A novel relay-sensor for highly sensitive and selective detection of Zn^sup 2+^/Pic^sup -^ and fluorescence on/off switch response of H^sup +^/OH^sup -

A novel naphthalenediol-based bis(Salamo)-type tetraoxime compound (H4L) was synthesized and characterized. Its Zn2+ complex was found to be highly sensitive for the detection of Pic− when dissolved in water-containing organic solvent. Sensor H4L acts as a relay-sensor for recognition of Zn2+ while the L-Zn2+ complex recognizes Pic− with high selectivity and sensitivity in acceptable physiological pH range. Moreover, The L-Zn2+ and its Pic− polymer complex display successive sensing of H+/OH− via increase (ON) and decrease (OFF) in fluorescence intensity. The crystal structure of the Zn2+ complex has been determined by single-crystal X-ray diffraction.