Site-selective growth of surface-anchored metal-organic frameworks on self-assembled monolayer patterns prepared by AFM nanografting

Abstract

SummarySurface anchored metal-organic frameworks, SURMOFs, are highly porous materials, which can be grown on modified substrates as highly oriented, crystalline coatings by a quasi-epitaxial layer-by-layer method (liquid-phase epitaxy, or LPE). The chemical termination of the supporting substrate is crucial, because the most convenient method for substrate modification is the formation of a suitable self-assembled monolayer. The choice of a particular SAM also allows for control over the orientation of the SURMOF. Here, we demonstrate for the first time the site-selective growth of the SURMOF HKUST-1 on thiol-based self-assembled monolayers patterned by the nanografting technique, with an atomic force microscope as a structuring tool. Two different approaches were applied: The first one is based on 3-mercaptopropionic acid molecules which are grafted in a 1-decanethiolate SAM, which serves as a matrix for this nanolithography. The second approach uses 16-mercaptohexadecanoic acid, which is grafted in a matrix of an 1-octadecanethiolate SAM. In both cases a site-selective growth of the SURMOF is observed. In the latter case the roughness of the HKUST-1 is found to be significantly higher than for the 1-mercaptopropionic acid. The successful grafting process was verified by time-of-flight secondary ion mass spectrometry and atomic force microscopy. The SURMOF structures grown via LPE were investigated and characterized by atomic force microscopy and Fourier-transform infrared microscopy.

Nanoweb Surface‐Mounted Metal–Organic Framework Films with Tunable Amounts of Acid Sites as Tailored Catalysts

“…Its ability to detect metal-organic fragments directly, makes it ap owerful tool in SURMOF research. [24][25][26][27][28][29] Figure 2 shows the nanowebs synthesized with 10 (b, c) and 100 (d,e) mm of precursor.I ti si mportant to note that ac oncentration of 1mm hardly yieldedS URMOFs, as shown in Figure S1 (Supporting Information). The AFM micrographs in Figure 2b,d are accompanied by IR-points pectra recorded using AFM-IR.A general overview highlights the similarity in spectra for 10 mm precursor concentration, whereas 100mm showss ignificant differences.…”

Metal–Organic Framework Membranes: From Fabrication to Gas Separation

“…The layer-by-layer (LBL) growth method, developed by Shekhah et al in 2007, was successfully applied for fabricating thin films of HKUST-1 MOF [47,50,51,[101][102][103]. The LBL growth method for growing MOFs is based on exposing of the support surface to the reaction precursors in an alternating approach involving rinsing the excess/unreacted precursors after each their exposure to the surface.…”

Fabrication of Metal–Organic Framework Thin Films Using Programmed Layer‐by‐Layer Assembly Techniques

“…To achieve patters in the submicrometer or nanometerregime, Ladnorg et al used the so‐called nanografting technique, where an atomic force microscope is used as a structuring tool. As in the previous method, pattering is achieved by structuring the functionalized substrate (the SAM) using the atomic force microscope (AFM).…”

“…A) Scheme of the AFM‐nanografting process for the preparation of nanopatterned SAMs. Reproduced with permission . Copyright 2013, Beilstein‐Institut zur Förderung der Chemischen Wissenschaften.…”