Crystalline coordination framework endowed with dynamic gate-opening behaviour by being downsized to a thin film

Abstract

The fabrication of porous coordination frameworks in thin-film forms has been investigated intensively with a view to using their structural response to external stimuli and guests for potential nanotechnological applications, for example as membranes for gas separation. Here we report a coordination framework that exhibits a dynamic guest-sorption behaviour in a nanometre-sized thin-film form (16 nm thick), yet shows no guest uptake in the bulk. Highly oriented crystalline thin films of this coordination framework--which consists of interdigitated two-dimensional layers of {Fe(py)2[Pt(CN)4]} (py, pyridine)--were fabricated through liquid-phase layer-by-layer synthesis. The resulting thin film exhibited a clear guest uptake with a structural transformation of the gate-opening type as characterized by in situ X-ray diffraction. Increasing the film's thickness markedly suppressed this behaviour. We envisage that such a crystal-downsizing effect may be observed with other coordination frameworks, and may be of use to develop functional materials, for example, for switching or sensing devices.

Effect of ring rotation upon gas adsorption in SIFSIX-3-M (M = Fe, Ni) pillared square grid networks

“…We speculate that, relatedly, pyrazine ring rotation may be involved in a suspected phase change in SIFSIX-3-Zn 32,65 and gate opening in Fe(py) 2 [Pt(CN) 4 ]. 24 …”

Mechanistic Insights into Growth of Surface‐Mounted Metal‐Organic Framework Films Resolved by Infrared (Nano‐) Spectroscopy

“…Surface‐anchored films of metal‐organic frameworks (SURMOFs) can be synthesized in a straightforward manner by using a liquid phase layer‐by‐layer (LbL) synthesis approach 8, 9. The benefits of this method include the growth of highly homogeneous and oriented films at room temperature,8, 10 with diverse topologies,11, 12 enabling at the same time controlled mechanistic studies of MOF assembly13, 14 and guest‐induced framework changes 15, 16, 17…”

Magnetic functionalities in MOFs: from the framework to the pore

“…This kind of approach has also shown to be useful in preparing thin films of good optical quality based on Hofmann clathrates exhibiting spin crossover. 124,125,129 A different approach that can be foreseen to improve the quality of these ultrathin films is based on the deposition of two-dimensional (2D) crystals on electronic/magnetic surfaces which can provide very clean interfaces of direct application in electronics/spintronics, as has already been shown with graphene and graphene-like 2D materials. 130 This goal can be achieved either by using chemical vapour deposition (CVD) methods, or by direct micromechanical exfoliation of the bulk materials and subsequent transfer of the 2D layer onto the substrate.…”