Synthesis,Crystal Structure Of Novel Oxa-Imidazolium Cyclophanes And The Recognition To Anions

Anions（such as ATP,GTP,etc.）,which are ubiquitous in living organisms and in environment,play an important role in life science,medicine and chemical processes.Most reported anion fluorescent sensors are based on fluorescence enhancement or quenching.Whereas in practical applications,some factors such as microenvironment or/and concentration of molecules around the sensors may also induce fluorescence quenching or enhancement.Therefore,it is a novel research strategy to design and synthesize sensors,which show bathochromic-shift/hypochromatic-shift of fluorescence emission in recognition of anions.In this thesis,four series,a total of 9 imidazolium cyclophanes containing biphenyl,naphthalene,anthracene or/and acridine ring as fluorescent units were synthesized.The structures of the intermediates and products were confirmed by IR,¹H NMR,¹³C NMR and high mass spectrometry.Five oxa-Imidazolium cyclophanes were cultured by solvent evaporation and the crystal structures of cyclophanes 11,12,13,15 and 16 were characterized and analyzed.The anions of[1+1]cyclophanes 11 and[1+1]cyclophanes 12 containing naphthalene rings as fluorescent groups are different,but the crystal structures of both compounds are similar and the configurations of these rings are largely deformable.[2+2]cyclophane 13 has a small ring cavity due to two naphthalene rings facing into the ring.The anions of cyclophane 15 and cyclophane 16 containing anthracene as fluorescent groups are different,but the crystal structures of both compounds are similar and their cavities were large and symmetrical.The anions of five imidazolium cyclopentadienyl are all outside the ring,and the crystal structures of imidazolium cyclophanes 11,12,15and 16 look like a“bowl”.The supramolecular recognition of oxaimidazolium cyclophanes with F^-,Cl^-,Br^-,I^-,NO₃^-,CH₃COO^-,HSO₄^-and H₂PO₄^-are investigated by fluorescence spectra.It was found that the selective recognition propertiesof oxaimidazolium cyclophane on different anions is similar in acetonitrile.All the oxaimidazolium cyclophanes show recognition of H₂PO₄^-.After the addition of H₂PO₄^-,cyclophanes 9,12,14,18 and 19not only showed the fluorescence enhancement,but also the emission peaks of the host compounds showed bathochromic-shift in different degrees.After adding H₂PO₄^-,cyclophanes 16 and 20 showed the fluorescence quenching and fluorescence enhancement,respectively.The Job′s plot analysis indicate that 1:1 complexs can be formed between cyclophanes 16,18 and H₂PO₄^-.The competition experiments indicated that cyclophanes 16,18 and 20 have good selective recognition ability for H₂PO₄^-and strong anti-interference ability,which makes these four compounds showpotentials in fluorescent probes for H₂PO₄^-.Cyclophane 18 also show the bathochromic-shift in fluorescence emission,indicating that such compound showed potential in the development of H₂PO₄^-fluorescence probe.