摘要
合成了带萘、芘单标记、双标记的2-丙烯酰胺基-2-甲基丙磺酸(AMPS)与N,N-二甲基丙烯酰胺共聚强聚电解质, 测定了在NaCl和CaCl2水溶液中的分子内与分子间荧光非辐射能量转移(NRET).由于添加盐的屏蔽作用, 分子内与分子间的NRET都随盐浓度升高而加强, 而且钙离子的作用比钠离子显著.为了比较不同试样的NRET, 定义归一化NRET效率En为盐溶液中的NRET与纯水中的NRET之比.随试样电荷密度FAMPS上升, 分子内En减小而分子间En增大.尽管聚电解质的浓度低于接触浓度c*, 但因溶液中发生了反离子凝聚, 凝聚的反离子会引起大分子间的聚集.
Naphthalene and pyrene singly and doubly labeled polyelectrolytes were prepared by radical copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) from 5% to 99% (molar fraction) and N, N-dimethylacrylamide with the label monomers. Fluorescence nonradiative energy transfer (NRET) was measured in NaCl and CaCl2 aqueous solutions up to the concentration of 6×10-3 mol/L. Intra- and inter-molecular NRET determined with doubly labeled samples and mixtures of singly labeled samples indicated that owing to the salt screening effect, increasing salt concentration enhanced the NRET and the enhancement of calcium cation was stronger than that of sodium cation. The normalized NRET En, defined as the NRET in salt solution relative to that in water for a given sample, showed that intramolecular En decreased with the increase of charge density FAMPS in the samples with a maximum at FAMPS≈0. 45. In contrast, the intermodular Enincreased with the increase of FAMPS, suggesting that there were inhomogeneous intermolecular aggregates in polyelectrolyte solutions due to the condensed coun-terions even at a concentrations lower than the overlap threshold c*.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第9期1695-1699,共5页
Chemical Journal of Chinese Universities
基金
国家杰出青年科学基金(批准号:29725411)
广东省自然科学基金(批准号:015036)
