Facile synthesis of a class of aminochromene–aniliniumion conjugated far-red to near-infrared fluorescent dyes for bioimaging

An innovative class of aminochromene-aniliniumion conjugated far-red to near-infrared dyes, namely ACA, was developed. The design method for ACA dyes is straightforward and the synthesis of the ACA dyes is rapid and convenient. The ACA dyes display absorption and emission in the far-red to near-infrared region, good photostability and chemical stability. The ACA dyes could be used for bio-imaging not only in living cells but also in living animals. The design method described herein may be applicable to other types of long wavelength dyes and the ACA dyes may find interesting applications as sensing and labelling agents in diverse fields.