Syntheses And Properties Of Redox-active Metal-Organic Frameworks Based On Tetrathiafulvalene Ligands

Tetrathiafulvalene(TTF)and its derivatives have been intensively studied for their good electron-donor ability and redox activities.Using the redox-active TTF building block for the constructing of supramolecular structure is a big innovation in the field of coordination chemistry and material chemistry.A lot of structural aesthetic frameworks and wide used functional and intelligent materials are spring up.In this dissertation,we focus on TTF building block,a series of carboxylate substituted TTF ligands and its assemblied MOFs are designed and synthesized.The redox activity,gas adsorption,conductivity and magnetic properties of these new frameworks are studied.1.A new series of MOFs([RE2(TTFTB)1.5(H2O)3]·3DMF·13H2O)generated from tetrathiafulvalene-tetrabenzoate(H4TTFTB)and four different rare-earth(RE)ions derived from RECl3·6H2O(RE = Tb,Dy.Ho,and Er)using solvothermal methods.The powder X-ray diffraction(PXRD)patterms display chemical stability in a wide range of solvents,as well as thermal stabilities up to 400?.The solid-state cyclic voltammetry(CV)suggesting the redox-activity of these MOFs.The TTF core was partially oxidized by a solid-solution method using I2,as evidenced by a strong radical signal in the electron paramagnetic resonance(EPR)and solid-state UV-Vis-NIR spectra and the single crystal X-ray diffraction(SCXRD)data.At last,only the Dy and Er MOFs display slow magnetic relaxation behavior which is not affected by the introduction of the radical by oxidation.2.A series of MOFs formulated as[RE9(?3-OH)13(?3-O)(H2O)9](TTFTB)3]were constructed by H4TTFTB and RECl3·6H2O(RE = Tb,Dy,and Er)using solvothermal methods.The thermal stability,N2 adsorption,redox-activity and the luminescence of characteristic RE ions are fully studied.The TTF core was oxidized by a solid-solution method using I2,as evidenced by a strong radical signal in the EPR and solid-state UV-vis-NIR spectra.At last,only the Dy and Tb MOFs display slow magnetic relaxation behavior.After I2 oxidation,owing to solvent exchange and the introduction of the I2 derivatives,the slow magnetic relaxation behavior disappeared.3.In order to enhance the interaction of TTF matrix in the framework,a new ligand m-tetrathiafulvalene-tetrabenzoate(m-H4TTFTB)with a small dihedral angle between TTF and benzoate group was synthesized.A new series of MOFs(RE2(m-TTFTB)1.5(HCOO)(DMF)]·2DMF·3H2O)generated from m-H4TTFTB and four different rare-earth ions derived from RECl3·6H2O(RE = Gd.Tb,Dy,and Er)using solvothermal methods.The single crystal X-ray diffraction analysis showed the shortest S···S distance of the TTF dimer in the MOFs is 3.555 A.The PXRD patterms display chemical stability in a wide range of solvents and pH range of 1-12,as well as thermal stabilities up to 450?.At last,magnetic study showed the Dy-MOF displays slow magnetic relaxation behavior,while Er-MOF possesses field-induced slow magnetic relaxation behavior.4.In order to enhance the interaction of the TTF matrix in the framework and lower the dimensionality of the framework,a new series of MOFs([RE6(m-TTFTB)2.(?3-OH)8(H2O)2(HCOO)2]·1.5(NH2(CH3)2)·5DMF·8H20)were generated from m-H4TTFTB and RECl3·6H2O(RE = Tb,Dy,and Er)using solvothermal methods.The single crystal X-ray diffraction analysis showed the distance of the TTF in the TTF trimer in the MOFs is 3.703 A.Interestingly,the planer geometry of the TTF and the cental C-C distance of 1.40 A suggested the middle TTF in the trimer is in its radical state.The solid-state CV suggesting the redox-activity of MOFs.At last,magnetic study showed Dy-MOF displays slow magnetic relaxation behavior,while Er-MOF possesses field-induced slow magnetic relaxation behavior.5 Guided by topology,two flexible isomeric MOFs,compounds 1 and 2,with a formula of In(Me2NH2)(TTFTB),were constructed via combination of[In(COO)4]-metal nodes and tetratopic H4TTFTB linkers.The two compounds show different breathing behaviors upon the introduction of N2.Single crystal X-ray diffraction,accompanied by molecular simulations,reveal that the breathing mechanism of 1 involves the bending of metal-ligand bonds and the sliding of interpenetrated frameworks,while 2 undergoes simple distortion of linkers.Reversible oxidation and reduction of TTF moieties changes the linker flexibility,which in turn switched the breathing behavior of compound 2.The role of counterions on the breathing behavior was also studied by cation exchange experiments.6 In(COO)4-nodes and m-H4TTFTB ligands have been successfully assembled into a two-dimensional MOF,compound 1([(CH3)2NH2][In(m-TTFTB)]DMF·5H20),with a high proton conductivity of 6.66×10-4 S cm-1 at 303 K and 98%RH and an activation energy of 0.59 eV which suggesting the vehicular mechanism.Followed by the space-install of four additional carboxylic groups on the linker,a similar two-dimensional MOF,compound 2([(CH3)2NH2][In(H4TTFOC)]·5DMF·13H20),was assembled.Compared to 1,2 shows an ultrahigh proton conductive with 1.30×10-2 S·cm-1 at 303 K and 98%RH and an ultralow activation energy of 0.09 eV.The activation energy suggests the Grotthuss mechanism which together reveals an effective proton transportation pathway associated with aligned(CH3)2NH2+ and the free water molecules.In all,the successful space-install of additional carboxylic groups on 2D MOFs could obviously improve the proton conductivity.Additionally,a high electrical conductivity was simultaneously achieved with the pure protonic nature of the 2D MOF 2.The electrical conduction at the MOF-metal interface is enabled by the redox-switchable behavior of the TTF-based ligands.This unique charge transport mechanism,protonic/pseudo-capacitance coupling,offers a new strategy for utilizing the ionic conductivity from MOFs to construct functional electronic devices.7 We demonstrate that confined configuration design method is an efficient way to construct multifarious MOFs with independent structure and properties.Two Zr-MOFs,compounds 1([Zr6(TTFTB)2O8(OH2)8]·2(C3H7ON))and 2([Zr6(Me-TTFTB)1.5O4(OH)4(COO)4]·20(H2O)·4(C3H7ON)),were constructed via combination of Zr6 nodes and tetratopic H4TTFTB or Me-H4TTFTB linkers,respectively.The single crystal X-ray diffraction analysis showed different kinds of pores in compound 2.In addition,guide by the redox reaction between the TTF building block and the guest I2 give rise to TTF·+ and I3-proved by the SCXRD,noble metal nanoparticles(MNPs)were placed in the channel of a hierarchical Zr-MOF.We demonstrated an auto-reduction method to harvest MNPs loaded in a stable redox active MOFs.As a proof of concept,Pd NPs@compound 2 was utilized as a heterogenous catalyst for aerobic oxidation of alcohols,showing decent activity and recyclability.