Novel method for preparing stable near-infrared absorbers: a new phthalocyanine family based on rhenium() complexes

Rational design of near-infrared (NIR) absorbing molecules is crucial for developing photofunctional materials. Here, we synthesized dinuclear and mononuclear Re( i ) tricarbonyl phthalocyanine complexes that exhibit a sharp intense Q band in the NIR region. The unsymmetric coordination of electron-deficient metal unit(s) concomitantly produced a remarkable red shift of the Q band and improved the tolerance of the phthalocyanine ring to oxidation. This study presents a simple and effective strategy for the construction of NIR absorbers with high stability. Unsymmetric coordination of the electron-deficient Re( i ) unit(s) to the phthalocyanine ring concomitantly realized intense absorption in the near-infrared region and the improvement of tolerance to oxidation.