Redox‐Switchable Cyan Fluorescence of a BODIPY Analog Inspired by Propentdyopent Pigments

Abstract

The combination of reversible redox chemistry and bright redox‐responsive emission properties is key to the development of electrofluorochromic switches for applications in bioimaging and optoelectronics. Herein, the redox‐active dipyrrin‐1,9‐dione fragment, which is characteristic of the propentdyopent family of heme metabolites and urinary pigments, is employed for the synthesis of a BODIPY analog. This boron difluoride complex exhibits bright fluorescence in organic solvents and a significant ipsochromic shift to the cyan region when compared to typical green BODIPY dyes. Electrochemical and spectroscopic measurements show that the dipyrrindione ligand acts as an electron reservoir by hosting an unpaired spin upon one‐electron reduction. This ligand‐based redox event reversibly abolishes the fluorescence emission, thus switching off the novel electrofluorochromic system.

Stabilization of a Triplet Diradical on a Binuclear palladium(II) Dipyrrindione

“…In contrast, the dipyrrin-1,9-dione motif serves as a compact dipyrrolic platform to host ligand-centered radicals. [50][51][52] This bidentate ligand could therefore extend the diverse applications of dipyrrin complexes to include one-electron redox chemistry and a variety of spin states.…”

“…Historically referred to as propentdyopents, the naturally occurring dipyrrindione pigments result from the oxidative metabolism of heme 53,54 and were initially discovered within the urinary pigments collected from hyperbilirubinemia patients. 55 The first dipyrrindione complexes were isolated from the degradation of bilindione complexes; 23,56 however, we recently employed the Hpdp•MeOH adduct for the preparation of homoleptic 50 and heteroleptic 51,52 compounds (Chart 2). Because of the availability of lowlying π* molecular orbitals, these complexes typically undergo one-electron reduction processes localized on the dipyrrolic ligand framework.…”

“…The presence of low-intensity, near-IR bands in the monoanionic complex is consistent with intraligand π−π charge-transfer transitions associated with oligopyrrolic radicals, as previously reported. 26,[50][51][52] Furthermore, the intensity of these bands increases upon generation of the doubly-reduced species by electrolysis at -1.3 V with minor wavelength shifts (439, 695, and 758 nm), suggesting the formation of a dianionic diradical. ) by controlled potential electrolysis to produce the one-electron reduction product at ─1.00 V (green trace) and then the two-electron reduction product at ─1.30 V (orange trace).…”

Recent Progress on Synthesis of N,N′-Chelate Organoboron Derivatives

“…N , N ′-chelate tetracoordinated organoboron compounds have been widely applied in various science and technology areas. For example, boron dipyrromethene derivatives (BODIPY) were developed in luminescent materials [ 1 , 2 , 3 , 4 , 5 ], dyes [ 6 , 7 , 8 , 9 ], photosensitizers [ 10 , 11 , 12 , 13 , 14 ], molecular switches [ 15 , 16 , 17 ], photodynamic therapy [ 18 , 19 , 20 , 21 , 22 ], molecular probes [ 23 , 24 , 25 , 26 ], and bioimaging [ 27 , 28 , 29 ]. In recent decades, N , N ′-chelate compounds become a popular topic and have gradually attracted the attention of scientists.…”

“…The data presented in this study are openly available in references [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , …”