Crystal Engineering Approach To Design Colorimetric Indicator Array To Discriminate Positional Isomers of Aromatic Organic Molecules

Discriminating by color : A 2D colorimetric indicator array has been designed by a crystal engineering approach (N???H? O hydrogen bonding and charge‐transfer complexation) involving solid‐state co‐grinding for the visual discrimination of positional isomers of dihydroxynaphthalene. Factors governing the close packing of π planes, and hence color of the complex, were determined by single‐crystal X‐ray analysis, allowing fine tuning by crystal engineering.