外围萘修饰PAMAM树枝形聚合物的合成及其质子化过程研究

合成了外围修饰有萘基团的0～3代聚酰胺-胺树枝形聚合物GnN (n＝0～3), 化合物通过了IR, 1H NMR, 13C NMR和MALDI TOF的表征. 稳态光物理研究表明, 甲醇溶液中GnN外围萘基团与骨架胺之间发生电子转移过程, 形成最大发射峰在450 nm的激基复合物, 萘的荧光被明显猝灭; 当GnN骨架被质子化, 分子内光致电子转移过程和萘与骨架胺基间激基复合物的形成被抑制, 萘单体荧光发射大大增强; 由于质子化后树枝形聚合物骨架趋于伸展构象, 外围萘基团间相互作用增强, 部分形成最大发射峰在400 nm的激基缔合物.

Synthesis and Protonation Investigation of PAMAM Dendrimer with Naphthyl Decorated at Periphery

Naphthyl decorated polyamidoamine(PAMAM)dendrimers,from zeroth-to third-generation (GnN,n=0～3),have been synthesized and their structures characterized by IR,~1H NMR,~(13)C NMR and MALDI TOF mass spectra.Steady state photophysical studies indicate that the fluorescence of naphthyl is quenched by the amine units of dendrimers GnN via intramolecular electron transfer,and a naphthyl-amine exciplex is formed with a structureless emission around 450 nm.The protonation of GnN by addition of excess trifluoroacetic acid made the fluorescence intensity of dendrimers increase dramatically due to suppression of the photoinduced electron transfer and the exciplex formation.and a weak naphthyl excimer emission with maximum at ca.400 nm could be observed indicative of close-packed periphery and stretched conformation of protonated dendrimers.