Biplane Ion-Pairing Induced Supramolecular Assembly for High-Performance Uranium Detection

Area of Science:

• Environmental Chemistry
• Supramolecular Chemistry
• Analytical Chemistry

Background:

• Direct optical detection of the anionic uranyl carbonate species [UO2(CO3)3]4- is challenging due to its thick hydration shell.
• This species is environmentally dominant, comprising 82%-93% of uranium in certain conditions.

Purpose of the Study:

• To design a novel supramolecular probe for direct detection of [UO2(CO3)3]4-.
• To overcome the limitations imposed by the ion's hydration layer.
• To develop a sensitive and selective sensing platform for environmental uranium.

Main Methods:

• Design and synthesis of a water-soluble Pt(II) methylated terpyridine complex, [Pt(CH3-tpy)NCO]+.
• Utilizing a "thick hydration shell overlapping arrangement" strategy for targeted binding.
• Experimental and theoretical investigations of the supramolecular structure and detection mechanism.
• Construction of a [Pt(CH3-tpy)NCO]+-based hydrogel platform.

Main Results:

• The probe ([Pt(CH3-tpy)NCO]+) exhibits excellent selectivity for [UO2(CO3)3]4- among approximately 30 interfering substances.
• Achieved rapid response time (≈15 s), high sensitivity (64.1 nm spectral shift), and dual-signal output.
• Confirmed formation of a unique supramolecular structure with biplane-like building blocks, bicolumnar stacking, and water-bridged anionic networks.
• Identified four types of Pt-Pt interactions contributing to low-energy metal-to-metal charge transfer adsorption/emission.
• Hydrogel platform demonstrated detection of both anionic and cationic uranium with a limit of 14.89 fg.

Conclusions:

• The study presents a breakthrough in directly detecting the challenging [UO2(CO3)3]4- species.
• The developed strategy offers a new paradigm for sensing ions with substantial hydration layers.
• The [Pt(CH3-tpy)NCO]+ probe and hydrogel platform show significant potential for environmental uranium monitoring.