"Photochemical Surgery" of 1D Metal-Organic Frameworks with a Site-Selective Solubilization/Crystallization Strategy.

One-dimensional (1D) hybrid MOFs are attractive if they consist of different MOF blocks with interconnected channels. However, the precision synthesis of such 1D multiblock MOFs with the desired block lengths and sequences remains a formidable challenge. Herein we propose the "photochemical surgery" method, which combines top-down and bottom-up approaches to enable the site-selective solubilization (removal)/crystallization (reconstruction) of 1D MOFs. We employed photoreactive MOFs, which were prepared by complexing either Cd 2+ or Zn 2+ with a mixture containing a photochromic bispyridyl ligand ( Py DTE open or Py DTZE open ) and an isophthalate (5-nitroisophthalate (nip 2- ) or 5-bromoisophthalate (bip 2- )). These MOFs were obtained as high-aspect-ratio, needlelike, colorless crystals that bore 1D channels oriented parallel to the long needle axis. When photoreactive DTE CdMOF NO 2 ([Cd(nip)( Py DTE open )(H 2 O)] n ), for example, was immobilized at both ends with a metal alloy on a glass substrate and exposed to UV light through a photomask for 60 min in N , N -dimethylformamide/methanol (DMF/MeOH), the unmasked part was removed via solubilization to produce a 50 μm gap. The resulting specimen was immersed for 24 h at 25 °C in DMF/MeOH containing the necessary components for the construction of DTZE CdMOF NO 2 ([Cd(nip)( Py DTZE open )(H 2 O)] n ). Eventually, the gap was filled with DTZE CdMOF NO 2 to produce a triblock hybrid MOF ( DTE CdMOF NO 2 - DTZE CdMOF NO 2 - DTE CdMOF NO 2 ). The result of a guest diffusion experiment confirmed that the newly formed DTZE CdMOF NO 2 block shared its 1D channels with the host DTE CdMOF NO 2 blocks. "Photochemical surgery" can be applied to synthesize 1D hybrid MOFs bearing unconventional sequences and morphologies, e.g., honeycomb- and inverted-honeycomb-patterned hybrids.