Recent progress in the electron paramagnetic resonance study of polymers

Naveed, Kaleem‐ur‐Rahman; Wang, Li; Ullah, Raja Summe; Haroon, Muhammad; Fahad, Shah; Li, Jiyang; Elshaarani, Tarig; Khan, Rizwan Ullah; Nazir, Ahsan

doi:10.1039/c8py00689j

Cited by 62 publications

(33 citation statements)

References 151 publications

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“…[16a] The solid-state EPR spectrum of 6 was next acquired (Figure 3D,m iddle). [20] The signature at 298 Kc onsists of ab roadened signal with two prominentf eatures (an identical signal is observeda t1 27 K). Importantly,t his signal does not appear in the diamagnetics tarting materials (4 or 4,4'-bpy) and is consis-tent in signali ntensity between batches.…”

Section: Resultsmentioning

confidence: 85%

Octaboraneyl Complexes of Nickel: Monomers for Redox‐Active Coordination Polymers

Drover

Dufour

Lesperance-Nantau

et al. 2020

Chemistry A European J

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Herein, we establish the preparation, characterization, and reactivity of a new diphosphine ligand, 1,2‐bis(di(3‐dicyclohexylboraneyl)propylphosphino)ethane (P2BCy4), a scaffold that contains four pendant boranes. An entryway into the coordination chemistry of P2BCy4 is established by using nickel, providing the octaboraneyl complex [Ni(P2BCy4)2]—this species contains a boron‐rich secondary coordination sphere that reacts readily with Lewis bases. In the case of 4,4′‐bipyridine, an air‐sensitive coordination polymer is obtained. Characterization of this material by solid‐state NMR and EPR spectroscopy reveals the presence of a charge‐transfer polymer, which forms as a function of intramolecular Ni→4,4′‐bpy electron transfer (ET), providing an array of oxidized nickel sites and reduced 4,4′‐bpy radical anion sites. Notably, the related intermolecular reaction between the model fragments [Ni(dnppe)2] (dnppe=1,2‐bis(di‐n‐propylphosphino)ethane) and a bis(boraneyl)‐protected 4,4′‐bpy, provides no ET. Overall, the P2BCy4 fragment provides a unique opportunity for Lewis base activation, in one case allowing for the facile construction of monomers for incorporation into redox‐active macromolecules.

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Section: Resultsmentioning

confidence: 85%

Octaboraneyl Complexes of Nickel: Monomers for Redox‐Active Coordination Polymers

Drover

Dufour

Lesperance-Nantau

et al. 2020

Chemistry A European J

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“…Electron Paramagnetic Resonance (EPR) can provide valuable information about the oxidation state of an atom or atoms within a (macro)molecule and its environment by using unpaired electrons as probes. The technique has been used to study various paramagnetic species [1,2] such as organic radicals, [3][4][5] proteins, [6][7][8][9] polymers [5,10] and transition-metal complexes. [11,12] Although EPR spectrometers operating at up to 263 GHz are now commercially available, X-band (~9 GHz) equipment is still the most widely used.…”

Section: Introductionmentioning

confidence: 99%

A Versatile In‐Situ Electron Paramagnetic Resonance Spectro‐electrochemical Approach for Electrocatalyst Research

et al. 2020

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Empirical electrocatalyst research generally consists of the synthesis and experimental characterization of catalysts and the analysis of electrolysis products by conventional analytical techniques. In‐situ electron paramagnetic resonance spectro‐electrochemistry provides an evidence‐based in‐depth understanding of the formed intermediates and the reaction mechanism enabling the desired tuning of electrocatalysts. The use of this technique has been underexploited because of the opposite requirements they impose on the conventional setup. In this work, a versatile electrode with commercially available indium tin oxide on polyethylene terephthalate (PET) was constructed for the first time which can fit inside commonly used flat cells. It allows reproducible electrodeposition of catalytic material combined with sensitive radical detection, owing to its large surface area and minimal disruption to the resonator's Q‐factor. Moreover, with a resistivity of 8–10 Ω sq−1, the surface potential of the thin semiconductor electrode within the resonator was well‐controlled, allowing targeted radical production.

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“…In spite of this, Figure a–c provides the dark and photo‐induced (721 nm) EPR spectra for PBDB‐T, PBPD‐Th, and ITIC, respectively. In principle, the appearances of the EPR signals with respect to the field widths (i.e., approximately 1.5 mT) should be attributed to the generation of polaron pairs . The remarkable EPR spectra of PBDB‐T and PBPD‐Th can be captured even at the dark condition, indicating the presence of some paramagnetic species for PBDB‐T and PBPD‐Th.…”

Section: Resultsmentioning

confidence: 98%

Spin‐Dependent Electron–Hole Recombination and Dissociation in Nonfullerene Acceptor ITIC‐Based Organic Photovoltaic Systems

et al. 2019

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A nonfullerene acceptor (NFA), named 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′] dithiophene (ITIC) with the fused aromatic conjugated backbone structure, is an intriguing small molecular semiconductor in the application of organic bulk heterojunction (BHJ) solar cells. However, the underlying spin‐dependent photo‐physics in the photovoltaic process remains deficient. Here, ITIC‐based thin solid film, binary, and ternary organic blends are designed and fabricated with two polymeric donors, poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]‐dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBDB‐T) and poly[(2,6‐(4,8‐Bis(3‐((2‐ethylhexyl)oxy)‐phenyl)‐benzo[1,2‐b:4,5‐b′]‐dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBPD‐Th). With the spin‐sensitive magneto‐photocurrent and magneto‐electroluminescence measurements, ITIC always exhibits large magnetic field effects with negative signs in the ambient temperature. The effect is attributed to the exciton‐charge reaction. However, both positive and negative signs are detected in the binary and ternary organic blends at small and large fields, respectively. The results elucidate that the mutual combination of the spin‐dependent polaron pair dissociation and exciton‐charge reaction plays a decisive role in the photovoltaic process. Furthermore, with photo‐induced electron paramagnetic resonance (EPR) studies, the full width at half maximum (FWHM) of the line shape for the positive magneto‐photocurrent is firmly associated to the magnitude of the effective g‐factor. The present study may shed a new light on the deep understanding of spin‐dependent photo‐physical process in NFA‐based solar cells for organic opto‐spintronic developments.

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Recent progress in the electron paramagnetic resonance study of polymers

Abstract: This review article provides an overview of the contemporary research based on a tailor-made technique to understand the paramagnetic behavior of different polymer classes.

Cited by 62 publications

References 151 publications

Octaboraneyl Complexes of Nickel: Monomers for Redox‐Active Coordination Polymers

Octaboraneyl Complexes of Nickel: Monomers for Redox‐Active Coordination Polymers

A Versatile In‐Situ Electron Paramagnetic Resonance Spectro‐electrochemical Approach for Electrocatalyst Research

Spin‐Dependent Electron–Hole Recombination and Dissociation in Nonfullerene Acceptor ITIC‐Based Organic Photovoltaic Systems

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