Patent ID: 6902861

Claim:
An infrared absorbing compound, the compound having the structure: in which: R 1 and R 2 are each independently an alkyl group, an aryl group, an aralkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an aminoalkyl group, a carboxyalkyl group, or a sulfoalkyl group; Y is hydrogen, halo, alkyl, diphenylamino, or phenylthio; Z 1 and Z 2 are each independently a benzo group or a naphtho group; Z 3 is two hydrogen atoms, a cyclohexene residue, or a cyclopentene residue; X 1 and X 2 are each independently S, O, NH, CH 2 , or C(CH 3 ) 2 ; A is selected from the group consisting of 5-isatinsulfonate, 10-camphorsulfonate, and 4,5-dihydroxy-1,3-benzenedisulfonate; and n is 1 when A is 10-camphorsulfonate, and n is 2 when A is 5-isatinsulfonate or 4,5-dihydroxy-1,3-benzenedisulfonate.