Accurate Matching of a Secondary Amino-Functionality Metal–Organic Cage for Selective Recognition and Supramolecular Binding during Photoinduced Hydrogen Evolution

Abstract

Accurate matching of the active sites between the host and guest molecules has a great effect on the selective recognition of different but similar guest molecules or different binding abilities toward the same molecule. Herein, a pseudotetrahedral metal–organic cage (MOC, Co-TAP) that contains secondary amino groups designed as guest-interacting sites was achieved. Co-TAP exhibits the selective recognition of uridine over other similar natural molecules via a fluorescent response. However, a reference structure (Co-TOP) with the same configuration was also synthesized by replacing the secondary amine group with an oxygen atom of the ligand, and it reveals the selective recognition of guanosine. In addition, the accurate matching also enables Co-TAP to strongly bind the organic dye as a guest molecule via host–guest interactions, thus facilitating photoinduced electron transfer between the redox catalytic sites in MOC and the excited guest via a pseudointramolecular pathway.

Luminescent metal–organic frameworks as optical sensors for selective sensing towards Fe3+ and Cu2+

“…Due to their designable structure, tunable configuration, high surface area, and high porosity, as well as the combination of organic and inorganic components, MOFs have emerged as a promising platform with a wide range of applications, such as gas adsorption and separation, drug delivery, heterogeneous catalysis, proton conduction, and sensing. 27–33 Especially for luminescent sensing, the coordinated-driven MOF materials exhibit superior structural advantages compared to other organic or inorganic sensors: (1) the structure of MOFs can be easily modified by incorporating diverse functional and photoactive groups or lanthanide ions as coordination sites, forming luminescent MOFs (LMOFs) and thus endow them with fine-tuned luminescence emission properties, including their emission range and intensities, with multiple optical responses when applied as luminescent sensors. (2) The unique porosity of MOF sensors is also tunable and tailored to specific sizes by designing and controlling the construction of the selected ligands and metal sites, and the precise control over the size and shape of the pores in MOFs allows for the selective sensing of the target ions or molecules.…”