Control of nucleation and crystal growth kinetics of MOF-5 on functionalized gold surfaces

• Large crystals and dense film of MOF-5 formed on top of SAM-functionalized gold substrates.
• Nucleation of MOF-5 crystals facilitated by Zn2+-pretreatment of the substrates.
• Kinetics of crystal growth analyzed by image analysis at different crystallization times.

Self-assembled monolayers (SAMs) on gold (Au) substrates have been used to prepare metal–organic framework (MOF) thin films. Both highly-oriented single crystals (∼100 μm) and dense films of zinc terephthalate (MOF-5) were grown by room-temperature pretreatment of Au-SAM substrates with Zn2+ ions to control nucleation and crystal growth in MOF-5 synthesis solutions. The particle size distribution in the film samples (1 × 104–5 × 104 μm2) was determined by image analysis of optical micrographs collected at different times during crystallization in order to study the crystal growth kinetics. An induction period of 2–3 d was observed before the onset of crystal growth. The crystal sizes saturate at a mean cross sectional area of 2.0–2.5 × 104 μm2.

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