New near-infrared absorbing metal complex dyes with heterocyclic phenyliminoquinone-type ligands

Abstract

N,N-Bidentate pyrido[2,3-a]phenothiazine (or phenoxazine)-type ligands have been prepared. Formation of metal complexes causes a large bathochromic shift of the absorption bands and an increase in the molar extinction coefficient. The metal complex dyes have absorption bands in the near-infrared region at 746–842 nm and were isolated as stable compounds. The reaction of 5-(4-dialkylaminophenylimino)-7-chloroquinolin-8(5H)-ones with o-phenylenediamine in acetic acid gave the corresponding leuco dyes.