Eu(III) complexes as anion-responsive luminescent sensors and paramagnetic chemical exchange saturation transfer agents.
Eu(III) complexes as anion-responsive luminescent sensors and paramagnetic chemical exchange saturation transfer agents.
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Eu(III) 配合物作为阴离子响应发光传感器和顺磁化学交换饱和转移剂。
DOI：
10.1021/ic200075w
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发表时间：
2011-06-06
影响因子：
4.6
通讯作者：
Morrow JR
中科院分区：
文献类型：
--
作者：
Hammell J;Buttarazzi L;Huang CH;Morrow JR
研究了Eu（III）配合物(1S,4S,7S,10S)-1,4,7,10-四氮杂环十二烷（2-羟丙基）-1,4,7,10-四氮杂环十二烷（S-THP）作为生物相关阴离子的传感器。阴离子相互作用使Eu（III）配合物的发光发射光谱、1H NMR谱以及相应的配合物PARACEST谱（PARACEST =顺磁化学交换饱和转移）发生变化。Eu（S-THP）的直接激发光谱和发光寿命研究提供了有关pH值为7.2的阴离子相互作用的种类和性质的信息，包括碳酸盐、醋酸盐、乳酸盐、柠檬酸盐、磷酸盐和甲基磷酸盐。数据与Eu（S-THP）与醋酸盐、乳酸盐和碳酸盐的内球和外球配合物的形成一致。这些阴离子具有较弱的解离常数，在19 ~ 38 mM之间。柠檬酸盐与Eu（S-THP）的结合主要在胞内，解离常数为17 μM。Eu（S-THP）中加入阴离子后的发光发射峰变化表明，磷酸盐和甲基磷酸盐存在两种不同的结合事件，磷酸盐的解离常数分别为0.3 mM和3.0 mM，甲基磷酸盐的解离常数分别为0.6 mM和9.8 mM。Eu（THPC）含有一个附加的carbostyril衍生物作为天线来敏化Eu（III）的发光。Eu（THPC）结合磷酸盐和柠檬酸盐的解离常数比Eu（S-THP）亲本的解离常数小10倍，这表明通过一个悬空基团的功能化破坏了阴离子结合位点。Eu（S-THP）作为一种阴离子反应性的PARACEST试剂，通过与散装水交换醇质子而起作用。在醋酸盐、乳酸盐、柠檬酸盐和甲基磷酸盐的存在下，Eu（S-THP）的醇质子共振向下移动，产生明显的PARACEST峰。相比之下，磷酸盐与Eu（S-THP）结合抑制了PARACEST醇OH峰，碳酸盐在5 mM Eu（S-THP）和15 mM碳酸盐在pH 6.5或7.2时不会显著改变醇峰。这项工作表明，Eu（S-THP）配合物对生物相关阴离子的结合具有独特的选择性，阴离子结合导致配合物的发光光谱和PARACEST光谱发生变化。
The Eu(III) complex of (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane (S-THP) is studied as a sensor for biologically relevant anions. Anion interactions produce changes in the luminescence emission spectrum of the Eu(III) complex, in the 1H NMR spectrum, and correspondingly, in the PARACEST spectrum of the complex (PARACEST = paramagnetic chemical exchange saturation transfer). Direct excitation spectroscopy and luminescence lifetime studies of Eu(S-THP) give information about the speciation and nature of anion interactions including carbonate, acetate, lactate, citrate, phosphate and methylphosphate at pH 7.2. Data is consistent with the formation of both innersphere and outersphere complexes of Eu(S-THP) with acetate, lactate and carbonate. These anions have weak dissociation constants that range from 19–38 mM. Citrate binding to Eu(S-THP) is predominantly innersphere with a dissociation constant of 17 μM. Luminescence emission peak changes upon addition of anion to Eu(S-THP) show that there are two distinct binding events for phosphate and methylphosphate with dissociation constants of 0.3 mM and 3.0 mM for phosphate and 0.6 mM and 9.8 mM for methyl phosphate. Eu(THPC) contains an appended carbostyril derivative as an antenna to sensitize Eu(III) luminescence. Eu(THPC) binds phosphate and citrate with dissociation constants that are 10-fold less than that of the Eu(S-THP) parent, suggesting that functionalization through a pendent group disrupts the anion binding site. Eu(S-THP) functions as an anion responsive PARACEST agent through exchange of the alcohol protons with bulk water. The alcohol proton resonances of Eu(S-THP) shift downfield in the presence of acetate, lactate, citrate and methylphosphate, giving rise to distinct PARACEST peaks. In contrast, phosphate binds to Eu(S-THP) to suppress the PARACEST alcohol OH peak and carbonate does not markedly change the alcohol peak at 5 mM Eu(S-THP), 15 mM carbonate at pH 6.5 or 7.2. This work shows that the Eu(S-THP) complex has unique selectivity toward binding of biologically relevant anions and that anion binding results in changes in both the luminescence and PARACEST spectra of the complex.
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