Cu^(2+)对碳点的荧光猝灭机理研究

Study of the Mechanism of Quenching Effect of Cu^(2+) on Fluorescent Carbon Dots

在pH=5.8的Britton-Robinsion(B-R)缓冲溶液中,Cu2+可有效猝灭O,O-2(3-氨丙基)聚乙二醇1500(PEG1500N)钝化的碳点荧光.通过对猝灭机理的研究得出Cu2+对碳点荧光的猝灭是静态猝灭过程.加入Cu2+后,碳点的荧光强度和紫外吸收都明显减弱,且温度越高猝灭越弱,但荧光寿命没有变化.另外,猝灭速率常数Kq=1013 L/(mol·s)也比典型的溶液中扩散控制猝灭速率常数的上限值高很多,这些都证明该过程是静态猝灭过程.猝灭常数为9.0×104 L/mol,Cu2+与碳点的结合比为6∶1.

We found in a previous study that fluorescence of PEG 1500N-passivated carbon dots (C-Dots ) could be quenched effectively by copper ions (Cu2+ ) in pH 5.8 Britton-Robinsion (B-R) buffer solution .In the present study ,the quenching mechanism was discussed and a static quenching process was supposed .A significant decrease in UV absorption and fluorescent intensity were found after Cu2+ addition .A smaller amount of quenching was also found at higher temperature .But no change in fluorescence lifetime was de-tected .Additionally ,the Kq value of 1013 L/(mol · s) was larger than the upper limit of typical diffusion-controlled quenching in solution .All of the above results confirmed the view of static quenching .The quenching constant was 9.0 × 104 L/mol ,and the binding ratio of Cu2+ to C-Dots was 6:1 .