Experimentation and theoretic calculation of a BODIPY sensor based on photoinduced electron transfer for ions detection.
Experimentation and theoretic calculation of a BODIPY sensor based on photoinduced electron transfer for ions detection.
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DOI：
10.1021/jp907331q
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发表时间：
2009-12
期刊：
影响因子：
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通讯作者：
Hua Lu;Shushu Zhang;Hanzhuang Liu;Yanwei Wang;Zhen Shen;Chung‐Tsing Liu;X. You
中科院分区：
文献类型：
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作者：
Hua Lu;Shushu Zhang;Hanzhuang Liu;Yanwei Wang;Zhen Shen;Chung‐Tsing Liu;X. You
以2,6-吡啶二羧基甲醛与8-（4-氨基）-4,4-二氟-1,3,5,7-四甲基-4-硼-3a，4 -二氮杂-s-茚二烯缩合，NaBH(4)还原，制备了具有N，N'-（吡啶- 2,6-二基双（亚甲基））-二苯胺取代基(1)的硼二吡啶（BODIPY）基荧光探针。用甲醇荧光滴定法研究了化合物1对各种金属离子的传感特性，发现在Hg（2+）存在时，化合物1对Li（+）、Na（+）、K（+）、Ca（2+）、Mg（2+）、Pb（2+）、Fe（2+）、Co（2+）、Ni（2+）、Cu（2+）、Zn（2+）、Cd（2+）、Ag（+）、Mn（2+）等金属离子具有高度选择性的荧光开启反应。采用计算方法研究了化合物1对Hg（2+）和其他离子提供不同荧光信号的机理。能级的理论计算表明，硼二氮二烯荧光团的亮绿色荧光猝灭是由于苯胺亚基向BODIPY荧光团激发态的还原性光诱导电子转移（PET）所致。在金属配合物中，前沿分子轨道能级变化很大。结合Zn（2+）或Cd（2+）离子导致受体的HOMO和LUMO能级显著降低，从而抑制了PET的还原性过程，而从激发态荧光团到受体的氧化PET发生，反之亦然，这也使荧光猝灭。然而，对于1-Hg（2+）配合物，还原性和氧化性pet均被禁止；因此，从实验中可以观察到荧光团的强荧光发射。实验结果与理论计算的一致性表明，本文的计算方法可用于指导其它金属离子化学传感器的设计。
A boron-dipyrromethene (BODIPY)-based fluorescence probe with a N,N'-(pyridine-2, 6-diylbis(methylene))-dianiline substituent (1) has been prepared by condensation of 2,6-pyridinedicarboxaldehyde with 8-(4-amino)-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene and reduction by NaBH(4). The sensing properties of compound 1 toward various metal ions are investigated via fluorometric titration in methanol, which show highly selective fluorescent turn-on response in the presence of Hg(2+) over the other metal ions, such as Li(+), Na(+), K(+), Ca(2+), Mg(2+), Pb(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Ag(+), and Mn(2+). Computational approach has been carried out to investigate the mechanism why compound 1 provides different fluorescent signal for Hg(2+) and other ions. Theoretic calculations of the energy levels show that the quenching of the bright green fluorescence of boradiazaindacene fluorophore is due to the reductive photoinduced electron transfer (PET) from the aniline subunit to the excited state of BODIPY fluorophore. In metal complexes, the frontier molecular orbital energy levels changes greatly. Binding Zn(2+) or Cd(2+) ion leads to significant decreasing of both the HOMO and LUMO energy levels of the receptor, thus inhibit the reductive PET process, whereas an oxidative PET from the excited state fluorophore to the receptor occurs, vice versa, which also quenches the fluorescence. However, for 1-Hg(2+) complex, both the reductive and oxidative PETs are prohibited; therefore, strong fluorescence emission from the fluorophore can be observed experimentally. The agreement of the experimental results and theoretic calculations suggests that our calculation method can be applicable as guidance for the design of new chemosensors for other metal ions.