二芐環庚烯衍生之螺旋烯在光學開關和電致發光二極元件的應用

• Main Authors: Tai-Wei Li, 李泰瑋
• Other Authors: Chien-Tien Chen
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/98803132866150405457

碩士 === 國立臺灣師範大學 === 化學研究所 === 89 === Abstract The triarylethenes synthesized adopt helical shapes(ie. helicenes) due to the steric overlap of symmetrical upper-part(ie dibezosuberene or dibenzosuberane) and the unsymmetrical lower part (e.g a.-tetralone at (C2) substituted chiral auxilary or b-naphthol-flavone). The chirality in these inherently pseudoenatiomeric alkenes, was denoted as M or P for left- or right-handed helical handness. When the steric overcrowded alkenes were excited to the singlet excited states, the double bond connecting both parts would exhibits diradical character. It has been documented that the relaxation of the transition state to the ground state proceeds through two ways: Route I, planarization around the diradical single bond with overcomes the torsional and ring strain to a perpendecular excited state enroute to another photostationary isomer. Route II, the energy relaxation is another phenomena often refer to a general term fluorescenct emission procedure. We have so far examined two systems adopted here, the first system consists of dibenzosuberene upper part and a.-tetralone (C2) substituted with L-menthyl and (1R,2S)-2-(1-methyl-1-phenyl-ethyl)-cyclohexy esterl lower part. The de values of L-menthyl based episulfide is 16%, and we can not separate the two diastereomers by flash column chromatography. The de values of Cu-desulfuration helicene of L-menthyl type is 20%. However, we treat another chiral auxilary: (1R, 2S)-2-(1-Methyl-1-phenyl-ethyl)-cyclohexanol, the de values of the episulfide is 34%, and we can get diastereomeric pured episulfides. We demonstrated the absolute configuration by X-ray diffraction. By correlating the retention order in chiral HPLC and CD exciton chirality, we can construct a rule of absolute stereochemistry. The separated episulfides could be treated more mild desulfurized process by HMPT in ice bath. The absolute configuration of helicenes after desulfuration by HMPT is almost diastereomeric pure, and we also construct the rule in determining the absolute stereochemistry. The last work of this system is the study of photochemistry if the helicenes are suitable for optical switches. The other system consists of dibenzosuberane upper part and b-naphthyl-flavone lower part . The energy relaxation of this system we suggested it to be a fluorescence process by the forward works( Route II). We using the difference in energy relaxation route to design the structure based on DBS and b-naphthyl-flavone helicenes. The absorption band λmax = 358 nm ( in n-Hexane ) and the emission bandλmax = 478nm ( in n-Hexane ). The Stokes shift are 120nm. We applied the compounds to the OLED ,and the properties of EL and PL are almost the same( DBS or DBS(MeO)2/PVK(dopant/host)). From the results of cyclic voltammetry and absorption spectrum, we can calculate the energy levels of the helicences( HOMO = -5.92 e.v, LUMO = -2.21e.v). The C(10), C(11) dimethoxy substituted helicence enhanced the quantum yield, but the red shift does not matcht our expectation. This is the first time using this type helicences acted as OLED dopant and host materials. We believed it would be helpful for designing new OLED materials.