Department of Chemistry, Guru Nanak Dev University, Amritsar, India.
Dalton Trans. 2011 Mar 21;40(11):2451-8. doi: 10.1039/c0dt01016b. Epub 2011 Feb 1.
Dansyl-anthracene dyads 1 and 2 in CH(3)CN-H(2)O (7:3) selectively recognize Cu(2+) ions amongst alkali, alkaline earth and other heavy metal ions using both absorbance and fluorescence spectroscopy. In absorbance, the addition of Cu(2+) to the solution of dyads 1 or 2 results in appearance of broad absorption band from 200 nm to 725 nm for dyad 1 and from 200 nm to 520 nm for dyad 2. This is associated with color change from colorless to blue (for 1) and fluorescent green (for 2). This bathochromic shift of the spectrum could be assigned to internal charge transfer from sulfonamide nitrogen to anthracene moiety. In fluorescence, under similar conditions dyads 1 and 2 on addition of Cu(2+) selectively quench fluorescence due to dansyl moiety between 520-570 nm (for 1)/555-650 nm (for 2) with simultaneous fluorescence enhancement at 470 nm and 505 nm for dyads 1 and 2, respectively. Hence these dyads provide opportunity for ratiometric analysis of 1-50 μM Cu(2+). The other metal ions viz. Fe(3+), Co(2+), Ni(2+), Cd(2+), Zn(2+), Hg(2+), Ag(+), Pb(2+), Li(+), Na(+), K(+), Mg(2+), Ca(2+), Ba(2+) do not interfere in the estimation of Cu(2+) except Cr(3+) in case of dyad 1. The coordination of dimethylamino group of dansyl unit with Cu(2+) causes quenching of fluorescence due to dansyl moiety between 520-600 nm and also restricts the photoinduced electron transfer from dimethylamino to anthracene moiety to release fluorescence between 450-510 nm. This simultaneous quenching and release of fluorescence respectively due to dansyl and anthracene moieties emulates into Cu(2+) induced ratiometric change.
Dansyl-anthracene 二聚体 1 和 2 在 CH(3)CN-H(2)O（7:3）中可以通过吸收和荧光光谱选择性地识别 Cu(2+)离子，而不是其他碱金属、碱土金属和重金属离子。在吸收光谱中，向二聚体 1 或 2 的溶液中加入 Cu(2+)会导致从 200nm 到 725nm 的宽吸收带出现，对于二聚体 2 则从 200nm 到 520nm。这与从无色到蓝色（对于 1）和荧光绿色（对于 2）的颜色变化有关。这种光谱的红移可以归因于磺酰胺氮到蒽部分的内部电荷转移。在荧光光谱中，在类似条件下，二聚体 1 和 2 在加入 Cu(2+)后，由于在 520-570nm（对于 1）/555-650nm（对于 2）之间的丹磺酰基部分，荧光选择性猝灭，同时对于二聚体 1 和 2，分别在 470nm 和 505nm 处荧光增强。因此，这些二聚体为 1-50μM Cu(2+)的比率分析提供了机会。其他金属离子，如 Fe(3+)、Co(2+)、Ni(2+)、Cd(2+)、Zn(2+)、Hg(2+)、Ag(+)、Pb(2+)、Li(+)、Na(+)、K(+)、Mg(2+)、Ca(2+)、Ba(2+)，除了在二聚体 1 中 Cr(3+)之外，不会干扰 Cu(2+)的估计。丹磺酰基单元的二甲氨基与 Cu(2+)的配位导致丹磺酰基部分在 520-600nm 之间的荧光猝灭，并且还限制了从二甲氨基到蒽部分的光致电子转移，以在 450-510nm 之间释放荧光。由于丹磺酰基和蒽部分分别猝灭和释放荧光，因此模拟为 Cu(2+)诱导的比率变化。
