Sensitive and selective fluorometric determination and monitoring of Zn2+ ions using supermicroporous Zr-MOFs chemosensors

• Published in: Microchemical journal 2018-06, Vol.139, p.24-33
• Main Authors: El-Sewify, Islam M., Shenashen, Mohamed A., Shahat, Ahmed, Selim, Mahmoud M., Khalil, Mostafa M.H., El-Safty, Sherif A.
• Format: Article
• Language: English
• Subjects: Chemosensors; Detection; Determination; Fluorescent; Supermicroporous; Zn2+ ions
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2018.02.002

We report the fabrication of water-stable, supermicroporous fluorescent chemosensors (MFCs) using Zr-based metal-organic frameworks (MOFs) as scaffolds for selective fluorescent determination of the ultra-traces of heavy metals, such as Zn2+ ions from water resources. The MFCs structures was developed by direct decoration of hydrophobic fluorescent probes (2,2′-((1Z,12Z)-5,9-dithia-2,12-diazatrideca-1,12-diene-1,13 diyl) diphenol), (S1) into the Zr-based metal-organic frameworks (MOFs). Significantly, the MFCs design with uniform super-microgroove pores, long-range intergrowing crystal, and dense decoration of fluorescent probes, leading to create active hook surface sheaths as sensitive and selective chemosensors platforms for ultra-trace monitoring of Zn2+ ions. The MFCs supermicro-crystal structures have shown synergistic enhancement in selective sensing assay associated with low-detection limit up to part-per-billion (ppb), wide-range determination (0.5ppb to 2000ppb) and fast response monitoring in the order of second during the binding of Zn2+ ion target. The selectivity of Zn2+ ions fluorometric sensing process in a heterogeneous mixture of inorganic cations and anions was mainly dependent on the structure of the fluorescent probe, pH condition, competitive ion system composition, and Zn-to-fluorescent probe binding procedure. Our developed MFCs showed a wide range of detection of Zn2+ ions with a considerably low detection limit of approximately 10−9mol/L, in optimal working condition. The long-term stability of MFCs with fluorescent surface functionality enabled the practical and multiple reuse/cycles of Zn2+ ion determination. [Display omitted] •Supermicroporous fluorescent chemosensors (MFCs) were successfully fabricated.•MFCs creating active hook surface as sensitive and selective chemosensors platform•The water-stable MFCs providing a high sensitivity of Zn2+ ions up to 10–9M•The MFCs displayed superior sensitivity and selectivity toward Zn2+ ions.•The low-cost MFCs enabled for multiple reuse/cycles of Zn2+ ions.