Study On Polypyridine Derivatives/complexes, Anthracene Derivatives And 1,8-naphthyridine Complexes As Optical Chemosensors

Molecular recognition has been an important research field of supramolecular chemistry as it plays pivotal roles in many fundamental physiological processes in organisms. Then the design and synthesis of chemosensor with spectral responding, which are based on the principles of molecular recognition, have great application for life science as well as related research areas. Moreover, the detecting and monitoring of volatile organic compounds (VOCs) and metal ions, specially, transition metal ions, heavy metal ions and metal ions with physiological activities, always are the intriguing topic of molecular recognition. In this dissertation, some compounds were synthesized based on different sensing mechanisms and characterized. And some interesting results were obtained from investigations of their spectroscopic characters and spectral response to some VOCs/metal ions.1. Two new compounds, C1 and C2, containing naphthalene (electron donor) 4′-phenyl-2,2′:6′,2″-terpyridine or 6-phenyl-2,2′-bispyridine (electron acceptor) moieties connected by phenyl spacer were synthesized and characterized. The two chemosensors presented intramolecular charge transfer (ICT) mechanism. The compound C1 showed highly sensitivity and selectivity to Fe(II) and Fe(III): the color of C1 solution could change from colorless to magenta and orange red, respectively. And the limit of detection (LOD) to Fe²⁺/Fe³⁺ is 8.0×10^-7 M and 4.1×10^-6 M, respectively. In the case of C2, the changes of spectral response to Cu²⁺ showed highly selectively and sensitively: the color of C2 solution could change from colorless to yellow only in the presence of Cu²⁺; the emission intensity of C2 solution were nearly quenched by Cu²⁺. LOD to Cu²⁺ is 3.8×10^-6 M。2. A polymeric metal complex [(P4VP)Pt(C^N^N)]Cl (C4) were prepared by a substituted reaction of Cl atom in [Pt(C^N^N)]Cl (C3) by P4VP. The response to alcohol vapours of spin-coated film prepared by C4 was interesting: the emission intensity of film could be quenched in alcohol vapors and restored out of alcohol vapors quickly. And the sensitivity to different vapors follows this order: methanol> ethanol> isopropanol. LOD to them are 9.5, 16.1 and 11 ppm, respectively. The sensing principle is atributed to the reversible axial coordination of polymer ligand and alcohol molecule to unsaturated Pt(II) center.3. Two compounds, C5 and C6, containing anthracene fluorophore and amino pyridine as cation receptor were synthesized and characterized. These chemosensors were designed according to photoinduced electron transfer (PET) mechanism. The spectral response of C5 to Fe(III) was featured with significant increase in emission intensity (4.1-fold), even through in the presence of other metal ions. As for C6, Hg²⁺ not only could quench its emission intensity, but also result in special change in two bnads (242-252 nm and 300-425 nm) of its UV-Vis spectrum.;Cu²⁺ also could quench the luminescence of C6,and result in the special variation between 300-425 nm of its UV-Vis spectrum.4. Two novel 2-phenmethylamino-7-methyl-1,8-naphthyridine/alkali metal ion complexes, C9 (Li⁺) and C10 (Na⁺), were synthesized and characterized. The emission colours of the complexes in solid state could change rapidly (about 2-3s) from red-orange or pink to blue, respectively, upon exposure to alcohol vapour. Moreover, the original emission colours of them could be restored quickly (about 2-3s) by removing the alcohol vapours. The response of two complexes to different alcohol vapours follows this order: methanol> ethanol> isopropanol. These phenomena could be ascribed to the effect of alcohol vapours on the strong intermolecular interaction of naphthyridine moieties which is introduced by the coordinated metal ions.