Serendipitous Synthesis of Fractal Pattern‐Like Polymer Carbon Dots and Carbon Nano Dot via Surface Molecular Engineering

ABSTRACT The synthesis and photoluminescent properties of carbon dots (C‐Dots) are influenced by various reaction conditions, yet the mechanisms driving these properties remain poorly understood. This study investigates the synthesis of surface‐modified C‐Dots derived from Nyctanthes arbor‐tristis flowers, modified with cysteamine and folic acid, to explore the impact of reaction temperature and surface functionalization on their photoluminescence and metal ion sensing capabilities. Four types of C‐Dots were synthesized under different temperatures (175°C and 200°C) and characterized for their structural, optical, and surface properties. Our findings reveal that higher temperatures promote the formation of well‐dispersed ‘ carbon nanodots’ (CND), whereas lower temperatures lead to the formation of ‘ fractal‐pattern‐like polymer carbon dots’ (PCD). Simultaneously, these surface‐modified CPD/CNDs were employed for the selective detection of metal ions (Fe 3+ ), and the results demonstrate that they did not exhibit significant quenching effects and support the hypothesis that surface ligands shield functional groups or reduce surface defects and prevent the formation of a stable complex with metal ions. These results underscore the role of synthesis conditions and surface engineering in tailoring the optical properties and functionality of C‐Dots, with implications for their use in bioimaging and sensing applications.