Switchable luminescence and morphology through acid-base vapor annealing in organic materials

•New organic materials were facilely synthesized.•Novel seven-membered ring compound reveals the enhanced luminescence.•Reversible luminescent color switching in the response to acid-base vapor stimuli.•The acid-base vapor induced morphological transformation.

Through simple and green strategy, we unprecedentedly synthesized a novel organic compound through methyl-directed aromatic electrophilic substitution reactions. This work indicates that only introduction of methyl group at molecular framework can construct novel seven-membered ring organic materials. Interestingly, this organic material not only reveals the enhanced luminescence, but also the reversible luminescent color (red↔green) switching in the response to acid-base vapor stimuli, which is accompanied by the reversible morphological transformation (3D microbrick↔2D hexangular microflake). The present work provides a promising approach for synthesizing organic materials and a new access to develop dynamic functional materials which can be reversibly switched between different luminescence and morphology based on external acid-base vapor stimuli.

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