Germanium-Doped Carbon Dots Nano Fluorometric Chemosensor for Mg2+: A Comprehensive Dft and Td-Dft Study

Through a straightforward chemical surface modification with germanium, carbon dots (Cdots) with a single fluorescent emission peak and no sensitivity to metal ions were transformed into a high sensitive and selective ratiometric fluorescence probe for the detection of Mg2+ in this study. The stimulated Cdots exhibit an emission peak at a distance of 402 nm, which were stimulated by a single excitation wavelength. This probe will offer a perfect ratiometric fluorescent probe with a low concentration detection limit for Mg2+ measurement throughout a linear concentration. The surface modification of Cdots with germanium results in the formation of new emitting centers on their surface, which theoretical calculations based on density functional theory (DFT) theory showed were suppressed through a photo-induced electron transfer (PET) process from the nitrogen lone pair electrons of the surface Cdots tooth. The nitrogen atoms on the surface pyrazino[2,3-f][1,10]-phenanthroline (PPT) of adjacent Cdots, chemically bonded with Mg2+ to form aggregated Cdots. The PET process involved in this complex creation was terminated, and a new emission peak at longer wavelengths then arose.