Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, CA, Italy.
Dalton Trans. 2013 Oct 28;42(40):14516-30. doi: 10.1039/c3dt51292d.
Four new fluorescent chemosensors for metal ions based on 8-hydroxyquinoline (8-HDQ) derivatives and sulfur-containing macrocyclic units were synthesized and characterized, namely 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L1), 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L2), 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L3), and 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L4). Preliminary fluorimetric titrations indicated L1 as the only member of the family of ligands to give a selective CHEF-type response to the presence of Zn(2+) in MeCN-H2O (1:1, v/v) solutions, which allowed imaging of this metal ion in Cos-7 cells in vitro. The other ligands either did not show any fluorescence response (L3, L4) to any of the metal ions considered (Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+)) or gave (L2) a CHEF-type response also to the presence of Cd(2+). The coordination properties of L1 towards Zn(2+) were, therefore, fully investigated by potentiometric measurements and absorption and emission spectroscopy at different pH values, which indicated that the formation of 2:1 L1/Zn(2+) complexes is responsible for the CHEF-type effect observed. The complexes Zn(L1)2H2O2 and Zn(L3)2 were characterized in the solid state by X-ray crystallography, and DFT calculations were performed to understand the origin of the Zn(2+)/Cd(2+) optical discrimination of the 8-HDQ-based "conjugate" fluorescent chemosensors reported.
基于 8-羟基喹啉（8-HDQ）衍生物和含硫大环单元，合成并表征了四种新的荧光化学传感器用于金属离子，分别为 1-(5-氯-8-羟基-7-喹啉基甲基)-1-氮杂-4,7,10-三硫杂环十二烷（L1）、1-(5-氯-8-羟基-7-喹啉基甲基)-1-氮杂-4,13-二硫杂-7,10-二氧杂环十五烷（L2）、1-(8-羟基-2-喹啉基甲基)-1-氮杂-4,7,10-三硫杂环十二烷（L3）和 1-(8-羟基-2-喹啉基甲基)-1-氮杂-4,13-二硫杂-7,10-二氧杂环十五烷（L4）。初步荧光滴定表明，L1 是该配体家族中唯一对 MeCN-H2O（1:1，v/v）溶液中 Zn(2+)存在表现出选择性 CHEF 型响应的成员，这使其能够在体外对 Cos-7 细胞中的这种金属离子进行成像。其他配体要么对任何考虑的金属离子（Cu(2+)、Zn(2+)、Cd(2+)、Hg(2+)和 Pb(2+)）都没有表现出任何荧光响应（L3、L4），要么（L2）也对 Cd(2+)的存在表现出 CHEF 型响应。因此，通过电位测量和在不同 pH 值下的吸收和发射光谱，对 L1 与 Zn(2+)的配位性质进行了充分研究，结果表明，形成 2:1 L1/Zn(2+)配合物是导致观察到 CHEF 型效应的原因。配合物Zn(L1)2H2O2 和Zn(L3)2 通过 X 射线晶体学在固态中进行了表征，并进行了 DFT 计算以了解报道的基于 8-HDQ 的“共轭”荧光化学传感器对 Zn(2+)/Cd(2+)光学选择性的起源。
