A triphenodioxazine compound with near infra‐red absorption characteristics

Abstract

A sulphonated triphenodioxazine compound has been synthesised which, in an aqueous medium, absorbs strongly in the near infra‐red region of the spectrum and displays a bathochromic shift of 236 nm compared with other more soluble members of the same series. The compound proved to be pigmentary in nature and the unexpected optical behaviour can be explained in terms of orientation and packing of the crystalline form.