Aggregation-Induced Emission, Mechanofluorochromism, and Selective Fluoride Detection by a Tripodal Salicylaldimine.

ABSTRACT

Fluoride ions are indispensable in biology and environmental science and hence the selective and sensitive detection of fluoride is important. This work reports the design and synthesis of a tripodal Schiff's base 1 through a simple condensation reaction between a commercially available aldehyde and an amine. Single crystal X-ray crystallography revealed that compound 1 is a planar entity with the three salicylidene derivatives on the three arms of the central phenyl moiety linked by imine groups. Compound 1 forms a molecular dimer that resembles a six-petal flower and is stabilized through multiple intermolecular interactions such as C-H.π and π.π interactions. Compound 1 exhibited moderately good emission in the solid state with aggregation induced emission and reversible mechanofluorochromic properties. Moreover, 1 was observed to selectively detect fluoride among various anions with a limit of detection of ∼9 ppm. Compound 1 was also capable of detecting fluoride under a variety of conditions such as in thin films and under cellular conditions.