摘要
本文报道带有疏水长链的桥环菁染料的合成.并研究这类菁染料的质子化过程和平衡常数、取代效应,以及胶束、糖淀粉和环糊精对染料的可见光谱及质子化过程的影响,本文也考察了桥环菁染料的荧光光谱,这些研究在理论上和实际应用有一定意义.
1, 3-Di (4-pyridyl) propane (1) is alkylated with benzyl bromide and n-ootyl iodide respectively to form bis-pyridininm salt 2, which condenses readily with α-diketones in the presence of piperidine to afford the bridged cyanine dyes 3 containing hydrophobic alkyl groups. In acidic solution, the entire ~1H NMR spectra of the cyanines 3, 4 and 5 were shifted to lower field 0.4—0.7ppm, and the CH singlet corresponding to the fulvene ring proton of 3 and 4 is replaced by a two proton singlet at 4.25—4.70ppm for the methylene groups of dications 3' and 4'. A dramatic hypsochromic shift and a very strong hypochromic effect in their visible spectra are observed in acidic media. Thus, the bridged cyanine dyes 3, 4 and 5 are evidently protonated at the central ring to form dication 3′, 4′ and 5′ with resulting loss of the cyanine conjugation. The PK_b values of these cyanines 3, 4 and 5 were evaluated from the pH dependence of dye absorption spectra. Substituents at the 4, 5-position of the central cyclopentadiene ring have great effect on the pK_b, but the N-alkyl groups and counterion play no role on the pK_b of the cyanines. The micelle, amylose and β-cyclodextrin have very small effect on the visible absorptions and protonation processes of cyanine dyes except one case. These bridged eyanines show fluorescence emissions at around 600nm with moderate fluorescence quantum yield.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1990年第4期399-405,共7页
Acta Chimica Sinica
基金
国家自然科学基金会青年科学基金资助的课题
