Reaching strong absorption up to 700 nm with new benzo[g]quinoxaline-based heteroleptic copper(i) complexes for light-harvesting applications?

Dalton Transactions Pub Date: 2023-05-03 DOI: 10.1039/D3DT00902E

Abstract

Heteroleptic copper(I) complexes, with a diimine as a chromophoric unit and a bulky diphosphine as an ancillary ligand, have the advantage of a reduced pseudo Jahn–Teller effect in their excited state over the corresponding homoleptic bis(diimine) complexes. Nevertheless, their lowest absorption lies generally between 350 to 500 nm. Aiming at a strong absorption in the visible by stable heteroleptic Cu(I) complexes, we designed a novel diimine based on 4-(benzo[g]quinoxal-2′-yl)-1,2,3-triazole derivatives. The large π-conjugation of the benzoquinoxaline moiety shifted bathochromically the absorption with regard to other diimine-based Cu(I) complexes. Adding another Cu(I) core broadened the absorption and extended it to considerably longer wavelengths. Moreover, by fine-tuning the structure of the dichelating ligand, we achieved a panchromatic absorption up to 700 nm with a high molar extinction coefficient of 8000 M?1 cm?1 at maximum (λ = 570 nm), making this compound attractive for light-harvesting antennae.

Graphical abstract: Reaching strong absorption up to 700 nm with new benzo[g]quinoxaline-based heteroleptic copper(i) complexes for light-harvesting applications
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