Design, Synthesis And Properties Of Carbazole Derivatives With Anion Recognition Sensing

Molecular recognition is that the host selectivity binds with the guest and produces a specific functinality, it is a necessary way to assemble advanced structure and research the functions of assembly. As we all know, DNA is a kind of polyanionic species and most of enzymes & coenzymes are anionic species. People have realized very important roles played by anions in the systems of biology, catalysis, environment, medicine and so on. Therefore, design and synthesis of artifical anion receptors capable of selective recognition and sensing for specific anions has been becoming a research focus in the field of supramolecular chemistry.Carbazole derivatives are an important type of nitrogen-containing aromatic heterocyclic compounds, having a large π-conjugated system and strong ICT effect. The above characteristics make carbazole compounds have many unique properties, and find extensive applications in the fields of photoelectrical materials, dyes, medicinal agents, supramolecular recognition and so on. More importantly, carbazole compounds are easily modified and various functional groups can be conveniently introduced into carbazole ring. Additionally, carbazole 9-position NH by itself can act as one additional H-bonding recognition unit for anions. In recent years, many carbazole-based anion receptors relying on H-bonding motif had been successfully developed. In this thesis, we designed a series of carbazole-based anion receptors with cleft-shaped or cyclic structures and studied their recognition and sensing properties towards common anions.1. A simple introduction was carried out about the basic knowledges of anion recognition, the method to determine binding ratio & binding constant as well as research progresses on carbazole-based anion receptors;2. A novel carbazole sulfonohydrazide receptor(1) bearing 1,8-naphthalimide units was designed and synthesized, which selectively recognized biologically important F-, AcO- and H2PO4- in DMSO, as evidenced by fluorescence and UV-vis titration experiments. Receptor 1 formed 1:1 complexes with these anions, affording the binding constants larger than 103 M-1. Interestingly, receptor 1 displayed a specific recognition towards F- in DMSO containing 10% H2O(v/v). The 1H NMR titration experiments in DMSO-d6 proved that five-fold intermolecular H-bonding interactions were responsible for effective complexation between 1 and F-(at a low concentration);3. A novel carbazole disulfonamide-based macrocyclic receptor 2 was designed and synthesized, which showed a remarkable fluorescent color change(from violet to light blue) upon interaction with F? under irradiation with a UV-lamp at 365 nm. Its anion recognition properties were studied by UV-vis, fluorescence and 1H NMR titration spectra. In both DMSO and DMSO-CH2Cl2(1:99, v/v), 2 exhibited a high selectivity and affinity for F? over other anions tested;4. A novel 1, 8-disulfonamidocarbazole-dipyrromethane Schiff-base macrocycle(3) and its amine analogue(4) were designed and synthesized, and their anion binding properties were studied via UV-vis and 1H NMR spectroscopic titrations conducted in DMSO solution. The obtained results indicated that a small modification in the macrocyclic structure(by reducing imines to the corresponding amines) had a remarkable impact on their anion binding affinities and selectivities. For example, macrocycle 3 displayed a 7.9:1 F?/H2PO4? selectivity, whereas its reduced product 4 showed a 78.5:1 selectivity favorable for F?;5. Macrocyclic receptors(5 and 6) bearing m-phenylenediamine bridges and carbazole backbone and its conference compound(7) were synthesized. The main aim is to examine the effects of changing the interior atom on macrocyclic framework and receptor’s structures(open-chain or cyclic) on their anion recognition properties. UV-vis titration results indicated that receptors 5~7 could selectively bind biologically important F?, AcO? and H2PO4? over other anions in DMSO, and the strongest binding was observed for macrocycle 5.