How molecular architecture defines quantum yields

Understanding the relationship between molecular architecture and function underpins many challenges in chemical innovation. Bond-forming reactions are strongly influenced by topology in both small molecules and macromolecular frameworks. Here, we elucidate how molecular architecture impacts photo-induced cyclisations in a series of monodisperse macromolecules bearing defined spacers between photodimerisable pyrene–chalcone moieties, examining the relationship between intramolecular cyclisation propensity and intermolecular network formation. We identify a goldilocks zone of maximum reactivity between sterically hindered and entropically limited regimes, with a quantum yield of intramolecular cyclisation nearly an order of magnitude higher than the lowest value. The trifunctional macromolecular design allows deconvolution of quantum yields into formation of two distinct cyclic isomers, rationalised via molecular dynamics simulations. We visualize solution-based findings in light-based additive manufacturing by formulating four photoresists for two-photon microprinting, revealing that precise positioning of functional groups is critical: lower intramolecular quantum yields generally lead to higher-quality printing.

Fred Pashley-Johnson, Rangika Munaweera, Sheikh I. Hossain, Steven C. Gauci, Laura Delafresnaye, Hendrik Frisch, Megan L. O’Mara, Filip E. Du Prez, Christopher Barner-Kowollik