Semi‐Automatic Deposition of Oriented Cu(OH)₂ Nanobelts for the Heteroepitaxial Growth of Metal–Organic Framework Films

Abstract

Processing oriented metal–organic frameworks (MOFs) as thin films is a key challenge for their application to device fabrication. However, typical fabrication methods cannot generate precisely oriented crystals on commercially relevant scales (i.e., cm2). This limits access to applications that require anisotropic functional properties (e.g., separation, optics, and electronics). Currently, highly oriented copper‐based MOFs are synthesized via the addition of the organic MOF component to an ethanolic solution of manually aligned Cu(OH)2 nanobelt films. In this work, the optimization of a semi‐automatic method for the fabrication of precisely oriented MOF films that affords a 100% yield of high quality ceramic films at the centimeter scale is reported. This improved fabrication protocol will facilitate the progress of heteroepitaxially grown MOFs for molecular separators and micro‐opto‐electronic devices.

Unraveling the timescale of the structural photo-response within oriented metal–organic framework films

“…S2(d) †). 41 To evaluate the porosity, the DMOF-1-on-Cu 2 BDC 2 -on-Cu(OH) 2 lm was deposited on a quartz crystal microbalance (QCM), where the resonance frequency change of each MOF layer was measured upon exposure to methanol vapor (Fig. S3(a) †).…”

“…The lower MOF layer comprises the oriented Cu 2 BDC 2 structure grown on the Cu(OH) 2 nanobelt film, which is fabricated by following the secondary heteroepitaxial growth strategy 38 based on an automated nanobelt deposition procedure. 41 The subsequent DMOF-1 growth occurs by matching its crystal lattice with the lower Cu 2 BDC 2 -on-Cu(OH) 2 layer ( Fig. 1(b and c) ) 38 and is obtained by following a two-step method: Firstly, the Zn(acetate) 2 nodes are covalently attached to the loose carboxylate groups of the Cu 2 BDC 2 -on-Cu(OH) 2 layer, which is then followed by converting the film in a methanolic linker solution (H 2 BDC = terephthalic acid, DABCO = 1,4-diazabicyclo[2.2.2]octane).…”

“…34 The oriented lm growth is ensured by matching the lattice constants of the upper DMOF-1 structure with the lower Cu 2 BDC 2 -on-Cu(OH) 2 MOF layer, 37,38 where the latter is grown in a rst step with its (001) plane oriented parallel to the glass substrate. 38,40,41 The absorption of ultraviolet light provokes the inltrated azobenzene molecule 3,36,42 in the DMOF-1 pores 34,43 to isomerize between its transto-cis conguration (ON), whilst visible light triggers the reversed cis-to-trans transition (OFF). 3,8,44 Our ndings show that within seconds this photo-induced isomerization process forces the DMOF-1 lm structure to adapt, 28,34,42a thus switching between the ON and OFF state.…”

Fabrication of 3D Oriented MOF Micropatterns with Anisotropic Fluorescent Properties

“…Mixed-linker MOF films were prepared by depositing aligned Cu(OH)2 nanobelts (NBs) on a silicon substrate according to our previously reported protocol (see SI for details). [13] The Cu(OH)2 NB films were then immersed in 10 mL of a methanolic solution containing DABCO and the dicarboxylate linkers Br2BDC and BDC in different molar ratios to yield a set of films composed of Cu2[(Br2BDC)x(BDC)1-x]2DABCO (x = Br2BDC/(BDC + Br2BDC). We will refer to these samples according to the nominal mole ratio of the dicarboxylate ligands, e.g., B0 for x = 0, B94 for x= 0.94, and B100 for x=1.…”

“…To this end, a recent and significant advance in MOF film research [12] showed that oriented polycrystalline MOF films can be prepared at commercially relevant scales. [13] These films were synthesized from pre-aligned metal hydroxide nanostructures (Cu(OH)2 nanobelts (NBs)) where the ceramic material simultaneously acts as a metal source and directs epitaxial growth of the aligned MOF crystals.…”