We report a theoretical study on graphdiyne (GD) palced with vitamin C derivative as a fluorescent sensor for the detection of vitamin C. First, we performed frontier molecular orbital (FMO) calculations to determine the electronic properties of the sensor. Geometry optimization was then performed to obtain the optimized structure of the sensor. The UV spectra and emission spectra of the sensor were calculated using time-dependent density functional theory (TD-DFT). Our calculations show that the sensor exhibits a strong fluorescent response upon interaction with vitamin C, with a possible range of values between 340-353 nm. Their absorbance maxima (λ_max) were reported to be 1005-1115 nm range. The Stokes shift of the sensor was calculated to be 30 nm. The global chemical reactivity values of the sensor were calculated using density functional theory (DFT). The results showed a Stokes shift correlation of 0.69 and an electrophilicity (ω) value of 0.70eV for vitamin C-placed on graphdiyne, indicating a positive correlation between the polarity of the solvent and the Stokes shift and the sensor with its capability of accepting electrons. Our calculations show that the sensor is highly reactive towards vitamin C with a low energy gap (E_gap) between the HOMO and LUMO orbitals. This work presents a promising platform for the development of new vitamin C detection strategies with potential applications in the food and pharmaceutical industries.

Keywords: DFT; GD; TD-DFT; Vitamin C, Fluorescent, Graphdiyne