Bandara H M Dhammika, Kennedy Daniel P, Akin Elif, Incarvito Christopher D, Burdette Shawn C
Department of Chemisty, University of Connecticut, 55 North Eagleville Road U- 3060, Storrs, Connecticut 06269.
Inorg Chem. 2009 Sep 7;48(17):8445-55. doi: 10.1021/ic901062n.
Caged complexes are metal ion chelators that release analytes when exposed to light of a specific wavelength. The synthesis and properties of ZinCleav-1, a cage for Zn(2+) that fragments upon photolysis, is reported. The general uncaging strategy involves integrating a nitrobenzyl group on the backbone of the ligand so that a carbon-heteroatom bond is cleaved by the photoreaction. The caged complex was obtained using a new synthetic strategy involving a Strecker synthesis to prepare a key aldehyde intermediate. ZinCleav-1 has a K(d) of 0.23 pM for Zn(2+) as measured by competitive titration with [Zn(PAR)(2)] (PAR = 4-(2-pyridyl-2-azo) resorcinol). The quantum yield for ZinCleav-1 is 2.4% and 0.55% for the apo and Zn(2+) complex, respectively. The ability of ZinCleav-1 to increase free [Zn(2+)] is calculated theoretically using the binding constants for the uncaged photoproducts, and demonstrated practically by using a fluorescent sensor to image the liberated Zn(2+). Free Zn(2+) may function as a neurotransmitter and have a role in the pathology of several neurological diseases. Studying these physiological functions remains challenging because Zn(2+) is silent to most common spectroscopic techniques. We expect ZinCleav-1 to be the first in a class of caged complexes that will facilitate biological investigations.
笼形配合物是金属离子螯合剂，当暴露于特定波长的光时会释放分析物。本文报道了一种用于锌离子（Zn(2+)）的笼形化合物ZinCleav-1，其在光解时会发生片段化，介绍了其合成方法和性质。一般的解笼策略是在配体主链上引入一个硝基苄基，使得碳-杂原子键通过光反应断裂。该笼形配合物是通过一种新的合成策略制备的，该策略涉及使用斯特雷克合成法制备关键的醛中间体。通过与[Zn(PAR)(2)]（PAR = 4-(2-吡啶基-2-偶氮)间苯二酚）进行竞争滴定测量，ZinCleav-1对Zn(2+)的解离常数K(d)为0.23 pM。ZinCleav-1的脱辅基蛋白和Zn(2+)配合物的量子产率分别为2.4%和0.55%。利用解笼光产物的结合常数从理论上计算了ZinCleav-1增加游离Zn(2+)浓度的能力，并通过使用荧光传感器对释放的Zn(2+)进行成像进行了实际验证。游离Zn(2+)可能作为一种神经递质发挥作用，并且在几种神经疾病的病理过程中起作用。由于Zn(2+)对大多数常见的光谱技术不敏感，研究这些生理功能仍然具有挑战性。我们期望ZinCleav-1成为一类有助于生物学研究的笼形配合物中的首个成员。
