Open Access Article
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Spin-Selective Charge Transfer Pathways in Photoexcited Helicene-Perylenediimide Dyads
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Giulia Agnoloni , Angelo Carella , Jakob Staab , Maxim Arsentev , Michela Lupi , Stefano Menichetti , Caterina Viglianisi , Ryan Michael Young , Federico Totti , Michael R Wasielewski , Alberto Privitera and Roberta Sessoli
First published on 17th June 2026
Abstract
Spin-selective charge-transfer pathways in helicene-based dyads are relevant to applications ranging from energy conversion to quantum information science. Here, we report a series of molecular systems comprising a thiahelicene donor and a perylenediimide (PDI) acceptor connected by oligophenyl bridges of varying length. The influence of donor-acceptor distance and relative orientation on the photophysical and spin-selective properties is investigated using a combined approach based on DFT calculations, transient absorption, and time-resolved electron paramagnetic resonance spectroscopies. Particular attention is given to the role of the bridge in tuning exchange coupling within charge-transfer states and its impact on spin-selective recombination pathways to the PDI triplet state. Efficient formation of long-lived PDI triplets is observed and shown to sensitize singlet oxygen generation with high efficiencies. These results establish structure-property relationships governing spin-selective processes in helicene-based dyads.