Abstract
Consecutive two-dimensional frameworks comprised of molecular or cluster building blocks in large area represent ideal candidates for membranes sieving molecules and nano-objects, but challenges still remain in methodology and practical preparation. Here we exploit a new strategy to build soft single-layer ionic organic–inorganic frameworks via electrostatic interaction without preferential binding direction in water. Upon consideration of steric effect and additional interaction, polyanionic clusters as connection nodes and cationic pseudorotaxanes acting as bridging monomers connect with each other to form a single-layer ionic self-assembled framework with 1.4 nm layer thickness. Such soft supramolecular polymer frameworks possess uniform and adjustable ortho-tetragonal nanoporous structure in pore size of 3.4–4.1 nm and exhibit greatly convenient solution processability. The stable membranes maintaining uniform porous structure demonstrate precisely size-selective separation of semiconductor quantum dots within 0.1 nm of accuracy and may hold promise for practical applications in selective transport, molecular separation and dialysis systems.
Highlights
Consecutive two-dimensional frameworks comprised of molecular or cluster building blocks in large area represent ideal candidates for membranes sieving molecules and nano-objects, but challenges still remain in methodology and practical preparation
When the POM cluster is considered as connection node and the electrostatic interaction between POM and cationic linker is applied as binding force, the construction of ionic organic–inorganic frameworks (IOIFs) in supramolecular network can be expected in principle
The integration of identical porosity and convenient processability can be predicted to exist in the IOIFs
Summary
Consecutive two-dimensional frameworks comprised of molecular or cluster building blocks in large area represent ideal candidates for membranes sieving molecules and nano-objects, but challenges still remain in methodology and practical preparation. Upon consideration of steric effect and additional interaction, polyanionic clusters as connection nodes and cationic pseudorotaxanes acting as bridging monomers connect with each other to form a single-layer ionic self-assembled framework with 1.4 nm layer thickness. Such soft supramolecular polymer frameworks possess uniform and adjustable ortho-tetragonal nanoporous structure in pore size of 3.4–4.1 nm and exhibit greatly convenient solution processability. We report a new strategy to construct free-standing single-layer 2D supramolecular polymer frameworks by means of synergistic ionic self-assembly of cationic a-cyclodextrin (CD)-based pseudorotaxane bridging sticks with the anionic PW11VO440À (PWV4 À ) cluster nodes in water. The membrane can realize the pinpoint size-selective separation of semiconductor quantum dots (QDs) in accuracy of 0.1 nm, just encountering a quick filtration under reduced pressure
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