Incorporation Of Aryls Onto Tetrathiafulvalene Through Sulfur-bridges:Molecule Design And Highly Efficient Synthesis,Structures And Properties Of Supramolecular Assembly Materials

Tetrathiafulvalene(TTF),firstly synthesized in early 1970s,and its derivatives are widely employed as the key conducting component for organic conductors stimulated by the first organic metal(TTF)(TCNQ).Recently,the peripheral functionalization of TTF has attracted intensive attentions,and leads to the application of TTFs in supramolecular chemistry,organic functional materials,and molecular devices as well.The incorporation of aryls onto TTF framework is of special interest since the peripheral aryls can affect both the electronic and crystallographic nature of the resulting molecules.In this thesis,we disclose a facile and highly efficient synthetic approach toward "aryl substituted/fused TTF derivatives through sulfur bridges".We have created a library of such TTFs,and made thorough investigations on their physical properties and solid state structures.As expected,the peripheral aryls show the significant perturbation on the electronic state of the resulting TTFs,and can rotate around two C-S bonds of the sulfur bridges that makes the molecular geometry of TTFs sensitive to the environmental variations.Under certain conditions,these TTFs can form the bowl-like internal cavity.The supramolecular assembly of these TTFs is achieved through the intermolecular π-π interactions,coordination with metal ions,and charge-transfer(CT)interactions,as well as the size and shape complementarity between TTF internal cavity and guest molecule.Consequently,we have prepared the inclusion complexes between TTFs and fullerene molecules(C60,C70),TTF-based metal-organic-frameworks(MOFs)with controllable dimension,and CT salts with CuBr2.The main content of each chapter is described as follows:In Chapter 1,we firstly made the brief introduction about the molecular electronics and the traditional application of TTF derivatives in the field of organic conductors.We,in particularly,summarized the applications of TTFs in molecular electronic devices and supramolecular chemistry.Then,we focus on the peripheral arylation of TTF,mainly on synthetic methodology.Finally,our strategies on molecular design,synthesis,and supramolecular assembly were outlined.In Chapter 2,we reported a facile and highly efficient synthetic approach toward"aryl substituted/fused TTF derivatives through sulfur bridges".The key step of synthesis is the copper-catalyzed C-S coupling between(TBA)2[Zn(DMIT)2]and aryl iodide,which afforded the synthetic precursors of title TTFs,1,3-dithiole-2-thione.Firstly,we optimized the reaction conditions for the C-S coupling between(TBA)2[Zn(DMIT)2]and aryl iodide,and found the best reaction conditions as Cu20(20%)/Ethyl acetoacetate(40%)/DMF/120℃/10 h.Then,we prepared a series of 1,3-dithiole-2-thiones(41 examples)incorporated by aryls with different electronic effect and steric hindrance.Finally,we synthesized a library of title TTFs(58 examples)via the coupling reaction of 1,3-dithiole-2-thiones mediated by P(OEt)3.In Chapter 3,we reported the optical and electrochemical properties of the title TTFs to elucidate the effects of aryls on the electronic states of the resulting TTFs,In comparison with the pristine TTF,the title TTFs show the additional broad absorption band at 400-500 nm.Theoretic calculation indicates that this broad absorption band comes from the intramolecular CT transition from HOMO(mainly on central TTF core)to the LUMO(mainly on peripheral aryls).These TTFs possess two reversible redox potentials and their first redox potentials(E1/21)increase with the electron-withdraw ability of the peripheral aryls.The electron donating ability of the TTFs were also sorted by complexation of TTFs with strong electron acceptor TCNQF4.When E1/21<0.6 V,the electron transfer between TTFs and TCNQF4 took place,as proved by the appearance of three new broad absorption bands centered at 700 nm(TTF+·),760 nm and 865 nm(TCNQF4-·).As E1/21 value increases,the absorption intensity of these three band decreases.When E1/21 0.6 V,the broad absorption bands disappeared,indicating there is no electron transfer between TTFs and TCNQF4.In Chapter 4,we reported the solid state structures of the title TTFs to elucidate the effects of aryls on the crystallographic nature of TTFs.We have prepared the single crystals of 26 TTF derivatives and solved their crystal structures.The central TTF core of these TTFs took four types of conformations including chair,half-chair,boat,and planar.The molecular geometries,packing patterns,and intermolecular interaction modes were significantly affected by the rotation of aryls around the C-S bonds of sulfur bridges.Additionally,these TTFs have afforded many interesting packing structures,for examples,the helical chain type arrangement formed by the achiral molecule TTF-15,the polymorphism of TTF-29,and the co-existence of chair and boat conformations in TTF-35.In Chapter 5,we reported supramolecular assembly of title TTFs with fullerene molecules(C60,C70).We have prepared a series of inclusion complexes between the title TTFs and fullerene molecules(C60,C70)by slow evaporation of their mixed solution at room temperature.Crystallographic investigation indicates that in these inclusion complexes the TTF molecules form the cavities by modulation of their molecular geometry.These cavities encapsulate the fullerene molecules to make them form the columnar stacks with short center-to-center distance,and consequently provide the electron transport pathway.There are electronic transitions between the TTFs and fullerene molecules as proved by the broad absorption band centered at 800 nm.These inclusion complexes are thought to have the potential applications as electronic conducting materials.In Chapter 6,we reported the preparation and crystal structures of the MOFs based on the title TTFs.The MOFs were prepared by solvothermal method,where the tetrapheny lcarboxyl-TTF s acted as ligand.The coordination of ligands(C6H5-3-COOH)4-TTF,(C6H5-2-COOH)4-TTF,and(C6H5-4-COOH)4-TTF with Zn2+afforded the quasi-one-dimensional(Q-1-D),two-dimensional(2-D),and three-dimensional(3-D)MOFs,respectively.Additionally,(C6H5-3-COOH)4-TTF and(C6H5-2-COOH)4-TTF afforded Q-1-D and 2-D MOFs,respectively,when coordination with Pb2+.These results indicate that the dimensionality of the MOFs can be finely tuned by the modulation of position of-COOH group in phenyl.In Chapter 7,we reported the CT salts between the title TTFs and CuBr2.The CT salts were prepared by the conventional two-layer diffusion method.We found that only the[TTF2+]-type salts were formed when E1/21<0.60 V,and the[TTF+·]-type salt were obtained when E1/21>0.6 V.In the crystal structure of these CT salts,the counter anions derived from CuBr2 can be distorted tetrahedron-type[CuBr4]2-,planar-type[Cu2Br6]2-,and linear-type[CuBr2]-.It should be noted that in[(TTF-7)2+][(CuBr4)2-]salt,two dithiole rings of the central TTF core in TTF-7 are distinctly twisted with a dihedral angle of 38°,a very rare case in TTF-based cation radical salts.The temperature-dependent magnetic susceptibilities of these salts followed the Curie-law,indicating these salts were intrinsically paramagnetic.