Bisanthracene bis(dicarboxylic imide)s as soluble and stable NIR dyes

Abstract

A series of soluble and stable near-infrared (NIR) dyes based on laterally expanded bisanthracene bis(dicarboxylic imide)s M1-M4, which can also be regarded as dibenzoperylene derivatives, was reported. The anthracene dicarboxylic imide dimer 5 was synthesized by [Ni(cod)2]-mediated Yamamoto homocoupling of 4b and this was followed by tBuOK- and 1,5- diazabicyclo[4.3.0]non-5-ene (DBN)-mediated cyclization reaction to afford the desired cis-bisanthracene bis(dicarboxylic imide)s M2 in 85% yield. The transisomer M3 was obtained in 8% yield by heating the anthracene dicarboxylic imide 4a in melted KOH. Separation of the compound 7a from other isomers was successful after the attachment of the 2,6-diisopropylaniline groups. The dimer 8 was then prepared by a similar Yamamoto coupling and followed by tBuOK- and DBN-mediated cyclization reaction. M1-M4 have very good solubility in common organic solvents such as CH2Cl2 and THF and they showed intense absorptions in NIR regions with absorption maximum at 830nm.