Diverse quantum interference regimes in intramolecular singlet fission chromophores with thiophene-based linkers.

An array of thiophene-based π-conjugated linkers in covalently linked pentacene dimers allow us to access diverse quantum interference (QI), modulating nonadiabatic coupling (NAC) in the singlet fission (SF) process. Simulations show that structural isomerism in terms of S atom orientation substantially alters NAC with relatively marginal impacts on energies. Extended curly arrow rules (ECARs) reveal sensitive dependence of QI on SF linker topologies and connectivity, categorizing regimes of constructive, destructive, and previously unrealized in SF research, shifted destructive QI.