Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, 700 032, India.
Dalton Trans. 2011 Jun 28;40(24):6411-9. doi: 10.1039/c1dt10177c. Epub 2011 May 16.
A new iminocoumarin based receptor L (C(27)H(26)N(4)OS) is synthesized with pyridyl and benzothiazolyl functionality. Synthesis of L is easy and it is isolated in good yield. L shows a selective and distinct color change from yellow to orange with Cu(2+) over Li(+), Na(+), Ca(2+), Mg(2+), Cr(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), and Ag(+) whereas a slight change in color is also observed in the case of Hg(2+) but L shows selective fluorescent quenching only in the presence of Cu(2+) in aqueous HEPES buffer (pH 7.0). The naked eye detection limit of Cu(2+) is determined at 2 μM whereas an emission experiment shows a lower detection limit at 200 nM. Selectivity studies of L in presence of 50 equivalents of other ion(s) by emission experiment show no interference toward the detection of 1 equivalent of Cu(2+). Both UV-Vis and fluorescence studies in the presence of Cu(2+)-salts of different counter anions with various sizes and shapes (Cl(-), ClO(4)(-), NO(3)(-), CF(3)SO(3)(-), SO(4)(2-) and BF(4)(-)) show almost similar spectral output in buffer media irrespective of the nature of the counter anions. The detailed UV-Vis and fluorescence titration experiments suggest the existence of both 1:1 and 2:1 (L:Cu(2+)) complexation stoichiometry and EPR study shows d(x(2)-y(2)) ground state of the Cu(II) centre in the complex. Furthermore the formation of a mononuclear [Cu(L)(CH(3)CN)].2ClO(4) complex and the flexible conformation of L in the solid state are confirmed by the single-crystal X-ray structural study.
一种新的基于亚氨基香豆素的受体 L（C(27)H(26)N(4)OS），具有吡啶基和苯并噻唑基功能。L 的合成简单，产率高。L 与 Cu(2+)相比，对 Li(+)、Na(+)、Ca(2+)、Mg(2+)、Cr(2+)、Mn(2+)、Fe(2+)、Co(2+)、Ni(2+)、Cu(2+)、Zn(2+)、Cd(2+)、Pb(2+)和 Ag(+)具有选择性和明显的颜色变化，从黄色变为橙色，而 Hg(2+)的颜色变化也很轻微，但 L 仅在存在 Cu(2+)时在水性 HEPES 缓冲液（pH 7.0）中表现出选择性荧光猝灭。Cu(2+)的肉眼检测限为 2 μM，而发射实验显示在 200 nM 时检测限更低。通过发射实验在存在 50 当量的其他离子的情况下对 L 的选择性研究表明，对 1 当量的 Cu(2+)的检测没有干扰。在存在不同大小和形状的 Cu(2+)-盐（Cl(-)、ClO(4)(-)、NO(3)(-)、CF(3)SO(3)(-)、SO(4)(2-)和 BF(4)(-)）的情况下，UV-Vis 和荧光研究均在缓冲介质中显示出几乎相似的光谱输出，而与抗衡阴离子的性质无关。详细的 UV-Vis 和荧光滴定实验表明，存在 1:1 和 2:1（L:Cu(2+)）络合化学计量比，EPR 研究表明络合物中 Cu(II)中心的 d(x(2)-y(2))基态。此外，通过单晶 X 射线结构研究证实了单核 [Cu(L)(CH(3)CN)].2ClO(4) 配合物的形成和 L 在固态中的柔性构象。
