Solid-State Luminescence in Self-Assembled Chlorosalicylaldehyde-Modified Carbon Dots

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.

Automated summary

In this study, four chlorosalicylaldehyde-functionalized carbon dots (CDs) with solid-state fluorescence were prepared via molecular self-assembly. The CDs emitted light at wavelengths ranging from 456 to 584 nm, covering the blue to yellow range. The position of the chlorine atom on the aromatic core of chlorosalicylaldehyde affected the conjugation and molecular orbital energy levels of the CDs, resulting in the observed emission. The self-assembly process exhibited isomeric effects and the multicolor luminescence of the CDs makes them potentially useful in light-emitting diodes and fingerprint detection.