Triple Helical Molecular Braid and Parallel Packed Wavy Chain-Based Supramolecular Organic Frameworks with Conformation- and Packing-Dependent Luminescent Properties

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• 作者：Kai Xing ; Ruiqing Fan ; Jizhuang Fan ; Xi Du ; Yang Song ; Song Gao ; Ping Wang ; Yulin Yang
• 刊名：Crystal Growth & Design
• 出版年：2016
• 出版时间：August 3, 2016
• 年：2016
• 卷：16
• 期：8
• 页码：4727-4735
• 全文大小：588K
• 年卷期：0
• ISSN：1528-7505

文摘

Two three-dimensional supramolecular organic frameworks, [(H₂bpdc)_0.5(bipy)_0.5] (1) and [(H₃dpob)(bipy)·3H₂O] (2), have been successfully constructed and structurally characterized (H₂bpdc = 2,2′-biphenyldicarboxylic acid; H₃dpob = 3-(2′,3′-dicarboxylphenoxy)benzonic acid; bipy = 4,4′-bipydine). 1 is driven by C–H···π hydrogen-bonded packing to three dimension. 2 origins form parallel-packed wavy chains and show π–π stacking-directed structure. After the SOFs are formed via weak noncovalent interaction, 1 and 2 show an enhancement in thermostability. The different conformations of bipy induced by weak noncovalent interactions are responsible for the huge dissimilarity of structural and luminescence behavior between them. Under the excitation of 365 nm ultraviolet light, 1 and 2 show stronger blue-white and green-white luminescent emissions in the solid state, respectively. In comparison with 2, supramolecular organic framework 1 shows superior performance in aggregation-induced emission (AIE) activity, which is explained and elaborated via the simple model from the viewpoint of planarity (Ψ_r) and rotatability (θ_r). Moreover, stimuli-responses behaviors to mechanical force were evaluated to explore stability of AIE materials, luminescent shift (Δλ_em ≈ 36 nm) was observed in 2, whereas almost no change of 1 was found. Subsequently, 1 doped poly(methyl methacrylate) film demonstrates the comparable intensity with the solid state at concentrations of 2.0%, accompanied by the improvement of thermal stability.