Directing energy transfer in Pt(bodipy)(mercaptopyrene) dyads

Irmler, Peter and Gogesch, Franciska S. and Mang, Andé and Bodensteiner, Michael and Larsen, Christopher B. and Wenger, Oliver S. and Winter, Rainer F.. (2019) Directing energy transfer in Pt(bodipy)(mercaptopyrene) dyads. Dalton Transactions, 48 (31). pp. 11690-11705.

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Official URL: https://edoc.unibas.ch/73107/

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We report on the photophysical properties of three dyads that combine a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (bodipy, BDP) and a mercaptopyrene (SPyr) dye ligand at a Pt(PEt3)(2) fragment. sigma-Bonding of the dyes to the Pt ion promotes intersystem crossing (ISC) via the external heavy atom effect. The coupling of efficient ISC with charge-transfer from the electron-rich mercaptopyrene to the electron-accepting BDP ligand (PB-CT) gives rise to a multitude of (potentially) emissive states. This culminates in the presence of four different emissions for the mono- and dinuclear complexes BPtSPyr and BPtSPyrSPtB with an unsubstituted BDP ligand and either a terminal 1-mercaptopyrene or a bridging pyrene-1,6-dithiolate ligand. Thus, in fluid solution, near IR emission at 724 nm from the (PB)-P-3-CT state is observed with a quantum yield of up to 15%. Excitation into the BDP-based (1)pi pi* or the pyrene-based (1)pi pi* band additionally trigger fluorescence and phosphorescence emissions from the BDP-centred (1)pi pi* and (3)pi pi* states. In frozen solution, at 77 K, phosphorescence from the pyrene ligand becomes the prominent emission channel, while PB-CT emission is absent. Alkylation of the BDP ligand in KBPtSPyr funnels all excitation energy into fluorescence and phosphorescence emissions from the KBDP ligand. The assignments of the various excited states and the deactivation cascades were probed by absorption and emission spectroscopy, transient absorption spectroscopy, electrochemical and UV/Vis/NIR spectroelectrochemical measurements, and by quantum chemical calculations. Our conclusions are further corroborated with the aid of suitable reference compounds comprising of just one chromophore. All dyads are triplet sensitizers and are able to generate singlet oxygen.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Wenger)
UniBasel Contributors:Wenger, Oliver and Larsen, Christopher Bryan
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:21 Aug 2020 01:30
Deposited On:04 Feb 2020 10:26

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