Oxidative C–H Homocoupling of Push–Pull Benzothiazoles: An Atom-Economical Route to Highly Emissive Quadrupolar Arylamine-Functionalized 2,2′-Bibenzothiazoles with Enhanced Two-Photon Absorption

Copper­(II)-catalyzed
C–H/C–H coupling of dipolar
2-H-benzothiazoles end-capped with triphenylamine
moieties affords highly fluorescent 2,2′-bibenzothiazoles with
quadrupolar (D-π-A-π-D) architecture displaying large
two-photon absorption (TPA) cross sections (543–1252 GM) in
the near-infrared region. The notably higher TPA performance as compared
to quadrupolar π-systems with a widely used 2,2′-bipyridine
core, along with the ease of the synthesis and chelating N^N ability,
makes the title biheteroaryl platform an attractive building block
for a large scope of functional dyes exploiting nonlinear optical
phenomena.