Book Description

Important issues such as the capture of greenhouse gases, the detection of hazardous chemicals, and the storage of energy require materials with tunable properties. Coordination polymers are a type of hybrid polymeric crystalline material formed from the connection of organic ligands and metal ions or clusters through coordination bonds. The wide array of building blocks that can be used enables coordination polymers to be rationally designed and tuned to possess specific properties. Amongst coordination polymers, Metal-Organic Frameworks (MOFs) stand out due to their porosity, large internal surface areas, and diversity of structures. These features can be achieved through direct synthesis as well as through directed modification of the framework post-synthetically. The study of the structures of MOFs and how they relate to the properties of the material, such as luminescence, is important to help gain a deeper understanding and to facilitate the development of new materials with desired functionality. Luminescent MOFs are of particular interest due to their potential as selective chemical sensors. Ligand-based fluorescence is one of the most common forms of luminescence in MOFs. Ligands built from the molecule tetraphenylethene (TPE) are ideal candidates for these systems. The aggregation-induced emission properties of TPE molecules can be enhanced through rigidification within a coordination network. This work seeks to further understand how the structures of TPE MOFs relate to the properties of the framework. To accomplish this, a variety of new coordination polymers were synthesized using TPE ligands with carboxylate functionalization at the para- and meta-positions. The fluorescent properties of coordination polymers constructed from para-functionalized TPE ligands was controlled through post-synthetic insertion of additional ligands. Coordination polymers formed from meta-functionalized TPE ligands tended to form dense, non-porous structures but the properties of these materials could be controlled through mixed ligand synthesis. This approach allowed for the control of the fluorescence emission as well as the porosity of the frameworks. Through this work, a better understanding of how TPE ligands and their conformations influence the structure and properties of coordination polymers is gained, which will aid in the rational design of these types of materials.