Gas-phase molecular structure and energetics of UVB filter 4-methylbenzylidene camphor: A computational study

4-Methylbenzylidene camphor (4MBC) is an organic UV filter commonly used in sunscreens and many personal care products due to its ability to protect human skin against UVB solar radiation. 4MBC can exist as a (E)- or (Z)-isomer due to an exocyclic carbon–carbon double bond. In sunscreen formulations the (E) isomer predominates but under light exposure isomerization occurs from (E) to (Z). s study we have performed density functional theory calculations with the B3LYP hybrid functional and two basis sets: 6-31G(d) and 6-311G(d, p) to obtain the gas-phase molecular structure and energetics of the (E)- and (Z)-isomers of 4MBC. For comparison and validation purposes this study has been extended to the parent molecule: camphor. ain more accurate energy values we have also used the G3(MP2)//B3LYP method. The standard molar enthalpy of formation of 4MBC in the gas-phase, at T = 298.15 K, was derived from these calculations using appropriately chosen reactions.