A compound of the formula: wherein: each R is independently selected from halogen, H, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, SO 3 H, and alkyl, alkyl being optionally substituted with one or more heteroatoms independently selected from N, O, and S, halogen, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, and/or SO 3 H; Q is selected from CR, NR, O, SiR, and Se; W is selected from C and N; X is selected from a lone pair of electrons, H, alkyl, aryl, halogen, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, and SO 3 H, X being optionally substituted with one or more heteroatoms independently selected from N, O, and S, halogen, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COO, COOH, C NR 2, COO(alkyl), COO(aryl), C NR 2, PO 3 H 2, and/or SO 3 H; Y is selected from CR, C NR 2, NR, O, and S; and Z is selected from H, halogen, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, SO 3 H, aryl, and alkyl, alkyl and aryl being optionally substituted with one or more heteroatoms independently selected from N, O, and S, halogen, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, and SO 3 H, or wherein Z and Y, taken together with the atoms to which they are bonded, can form a 5-7 membered ring which is unsubstituted or substituted with (a) one or more additional heteroatoms selected from N, O and S or/and one or more substituents selected from halogen, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, SO 3 H, and alkyl or (b) an azetidine group; wherein amine is independently selected from NH 2, NH(alkyl), NH(aryl), N(alkyl) 2, and N(aryl) 2; the term "alkyl" means a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, which can be cyclic or acyclic; the term "aryl" means a carbon-based aromatic group, the term "aryl" also including "heteroaryl" which means an aromatic group that has at least one heteroatom incorporated within the ring of the aromatic group; and the term "5-7 membered ring" means a 5-7 membered cycloalkyl, a 5-7 membered heterocycloalkyl or a 5-7 membered aryl (which includes heteroaryl). each R is independently selected from halogen, H, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, SO 3 H, and alkyl, alkyl being optionally substituted with one or more heteroatoms independently selected from N, O, and S, halogen, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, and/or SO 3 H; Q is selected from CR, NR, O, SiR, and Se; W is selected from C and N; X is selected from a lone pair of electrons, H, alkyl, aryl, halogen, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, and SO 3 H, X being optionally substituted with one or more heteroatoms independently selected from N, O, and S, halogen, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COO, COOH, C NR 2, COO(alkyl), COO(aryl), C NR 2, PO 3 H 2, and/or SO 3 H; Y is selected from CR, C NR 2, NR, O, and S; and Z is selected from H, halogen, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, SO 3 H, aryl, and alkyl, alkyl and aryl being optionally substituted with one or more heteroatoms independently selected from N, O, and S, halogen, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, and SO 3 H, or wherein Z and Y, taken together with the atoms to which they are bonded, can form a 5-7 membered ring which is unsubstituted or substituted with (a) one or more additional heteroatoms selected from N, O and S or/and one or more substituents selected from halogen, CN, OH, O(alkyl), O(aryl), SH, S(alkyl), S(aryl), amine, NO 2, CHO, COOH, C NR 2, COO(alkyl), COO(aryl), PO 3 H 2, SO 3 H, and alkyl or (b) an azetidine group; wherein amine is independently selected from NH 2, NH(alkyl), NH(aryl), N(alkyl) 2, and N(aryl) 2; the term "alkyl" means a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, which can be cyclic or acyclic; the term "aryl" means a carbon-based aromatic group, the term "aryl" also including "heteroaryl" which means an aromatic group that has at least one heteroatom incorporated within the ring of the aromatic group; and the term "5-7 membered ring" means a 5-7 membered cycloalkyl, a 5-7 membered heterocycloalkyl or a 5-7 membered aryl (which includes heteroaryl).