Cyanine compounds, optical filters, and optical recording materials

A cyanine compound represented by the general formula (I):

• wherein ring-A1 is an optionally substituted benzene or naphthalene ring;
• B is a group represented by the general formula (II) or (III);
• R1 is a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an aryl group having 6 to 30 carbon atoms;
• R2 is a substituent represented by the general formula (IV);
• and Y1 is a hydrogen atom, an organic group having 1 to 30 carbon atoms, or a substituent represented by the general formula (IV):
• in the general formula (II), Y2 is the same group as Y1 in the general formula (I);
• X1 is an oxygen atom, a sulfur atom, a selenium atom, —CR3R4—, —NH—, or —NY′—;
• each of R3 and R4 is independently an alkyl group having 1 to 4 carbon atoms, a group represented by the general formula (IV), a group represented by the general formula (V) or a group forming a 3 to 10 membered ring by linking together;
• Y′ is an organic group having 1 to 30 carbon atoms;
• each of R21 and R22 is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an aryl group having 6 to 30 carbon atoms;
• and R21 and R22 may form a ring structure by liking together:
• in the general formula (III), R5 is the same group as R1 in the general formula (I);
• Y3 is the same group as Y1 in the general formula (I);
• and R21 and R22 are the same groups as R21 and R22 in the general formula (II):
• wherein each of Ra to Ri is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
• the methylene group in the alkyl group may be replaced by —O— or —CO—;
• Z is a direct bond or an optionally substituted alkylene group having 1 to 8 carbon atoms;
• the methylene group in the alkylene group may be replaced by —O—, —S—, —CO—, —COO—, —OCO—, —SO2—, —NH—, —CONH—, —NHCO—, —N═CH—, or —CH═CH—;
• and M is Fe, Co, Ni, Ti, Cu, Zn, Zr, Cr, Mo, Os, Mn, Ru, Sn, Pd, Rh, Pt, or Ir:
• wherein each of R6 to R9 is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms optionally substituted by a halogen atom, or an alkoxy group having 1 to 4 carbon atoms optionally substituted by a halogen atom;
• and R6 and R7 may form a ring structure by linking together.