| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new metal complex having near infrared absorbency and suitably applicable to a near infrared absorbent and filter for plasma display panel. SOLUTION: This metal complex is a complex of a squalirium compound of formula I [wherein, R1 and R1' are each H, an alkylamino, a dialkylamino, a cycloalkylamino or the like; X and X' are each a group having active hydrogen; rings A and B are each an aromatic carbocycle or an aromatic heterocycle; (k) and (k') are each 1-4], [preferably a compound of formula II (wherein, R2-R4 are each H, an alkyl, a cycloalkyl or the like)] with a metal (preferably copper, cobalt, zinc or nickel). The metal complex is obtained by reacting the squalirium compound of formula I with a metal source in an organic solvent. The metal complex has absorbency in a near infrared region of 700-950 nm and can manifest excellent effect as coloring matter for writing in or readout in optically recording media using semiconductor laser or the like and liquid crystal displays, or the like.
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