Molecular modeling for the investigation of UV absorbers for sunscreens: Triazine and benzotriazole derivatives

[Display omitted] •TDDFT reproduced accurately experimental UV absorption spectra.•Molecular orbitals involved in the dominant excitations are described.•Band gap energy, chemical potential and hardness are related to photoprotection. Investigations on the photoprotection mechanisms of molecular sunscreens is critical to developing more efficacious sunscreen products. Molecular modeling has proved to be very helpful in understanding intrinsic properties of molecules that protect our skin from the harmful rays of the sun and gathering useful features to developing improved sunscreens. Herein the investigation focuses on the stereoelectronic properties related to photoprotection mechanisms of triazine and benzotriazole derivatives, important compound classes based on their physical-chemical properties, such as resonance and ultraviolet (UV) broad spectrum absorption (UVA and UVB). The method proved to be a valuable tool to reproduce the experimental UV absorption of a set of triazine and benzotriazole derivatives with compromise between the accuracy and the computational speed. All calculations were carried out considering only the isolated UV filter (in vacuum) and have provided a qualitative prediction and interpretation of absorption properties. The lowest band gap energy (Ebg), highest chemical potential (μ) and lowest chemical hardness (η) values were observed to the orthohydroxy substituted derivatives that are able to undergo excited-state proton transfer (ESPT), supporting the UVA absorption and resulting in excellent photostability.