Dipyridylamine-based Fluorescent Sensors And Supramolecular Coordination Assemblies

Ligands containing multiple dipyridylamine units have strong coordination properties to form various novel supramolecular structures, thus they have attreacted extensive interest in the area of supramolecular and cooridination chemistry. In this thesis, a series of novel ligands containing multiple dipyridylamine units were designed and utilized as metal cation sensors and solid state luminescence of their coordination compounds are investigated.In Chapter 2, the ligands were synthetized by facile necleophilic reactions, Goldberg coupling reactions and Sonogashira coupling reactions.In Chapter 3, fluorescent sensors 1 and 2 were developed for Cu2+. Considering the excellent coordination ability of 2,2'-dipyridylamine (2,2'-DPA) and the strong fluorescence of anthracene (AN), one or two AN units were introduced to a 2,2'-DPA platform. Both of them exhibit strong emissions in solution with the quantum yields of 0.64 and 0.63, respectively. Upon sensing Cu2+, both of 1 and 2 show almost quantitative fluorescence quenching, showing good selectivity and sensitivity, with the detection limits of 3.89×10-7 and 6.41×10-1 M, respectively.In Chapter 4, a novel ligand bis(4,4'-dipyridylaminophenylene)butadiyne (L) were used to synthesize three coordination polymers, [Cd2L2Cl4]n·3nDMF·3nH2O(C1), [CdLBr2]n(C2) and [Cd6L3(SO4)6]n·4nMeCN (C3) by solvothermal method. Single-crystal X-ray diffraction analyses revealed that the free ligand may present two different conformations due to the flexibility of the butadiyne unit. In complexes C1 and C3, the ligand molecules are linked by metal atoms, affording 3D supramolecular structures. It is noteworthy that complex C3 contains interesting infinite{Cd6(SO4)6}∞chains. Complex C2 exhibits a 2D network structure. The solid state photoluminescence properties of the free ligand and all the complexes were investigated at room temperature. The emission maxima vary within the wavelength range of 420-515 nm. It can be expected that design and utilization of similar tetrapyridyl ligands with the diacetylene unit connected to the pyridine rings is a practical approach to extend the aromatic systems, and thus tune the fluorescence wavelength and intensity.