Dutta Choudhury Sharmistha, Chethodil Jiddhu M, Gharat Poojan Milan, P K Praseetha, Pal Haridas
Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
Department of Nanotechnology, Noorul Islam Centre for Higher Education , Kumaracoil, Kanyakumari District, Tamil Nadu 629180, India.
J Phys Chem Lett. 2017 Apr 6;8(7):1389-1395. doi: 10.1021/acs.jpclett.7b00153. Epub 2017 Mar 15.
Remarkable and systematic pH-dependent changes are observed in the absorption and emission spectra of carbon dots derived for the first time from lemon juice, a natural bioresource. Detailed photophysical studies of these novel carbon dots (henceforth termed LD), in conjunction with Fourier transform infrared spectra, reveal that among the two possible prototropic equilibria, phenol ↔ phenolate and carboxylic ↔ carboxylate, that occur at the surface of LD, it is the former that is actually coupled with the emissive moiety and directly involved in determining the nature of the electronic energy levels and the associated optical transitions. Apart from providing valuable mechanistic insights on the photoluminescence (PL) of carbon dots, the pH dependence of LD is also demonstrated to yield variable PL signals and perform elementary Boolean logic operations in response to chemical stimulants. The pH effect can therefore complement the optoelectronic functionalities of these promising luminescent nanomaterials and help in the future development of molecular devices and intelligent multianalyte detection systems.
首次从天然生物资源柠檬汁中获得的碳点，其吸收光谱和发射光谱呈现出显著且系统的pH依赖性变化。结合傅里叶变换红外光谱对这些新型碳点（以下简称LD）进行的详细光物理研究表明，在LD表面发生的两种可能的质子转移平衡，即苯酚⇌酚盐和羧酸⇌羧酸盐中，前者实际上与发光部分耦合，并直接参与确定电子能级的性质和相关的光学跃迁。除了为碳点的光致发光（PL）提供有价值的机理见解外，LD的pH依赖性还被证明可以产生可变的PL信号，并响应化学刺激执行基本的布尔逻辑运算。因此，pH效应可以补充这些有前景的发光纳米材料的光电功能，并有助于未来分子器件和智能多分析物检测系统的发展。
