Ether-linked porphyrin covalent organic framework with broadband optical switch

It is still a challenge to design and synthesize novel switchable optical materials with ultrafast nonlinear optical (NLO) response in a broad spectral range. These materials have exhibited great application potential in many high-technology fields such as biological imaging, chemical sensors, optical data storage, laser protection, and controllable intelligent and optoelectronic devices. By using porphyrins with highly delocalized 18 π-electron conjugated system as functional building blocks, the first ether-linked porphyrin covalent organic framework materials (COF-Pors) with highly ordered lattice structure have been successfully synthesized. In contrast to the starting porphyrins that only exhibit reverse saturable absorption (RSA) response at 532 nm, the as-prepared COF-Pors shows large NLO effect in a broad range from visible to near infrared. Upon laser illumination, COF-Pors exhibits typical saturable absorption (SA) effect at lower incident laser energy, and RSA response at higher pulse energy.