A compound, in particular a fluorescent dye, having the structural formula: wherein: each X 1 , X 2 , X 3 , X 4 is independently selected from H, halogen (F, Cl, Br, I), CN, NO 2 , OR 1 , SR 1 , NR 1 R 2 , COR 1 , COOR 1 , CONR 1 R 2 , PO 3 R 1 R 2 , SO 2 R 1 , SO 3 R 1 and R 3 , where: R 1 and R 2 can represent H, alkyl, aryl or heteroaryl, and wherein R 1 and R 2 can form together a substituted or unsubstituted 4-7 membered ring; R 3 is alkyl, alkenyl, alkynyl, aryl or cycloalkyl, optionally substituted with one or more heteroatoms independently selected from N, O, S, halogen (F, Cl, Br, I), N 3 , amine, OH, OR 1 , OCOR 1 , aryl, COOR 1 , CONR 1 R 2 , PO 3 H 2 and SO 3 H, where R 1 and R 2 are defined as above; Y is selected from OR 1 , NR 1 R 2 , or NR 1 R 3 , where R 1 , R 2 and R 3 are defined as above; Q is selected from O, S, SO 2 , NR, C(R 3 ) 2 , Si(R 3 ) 2 , Ge(R 3 ) 2 , P(=O)R 3 , P(=O)OR 3 , where R 3 is defined as above, and wherein Q and X 1 , taken together with the atoms to which they are bonded, can form a substituted or unsubstituted 5-7 membered ring; L and M are independently selected from OR 1 , SR 1 , NR 1 R 2 and R 3 , where R 1 , R 2 and R 3 are defined as above, and wherein L and M, taken together with the atoms to which they are bonded, can form a substituted or unsubstituted 5-7 membered ring; Z is selected from O, S, NR 1 , CR 1 R 3 or aryl, where R 1 and R 3 are defined as above, and wherein Z and X 4 , taken with the atoms to which they are bonded, can form a substituted or unsubstituted 5-7 membered ring. each X 1 , X 2 , X 3 , X 4 is independently selected from H, halogen (F, Cl, Br, I), CN, NO 2 , OR 1 , SR 1 , NR 1 R 2 , COR 1 , COOR 1 , CONR 1 R 2 , PO 3 R 1 R 2 , SO 2 R 1 , SO 3 R 1 and R 3 , where: R 1 and R 2 can represent H, alkyl, aryl or heteroaryl, and wherein R 1 and R 2 can form together a substituted or unsubstituted 4-7 membered ring; R 3 is alkyl, alkenyl, alkynyl, aryl or cycloalkyl, optionally substituted with one or more heteroatoms independently selected from N, O, S, halogen (F, Cl, Br, I), N 3 , amine, OH, OR 1 , OCOR 1 , aryl, COOR 1 , CONR 1 R 2 , PO 3 H 2 and SO 3 H, where R 1 and R 2 are defined as above; R 1 and R 2 can represent H, alkyl, aryl or heteroaryl, and wherein R 1 and R 2 can form together a substituted or unsubstituted 4-7 membered ring; R 3 is alkyl, alkenyl, alkynyl, aryl or cycloalkyl, optionally substituted with one or more heteroatoms independently selected from N, O, S, halogen (F, Cl, Br, I), N 3 , amine, OH, OR 1 , OCOR 1 , aryl, COOR 1 , CONR 1 R 2 , PO 3 H 2 and SO 3 H, where R 1 and R 2 are defined as above; Y is selected from OR 1 , NR 1 R 2 , or NR 1 R 3 , where R 1 , R 2 and R 3 are defined as above; Q is selected from O, S, SO 2 , NR, C(R 3 ) 2 , Si(R 3 ) 2 , Ge(R 3 ) 2 , P(=O)R 3 , P(=O)OR 3 , where R 3 is defined as above, and wherein Q and X 1 , taken together with the atoms to which they are bonded, can form a substituted or unsubstituted 5-7 membered ring; L and M are independently selected from OR 1 , SR 1 , NR 1 R 2 and R 3 , where R 1 , R 2 and R 3 are defined as above, and wherein L and M, taken together with the atoms to which they are bonded, can form a substituted or unsubstituted 5-7 membered ring; Z is selected from O, S, NR 1 , CR 1 R 3 or aryl, where R 1 and R 3 are defined as above, and wherein Z and X 4 , taken with the atoms to which they are bonded, can form a substituted or unsubstituted 5-7 membered ring. <EOS>