Synthesis, Anion Recognition And Self-Assembly Of Oligopyrroles

Pyrrole is a five-membered heterocyclic aromatic compound with a NH moiety, and its derivatives have important physiological roles in biological systems and optical functional systems. Due to the strong ability of hydrogen binding, oligopyrroles could be developed as versatile anion binding agents. Pyrrole-containing entities are playing increasingly important roles in the area of anion recognition. Porphyrins, as tetrapyrrole macrocycles, have rich opto-electronic properties. Thus, they have also shown broad prospects in the construction of anion supramolecular self-assemblies, anion receptors, and dye-sensitized solar cells.In chapter 1, the research progress of polypyrroles in anion recognition based on H-bonding mechanism was reviewed. In chapter 2, highly efficient colorimetric F- sensors 1 and 2 incorporating various numbers of hemiquinone and pyrrole units have been developed. In these two receptors, pyrrole was designed as the binding sites, and the hemiquinones were introduced as electron withdrawing groups and signaling units. For 1 and 2 in apolar solvents, interesting keto-enol tautomerism behaviors were observed. Regarding the anion binding of receptor 1, in both CH2Cl2 and DMSO, only the addition of F- results in vivid color change from orange to blue due to a deprotonation process. In contrast to 1, receptor 2 exhibits anion sensing properties with a great influence exerted by solvents due to a more pronounced tautomerism effect. Crystal structures of 2-2MeOH-H2O and 2-DMF have clearly demonstrated the conformation of 2 and the hydrogen binding mode in the solid state. In summary,1 and 2 may be developed as a novel prototype of efficient colorimetric F- sensors.In chapter 3, a novel supramolecular approach for detecting fluoride ion via fluorescence enhancement based on intermolecular energy transfer is developed. In the CH2CI2 solution of 1 and 3, the fluorescence of 3 can be quenched by 1 due to an intermolecular energy transfer process. When fluoride ion was added.to this system, the shift of the absorption maxima of 1 results in the cut-off of the energy transfer process and coincident fluorescence recovery. Thus, the combination of 1 and 3 may afford a novel supramolecular fluorescence enhancing F-sensor system.In chapter 4, two novel coordination supramolecular assemblies were obtained via hydrothermal method through axial coordination of ZnTPP with two polypyridyl ligands L1 and L2. Crystal structure analyses have revealed that ZnTPPL1·3DMF is a mononuclear complex and [(ZnTPP)3L2]n·(DMF)2n is a coordination polymer with a novel triple chain structure. Their spectral properties were also studied.In chapter 5, two novel porphyrins were synthesized as the potential sensitizing dyes for dye-sensitized solar cells. In these molecules, multi-triphenylamines were introduced as electron donors and the anchoring carboxyl groups were attached to the meso positions through acetylene bonds. This structure design strategy may afford promising sensitizers.