High-efficient liquid exfoliation of 2D metal-organic framework using deep-eutectic solvents

Area of Science:

• Materials Science
• Nanotechnology
• Green Chemistry

Background:

• Two-dimensional (2D) metal-organic framework (MOF) nanosheets are gaining attention for their unique properties.
• Conventional methods for MOF exfoliation often rely on harsh organic solvents, posing environmental concerns.
• Developing sustainable and efficient routes for MOF nanosheet production is crucial.

Purpose of the Study:

• To develop an environmentally friendly method for exfoliating layered MOF (MAMS-1) into few-layered nanosheets.
• To investigate the use of deep eutectic solvent (DES) as a sustainable alternative to conventional organic solvents.
• To evaluate the potential of MAMS-1 nanosheets for sensing applications.

Main Methods:

• Exfoliation of layered MOF (MAMS-1) using deep eutectic solvent (DES) under sonication.
• Utilized poly(vinylpyrrolidone) (PVP) as a surfactant to assist in the delamination process.
• Encapsulated Eu³⁺ cations within the MAMS-1 nanosheets (MAMS-1-NS) for luminescence studies.

Main Results:

• Achieved a high exfoliation rate of up to 70% for MAMS-1 into two-host-layer nanosheets using DES and PVP.
• The resulting MAMS-1 nanosheets exhibited stable suspensions for over a month due to their atomically thin structure and tert-butyl exteriors.
• Eu³⁺@MAMS-1-NS demonstrated highly sensitive and selective detection of Fe³⁺, Hg²⁺, Cr₂O₇^2-, and MnO₄^- through fluorescence quenching.

Conclusions:

• The DES-assisted exfoliation offers a sustainable and efficient route for producing MOF nanosheets.
• The ultrathin morphology and accessible active sites of MAMS-1-NS significantly enhance luminescence sensing capabilities compared to bulk materials.
• Eu³⁺@MAMS-1-NS shows promise as a multi-responsive luminescent sensor for various analytes.