Three-branched coumarin derivatives for two-photon uncaging. How does branching influence the efficacy?

In the design of non-linear optical chromophores, conjugation pathways in multi-branched dyes are known to influence heavily their properties. Herein, we investigate this strategy for two-photon (2P) responsive photolabile protecting groups (PPG) by assembling via a triphenylamine core extended coumarinylmethyl derivatives. The experimental study reveals an enhancement 2P absorption tri-branched compound, but strikingly different photophysics behaviour resulting decrease bond cleavage efficiency, and aggregation aqueous acetonitrile. These combined effects results much poorer uncaging efficiency three-branched contrast, corresponding mono-branched coumarin exhibit very high photochemical (450 GM).