罗丹明类荧光探针的合成及对铜离子的检测

合成了罗丹明类Cu2+荧光增强型分子探针3',6'-双(二乙氨基)-2-(N-乙叉基氨基)螺异吲哚-1,9'-占吨]-3-酮（RA），并研究了它的光谱性能及对铜离子的识别作用.在乙腈/水（体积比1/1）的介质中，当加入Cu2+后探针RA显玫瑰红色，最大吸收波长为548 nm，最大发射波长为571 nm，且荧光强度显著增强，但是，其它常见离子如Na+, K+, Mg2+, Ca2+, Mn2+, Cd2+, Cr3+, Co2+, Ni2+, Ag+, Pb2+, Zn2+, Fe3+, Hg2+不引起或引起很小的紫外/可见或荧光光谱变化.RA的选择性荧光增强主要是由于Cu2+诱导分子中的酰胺闭环结构发生开环，导致分子结构的共轭程度增大.在6.5×10-8～2.9×10-6 mol?L-1范围内RA可以有效检测Cu2+，检测限为5.0×10-8 mol?L-1.RA对Cu2+的识别不可逆，而且探针RA对pH值不敏感，可以在比较宽的范围内（pH=4.1～10.5）高灵敏、高选择性检测Cu2+.

Synthesis of Fluorescent Probe Based on Rhodamine and Its Appalication in the Determination for Cu2+

In this paper, Cu2+ fluorescence enhancement probe RA based on rhodamine B have been synthesized. It was discovered that the fluorescence intensity of RA increased with the addition of Cu2+ in acetonitrile/water (1/1, V/V) solution, the maximum absorption wavelength was 548 nm. The maximum emission wavelength was 571 nm. Addition of a Cu2+ ion lead to an obvious color change to pink as well as significantly enhanced fluorescence, while other common metal ions such as Na+, K+, Mg2+, Ca2+, Mn2+, Cd2+, Cr3+, Co2+, Ni2+, Ag+, Pb2+, Zn2+, Fe3+, Hg2+ induced no or much smaller color/fluorescent spectral changes. The selective fluorescence enhancement of RA attributed to the spirolactam ring being opened upon the addition of Cu2+ to RA, and a highly delocalized conjugated structure of RA was formed. The sensor was useful for measuring Cu2+ at concentrations ranging from 6.5×10-8 to 2.9×10-6 mol?L-1 with a detection limit of 5.0×10-8 mol?L-1. The recognition of Cu2+ was not reversible, and compound RA was pH-insensitive Cu2+ fluorescent probe, which would detect Cu2+ effectively in a relatively wide range of pH (pH=4.1-10.5) including the significant physiological region.