Dansylamide derivatives of an 1,8-anthraquinone-18-crown-5 anthracenone macrocycle have been synthesized by acid catalyzed nucleophilic substitution followed by reduction with sodium borohydride to yield new fluorosensors, 2 and 3, as characterized by elemental analyses, 1H and 13C NMR, ESI–MS, and X-ray crystallography. The optical properties of 2 and 3 were investigated with various metal cations and found to be selective for Pb(II) ion. Substantial ON-OFF quenching of the dansylamide fluorescence was observed after addition of Pb(II). Competition studies with other metal ions were conducted with Pb(II) and ESI–MS, UV/Vis and NMR titrations were carried out to determine a 1:1 binding stoichiometry and association constants with Pb(II) (7.5 × 103 M−1) and compared to fluorescence quenching of the free dansylamide fluorophore (80 M−1). While Pb(II) binding is reversible, as determined by addition of EDTA in an aqueous solution, cations with higher oxidation potentials quench fluorescence via a different mechanism involving oxidation of the macrocycle in a chemodosimeter type response.
1,8-
蒽醌-18-冠-5
蒽酮大环的丹酰酰胺衍
生物是通过酸催化亲核取代,然后用
硼氢化钠还原合成的,从而得到新的荧光传感器2和3,其元素分析、1H和13C NMR、ESI-MS和X射线晶体学特征如下。用各种
金属阳离子研究了2和3的光学性质,发现其对Pb(II)离子具有选择性。在添加Pb(II)后,观察到丹酰酰胺荧光的大量ON-OFF淬灭。用Pb(II)和其他
金属离子进行了竞争研究,并进行了ESI-MS、UV/Vis和NMR滴定,以确定与Pb(II)的1:1结合
化学计量和结合常数(7.5 × 103 M−1),并将其与游离丹酰酰胺荧光团的荧光淬灭(80 M−1)进行了比较。虽然Pb(II)结合是可逆的,但通过在
水溶液中添加
EDTA确定,具有更高氧化电位的阳离子通过不同的机制淬灭荧光,该机制涉及大环的氧化,具有
化学指示剂类型的响应。