Ether-linked porphyrin covalent organic framework with broadband optical switch

Abstract

Summary 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.

Efficient Strategy for Investigating the Third-Order Nonlinear Optical (NLO) Properties of Solid-State Coordination Polymers

“…At low input pulse energy, the energy of the incident photon is insufficient to excite the electrons from the ground state to the excited state. 1-MC /PVA and 2-MC /PVA undergo the ground-state bleaching process, resulting in a SA response. , With the increase in pulse energy, the ground-state electrons can absorb more photons and be excited to the excited state, which will lead to the characteristic RSA behavior. However, the NLO refraction behavior was not observed at an input pulse energy of 2 μJ and 3 μJ, which is because strong NLO absorption makes the NLO refraction behavior difficult to monitor.…”

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…712–716 Several design strategies have been shown to improve their fluorescence quantum yield. For example, photoluminescent COFs can be synthesized by introducing large π-conjugated structures, such as pyrene, 717–719 porphyrin, 190,720–722 triazatruxene, 723 and triphenylene, 724 into monomers. In these COFs, the large π-conjugation enhances the probability of the π–π* transition; thus, this transition is easily excited and is accompanied by a redshift of the maximum absorption and emission wavelengths.…”

Nonlinear optical properties of porphyrin-based covalent organic frameworks determined by steric-orientation of conjugation

“…33 Chen et al first synthesized an ether-linked porphyrin-based 2D COF which realized the switch of the NLO response in a broad range from visible light to the near infrared region. 34 The effect of conjugation of small organic molecules on their nonlinear absorption has been studied extensively. [35][36][37] (1) By extending the p-conjugated length, the molecules would have high transition dipole moments and narrow linewidth, which endow them with stronger nonlinear absorption.…”