The Sythesis And Mechanism Explorations Of Extreme PH, Force-Sensitive Molecules

Environment-sensitive materials is a subject attracting many researcheres. Since this kind of materials enable materials variety proporties with the changing of environment specifically and reversibly, they are applied to wide areas like information and energy-storage. Reported environment-sensitive materials including pH sensitive, light-sensitive, temperature-sensitive and mechanochromic sensitive materials. In this paper we discuss two kinds of them, which are pH sensitive and mechanochromic sensitive materials. Although pH sensitive materials are well developed, the materials which can be sensitive to the extreme pH range, especially one fluorophores with two extreme pH switches, are relatively rarely been reported. Mechanochromic materials are rapidly developed these years. Because this is a new subject which have not been explored much, there are still problems to be solved.In the second chapter we discuss a spiropyran-based probe which is sensitive to both extreme acid and alkali. Different from the reported spiropyran probes, this spiropyran probe proposes ring-opening procedure only under extreme acid. Moreover, this probe can induce an obvious red-shift under the stimuli of extreme alkali. In order to explore the mechanism, we synthesized another four spiropyran probes. First, to explore the mechanism of acidic response, we synthesized spiropyran without COOH on indole and without bulk group on N-position. Second, for the alkali response mechanism, we synthesized spiropyran without three acidic groups and without phenolic hydroxyl group. We analyzed their optical properties and 1H NMR spectra. At last we apply this probe to bioimagining. The results indicate that this probe can be responded to the extreme pH range in bacteria as like in the solutions.In the third chapter we discuss a supramolecule system which can induce covalent-activated mechaonochromism. This is first report proposing a combination of cyclodextrin and organic molecules to facilitate the ring-opening procedure of organic molecules upon shearing. First we synthesized two organic molecules rodamine and spiropyran, and then we complex these two molecules with cyclodextrins, the experimental data demonstrates the obtainment of complex inclusions. We compare the mechaochromic switches before and after complexing and explore the mechanism through calculating and experimental data. The strong hydrogen bonds provided by cyclodextrin play a crucial role in triggering the mechanochromic switch.First, the hydrogen bonds seize both sides of the fluorophore’s weak chemical bonds and tightly lock the fluorophore in the cavity of cyclodextrin. Second, hydrogen bonds prompt the aggregation of complex inclusions in large ordered array, strengthen the interations between molecules. In this way, the weak chemical bonds can focus more external force and stretch easier upon shearing. This study opens an avenue to correlate mechanochemical reaction with supramolecule system.