Phosphinine vs Pyridine in Luminescent Cu^I Complexes and Application in Lifetime‐Based Molecular Thermometer

Abstract

Luminescent Cu(I) complexes have attracted significant interest due to their adjustable emission properties, diverse structures, and reasonable cost. In this work, two class of complexes, namely phosphinine and pyridine ligated Cu(I) complexes that differ by only one atom, were synthesized and characterized. Photophysical analysis and theoretical studies reveal an emissive phosphinine‐localized triplet states for Cu(I) phosphinine complexes, and a temperature‐dependent interplay between metal‐to‐ligand charge‐transfer (MLCT) singlet and triplet states for Cu(I) pyridine complexes. In general, the Cu(I) phosphinine complexes exhibit a longer lifetime and greater temperature‐dependent lifetime changes than the pyridine complexes. A molecular thermometer incorporating Cu(I) phosphinine complexes 2c as indicator was fabricated. This thermometer exhibits a rare linear correlation between temperature and lifetime ranging from 77–297 K with a high sensitivity of –13.5 μs K–1.

The case of a μ2-P aromatic phosphinine as a 4-electron donor forming σ- and π-three–center-two-electron bonds

“…Phosphinines have shown promising applications in synthetic chemistry and materials science 1 following the pioneering syntheses of 2,4,6-triphenylphosphinine by Märkl in 1966 2 and the parent phosphinine by Ashe III in 1971. 3 They have demonstrated diverse coordination chemistry stemming from their possession of both a σ-lone pair and an aromatic 6π-heterocycle.…”