Fluorescent Chemosensors And Molecule Logic Gates Based On The Hemicyanine-Based Dyes

The cyanine dye is a typical kind of dyes. It has excellent spectroscopic properties, such as large molar extinction coefficient (ε=1.0×104L.mol-1.cm-1in the visible region), good fluorescence quantum yield. And the hemicyanine-based dye is part of the cyanine dyes. It contains the acceptor group and the donor group, and they are connected by a conjugated chain which has an odd number of carbon atoms. The hemicyanine-based dyes were used in some fields, for example, biological probes of complex biological systems, the photosensitizer of the dye-sensitized solar cell and so on. But literature reports on the the anionic chemical sensors and combinatorial molecular circuits are rare. This paper focuses on these aspects. Spectroscopic properties of the molecular were identified by UV-visible and fluorescence spectra. The mechanism which can detect certain anions and can form the molecular logic circuit was discussed. The details are summarized as follows:Compared with the receptor-based metal ions and small-sized anions sensing, the design of receptors with the complementary conformation for the detection of tetrahedral anionic species, such as SO42-, HSO4-, H2PO4-, HPO42-etc, is quite challenging because of their extremely large hydration energy according to the Hofmeister bias. Thus, it is highly desirable to seek novel simple and efficient paradigms to realize the high selectivity and sensitivity for anion detection. In chapter2, a series of the hemicyanine-based dyes were synthesized-L1, L2, L3, and L4. Their structures were characterized by1H NMR,13C NMR, MS, and elemental analysis. We found that L1and L2exhibit high sensitivity and selectivity for HSO4". Due to m-hydroxy of L3and L4, they cannot select HSO4-. The marvelous anion-induced H-aggregate strategy opens new routes to simple synthesis of receptors for tetrahedral anionic species. The detection limits of L1and L2were estimated to be1.0×10-7and1.0×10-6M range, respectively.The silicon-base computer devices have encountered series of challenges from manufacturing and physical limits, the idea of a molecular computer replacing traditional computer system was emerged. Now most of the molecular systems express a single logic function by a combination of a certain two chemical inputs. Such gates are important for the realization of complex information processing, such as sensors, medical diagnostics, molecular memory devices, and molecular computational identification (MCID) tags. In chapter3, the compound CJ4was synthesized. The obtained results indicate that CJ4can exist in three ionization forms of CJ4(+1), CJ4(0) and CJ4(-1). These forms exhibit different absorption and emission properties. Changes in the absorption and emission intensities at two chosen wavelengths with two independent ionic inputs like H+and OH" leads to a truth table that demonstrate operation of comparator and half-subtractor simultaneously. Up to date, the reported logic gates for half-subtractor or the digital comparator have been designed by taking advantage of chelation or the deprotonation and protonation of phenolate groups or amine group. Now, we reported our successful development of a novel indolium-based naphthol molecular species CJ4, which can exhibit a complex algebraic operation.