Table 1. Free energies of UV-induced reactions.

Reaction	Note	ΔG	ΔH	ΔE+ZPE
(a)+(a)→DPDS	Recombination of sulphenyl radicals	−22.25	−34.23	−34.40
(a)+(b1)→(c1)	OCH3 removed from side chain	−37.43	−51.62	−51.26
(a)+(b2)→(c2)	CH3 removed from side chain	−24.65	−36.47	−36.55
(a)+(b3)→(c3)	Side chain removed	−30.43	−46.08	−45.34
(a)+(b4)→(c4)	CH3 removed from main chain	−23.34	−37.07	−36.90

The relative energy values (in kcal mol⁻¹) of ΔG, ΔH and ΔE+ZPE calculated at the B3LYP/6–311++G(d,p) level of theory.