An amphiphile, 9-octanyl adenine trimethylammonium bromide(OATMAB amphiphile 3), was synthesized as the receptor. The coliposomes were prepared from phosphatidylcholine and 9-octyl adenine trimethylammonium bromide by sonication of CHCl 3-cast films of amphiphiles mixtures [n(PC)∶ n(MOATMAB)=10∶1] in doubly distilled water with a bath-type sonicator at 80 W for 3 h. As thymine was added into PC/MAOTMAB coliposomal solution, the absorbability of thymine at 263 nm decreased slowly with time change from 0 to 72 h. The UV-Vis spectroscopic behavior of the thymine in PC/OATMAB/thymine coliposomes(molar ratio=10∶1∶1) was slowly decreaced with the increase of time. The onset of a hypochromic effect can be ascribed to adenine-thymine interaction. The absorption band levels off at 45.4% of its initial value and stabilizes after several weeks.
The photoluminescence(PL) and the electroluminescence(EL) properties of a novel organic compound, 2,5-bis(2,2′-bis(5-phenyl)-1,3,4-oxadiazole(T-OXD), were studied in chloroform and in a solid thin film. The PL and the EL properties of T-OXD/poly(9-vinylcarbazole)(PVK) blends were also studied, which contained various contents of T-OXD. The PL maximum emission peaks of T-OXD/PVK blends show gradual bathochromtic-shift with the increase of the T-OXD content. The EL spectra of T-OXD/PVK devices are similar to their PL spectra, and all the EL maximum emission peaks show bathochromtic-shift compared with the corresponding PL spectra, which is ascribed to the formation of electroplex. The turn-on voltages for ITO/T-OXD:PVK/Al devices decreased from 13.5 V of the device cotaining 0.1% T-OXD(mass fraction) to 5 V of the device containing 5% T-OXD, which suggests that T-OXD improves the energy level match between T-OXD and PVK and enhances the emission efficiency. The experimental results indicate that T-OXD can be used as a good electron transporting material.
A functional amphiphile, N^6 -myristoyl-9-[ 8-（ 1-trimethylamino） octyl ] adenine bromide （MTOAB）, was used to form coliposomes of phosphatidyleholine（PC）, PC/thymine, and PC/TOTB using sonication . The morphologies of the coliposomes were characterized using TEM （transmission electron microscopy）. The UV-Vis spectroscopic behavior of PC/MTOAB/thymine （molar ratio = 5： 1： 1 ） and PC/MTOAB/TOTB （molar ratio = 5： 1： 1 ） of coliposomal solutions showed that as a result of base pairing, absorption intensity showed a decrease at 263 nm with increase of time. The decrease of absorption intensity is ascribed to the hypochromic effect, which is because of the formation of hydrogen bonds between adenine and thymine in the coliposomes. The same effect was also observed for the mixture of aqueous PC/MTOAB liposomes and PC/TOTB liposomes after fusion, whereas the nocomplementary coliposomcs formed from PC/MTOAB and PC/TOTB did not show these spectroscopic changes. The molecular recognition through hydrogen interactions between adenine and thymine is very slow because of the possible occurrence of molecular lateral diffusion and exchange of amphiphile before recognition progresses in coliposomes. These results provide useful information for the design of supramolecular devices such as vesicles and liposomes,which can be used to mimic primitive recognition processes observed in biological systems.
SONG Li-ming ZHU Tao WANG Qiu-sheng ZHANG Xiao LI Guo-wen
