The nanosheets of highly symmetric materials with a facecentered cubic lattice such as gold have been synthesized by adsorbing the precursors on a flat surface, whose chemical specificity induces the anisotropy of growth rates. We have succeeded in the fabrication of gold nanosheets in a hydrophilic space inside highly separated bilayers, which work as two-dimensional hydrophilic reactors, in a hyperswollen lamellar liquid crystalline phase of an amphiphile solution. One of the physical properties, amphiphilicity, confines the ingredients therein. The nanosheets can only grow in the in-plane direction due to the inhibition of the out-of-plane growth rather than the anisotropy of growth rates probably. Thus, the synthesis can be accelerated; the particles can be completed within 15 min. As not relying on chemical specificity, silver nanosheets could also be synthesized in the same way. The suspension of gold and silver nanosheets without any amphiphiles could be obtained, and the solvent is replaceable. We found that the width of the obtained gold nanosheets is proportional to the Reynolds number of the solution because the area of the bilayer in the hyperswollen lamellar phase depends on shear stress. This implies that the areas of gold nanosheets depend on the areas of the bilayers, and it can be controlled by changing the Reynolds number. This method could be widely used to continuously obtain large-area nanosheets of various materials in a roll-to-roll manufacturing process.

Elastic layer-structured metal−organic frameworks (ELMs) are a family of flexible nanoporous metal organic frameworks (MOFs) showing gate-opening gas adsorption. The gate-opening pressure shifts to a higher value by crystal downsizing. However, the MOF nanoparticles and nanorods showing the gate-opening gas adsorption grow more than 50 nm even for their shortest sides. Here, we describe the synthesis and unique gas adsorption behavior of the first example of nanosheets of ELMs (ELM-NSs). The thickness and horizontal width of the ELM-NSs obtained from a new synthetic method using the inside the bilayers in hyperswollen lyotropic lamellar (HL) phases as sandwich-like reaction fields (SRFs) are a few nanometers and several hundreds of nanometers, respectively. The previously reported rationalization of the temperature dependence of the gate-opening pressures for ELMs enables us to discuss the size effects in terms of the adsorption-induced structural transitions and the Helmholtz free energy change of the host.

Several nm thick ZIF-8 nanosheets can be synthesized from multiple hydrophilic precursors in the hydrophilic space inside bilayers in a decane solution of the amphiphile Brij L4.

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