Amplification of the Quantum Yields of 2-λ⁵-Phosphaquinolin-2-ones through Phosphorus Center Modification

Abstract

We report the synthesis and characterization of P-phenyl modified phosphorus-and nitrogen-containing phosphaquinolinone heterocycles. The change from −OPh to −Ph results in a marked increase in the quantum yield of the scaffold as well as a moderate red-shifting of the emission. While calculations suggest that π to π* transitions are dominant, intramolecular charge transfer (ICT) also contributes in the excited state. Solution-and solid-state studies of the dimerization of this new congener to the P-phenoxy variant are also reported, showing retention of the dimerization behavior in this scaffold. Article pubs.acs.org/joc

Naphthyl‐Fused Phosphepines: Luminescent Contorted Polycyclic P‐Heterocycles

“…Accordingly, the energy of these orbitals shows only a minor change upon substitution (Table ), clearly explaining why the modification of the P−R bond only weakly affects the UV/Vis absorption. This is in marked difference to previously reported five‐ or six‐membered P‐rings . All phosphepines are good fluorophores with emission in the visible region in diluted solution.…”

Thionation of the 2‐λ5‐Phosphaquinolin‐2‐one Scaffold with Lawesson's Reagent

“…In addition to their well‐defined self‐specific meso‐dimerization, these phosphorus‐ and nitrogen‐containing (PN) heterocycles have tunable emissive properties. Similar to the aforementioned analyses of coumarin derivatives, we have reported a series of studies to modify and improve the physicochemical properties of the 2‐λ 5 ‐phosphaquinolin‐2‐ones through substituent group alteration, phosphorus center modification, and acene backbone elongation [13–15] . To further explore the versatility and modularity of the phosphaquinolinone scaffold, we report herein the conversion of the phosphine oxide into the corresponding thionate form using Lawesson's reagent and discuss in detail the resultant structural and photophysical changes.…”

Bumpy Roads Lead to Beautiful Places: The Twists and Turns in Developing a New Class of PN-Heterocycles

“…For this, Jeremy, Chun-Lin, and rotation student Hannah Bates performed the cyclization reaction on a smaller set of substituted ethynylanilines 26, except this time using PhP(OPh) 2 to afford the P-phenyl heterocycles 27 (Scheme 5). 81 There were two reasons that we were interested in examining this P-substitution: (a) derivatives 27 have one less degree of freedom than their heterocycle 11 analogues, suggesting a potentially higher quantum yield, and (b) the change in both the steric and electronic nature of the phenyl group in 27 might have substantial effects upon the solid-state properties.…”