Pyridinemethanol Ligands And Ligand-Appended Zirconium-based Metal-Organic Frameworks

Metal-organic frameworks(MOFs)have infiltrated multiple disciplines and developed rapidly in the past three decades because of their high surface areas,tunable architectures,and good biocompatibility.Among them.zirconium-based MOFs have gained particularly widespread attention due to their high thermal,mechanical,and hydrolytic stabilitiesIn the first chapter of this thesis,we start by introducing the historical development of the MOF field together with some iconic MOFs,as well as the progress of stable MOFs.This is followed by the discussion of bulk and nanoscale Zr-based MOFs materials of meso-tetra(4-carboxyphenyl)porphine(H2TCPP)ligands,including their synthetic methodologies and structural features.The state-of-the-art progress of these MOFs,such as catalysis,sensing,drug delivery,photodynamic therapy,and etc,are subsequently discussed.In order to incorporate pyridinealcohol-carboxylate ligands within the MOF pores for further applications,we briefly mentioned the progress of MOFs based on pyridinealcohol-carboxylate ligands in the final part of the chapter.In chapter two of the thesis,we focus on the development of Zr6-based nanoscale metal-organic framework(NMOF)of TCPP-Mn metalloligand,namely.PCN-222(Mn),for magnetic resonance imaging(MRI)and oxygen self-supplementing photodynamic therapy(PDT).PCN-222(Mn)with a regularly porous structure not only guarantees a high loading capacity of the TCPP photosensitizer but also prevents the self-quenching of the porphyrinic emission.A series of PCN-222(Mn)NMOFs with different particle sizes have been prepared through optimizing the synthesis conditions.The PCN-222(Mn)NMOFs obtained herein with embedded Mn thus shows good catalytic activity toward the decomposition of endogenous H2O2 to produce O2.which can be subsequently converted into singlet oxygen(1O2)under light irradiation,thereby are expected to overcome tumor hypoxia via enhanced O2 supply to achieve better PDT results.In chapter three,we have unexpectedly synthesized a novel lactone furo[3,4-b]pyridin-5(7H)-one(L1)using the same synthetic methodology as previously described for 2-(hydroxymethyl)isonicotinate(iso-hmnH,HL2).Ligand L1 undergoes a coordination-induced ring-opening reaction with Zn(NO3)2·6H2O to yield zwitterion[Zn(L1')2(H2O)2](1,L1'=2-(hydroxymethyl)nicotinate)with an uncoordinated carboxylate.The same reaction of L1 with Cd(NO3)2·4H2O provides a two-dimensional(2D)network of[Cd(L1')2]n(3)with the carboxylates coordinated to Cd2+propagating the assembly.The corresponding reactions of Zn(NO3)2·6H2O and Cd(NO3)2·4H2O with 2-(hydroxymethyl)isonicotinic acid(HL2)generated zwitterionic[Zn(L2)2(H2O)2](2)and 2D network[Cd(L2)2]n·nDMF(DMF=N,N'-Dimethylformamide),respectively.We reason that the Zn2+ preference for the zwitterionic complex formation and the Cd2+ preference for 2D matrices is due to their different binding affinities for the carboxylate relative to H2O.This work points to the potential of using "hidden" functionalities widely found in small synthetic organic molecules and natural products for the construction of coordination complexes with new functionality and potential applications.In the last chapter,we provide a summary of the three previous chapters and also some outlook of the project by associating highly stable,diverse,and porous Zr-based MOFs with pyridinealcohol-based ligands for future multi-modal theranostic applications.