Investigation Of The Switch And Logic Properties For The Salicylidene Schiff Base

Nowadays, molecular devices and machines has been one focus of the modern technology. For the preponderance in dimension and capability, these molecular-level devices and machines will lead a new revolution in the miniaturization and high capability. Recently, as a portion of molecular devices and machines, the molecular-level switches and logic operation has gained considerable attention. The consecutive development in the field of molecular switches and logic will become the basis of the high density and rapid information process.Whereas, until recently, the chemical molecules which can be used in the switch and logic research are rare, we design a new molecular system in this thesis. It includes two species and total twelve salicylidene Schiff bases. There are not chlorine atoms in the phenyl of the salicylidene in the first species. On the contrary, there are chlorine atoms at the third and the fifth position in the phenyl of the salicylidene in the second species. Besides the difference in the substituent group, the conjugation also has considerable differentia. The study based on our molecular system present that the excellent switch and logic function can been obtained. On the basis of our study, we firstly report the multi-switch and the logic function of salicylidene Schiff base. In addition, we also devote much effort to perform the logic operations with the solid materials. At the same time, we detailed study and report the assembly of the response molecules and the solid matrix as well as the excellent logic function of the hybrid.The work in this thesis mainly includes four parts as follow:First,the preparation of the molecular system studied by us. Considering the fact that the salicylidene Schiff bases have excellent response to many inputs such as: pH value, ultraviolet light, visible light, heat and metal ions, we select it as our molecular system to study their molecular switch and logic function. In addition, introducing strong electron-withdrawing group to the phenyl of the salicylidene can enhance the reactivity of salicylidene Schiff bases. We design two kinds of salicylidene Schiff bases: without and with chlorine atoms. On the other hand, we also change the middle or bridge group. As a whole, we synthesize two kinds, total twelve salicylidene Schiff bases.Second, the study of molecular switch for the salicylidene Schiff bases. We explore the switch character of salicylidene Schiff bases acted by the external stimulations in detailed. The experimental results demonstrate that in the alkaline circumstance, the phenol group of salicylidene Schiff bases can be deprotonated immediately. Acid can drive them protonated again. The molecules in this system can coordinate with zinc ion to form complex with bright blue emission. The complex will be dissociated and lose the luminescence under the ultraviolet light action. In addition, with the irradiation of ultraviolet light, these molecules can gradually transfer from the initial enol-form to keto-form. Heat or visible light will drive reversibly this reaction. As a result, based on the salicylidene Schiff bases, we can mimic a multi-switch which integrates pH switch, fluorescence switch and photochromic switch.Third, we select OH–, Zn2+ and UV light as inputs to stimulate the salicylidene Schiff bases, and study the logic properties of salicylidene Schiff bases in detailed,finding that the ones in the species with chlorine atoms in the phenyl of the salicylidene can well response three inputs. At the same time of responding, strong outputs can been observed. So, they can execute one excellent logic operation, which integrate one OR, two NOT, and four AND logic gates. Based on these work, we firstly report that the salicylidene Schiff bases have excellent logic function. In addition, this logic function is executed at the monomolecular system. So, comparing the logic functions which were finished with more than one molecule, the stability and the reliability of the information all have advantages.Fourth, in order to transfer the logic operation from solution to solid phase and overcoming the drawback in the solution, we select mesoporous molecular sieve, silica nanoparticles etc as the solid matrix to construct organic/inorganic hybrid with the salicylidene Schiff bases through the supramolecular self-assembly. The experimental results indicate that the salicylidene Schiff base can response to the OH–, Zn2+ and UV light in the hybrid yet. Attributing to the concurrent function of the supramolecular system, the response of the target molecule is more excellent, the intensity of the output is stronger. So, we not only can realize the transfer to the solid of the logic operation, but also can execute more complex logic operation. The solid materials selected by us and the method of assembly also can extend to the other molecular system. So, we provide two kinds of solid materials for the logic study and the method of assembly.In summary, we have designed a new intelligent response molecular system and synthesized two kinds, total twelve salicylidene Schiff bases. We detailedly explore the switch and logic functions of our target molecules. The experimental results indicate that all the molecules in our system can present the multi-switch functions which integrate pH switch, fluorescence switch and photochromic switch. Among them, the ones with chlorine atoms in the phenyl of the salicylidene can execute excellent logic character. In addition, we select mesoporous molecular sieve, silica nanoparticles etc as the solid matrix, transferring the logic function from solution to solid materials successfully.