfonate, S-sulfonamido, N-sulfonamido, carbocyclyl, aryl, heteroaryl and heterocyclyl; R 6 is alkyl substituted with carboxyl, -C OR 12, or -C NR 13 R 14; R 9 is H; each R 7 and R 8 is independently selected from the group consisting of H, alkyl, substituted alkyl, alkoxy, alkenyl, alkynyl, haloalkyl, haloalkoxy, alkoxyalkyl, amino, aminoalkyl, halo, cyano, hydroxy, hydroxyalkyl, heteroalkyl, C-carboxy, O-carboxy, C-amido, N-amido, nitro, sulfonyl, sulfo, sulfino, sulfonate, S-sulfonamido, N-sulfonamido, carbocyclyl, aryl, heteroaryl and heterocyclyl; X is selected from the group consisting of O, S, NR 11, and Se; R 11 is selected from the group consisting of H, alkyl, substituted alkyl, alkenyl, alkynyl, aminoalkyl, carboxyalkyl, sulfonatoalkyl, haloalkyl, heteroalkyl, alkoxyalkyl, sulfo, aryl, heteroaryl, carbocyclyl, and heterocyclyl; R 12 is selected from the group consisting of alkyl, aryl, heteroaryl, and 3 to 7 membered cycloalkyl; each R 13 and R 14 is independently selected from H, alkyl, aryl, heteroaryl and 3 to 7 membered cycloalkyl; and the bond represented by a solid and dashed line - - - - - - is selected from the group consisting of a single bond and a double bond, provided that when - - - - - - is a double bond, then R 3 is absent. wherein R 1 is each R 2, R 3, R 4, and R 5 is independently selected from the group consisting of H, alkyl, substituted alkyl, alkoxy, alkenyl, alkynyl, haloalkyl, haloalkoxy, alkoxyalkyl, amino, aminoalkyl, halo, cyano, hydroxy, hydroxyalkyl, heteroalkyl, C-carboxy, O-carboxy, C-amido, N-amido, nitro, sulfonyl, sulfo, sulfino, sulfonate, S-sulfonamido, N-sulfonamido, carbocyclyl, aryl, heteroaryl and heterocyclyl; R 6 is alkyl substituted with carboxyl, -C OR 12, or -C NR 13 R 14; R 9 is H; each R 7 and R 8 is independently selected from the group consisting of H, alkyl, substituted alkyl, alkoxy, alkenyl, alkynyl, haloalkyl, haloalkoxy, alkoxyalkyl, amino, aminoalkyl, halo, cyano, hydroxy, hydroxyalkyl, heteroalkyl, C-carboxy, O-carboxy, C-amido, N-amido, nitro, sulfonyl, sulfo, sulfino, sulfonate, S-sulfonamido, N-sulfonamido, carbocyclyl, aryl, heteroaryl and heterocyclyl; X is selected from the group consisting of O, S, NR 11, and Se; R 11 is selected from the group consisting of H, alkyl, substituted alkyl, alkenyl, alkynyl, aminoalkyl, carboxyalkyl, sulfonatoalkyl, haloalkyl, heteroalkyl, alkoxyalkyl, sulfo, aryl, heteroaryl, carbocyclyl, and heterocyclyl; R 12 is selected from the group consisting of alkyl, aryl, heteroaryl, and 3 to 7 membered cycloalkyl; each R 13 and R 14 is independently selected from H, alkyl, aryl, heteroaryl and 3 to 7 membered cycloalkyl; and the bond represented by a solid and dashed line - - - - - - is selected from the group consisting of a single bond and a double bond, provided that when - - - - - - is a double bond, then R 3 is absent.