2D supramolecular organic framework with tunable luminescence cucurbit[]uril-based hydrogen bonds, outer-surface interactions and host-guest interactions

Although a variety of 2D supramolecular organic frameworks (SOFs) constructed by cucurbit[8]uril (CB[8]) through host-guest interaction have been reported and found wide applications, the construction of 2D SOFs through the combined effects of hydrogen bonds, outer-surface interactions and host-guest interactions with multiple types of cucurbit[ n ]urils has also been a challenge. Herein, we describe the fabrication of four new flexible 2D SOFs utilizing cucurbit[8]uril (CB[8]), α,α′,δ,δ′-tetramethylcucurbit[6]uril (TMeCB[6]), CB[8]&TMeCB[6] and a rod-like bipyridine ligand ( L2 ) with 2-aminoethoxy and naphthalene through hydrogen bonds, outer-surface interactions and host-guest interactions. The crystal of L2 ⊂TMeCB[6] presents a complex multilayer staggered-stacking structure in solid state. L2 ⊂TMeCB[6], L2 ⊂2TMeCB[6], L2 ⊂2CB[8] and L2 ⊂TMeCB[6]&CB[8] show ordered structure and greatly different fluorescence in solid state under UV, representing the complexity of 2D supramolecular organic nanomaterials and the modification of fluorescence by effectively controlling the types of macrocyclic structures and the form of assembly. This work provides new valuable information and a new strategy for designing more 2D supramolecular organic nanomaterials and macrocycle-based luminescent materials. Four new 2D SOFs were formed by utilizing multi-type cucurbit[ n ]urils with a rod-like bipyridine ligands, realizing fluorescent conversion in the solid state.