Ink, inkjet ink, inkjet recording method and method for improving weather resistance of color image material

An ink comprising at least one coloring matter represented by a formula (I):

• wherein R1 represents one of an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, an acyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group, which may have a substituent;
• X1 represents one of —CR2═ and a nitrogen atom, R2 represents one of a hydrogen atom and a substituent, and when R2 represents a substituent, R2 may have a substituent;
• X2 represents one of —CR3═ and a nitrogen atom, and R3 represents an electron-withdrawing group having a σp value of 0.20 or more;
• when X1 represents —CR2═, a pair of R1 and R2 and/or when X2 represents —CR3═, a pair of R2 and R3 each may combine to form a 5- to 7-membered ring;
• the coloring matter may form one of a dimer and a trimer through R1, R2, R3 or A;
• and A represents one group selected from the monovalent substituent groups in a formula (2), which may have a substituent:
• wherein in the monovalent substituent groups (A-1) to (A-42) represented by the formula (2), R11 to R15 each independently represents one of a hydrogen atom and a substituent;
• Q1 in (A-12), Q2 in (A-41) and Q3 in (A-42) each represents a nonmetallic atom group necessary for forming one of a 5- to 7-membered hydrocarbon ring together with the nitrogen atom and a 5- to 7-membered heterocyclic ring together with the nitrogen atom;
• R represents a substituent;
• r represents an integer of 0 to 4;
• and when a plurality of substituent R are present, each R's may be independently the same or different.