π-Stacking Conversion and Enhanced Force-Stimuli Response of a Divinylanthracene Derivative in a Hydrogen-Bonded Framework

Abstract

Hydrogen bond-induced π-stacking conversion was used to achieve an enhanced force-stimuli response of 9,10-bis­(2-(pyridin-4-yl)­vinyl)­anthracene (BP4VA). In BP4VA crystals, the molecules adopted a J-aggregate pattern, and no overlap between the central anthracene planes was observed. Trimesic acid (TA) as a hydrogen bond donor could promote the transformation of the π-stacking type of BP4VA as a hydrogen bond acceptor. It was found that TA and BP4VA molecules formed two-dimensional lamellar hydrogen-bonded frameworks with large windows, which were filled by BP4VA molecules belonging to other layers. Within such three-dimensional packing, J-aggregate stacking type of BP4VA converted into a mixture of J-type and H-type dimers. Moreover, BP4VA adopted a highly twisted conformation, and π–π interaction between them was very weak. So, the hydrogen-bonded complex emitted a short wavelength fluorescence. More importantly, the yellow hydrogen-bonded complex turned into red solids under force stimuli, and its fluorescence had a fairly large shift of more than 110 nm. This is in contrast with a spectral shift of 43 nm from the sheared neat BP4VA crystals. Quantum chemical calculation and spectral observations implied that the planarization, shortened π-distance, and large overlap between anthracence units should be responsible for the large spectral shift. The results imply that the appropriate acid as a hydrogen bond donor might help distyrylanthracene derivatives possess outstanding functions.

Design Rules of Hydrogen-Bonded Organic Frameworks with High Chemical and Thermal Stabilities

“…Through the rational design of organic building blocks with geometric symmetry, planar molecules with diverse π-conjugated systems can coordinate to each other through intermolecular H-bonding interactions to form a single layer, and multiple layers pack together through strong π–π-stacking interactions to form a 3D framework with one-dimensional (1D) channels throughout the structure. HOFs that contain large, π-conjugated aromatic molecules as building blocks exhibit significantly enhanced thermal stabilities and increased chemical resistance to organic solvents and acidic or basic aqueous solutions due to the inert reactivity of the tectons (Figure ) (see refs , , , , , , − , − , − , , , , , , , − , , , , , − , , , − ). Several groups have independently demonstrated that HOFs with shape-fitted π–π-stacking interactions not only show type III stability upon desolvation but also become even more stable as the effective π–π-stacking areas become larger (Table ).…”

Metal–Organic Dimerization of Dissymmetrical Ligands toward Customized Through-Space Chromophore Interactions

“…Light-emitting materials have attracted considerable attention and been widely explored over the past few decades because of their diverse applications in light-emitting diodes, − light-harvesting systems, − biological sensing, − imaging, − etc. Interactions of chromophores directly have a significant effect on the photophysical properties of fluorescent materials. − Kasha and co-workers provided the theoretical conception of molecular exciton theory in their pioneering work, suggesting that the photophysical properties in the solid state can be largely influenced by interactions between molecular transition dipoles. − In some cases, crystals or solids with specific intermolecular interactions of chromophores exhibit tunable fluorescence properties. − However, this strategy is diffusion-controlled and intermolecular interactions cannot be maintained when dispersed in solution, which limits the exploration of interaction–property relationships (Scheme a).…”

Asymmetrical organic D–π–A conjugate with ‘V’-shaped crystal packing: quest to transcend the limits of photophysical properties and applications

“…Still, all of these materials are not dual-state emissive fluorogens (DSEgens). 9,10 The molecular design of dual-state emitters through isomeric substitution is somewhat realized but is tricky. However, the stimuli-responsive nature of such DSEgens was not always identified.…”

“…It is pertinent to mention that multitasking symmetrical systems such as anthracenyl π-conjugates are well-explored as AIE, MFC (mechanofluorochromic), and SSAC-active solid-state emitters in the literature 9 b , c ,14 b due to their easy accessibility, longer conjugation, and twisted molecular structure with numerous intermolecular interactions. 9 In contrast, we focused on investigating relatively smaller asymmetrically substituted anthracenyl π-conjugates that would also attain a twisted molecular system and multiple supramolecular interactions, offering intriguing photophysical features under different environments and displaying potential applications. Further, introducing non-symmetric substituents was reported to be useful in increasing the quantum yield.…”