酸碱控制的卟啉-苝酰亚胺分子阵列荧光开关

An Acid-base Controlled Fluorescence Switch Based on a Free-base-porphyrin-perylene-diimide Molecular Array

研究了氯仿溶液中分子阵列 N,N-二 [对 -5′-(间 -1 0′,1 5′,2 0′-三苯基卟啉 )基 -苯基 ]-3 ,4∶ 9,1 0 -四羧基二酰亚胺 ( Tr PP-PTCDI-Tr PP)在不同浓度的三氟乙酸作用下荧光光谱的变化 ,质子化无金属卟啉的光致激发态成为各种激发态中相对稳定的物种 ,因此无论激发无金属卟啉基元 ( λ=43 9nm)还是酰亚胺基元( λ=491 nm) ,分子阵列都表现出质子化无金属卟啉生色团的特征荧光发射 ,酸的引入使激发态下高效率的电荷转移衰变途径被关闭 ,辐射衰变途径被打开 .在溶液中引入三乙胺去质子化使电荷转移衰变途径被打开而辐射衰变途径被关闭 ,因此分子阵列构成了一个通过酸碱控制的荧光开关 .考虑到酸碱中和反应的方便性及分子阵列对不同波段光激发同时敏感的广谱性 ,该分子阵列开关具有特殊优势 .

The variations of the fluorescent spectral features with respect to a molecular array, N,N-bis[p-5′-(m-10′,15′,20′-triphenylporphyrin)phenyl]-perylene-3,4∶9,10-tetracarboxyl-diimide(TrPP-PTCDI-TrPP), were investigated at different concentrations of trifluoroacetic acid, the molecular array displays the characteristic emission of the protonated free-base-porphyrin subunit upon the photo-excitation of both the protonated free-base-porphyrin(λ=439 nm) and perylene-diimide subunits(λ=491 nm), because the excited state of protonated free-base-porphyrin in the molecular array was a relative stable species in comparison with other excitations. The incorporation of the acid leads to the closure of the efficient charge transfer decay, while results in the open of the radiation decay. Addition of triethylamine into the solution affords the reverse processes, i.e. the open of the efficient charge transfer decay while the closure of the radiation decay. Thus the molecular array provides a proton-type of fluorescent switch based on acid-base control. Such a molecular array switch has advantages of facility due to the acid-base neutralization and broad-band sensitivity due to the simultaneous response to different excitation wavelengths.