Fig. 1. (a) Chemical structures of palladium tetraphenyltetrabenzoporphyrin (1), perylene (2), [Ru(tpy)(bpy)(SRR′)]2+ (32+), and [Ru(tpy)(bpy)(H2O)]2+ (42+), and the photochemical reaction from 32+ to 42+. (b) Cartoon showing the sequence of photochemical events demonstrated in this work: red light is absorbed by compound 1, after which triplet–triplet annihilation upconversion (TTA-UC) occurs, followed by non-radiative energy transfer from 2 to 32+, and finally the ruthenium prodrug photodissociates from the lipid bilayer. (c) Absorption spectrum of 32+ in chloroform (solid, left axis, ε max = 7700 at λ max = 456 nm) and area-normalized emission spectrum of compound 2 in PEGylated DMPC liposomes (dashed, right axis, λ exc = 400 nm, 0.5 mol% of compound 2 with respect to the lipids).
