Synthesis And Properties Of Cyclic Anion Receptors Based On Carbazole Sulfonamide And Amide Unit

Due to the significance of anionic species in chemical,environmental,biological,and medicinal systems,the development of novel anion receptors/sensors has become a hot topic in supramolecular chemistry.By using carbazol-1,8-disulfonamide as the framework,three series of carbazole disulfonamide-diamide macrocycles with different bridging groups（for connecting sulfonamide and amide units）were designed and synthesized in this thesis,and their anion binding properties were studied carefully.The main work is summarized as follows:1.Two carbazole disulfonamide-diamide macrocycles 1 and 2 with semi-flexible meta-xylyl spacers were synthesized,and carefully studied for their anion recognition properties in DMSO-d₆ solution by ¹H NMR/UV-vis titration experiments.The ¹H NMR titration results showed that both macrocycles exhibited strong and selective binding of F^-in DMSO-d₆,which was superior to other test anions.In addition,the binding affinities of the two macrocycles were in the order F^->>AcO^->PhCOO^->H₂PO₄^->Cl^->NO₂^-/N₃^-/Br^-/HSO₄^-/NO₃^-/ClO₄^-（no binding）.Importantly,the macrocycle 1 bearing the pyridine-2,6-diamide units has better selectivity for F^-than AcO^-and H₂PO₄^-（selectivity factors of 30 and 182,respectively）,which was increased by about 3 times relative to macrocycle 2 containing isophthalamide group.2.The carbazole disulfonamide-diamide macrocycle 6 with semi-flexible meta-xylyl spacers and macrocycle 7 with flexible ethylidene spacers was synthesized,and carefully evaluated for their anion binding properties through ¹H NMR/UV-vis titration experiments.The UV-vis titration results revealed that the macrocycle 6 with m-dimethylphenyl spaces can strongly bind to F^-and AcO^-ions in DMSO solution(K_a>7000 M^-1,using a 1:1 binding mode),which was significantly better than other tested anions.It was worth noting that the binding affinities of macrocycle 7 with some anions（such as H₂PO₄^-,F^-,and AcO^-）were markedly stronger than these of 6after the introduction of flexible ethylidene spacers,especially the binding of macrocycle 7 with H₂PO₄^-（which was greatly improved by 17-fold）.Subsequently,¹H NMR titration results indicated that macrocycle 6 can make use of the four NH binding sites（namely two sulfonamide NH and two amide NH units）and three interior-pointing aromatic CH binding sites in 6 to bind anions,while the main recognition sites only included two amide NH and sulfonamide NH groups for macrocycle 7.3.Two carbazole disulfonamide-diamide macrocycles 11 and 12 with benzyl spacers were synthesized,and carefully evaluated for their anion binding properties through ¹H NMR/UV-vis titration experiments.UV-vis titration results indicated that macrocycle 11 displayed strongly binding for AcO^-in DMSO solution(K_a>10⁶ M^-1,with a 1:1 stoichiometry),which was dramatically superior to other test anions（including its competing F^-and H₂PO₄^-）.However,the binding affinities of macrocycle 12 to most anions were weaker than those of 11,probably attributed to the relatively large binding cavity of macrocycle 12.Moreover,¹H NMR titration results showed that macrocycle 11 bond towards anions via four NH binding sites in 11,involving two sulfonamide NH and amide NH groups.However,two amide NH and three aromatic CH binding sites in the bottom of the macrocycle 12 were observed to form intermolecular hydrogen bonds with anions.Finally,HRMS displayed that macrocycles 11 and 12 can form stable complexes with anions（such as H₂PO₄^-）in the gaseous state,with a 1:1 binding mode.