Assembly Behavior Of Stimulus Responsive Fluorescent Molecules

Stimuli responsive self-assembly that can sense the environment variation and emit corresponding signals will have more applications in many areas. Ultrasound and light responsive molecular assembly has caused much interest in recent years, due to their convenient adjust method, absence of chemical addition, fast responsive ability and so on. In this text, we have designed a series of new amphiphilic compounds that own ultrasound or light responsive abilities via molecular self-assembly. The ultrasound induced self-assembly pathways and photophysical behavior and the photochromic properties of photoswitchable molecules in the presence of DNA were explored. The molecular assembly exhibited photophysical and DNA gated responsive property and was applied in biomolecular detection area. The main text includes three parts:1. Ultrasound induced photophysical responsive terpyridyl platinum complex self-assemblyTwo organometallic terpyridyl platinum gelators containing hydrophobic cholesterol with or without large steric three tert-butyl hindrance were synthesized. The Spectral and morphological change induced by ultrasound treatment were studied. The results showed that the bulky steric hindrance of three tert-butyl groups in terpyridyl ligand played an important role in providing better gelation properties. The ultrasound triggered gelation and aggregation induced emission enhancement (AIE) were responsible for the color change and fluorescent enhancement in gelation process. The reversible sonication triggered gelation and emission enhancement might generate new ways of soft materials application in areas such as microfluidic systems and controlled drug release system in medical therapy.2. Photo responsive diarylethene-thiazole orange as DNA molecular switchSeveral diarylethene based thiazole orange derivatives with gated photochromic property were synthesized. In Tris-HCl buffer, these compounds had no photochromic behavior, however, the photochromic behavior recovered and a strong fluorescent emission was observed when interacted with DNA. The binding manner of diarylethene-thiazole orange to DNA was determined by the dye to basepair stoichiometric ratio and base sequence. The double helix structure of DNA afforded a hydrophobic environment and constrained the free rotation of single bond in thiazole orange, which might be account for the recovery of photochromic property and fluoresent enhancement. The fluorescent switch could be accomplished via alternative Ultra-violet and visible light irradiation in the presence of DNA, thus, a light and DNA double responsive fluorescent switch was obtained. Meanwhile, these compounds showed little toxicity and specifically localized in nucleolus region with reversible fluorescent switch property. These compounds can be used to trace DNA related physiological process kinetically.3. Photo responsive diarylethene based terpyridyl platinum complexes and the interaction with DNATerpyridyl platinum complexes containing different photochromic diarthethenyl ligands were synthesized by us. These complexes exhibited excellent photochromic property and high sensitivity toward environmental change, hence, its assembly pattern and photophysical property may change when interacted with DNA. When irradiated alternatively by Uv and visible light, these complexes undergone photo isomerization, and influenced the interaction with DNA. Thus, a photo responsive diarylethene based terpyridyl platinum complexes and DNA assembly switch was obtained, which may have potential applications in bio-engineering and information storage.