Improving Copper(II) Sensitivity by Combined use of AIEE Active and Inactive Schiff Bases

• Published in: Journal of fluorescence Vol. 34; no. 3; pp. 1065 - 1074
• Main Authors: Bhardwaj, Kanishk, Anand, Thangaraj, Jangir, Ritambhara, Sahoo, Suban K.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2024; Springer Nature B.V
• Subjects: Analytical Chemistry; Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biomedicine; Biophysics; Biotechnology; Copper; Emission; Fluorescence; Green tea; Imines; Water sampling; Schiff base; Aggregation-induced emission enhancement; Cu; Fluorescence sensor; Cu2
• ISSN: 1053-0509; 1573-4994
• DOI: 10.1007/s10895-023-03347-4

An aggregation-induced emission enhancement (AIEE) active Schiff base PNN was synthesized by condensing benzidine with 2-hydroxynaphthaldehyde. The green-fluorescent PNN (λ em  = 510 nm) in DMF turned to yellow-fluorescent PNN (λ em  = 557 nm) upon increasing the fractions of HEPES buffer (10 mM, pH 7.4) above 40%. The DLS study supports the self-aggregation of PNN that restricts the intramolecular rotation and activates the excited-state intramolecular proton transfer (ESIPT) process. The fluorescence emission of AIEE active PNN was quenched by Cu 2+ with an estimated detection limit of 2.1 µM. Interestingly, the detection limit of PNN towards Cu 2+ was improved in the presence of an AIEE inactive Schiff base PBPM obtained by reacting 1,4-diaminobenzene with pyridine-4-carbaldehyde. The mixed PNN-PBPM showed a detection limit of 0.49 µM. The practical utility of PNN-PBPM was validated by quantifying Cu 2+ ions in real environmental water samples and green tea.