The photothermal effect in MOFs

Abstract

This Thesis is devoted to the study of the interaction of light with Coordination Polymers (CPs) and Metal‐Organic Frameworks (MOFs). Two strategies have been followed to accomplish this objective. The first approach consisted on the study of the photothermal effect observed in different subfamilies of reported MOFs, which exhibited local heating upon UV‐Vis irradiation. Such temperature increase was proved useful for MOF activation and Covalent Post‐Synthetic Modification (CPSM) purposes. The second strategy was based on the synthesis of CPs following a ligand design approach using light‐harvesting Ru2+‐terpyridine complexes. Chapter 1 encloses a general introduction to CPs and MOFs, containing a historical overview of their discoveries and evolution, as well as some of the multiple applications in which these materials are involved. In this sense, we have focused on the applications arisen from the use of light as external stimulus. In Chapter 2, we have summarized the main objective of this Thesis and detailed the specific sub goals. Chapter 3 introduces the fundamentals of the light‐to‐heat conversion in different materials. Some examples of MOFs composites, where the nanoparticles exhibit the photothermal properties are reviewed. Moreover, a summary of some of the most common methods for removing guests from MOF pores (activation) is included. In this chapter, we demonstrate that MOFs also show photothermal effect and that this effect can be used to activate them by removing the solvent molecules after their irradiation with a UV‐Vis lamp for short periods. In Chapter 4, Post‐Synthetic Modification (PSM) of MOFs is reviewed based on the interactions between the framework and the desired modifying agents. To this end, some alternative strategies to perform such reactions are included. Thereafter, the use of the local heat generated upon MOF irradiation in CPSM reactions is reported. Amino‐tagged MOFs with strong photothermal effects and anhydrides or aldehydes were mixed (sovent‐free), and subsequent UV‐Vis exposure for short times allowed the melting of the reagents and the covalent reaction. In Chapter 5, the light‐harvesting and photothermal properties of some organometallic complexes are exemplified. The beneficial strategy of confining these moieties as building units in CPs and MOFs for enhancing their performance is described. The synthesis and characterization of three new CPs build up from Ru2+‐terpyridine complexes is reported here. Their photothermal characterization is performed and the new CPs showed maximum temperatures in the range of the MOFs with the strongest photothermal effect. In addition, future assessment of the CPs in photocatalytic reactions might be carried out, taking advantage of the close disposition of the Ru complexes and the metal ions of the nodes.

Date of Award	26 Oct 2018
Original language	English
Supervisor	Daniel Maspoch Comamala (Director), Inhar Imaz Gabilondo (Director) & Felix Busque Sanchez (Tutor)