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• We prepared three structurally different multi-peak emitting carbon dots using phenylenediamine isomers as precursors. • The fluorescence of all three carbon dots changes depending on the environment. • The multi-peak emission carbon dots have different fluorescence centers resulting from their different structures. Revealing the relationship between structure and optical properties of multi-peak emissive carbon dots (CDs) is important. Three types of multi-peak emission CDs were synthesized by one-step hydrothermal method with phenylenediamine (PD) isomers (o/m/p) and maleic anhydride serving as precursors. During the synthesis process, three PDs exhibited different microstructural and chemical states, resulting in various fluorescence emission centers. The multi-peak emission behavior of o-CDs and m-CDs is composed of molecular fluorophores and carbon core states, while that of p-CDs consists of surface states and carbon core states. These different fluorescence centers lead to diverse fluorescence behaviors of the CDs in different solvents and environments. This work inspires the clarification of the relationship between the structural and optical properties of multi-peak emissive CDs. [ABSTRACT FROM AUTHOR]