Fabrication of Metal–Organic Framework and Infinite Coordination Polymer Nanosheets by the Spray Technique

Abstract

We have developed a rapid and convenient method for fabricating metal-organic framework (MOF) and infinite coordination polymer (ICP) nanosheets by spraying the atomized solution of metal ions onto the organic ligand solution. Nanosheet formation could be attributed to the anisotropic diffusion of metal ions in the ligand solution, which may give rise to a lateral interface of metal ions and organic ligands, where the crystals tend to grow laterally in the form of nanosheets. Three kinds of Zn- and Cu-based MOF nanosheets and two kinds of Co-based ICP nanosheets have been successfully obtained by spraying under mild conditions. The two-dimensional structures of nanosheets with a nanometer thickness and a homogeneous size can be evidenced by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy measurements. Furthermore, the fabricated ICP nanosheets have exhibited efficient catalytic performance for the conversion of CO to high-value-added chemicals. This spray technique simplifies the nanosheet production process by industrialized means and enhances its controllability by the fast liquid-liquid interfacial fabrication, thus allowing access to the industrialized fabrication of MOF and ICP nanosheets.

Ultrasonic Exfoliation of Hydrophobic and Hydrophilic Metal–Organic Frameworks To Form Nanosheets

“…We recently communicated a study reporting the liquid exfoliation of Cu( 1 )(DMF), a layered MOF incorporating weakly interacting methoxy‐propyl chains designed to aid exfoliation of the layers into nanosheets . The nanosheets are based on the popular metal‐paddlewheel secondary building unit (SBU) which has a labile, Lewis acidic axial coordination site which makes it ideal for a wide range of sensing, catalytic, electronic, separation and storage applications . We hypothesized that liquid exfoliation of layered metal–organic frameworks functionalized with either hydrophobic or hydrophilic functionalities would produce nanosheets with different concentrations, stabilities and thicknesses in different solvents.…”

Metal–organic framework nanosheets (MONs): a new dimension in materials chemistry

“…The archetypal MOF-2 was amongst the rst layered MOFs to be exfoliated to form MONs and consists of layers of 1,4-benzene dicarboxylate (BDC) coordinated via Zn paddlewheels with water molecules occupying the axial positions of the paddlewheel. 35 Isostructural MONs have since been formed using a variety of metal ions (Cu, Zn, Co) and 1,4-BDC [36][37][38] and 1,3-BDC derivatives, [39][40][41] as well as longer linear diacid chains. 42 In our own work, we functionalised 1,4-BDC with weakly interacting alkylether chains designed to weaken interlayer interactions and aid exfoliation into solvent (Fig.…”

“…The cycloaddition of CO 2 with epoxides has also been demonstrated. 37 MONs have also been used as photocatalysts and in electrochemical reactions. Ding et al demonstrated Zn(Pd-TCPP) MONs perform better in singlet oxygen generation that the unexfoliated MOF, leading to increased rate of photooxidation of 1,5-dihydroxynaphthalene to juglone (Fig.…”

Fabrication of Monodisperse Flower-Like Coordination Polymers (CP) Microparticles by Spray Technique

“…Almost all CP synthesis methods have been employed to prepare nano- and microstructures, such as direct precipitation, hydrothermal reaction, microwave/ultrasound driven synthesis, electrochemistry, and so on [ 16 , 20 , 21 , 22 ]. Hence, a variety of nano-and microstructures have been achieved, including spheres, cubes, rods, wires, sheets, ribbons, straw-sheaf, and so on [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. However, structuring CP at the nano- and micro-scales is a nascent field and it is still a challenge to fabricate complex or desired CP nano- and microstructures through a facile and controllable approach.…”

“…As shown in Scheme 1 , the metal ion solution was nebulized by ultrasonic sounds and then sprayed on the surface of the organic ligands solution. The gentle touch of the droplet and the solution gave rise to a steady interface, where the crystal inclined to grow in the lateral direction and therefore generated the CP nanosheets [ 27 ]. Consequently, the resulting nanosheets concentrated in the zone of the droplets, making it possible for the nanosheets to aggregate further.…”