Ion Recognition And Construction Of Molecular Device Based On Anion Induced Assembly

Many inorganic and organic anions play important roles in the research fields of the biology, pharmacology, catalysis, environmental and chemical process, so the design and synthesis of artificial anion selective chemosensors, to qualitatively or quantitatively determine anions, have received more and more attention. Anion fluorescent chemosensors selectively bind the anion and transform this process to observable fluorescent signals. We have designed and synthesized a series of novel receptors for selectively sensing H2PO4-. Ratiometric fluorescence sensing for anions has received great attention during the past decades due to its high selectivity and sensitivity. Preassembly-driven sensing mechanism, in contrast, is a new concept. However, to the best of knowledge, this new sensing mechanism has never been employed to construct ratiometric anion sensing probes. Also, owing to its higher hydration energy, the ratiometric sensing of H2PO4- in water is very challenging. As rapid growth in supramolecular chemistry, remarkable progress has been received in the field of design and synthesis of electronic or photonic driven systems that function as molecular-level devices, such as simple logic gates as well as more advanced switches, wires, grids, and molecular machines. Mimicking the functions of semiconductor logic gates used in modern computing is of particular interest, which may extend the information processing to the molecular level. Even though the outputs of most molecular logic gates rely on photonic processes, their inputs are rather drivers, including light and chemical substances such as redox-active species, protons or metal ion guests and examples including anions are rare.1. Synthesis and properties of substituted anion receptor. We introduced the electron-donating group methoxyl group and the electron-withdrawing group nitro-group to L1 respectively to have designed and synthesized the receptors L1-L10. Their structure were characterized by NMR spectra and HRMS. The Uv-vis absorption and emission spectra in solution were studied. H2PO4- induced the fluorescence enhancement and the bathochromic shift of fluorescence emission, which was ascribed to the excimer emission between anthracene and the H2PO4--induced assembly of L1. However, the receptor L2 containing electron-withdrawing group nitro-group cannot sense H2PO4-.2. We describe a novel preassembly-driven mechanism available for ratiometric fluorescent sensing of H2PO4- both in organic solvent and in water. We believe this strategy would provide useful inspirations for employing the fluorophores with preassembly formation capability to design novel ratiometric probes in aqueous media.3. A new potential logic gate L based on anion receptor is designed, synthesized and characterized, which combines anion binding processes and host/guest triggered inhibition in a single molecule. This system show an inhibit (INH) gate function via an host-guest triggered disassembly process. Molecule L may provide the opportunity to realize an inhibit (INH) gate function using cyclodextrins (CDs) and dihydrogen phosphate as chemical inputs and the fluorescence intensity signal as output.