Exploring the photophysical properties of flavone-based dyes as an anti-angiogenic agent and with fluorescence emission in the near-infrared (NIR) region: a TD-DFT study

In this work, photophysical properties of the flavone-based dyes APG, BCN, CYS, LUT, and OX-A were investigated using TD-DFT calculations at PBE0/6-311++G (d,p) level in the gas phase and solvent media. The structural parameters, absorption and emission spectra, potential energy curves, natural charges, electron density properties, reduced density gradient, and protein–ligand docking properties were calculated. In the S1 state, the normal form of all dyes was directly converted to its tautomeric T form by no energy barrier. The results demonstrated that O1–H2···O6 H-bonding at S0 state is stronger than O1···H2–O6 one at S1 state. Upon photoexcitation to the S1 state, the flavones exhibit keto fluorescence emission in the near-infrared (NIR) wavelengths of 848.0 nm for APG to 1143.1 nm for OX-A, making the application of these molecules more attractive in the medical and physiological diagnostics. In addition, the anti-aging properties of the flavonoids were studied by docking process on the two aging targets brain-derived neurotrophic factor (BDNF) and nerve growth factors (NGF). Our study can provide insights into the design of a flavone-based ESIPT fluorescent probe and its anti-aging properties which might inspire future applications in the field of chemical sensing, imaging and drug design.