Soft 2D nanoarchitectonics

Nanoarchitectonics is a new paradigm to combine and unify nanotechnology with other sciences and technologies, such as supramolecular chemistry, self-assembly, self-organization, materials technology for manipulation of the size of material objects, and even biotechnology for hybridization with bio-components. The nanoarchitectonic concept leads to the synergistic combination of various methodologies in materials production, including atomic/molecular-level control, self-organization, and field-controlled organization. The focus of this review is on soft 2D nanoarchitectonics. Scientific views on soft 2D nanomaterials are not fully established compared with those on rigid 2D materials. Here, we collect recent examples of 2D nanoarchitectonic constructions of functional materials and systems with soft components. These examples are selected according to the following three categories on the basis of 2D spatial density and motional freedom: (i) well-packed and oriented organic 2D materials with rational design of component molecules and device applications, (ii) well-defined assemblies with 2D porous structures as 2D network materials, and (iii) 2D control of molecular machines and receptors on the basis of certain motional freedom confined in two dimensions. The pursuit of ever smaller functional materials has required nanotechnology to be combined with other fields such as self-assembly, or hybridization with biomolecules—these approaches are now unified in the concept of ‘nanoarchitectonics’. A Japan-based team led by Katsuhiko Ariga at the National Institute for Materials Science in Tsukuba review recent nanoarchitectonic developments with 2D soft materials, traditionally less explored than rigid 2D materials such as graphene. Sheets composed of organic molecules held together by weak forces, typically hydrogen bonding or metal coordination, have been constructed that serve as organic crystalline semiconductors, molecular machines, or receptors. A film of living cells has also been obtained at a liquid–liquid interface. These achievements show that soft 2D nanoarchitectonics holds great promise for a variety of fields ranging from organic electronics to biomaterials. A target of this review is soft 2D nanoarchitectonics because scientific views on soft 2D nanomaterials are not fully established as compared with rigid 2D materials. The presented examples are selected according to the following three categories on the basis of 2D spatial density and motional freedoms: (i) well-packed and oriented organic 2D materials with rational design of component molecules and device applications, (ii) well-defined assemblies with 2D porous structures as 2D network materials, and (iii) 2D controls of molecular machines and receptors on the basis of certain motional freedom with confined nature in 2D plain.