Synthesis And The Fluorescence Properties Of Ion Recognition Receptors Based On Nitrogen Heterocyclic Compound

This paper includes four chapters:Chapter 1: This chapter introduces the research progress of various organic hetero atom receptor molecules and receptor molecules to ions recognition. The main contents are:?1? Definition of molecular recognition and research summary;?2? The basic structure and characteristics of receptor molecules;?3? Ions recognition principle;?4? Significance ions recognition;?5? The influence factors of ion recognition;?6? High-selective cation receptors;?7? High-selective anion receptors;?8? sequential ion receptors;?9? Issues and research contents.Chapter 2: A water-soluble, non-sulfur sensor?Z₁? was synthesized to fluorescently sense Hg²⁺ in water. Z₁ exhibits highly sensitive, selective and rapid detection of mercuric ion directly in water through fluorescence quenching. To validate the selectivity of sensor Z₁. On the addition of Fe³⁺, Hg²⁺, Fe²⁺, Ag+, Ca²⁺, Cu²⁺, Al³⁺, Co²⁺, Zn²⁺, Ni²⁺, Cd²⁺, Mg²⁺, Pb²⁺ and Cr³⁺, the fluorescence intensity of sensor Z₁ quenched rapidly by Hg²⁺. None of these ions induced any significant changes in the fluorescence spectrum of the sensor. Furthermore, the detection limit of the fluorescent spectrum changes calculated on the basis of 3?/m is 8.859×10^-8 M. The test strips based on Z₁ were fabricated, which could act as a convenient and efficient Hg²⁺ test kits. The deprotonation mechanism of the sensor Z₁ with Hg²⁺ was investigated by IR spectra, ¹H NMR titration and ESI-MS spectral analyses methods.Chapter 3: A reversible and water-soluble 2, 4-dimethyl-7-amino-1, 8-naphthyridine?ZR? was synthesized to fluorescently sense CN- in water. This sensor combines naphthyridine groups as signaling subunits and the presence of the active hydrogen of primary amine confers the recognition capacity toward cyanide ion. The detection limit of the sensor towards CN- is 1.34×10^-8 M, which pointing to the high detection sensitivity. An immediate response of ZR to the CN- provided a real-time detection method. The detection mechanism of the sensor ZR with CN- was investigated by IR spectra, ¹H NMR titration and ESI-MS spectral analyses methods. The deprotonation reaction between cyanide and the primary amine would block the intramolecular charge transfer of the naphthyridine and primary amine. The reversible and reproducible fluorimetric switching process may be represented by a molecular “IMPLICATION” logic gate, employing CN- and Cr³⁺ as the inputs. In addition, test strips based on ZR were fabricated, which could act as a convenient and efficient CNtest kits.Chapter 4: A 2-?quinolin-2-ylmethylene? malononitrile?6? chemosensor have been designed and synthesized by Knoevenagel reaction. The recognition profiles of the chemosensor 6 toward various anions, including F^-, Cl^-, Br^-, I^-, AcO^-, H₂PO₄^-, HSO₄^-, ClO₄^-, SCN^-, CO₃^2-, N₃^-, S₂^-, HS^- and CN^- were primarily investigated in DMSO/H₂O?1:9, v/v? HEPES buffer?pH=7.2? solution. Probe 6 exhibits high selectivity and sensitivity to CN- as fluorescence ‘‘off–on'' behavior through Michael addition. The detection limit of the sensor towards CN- is 5.09×10^-8 M. Moreover, the in situ formed 6-CN- is further utilized to sense the Cu²⁺ through complexation reaction with high selectivity and fluorescence quenching performance in aqueous water. Probe 6 has selectively detected CN- in real water sample, and on test strips.