Synergistic photoredox and copper catalysis by diode-like coordination polymer with twisted and polar copper\u2013dye conjugation

Yusheng Shi,Chunying Duan,Cheng He,Xiao-Ming Jiang,Gang Xu,Tiexin Zhang

doi:10.1038/s41467-020-19172-3

Abstract

Synergistic photoredox and copper catalysis confers new synthetic possibilities in the pharmaceutical field, but is seriously affected by the consumptive fluorescence quenching of Cu(II). By decorating bulky auxiliaries into a photoreductive triphenylamine-based ligand to twist the conjugation between the triphenylamine-based ligand and the polar Cu(II)–carboxylate node in the coordination polymer, we report a heterogeneous approach to directly confront this inherent problem. The twisted and polar Cu(II)–dye conjunction endows the coordination polymer with diode-like photoelectronic behaviours, which hampers the inter- and intramolecular photoinduced electron transfer from the triphenylamine-moiety to the Cu(II) site and permits reversed-directional ground-state electronic conductivity, rectifying the productive loop circuit for synergising photoredox and copper catalysis in pharmaceutically valuable decarboxylative C(sp3)–heteroatom couplings. The well-retained Cu(II) sites during photoirradiation exhibit unique inner-spheric modulation effects, which endow the couplings with adaptability to different types of nucleophiles and radical precursors under concise reaction conditions, and distinguish the multi-olefinic moieties of biointeresting steride derivatives in their late-stage trifluoromethylation-chloration difunctionalisation.

Highlights

Synergistic photoredox and copper catalysis confers new synthetic possibilities in the pharmaceutical field, but is seriously affected by the consumptive fluorescence quenching of Cu (II)
Photoredox and copper catalysis are usually compromised by adopting the high loadings of Cu(I) precursors to kinetically balanced off the excited-state quenching effect of in situ generated Cu(II) ions[6,7,8]
The coordination polymer Cu–Twisted was obtained in a 70% yield by the solvothermal reaction between Cu(NO3)2 ∙ 3H2O and H3L–Twisted at 80 °C for 3 days (Supplementary Data 1)

Summary

Introduction

Synergistic photoredox and copper catalysis confers new synthetic possibilities in the pharmaceutical field, but is seriously affected by the consumptive fluorescence quenching of Cu (II). We show a new approach to modifying the electronic communications in the Cu(II)–TPA coordination polymer by introducing a bulky group at the ortho-position of the phenylcarboxylic coordination group of TPA-based ligand to twist the π-conjugation between phenyl moiety and the coordinated carboxylate (Fig. 1a) We envision that this special series connection of twisted conjugation and polar carboxylate–copper node within Cu(II)–TPA coordination polymer should kinetically alleviate the inter- and intramolecular photoinduced electron transfer (PET) from the excited-state TPA fragment to Cu(II) ion[19]. The ground-state electronic communication thermodynamically allows the alternative directional single electron transfer (SET) from the in situ formed Cu(I) to the oxidised TPA moiety (Fig. 1c)[20] This molecular diode-like behaviour of twisted conjugation and polar node rectifies the productive loop-circuit electron transfer route that required by synergising the photoredox and copper catalytic cycles (Fig. 1c)

Methods

Results

Conclusion