Solid-State Luminescence in Self-Assembled Chlorosalicylaldehyde-Modified Carbon Dots
Tengfei Liu, Guangchao Yin, Ziqi Song, Jingkun Yu, Xue Yong, Baowei Zhang, Lin Ai, Siyu Lu
Abstract
Carbon dots (CDs) have excellent optical properties with broad potential applications. However, obtaining CDs with multicolor emission in the solid state remains a great challenge. Four chlorosalicylaldehyde-functionalized CDs with solid-state fluorescence were prepared here via molecular self-assembly. Their emission wavelengths were 456, 494, 556, and 584 nm, ranging from blue to yellow. Experimental results and theoretical calculations indicated that the different positions (para-, meta-, and ortho-position) of Cl on the aromatic core of chlorosalicylaldehyde affect the coplanarity and degree of conjugation of the CDs, thereby changing their molecular orbital energy levels and adjusting the emission. The self-assembly showed distinct isomeric effects: with changing positioning of the Cl, three-dimensional to one-dimensional self-assembled morphologies appeared in turn. The multicolor luminescence of the CDs makes them potentially useful in light-emitting diodes and fluorescent films. Their fat solubility and strong ultraviolet absorption characteristics allow them to be applied in fingerprint detection.