Issue 21, 2021

The central role of the metal ion for photoactivity: Zn– vs. Ni–Mabiq

Abstract

Photoredox catalysts are integral components of artificial photosystems, and have recently emerged as powerful tools for catalysing numerous organic reactions. However, the development of inexpensive and efficient earth-abundant photoredox catalysts remains a challenge. We here present the photochemical and photophysical properties of a Ni–Mabiq catalyst ([NiII(Mabiq)]OTf (1); Mabiq = 2-4:6-8-bis(3,3,4,4-tetramethyldihydropyrrolo)-10-15-(2,2-biquinazolino)-[15]-1,3,5,8,10,14-hexaene1,3,7,9,11,14-N6)—and of a Zn-containing analogue ([ZnII(Mabiq)OTf] (2))—using steady state and time resolved optical spectroscopy, time-dependent density functional theory (TDDFT) calculations, and reactivity studies. The Ni and Zn complexes exhibit similar absorption spectra, but markedly different photochemical properties. These differences arise because the excited states of 2 are ligand-localized, whereas metal-centered states account for the photoactivity of 1. The distinct properties of the Ni and Zn complexes are manifest in their behavior in the photo-driven aza-Henry reaction and oxidative coupling of methoxybenzylamine.

Graphical abstract: The central role of the metal ion for photoactivity: Zn– vs. Ni–Mabiq

Supplementary files

Article information

Article type
Edge Article
Submitted
05 Nov 2020
Accepted
21 Apr 2021
First published
27 Apr 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2021,12, 7521-7532

The central role of the metal ion for photoactivity: Zn– vs. Ni–Mabiq

R. Lauenstein, S. L. Mader, H. Derondeau, O. Z. Esezobor, M. Block, A. J. Römer, C. Jandl, E. Riedle, V. R. I. Kaila, J. Hauer, E. Thyrhaug and C. R. Hess, Chem. Sci., 2021, 12, 7521 DOI: 10.1039/D0SC06096H

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