Driving Fluorescence by Forming AIEgens in a Hollow Azine-Linked Covalent Organic Framework

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure-property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references). This journal is © The Royal Society of Chemistry 2011

Recent advances in covalent organic frameworks (COFs) as a smart sensing material are summarized and highlighted. As a newly emerging kind of porous material, covalent organic frameworks (COFs) have drawn much attention because of their fascinating structural features ( e.g. , divinable structure, adjustable porosity and total organic backbone). Since the seminal work of Yaghi and co-workers reported in 2005, the COF materials have shown superior potential in diverse applications, such as gas storage, adsorption, optoelectronics, catalysis, etc. Recently, COF materials have shown a new trend in sensing fields. This critical review briefly describes the synthesis routes for COF powders and thin films. What's more, the most fascinating and significant applications of COFs in sensing fields including explosive sensing, humidity sensing, pH detection, biosensing, gas sensing, metal ion sensing, and other substance sensing are summarized and highlighted. Finally, the major challenges and future trends of COFs with respect to their preparation and sensing applications are discussed.

The targeted synthesis of 3D COFs has been considered challenging, especially adopting new topologies and bearing photoelectric units. Herein, for the first time, we report the synthesis and characterization of a novel 3D pyrene-based COF (3D-Py-COF), by selectively choosing the geometry of the precursors and the connection patterns. Based on X-ray diffraction measurement and detailed simulations, 3D-Py-COF is proposed to adopt a two-fold interpenetrated pts topology, which has never been reported before. In addition, 3D-Py-COF has a narrow pore size distribution and high surface area and also features selective absorption of CO2 over N2. Interestingly, due to the existence of isolated pyrene units in the 3D framework, 3D-Py-COF is the first fluorescent 3D COF and can be used in explosive detection. Our results not only show it is possible to rationally design and synthesize 3D COFs with other topologies but also demonstrate that the incorporation of photoelectric units into 3D COFs can allow the resulting materials with interesting properties.