The chameleon dye 1,7‐bis(dimethylamino)heptamethine

Abstract

The influence of the alignment and density of dye molecules on the spectroscopic properties of aggregates can be studied particularly well in J‐aggregates of 1,7‐bis(dimethylamino)heptamethine (BDH ⊕ ). Four different arrangements of BDH⊕ molecules can be obtained without changing the molecular structure simply by using different counterions. The relationship between structure and linear spectroscopic properties—including the color of crystals containing BDH⊕–is discussed.