The development of large pore single‐crystalline covalently linked organic frameworks is critical in revealing the detailed structure‐property relationship with substrates. One emergent approach is to photo‐crosslink hydrogen‐bonded molecular crystals. Introducing complementary hydrogen‐bonded carboxylic acid building blocks is promising to construct large pore networks, but these molecules often form interpenetrated networks or non‐porous solids. Herein, we introduced heteromeric carboxylic acid dimers to construct a non‐interpenetrated molecular crystal. Crosslinking this crystal precursor with dithiols afforded a large pore single‐crystalline hydrogen‐bonded crosslinked organic framework HCOF‐101. X‐ray diffraction analysis revealed HCOF‐101 as an interlayer connected hexagonal network, which possesses flexible linkages and large porous channels to host a hydrazone photoswitch. Multicycle Z/E‐isomerization of the hydrazone took place reversibly within HCOF‐101, showcasing the potential use of HCOF‐101 for optical information storage.
Single crystal X-ray diffraction is arguably the most definitive method for molecular structure determination, but the inability to grow suitable single crystals can frustrate conventional X-ray diffraction analysis. We report herein an approach to molecular structure determination that relies on a versatile toolkit of guanidinium organosulfonate hydrogen-bonded host frameworks that form crystalline inclusion compounds with target molecules in a single-step crystallization, complementing the crystalline sponge method that relies on diffusion of the target into the cages of a metal-organic framework. The peculiar properties of the host frameworks enable rapid stoichiometric inclusion of a wide range of target molecules with full occupancy, typically without disorder and accompanying solvent, affording well-refined structures. Moreover, anomalous scattering by the framework sulfur atoms enables reliable assignment of absolute configuration of stereogenic centers. An ever-expanding library of organosulfonates provides a toolkit of frameworks for capturing specific target molecules for their structure determination.
more » « less- NSF-PAR ID:
- 10154161
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The development of large pore single‐crystalline covalently linked organic frameworks is critical in revealing the detailed structure‐property relationship with substrates. One emergent approach is to photo‐crosslink hydrogen‐bonded molecular crystals. Introducing complementary hydrogen‐bonded carboxylic acid building blocks is promising to construct large pore networks, but these molecules often form interpenetrated networks or non‐porous solids. Herein, we introduced heteromeric carboxylic acid dimers to construct a non‐interpenetrated molecular crystal. Crosslinking this crystal precursor with dithiols afforded a large pore single‐crystalline hydrogen‐bonded crosslinked organic framework HCOF‐101. X‐ray diffraction analysis revealed HCOF‐101 as an interlayer connected hexagonal network, which possesses flexible linkages and large porous channels to host a hydrazone photoswitch. Multicycle Z/E‐isomerization of the hydrazone took place reversibly within HCOF‐101, showcasing the potential use of HCOF‐101 for optical information storage.
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null (Ed.)5-Methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile is a crystalline compound rich in conformational polymorphs largely owing to the flexible torsion angle that leads to distinct colors, earning it the moniker ROY (Red-Orange-Yellow). Guanidinium organosulfonate hydrogen-bonded frameworks form six crystalline inclusion compounds with ROY, described here, in which the framework limits conformational twisting out of plane. Three of the six inclusion compounds enforce greater planarity and π-conjugation than any of nine ROY polymorphs that have been characterized by single crystal X-ray diffraction.more » « less
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Abstract Various robust, crystalline, and porous organic frameworks based on in situ‐formed imine‐linked oligomers were investigated. These oligomers self‐assembled through collaborative intermolecular hydrogen bonding interactions via liquid–liquid interfacial reactions. The soluble oligomers were kinetic products with multiple unreacted aldehyde groups that acted as hydrogen bond donors and acceptors and directed the assembly of the resulting oligomers into 3D frameworks. The sequential formation of robust covalent linkages and highly reversible hydrogen bonds enforced long‐range symmetry and facilitated the production of large single crystals, with structures that were unambiguously determined by single‐crystal X‐ray diffraction. The unique hierarchical arrangements increased the steric hindrance of the imine bond, which prevented attacks from water molecules, greatly improving the stability. The multiple binding sites in the frameworks enabled rapid sequestration of micropollutant in water.
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Abstract Various robust, crystalline, and porous organic frameworks based on in situ‐formed imine‐linked oligomers were investigated. These oligomers self‐assembled through collaborative intermolecular hydrogen bonding interactions via liquid–liquid interfacial reactions. The soluble oligomers were kinetic products with multiple unreacted aldehyde groups that acted as hydrogen bond donors and acceptors and directed the assembly of the resulting oligomers into 3D frameworks. The sequential formation of robust covalent linkages and highly reversible hydrogen bonds enforced long‐range symmetry and facilitated the production of large single crystals, with structures that were unambiguously determined by single‐crystal X‐ray diffraction. The unique hierarchical arrangements increased the steric hindrance of the imine bond, which prevented attacks from water molecules, greatly improving the stability. The multiple binding sites in the frameworks enabled rapid sequestration of micropollutant in water.
