Improved colorimetric dual-emission and endued piezofluorochromism by inserting a phenyl between 9-anthryl and terpyridine

• Insertion of phenyl between anthryl and terpyridine could reserve the selectively sensing of ATP to Cd2+.
• Alter the response range of ATP–Cd(II) complex to polyvalent anions.
• Enlarge the dual emission interval, and endue ATP–Cd(II) complex piezofluorochromism.

Tridentate terpyridine is a functional building unit, and 9-anthylterpyridine has been used as ratiometric fluorescent sensor for Cd(II) and secondary sensor for pyrophosphate detection. Here we have inserted a phenyl unit between 9-anthryl and terpyridine to synthesize a new terpyridine derivative, 4-(9-anthryl)phenyl terpyridine (ATP) to investigate the effect of structure change on optical properties. The results show that ATP not only remains the selectively colorimetric fluorescence sensing to Cd2+ but also the interval of two emission bands from ATP and ATP–Cd(II) complex can be enlarged significantly to 185 nm. Unlike 9-anthylterpyridine–Cd(II) complex, ATP–Cd(II) complex could be decomplexed by most polyvalent anions. Moreover, the insertion of a phenyl ring can render ATP–Cd(II) complex remarkable piezofluorochromism with grinding-induced spectral shift of 54 nm. X-ray diffraction and differential scanning calorimetry experiments confirm the phase transformation between crystalline and amorphous states upon external stimuli is responsible for reversible PFC behavior.