Perception on aggregation induced multicolor emission and emission centers in carbon nanodots using successive dilution, anion exchange chromatography, and multi-way statistics

Abstract

Exploration in the way of understanding the optical behavior and structure of carbon nanodots has been increased due to their vast application. Their emission dependency on excitation wavelengths is the more prevalent and controversial subject. In this report we considered the optical structure of hydrothermally synthesized carbon nanodots using citric acid and 2,3-diaminopyridine as precursors. The presence of different emission centers experimented through anion exchange chromatography which resulted in fractions with more unique optical structures. The quantum confinement effect and energy exchange between different types of carbon nanodots, due to aggregation in higher concentration levels, was studied applying a stepwise dilution experiment. Analysis of the experimental data was done through the parallel factor analysis and the trajectory pattern recognition which resolved more about optical interactions and the presence of different emission centers in different particles. Results from infrared spectroscopy confirmed the dominating density of carboxyl functional groups on the nanodots with negative surface charges and higher influence of amine groups on dots with positive surface charges.

A dually emissive MPA-CdTe QDs@N, S-GQD nanosensor for sensitive and selective detection of 4-nitrophenol using two turn-off signals

“…This independence can be attributed to the presence of a single emission site in the QDs and the uniform size distribution of the QDs. 14,31,32 Excitation-dependent uorescence is typically observed in carbon-based QDs. 17,33,34 This, therefore, limits the possibility of using them at different excitation wavelengths in uorescence-based sensors.…”

“…13 GQDs, an emerging metal-free carbon material, offer special optical properties along with the advantages of green synthesis and ultralow toxicity. [14][15][16][17] Recent reports have utilized nanodots such as polyethyleneimine-capped carbon dots, 18 APTES-coated zinc oxide QDs, 3 nitrogen-doped CQDs, 2 and sulfur-doped CQDs 19 for the detection of 4-NP.…”