11,11,12,12-Tetracyano-4,5-pyrenoquinodimethanes: air-stable push-pull o-quinodimethanes with S2 fluorescence

Org Lett. 2014 Dec 5;16(23):6096-9. doi: 10.1021/ol5029332. Epub 2014 Nov 14.

Abstract

The synthesis and properties of 11,11,12,12-tetracyano-4,5-pyrenoquinodimethanes (4,5-TCNPs), a new family of isolable and air-stable o-quinodimethanes, are reported. The ortho disposition of the dicyanomethane substituents strongly polarizes the pyrene framework to promote broad and intense intramolecular charge-transfer transitions. In addition, spectroscopic studies reveal that 4,5-TCNPs violate Kasha's rule and emit from the S2 level.