Mechanistic studies on the photogeneration of o- and p-xylylenes from α,α'-dichloroxylenes

Two-colour two-laser techniques have unambiguously proved that photolysis of the o-/p-(chloromethyl)benzyl radical leads to the sequential two-photon generation of o-/pxylylene from α,α'-dichloro-o-/p-xylene.Perez Prieto, Julia, [email protected]

Sulfur-substituted perylenediimides: Easy tunability of the electronic character

Perylenediimides (PDIs) are the focus of a huge number of research lines for their awesome properties which can be modulated over a wide range by chemical modification of their structure. However, industrial applications require reduced costs in materials preparation and transformation. In this contribution we explore the ability of sulfur-substituted PDIs to vary their electronic character from strong electron-donating to strong electron-accepting in just one reaction.This research is part of the I+D+i project PID2022‐140315NB-I00, funded by MICIU/AEI/10.13039/501100011033 and by ERDF/EU

Diels–Alder reaction on perylenediimides: synthesis and theoretical study of core-expanded diimides

A one-step reaction for the fusion of aromatic rings to one or both bay areas of perylenediimides using benzynes is presented. Yields as high as 70% for naphthoperylenendiimide 2 and 80% for dibenzocoronenediimide 3 are obtained. The reaction is also carried out using substituted benzynes, heteroaromatic benzynes and substituted perylenediimides. A combined experimental/theoretical approach, based on measuring redox and absorption/emission properties and performing density functional theory calculations, indicates that increasing the π-skeleton of PDIs transversally leads to significant and unexpected changes in the electronic, redox and optical properties. The observed trends are rationalized in terms of molecular orbital topology and overlap according to three different levels of core expansion, and can be used as design principles for obtaining PDIs with improved functionalities

Directly Linked Zinc Phthalocyanine–Perylenediimide Dyads and a Triad for Ultrafast Charge Separation

Directly linked to promote strong intramolecular interactions, donor-acceptor dyads and a donor-acceptor-donor triad featuring zinc phthalocyanine (ZnPc) as electron donor and perylenediimide (PDI) as electron acceptor have been synthesized and characterized. Owing to complementary absorption features of the entities, improved light absorption was witnessed in these conjugates. The optimized geometry and electronic structures showed the majority of the highest occupied molecular orbital (HOMO) on the ZnPc entity, whereas the lowest unoccupied molecular orbital (LUMO) was on the PDI entity, suggesting that the charge-separated states would be ZnPc+ -PDI. - . The electrochemical and free-energy calculations suggested exothermic energy and/or electron transfer processes via the singlet states of PDI or ZnPc entities depending on the excitation wavelength of the laser used. The measured rates using femtosecond pump-probe spectroscopy coupled with global analysis of transient data revealed ultrafast energy transfer from 1 PDI* to ZnPc followed by charge separation. However, when ZnPc was selectively excited, only electron transfer was witnessed wherein the time constants for forward and reverse electron transfer processes followed Marcus predictions. The absorption in a wide section of the solar spectrum and the ultrafast charge separation suggest the usefulness of these systems as good photosynthetic models