Toxic and hazardous chemical species are ubiquitous, predominantly emitted by anthropogenic activities, and pose serious risks to human health and the environment. Thus, the sensing and subsequent capture of these chemicals, especially in the gas or vapor phase, are of extreme importance. To this end, metal–organic frameworks have attracted significant interest, as their high porosity and wide tunability make them ideal for both applications. These tailorable framework materials are particularly promising for the specific sensing and capture of targeted chemicals, as they can be designed to fit a diverse range of required conditions. This review will discuss the advantages of metal–organic frameworks in the sensing and capture of harmful gases and vapors, as well as principles and strategies guiding the design of these materials. Recent progress in the luminescent detection of aromatic and aliphatic volatile organic compounds, toxic gases, and chemical warfare agents will be summarized, and the adsorptive removal of fluorocarbons/chlorofluorocarbons, volatile radioactive species, toxic industrial gases and chemical warfare agents will be discussed.

Sensing and capture of toxic and hazardous gases and vapors by metal–organic frameworks

Since the realization in 2011 that most aggregation-induced emission (AIE) molecules exhibit mechano-responsive luminescence (MRL), research regarding the MRL of AIE molecules has drawn much attention, and this area has been expanding tremendously. As one of the most extensively studied AIE cores, tetraphenylethylene (TPE) has been widely used to construct MRL molecules. This review will focus on recent advances in MRL of TPE derivatives with AIE properties, including a brief history of mechano-responsive AIE-active materials, mechanistic studies on MRL, mechano-responsive luminogens based on TPE, mechano-responsive luminogens containing multiple AIE-active units, mechano-memory chromism and mechanoluminescence of TPE derivatives. Moreover, this review will give a perspective on the possible opportunities and future challenges that exist in this research area.

Recent advances in mechano-responsive luminescence of tetraphenylethylene derivatives with aggregation-induced emission properties

From the perspective of the chromophore, 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethane (TPPE) with the π-electron-rich tetraphenylethylene (TPE) and aggregation induced emission feature is selected as functional ligand to construct the fluorescent metal–organic frameworks. Three luminescent MOFs (1–3) have been successfully synthesized. Through combining 4,4′,4″-nitrilotrisbenzoic acid (H3TNB) with electron-donor triphenylamine (TPA), the highly porous pillared-layer compound 1 [Zn3(TPPE)1/2(TNB)2](4DMA·7H2O) was synthesized; interestingly, this MOF sensor film realizes the fast detection for nitrobenzene compounds with a response time of less than 3 min as well as good recyclability. Compound 2 [Zn7(TPPE)2(SO42–)7](DMF·H2O) exhibits the clear “turn-off” quenching responses for Cr2O72– in aqueous phase with high selectivity and sensitivity. Meanwhile, the fluorescent properties of compound 3 [Zn2(TPPE)3/2(NO3–)(OH–)(H2O)](DMF·2H2O) were also investigated. Thus, these MOF materials could serve as the prom...

Tetraphenylethylene immobilized metal-organic frameworks: highly sensitive fluorescent sensor for the detection of Cr2O72- and nitroaromatic explosives

Utilizing aggregation-induced emission luminogens (AIEgens) as ligands has proven to be an effective strategy for constructing metal-organic frameworks (MOFs) with intense luminescent properties. However, highly luminescent AIEgen-based MOFs with adjustable emission properties are rarely achieved because of the rigid conformation of AIEgens in the crystalline state. Here, a dual-node 3D silver chalcogenolate cluster MOF (1) is designed and synthesized, where the AIE ligand shows relatively flexible and rotatable conformations. The conformations of AIE ligands in 1 are switchable by the absorption/desorption of guest molecules. As a result, 1 exhibited not only intense but also guest molecule switched luminescent properties. More importantly, the switching rate is tunable by using different guest molecules. 1 provides a unique visualized prototype to understand the mechanism of guest-triggered aggregation-induced emission in MOFs.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201801304

Guest-Triggered Aggregation-Induced Emission in Silver Chalcogenolate Cluster Metal-Organic Frameworks.

The combination of the copper(i)-iodide entity with organic ligands gives rise to a large variety of CuII polynuclear structures in the form of molecular complexes or extended structures. An appropriate selection of these components allows the preparation of materials showing interesting physicochemical properties and potential applications, mainly focused on organic light-emitting diodes and optical sensors. The most prominent physical feature of these materials is their emission, which can be modulated using the chemical structure and composition. This review article collates the advances in this research field, rationalizing the information into two main blocks as a function of the dimensionality of the structures: molecular complexes and extended networks. We describe the most typical ways of preparation, structures, and properties, with particular attention to the processability of the material as a fundamental aspect of the integration of the materials into real devices. Therefore, we aim to integrate the basic elements of the coordination chemistry of CuII clusters from the materials science perspective to envision this promising research field's potential technological future.

Copper(i)-iodide cluster structures as functional and processable platform materials.

Two tetraphenylethene-containing coordination polymers for reversible mechanochromism

Controllable synthesis of coordination polymers (CPs) Isomers and reveal the corresponding relationship of structures and properties remains an enormous challenge. Three new supramolecular isomers have been synthesized by tuning the poly(ethylene glycol) (PEG) content in the feed. Those supramolecular isomers have the same framework formula of [Cu2I2(tppe)] and different architectures from the classical 2D stacking framework, to 3D entangled system with the co-existence of interpenetration and polycatenation, and 3D topological framework. Interesting, these CPs could be utilized for capture of iodine molecules. According to the multiple complementary experiments and crystallographic analysis, iodine capture is mainly due to halogen bonds interactions in the inorganic {Cu2I2} building blocks of the framework. The present study displays an elegant example for understanding the structure-property relationship in supramolecular isomerism with distinct topological structures.

Si-Si Zhao

Papers

Two tetraphenylethene-containing coordination polymers for reversible mechanochromism

PEG-Induced Synthesis of Coordination-Polymer Isomers with Tunable Architectures and Iodine Capture.