Covalent organic frameworks are a class of crystalline organic porous materials that can utilize π–π-stacking interactions as a driving force for the crystallization of polygonal sheets to form layered frameworks and ordered pores. However, typical examples are chemically unstable and lack intrasheet π-conjugation, thereby significantly limiting their applications. Here we report a chemically stable, electronically conjugated organic framework with topologically designed wire frameworks and open nanochannels, in which the π conjugation-spans the two-dimensional sheets. Our framework permits inborn periodic ordering of conjugated chains in all three dimensions and exhibits a striking combination of properties: chemical stability, extended π-delocalization, ability to host guest molecules and hole mobility. We show that the π-conjugated organic framework is useful for high on-off ratio photoswitches and photovoltaic cells. Therefore, this strategy may constitute a step towards realizing ordered semiconducting porous materials for innovations based on two-dimensionally extended π systems.

The molecular design of light-harvesting antennae requires not only the segregation of a large number of chromophore units in a confined nanospace but also the cooperation of these units in achieving highly efficient energy transduction. This article describes the synthesis and functions of a polyphenylene-based conjugated microporous polymer (PP-CMP). PP-CMP was recently designed and synthesized by Suzuki polycondensation reaction and used as an antenna for the noncovalent construction of a light-harvesting system. In contrast to linear polyphenylene, PP-CMP consists of conjugated three-dimensional polyphenylene scaffolds and holds inherent porous structure with uniform pore size (1.56 nm) and large surface area (1083 m(2) g(-1)). It emits blue photoluminescence, is capable of excitation energy migration over the framework, and enables rapid transportation of charge carrier with intrinsic mobility as high as 0.04 cm(2) V(-1) s(-1). The microporous structure of PP-CMP allows for the spatial confinement of energy-accepting coumarin 6 molecules in the pores and makes the high-throughput synthesis of light-harvesting systems with designable donor-acceptor compositions possible. Excitation of the PP-CMP skeleton leads to brilliant green emission from coumarin 6, with an intensity 21-fold as high as that upon direct excitation of coumarin 6 itself, while the fluorescence from PP-CMP itself is wholly quenched as a result of energy transfer from the light-harvesting PP-CMP framework to coumarin 6. The PP-CMP skeleton is highly cooperative, with an average of 176 phenylene units working together to channel the excitation energy to one coumarin 6 molecule, and features the energy-transfer process with quick, efficient, and vectorial character. These unique characteristics clearly originate from the conjugated porous structure and demonstrate the usefulness of CMPs in the exploration of pi-electronic functions, in addition to their gas adsorption properties thus far reported.

A light COF: Two‐dimensional covalent organic frameworks of a nickel phthalocyanine have been synthesized. Owing to well‐ordered stacking of the phthalocyanine units, the resulting 2D framework provides enhanced and broad light absorbance and facilitates charge transport. The material becomes highly photoconductive and is exceptionally sensitive to deep‐red visible and near‐infrared light.

Well conducted: a two-dimensional porphyrin covalent organic framework is described. Owing to the eclipsed stacking alignment, the framework is conductive and allows high-rate carrier transport through the porphyrin columns. The central metal in the porphyrin rings changes the conducting nature of the material from hole to electron, and to ambipolar conduction. It also drives the high on-off ratio photoconductivity of the framework.