Achieving Bright Mechanoluminescence in a Hydrogen-Bonded Organic Framework by Polar Molecular Rotor Incorporation

Abstract

Luminescent hydrogen-bonded organic frameworks (HOFs) have attracted increasing attention due to the corresponding luminescence readily enables visualization of structural dynamics. HOFs with the mechanoluminescence (ML) property, which can emit light without photon excitation, are greatly attractive for advanced applications but have not been reported so far. Herein, we report the first example of a ML-active flexible HOF with permanent porosity, named 8PCOM, which is assembled from polar molecular rotors with the aggregation-induced emission property. When responding to different solvent vapors, reversible structural transformations between ML-active and ML-inactive 8PCOM frameworks occur, including a single-crystal-tosingle-crystal transformation. Thus guest-induced breathing behaviours are mainly attributed to phenyl rotations of polar molecular rotors, which are induced by external stimuli. During reversible structural transformations of various 8PCOM frameworks with different pores, the significant ML property is successfully achieved through supramolecular dipole moment regulation. Upon mechanical force, bright emission of the

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 ).…”

Recent Advances in Luminescent Hydrogen‐Bonded Organic Frameworks: Structures, Photophysical Properties, Applications

“…Chi and coworkers reported the first flexible HOFs with mechanoluminescence, named 8PCOM. [ 24 ] The ML phenomenon appeared in polar organic molecules with lower symmetric structures. A dynamic polar molecule, TPE‐4PCOM (5), acted as the building block for mechanoluminescence‐active flexible HOFs ( Figure a).…”

Luminescent organic porous crystals from non-cyclic molecules and their applications

“…12) in 2021 and prepared six crystals from different solvents (8PCOM-DCM, 8PCOM-TOL, 8PCOM-DMSO, 8PCOM-DMF, 8PCOM-ACT, and 8PCOM-MeOH) to investigate the mechanoluminescence (ML) of crystals. 77 Each TPE-4PCOM molecule interacts with four adjacent ones via many H-bond interactions, and they extend to form a porous single layer. Many layers further stack together to construct a 3D porous framework with 1D channels.…”