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 (Ψr) and rotatability
(θr). Moreover, stimuli-responses behaviors to mechanical
force were evaluated to explore stability of AIE materials, luminescent
shift (Δλem ≈ 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.