The Formation Process and Mechanism of Carbon Dots Prepared from Aromatic Compounds as Precursors: A Review

Abstract

Fluorescent carbon dots are a novel type of nanomaterial. Due to their excellent optical properties, they have extensive application prospects in many fields. Studying the formation process and fluorescence mechanism of CDs will assist scientists in understanding the synthesis of CDs and guide more profound applications. Due to their conjugated structures, aromatic compounds have been continuously used to synthesize CDs, with emissions ranging from blue to NIR. There is a lack of a systematic summary of the formation process and fluorescence mechanism of aromatic precursors to form CDs. In this review, the formation process of CDs is first categorized into three main classes according to the precursor types of aromatic compounds: amines, phenols, and polycyclics. And then, the fluorescence mechanism of CDs synthesized from aromatic compounds is summarized. The challenges and prospects are proposed in the last section.

Supramolecular Surface Engineering of Carbon Dots Enables Matrix‐Free Room Temperature Phosphorescence†

“…Carbon dots (CDs), a new type of carbon nanomaterial, have attracted extensive attentions due to their unique optical properties as well as inherent advantages of superior stability, good solubility and low toxicity. [ 7‐11 ] CDs have been widely used in sensing, in vitro / in vivo imaging, cancer therapy, catalysts and optoelectronic devices. [ 12‐19 ] Despite the well documented fluorescent properties, CDs with RTP have also been reported by several groups.…”

Rapid Preparation of Long-Wavelength Emissive Carbon Dots for Information Encryption Using the Microwave-Assisted Method

“…The phenyl group of o -phenylenediamine has a conjugated structure that can generate an sp 2 domain, which is beneficial for the band emission of carbon dots. The amino group provides N-doped and hydrophilic functional groups . In this work, fluorescent carbon dots with long-wavelength emission are successfully synthesized using o -phenylenediamine as the carbon and nitrogen source, BA as the boron source, and potassium chloride as the catalyst using a microwave-assisted method in a short period.…”

“…The amino group provides N-doped and hydrophilic functional groups. 22 In this work, fluorescent carbon dots with long-wavelength emission are successfully synthesized using o-phenylenediamine as the carbon and nitrogen source, BA as the boron source, and potassium chloride as the catalyst using a microwave-assisted method in a short period. Three fluorescent colors, yellow, orange, and red, were obtained by adjusting the dosage of o-phenylenediamine, named Y-CDs, O-CDs, and R-CDs.…”

Nitrogen-doped orange emitting carbon dots for β-carotene detection and lysosomal imaging

“…26 The conjugated molecular structure of aromatic compounds can give rise to sp 2 structural domains, such as aniline and phenol, which promote the redshift of the luminescence wavelength of CDs. 27,28…”

“…26 The conjugated molecular structure of aromatic compounds can give rise to sp 2 structural domains, such as aniline and phenol, which promote the redshift of the luminescence wavelength of CDs. 27,28 In this work, 1,5-naphthalenediamine was used as the precursor, and nitric acid was added to the system of chemical reaction. The carbon dots (O-CDs) that emitted orange fluorescence were prepared by co-heating in ethanol solution.…”