Oxybenzone, avobenzone, and octinoxate are organic compounds commonly used as active ingredients in sunscreens to protect the skin from the harmful effects of ultraviolet UV radiation. Their photochemical properties play a crucial role in their effectiveness as sunscreen agents.1. Oxybenzone benzophenone-3 : Oxybenzone is an aromatic ketone that absorbs both UVA 320-400 nm and UVB 280-320 nm radiation. It acts as a UV filter by converting the absorbed UV radiation into less harmful infrared radiation heat . However, oxybenzone is known to be a weak photo-stabilizer, meaning it can degrade upon exposure to sunlight, leading to a decrease in its UV protection capability over time. To overcome this limitation, it is often combined with other UV filters or stabilizers in sunscreen formulations.2. Avobenzone butyl methoxydibenzoylmethane : Avobenzone is a dibenzoylmethane derivative that primarily absorbs UVA radiation especially UVA1, 340-400 nm . It is an effective UVA filter but has limited stability when exposed to sunlight, as it undergoes a reversible photochemical reaction called isomerization. This reaction reduces avobenzone's ability to absorb UVA radiation, thus decreasing its effectiveness. To improve its photostability, avobenzone is often combined with other photostabilizers or UV filters, such as octocrylene or ecamsule, in sunscreen formulations.3. Octinoxate ethylhexyl methoxycinnamate : Octinoxate is an ester of methoxycinnamic acid and primarily absorbs UVB radiation 290-320 nm . It is a highly effective UVB filter and has better photostability compared to oxybenzone and avobenzone. However, it does not provide adequate UVA protection, so it is often combined with other UVA filters in sunscreen formulations. Octinoxate can also act as a photostabilizer for avobenzone, enhancing the overall effectiveness of the sunscreen.In summary, the photochemical properties of oxybenzone, avobenzone, and octinoxate contribute to their effectiveness as sunscreen agents by absorbing and filtering harmful UV radiation. However, their photostability issues can limit their effectiveness over time, which is why they are often combined with other UV filters or photostabilizers in sunscreen formulations to provide broad-spectrum protection against both UVA and UVB radiation.