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分别对1-3代聚(酰胺-胺)(PAMAM)结构的dendron分子的外端基和focal point进行了修饰,得到了外端基为萘(给体)色团、焦点(focal point)为丹酰(受体)色团的树枝状化合物Dan-ABn-Nap(n=2,4,8).利用荧光光谱测定了不同浓度下所得一系列树枝状分子在水中的荧光强度,并计算了它们的临界聚集浓度(CAC)值.发现Dan-ABn-Nap(n=2,4,8)的CAC值随代数的增加而减小,这是由于随着代数增加,分子的聚集能力增强所造成的.TEM观察可见,Dan-ABn-Nap在水中形成不规则的球形聚集体,尺寸约在150 nm至650 nm之间.测试了Dan-ABn-Nap所形成聚集体的荧光性质.结果表明,当用萘的最大吸收波长激发聚集体Dan-ABn-Nap时,萘的荧光被大大猝灭,而发射出丹酰的荧光(400～650 nm).这说明在聚集体中发生了从萘到丹酰色团的能量转移.研究发现,在CAC浓度以下时,只发生低效率的能量转移,例如Dan-AB8-Nap的能量转移效率只有5.7%.而当浓度增至CAC以上时,由于形成聚集体,其对应的能量转移效率大大提高,达到77.1%.这是由于聚集体的形成,使树枝状分子的排列更加有序,色团间距离更加靠近,同时既可发生分子内的能量转移,又可发生分子间的能量转移,因此能量转移效率提高.
The exndrons and focal points of the dendron molecules of 1-3 poly (amide-amine) (PAMAM) structures were modified respectively. The outer end groups were naphthalene (donor) chromophores and the focal point was Dan-ABn-Nap (n = 2, 4, 8), the dendrimer of the dansyl (acceptor) chromophore. Fluorescence spectra were used to determine the fluorescence intensity of a series of dendrimers in water at different concentrations. Their critical aggregation concentration (CAC) values.It was found that the CAC value of Dan-ABn-Nap (n = 2,4,8) decreased with the increase of algebra, which is due to the increase of molecular aggregation ability with the increase of algebra .TEM observation shows that Dan-ABn-Nap forms irregular spherical aggregates in water ranging in size from about 150 nm to about 650 nm.The fluorescence properties of aggregates formed by Dan-ABn-Nap were tested.The results showed that , The fluorescence of naphthalene is greatly quenched when the aggregate Dan-ABn-Nap is excited by the maximum absorption wavelength of naphthalene, and the fluorescence of dansyl (400-650 nm) is emitted, which shows that there occurs a shift from the naphthalene Energy transfer to the dansyl group.The study found that under the CAC concentration, only low energy transfer occurs, for example, the energy transfer efficiency of Dan-AB8-Nap is only 5.7% When the concentration is above CAC, the corresponding energy transfer efficiency greatly increases to 77.1% due to the formation of aggregates, which is attributed to the formation of aggregates, more orderly arrangement of dendrimers and closer distance between chromophores, At the same time, intramolecular energy transfer can occur, and intermolecular energy transfer can occur, so the energy transfer efficiency is improved.