Recent Advances in Organic Radicals and Their Magnetism

Kumar, Sharvan; Kumar, Yogendra; Keshri, Sudhir Kumar; Mukhopadhyay, Pritam

doi:10.3390/magnetochemistry2040042

Cited by 97 publications

(85 citation statements)

References 163 publications

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“…In 1991 p ‐nitrophenyl nitronyl nitroxide ( p ‐NPNN) was the first organic ferromagnet to be discovered . Thereafter, there has been phenomenal progress in this field, and several organic radicals and radical ions with paramagnetic, ferromagnetic, and antiferromagnetic properties have been reported . Furthermore, organic paramagnetic molecules are important in the development of spintronics, as they increase the sensitivity of paramagnetic relaxation reagents and contrast agents in magnetic resonance imaging .…”

Section: Introductionsupporting

confidence: 53%

“…Such supramolecular interactions can lead to tunable optoelectronic, charge/ion transport, and magnetic properties . Organic radicals and radical ions have been shown to possess fascinating magnetic properties . It has been shown that the physical properties of these organic radicals and radical ions profoundly depend on the crystal packing, which is immensely difficult to predict and control .…”

Section: Introductionmentioning

confidence: 99%

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Ionic Assembly, Anion–π, Magnetic, and Electronic Attributes of Ambient Stable Naphthalenediimide Radical Ions

Kumar

Malik

Shukla

et al. 2019

Chemistry A European J

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Organic spin‐based molecular materials are considered to be attractive for the generation of functional materials with emergent optoelectronic, magnetic, or magneto‐conductive properties. However, the major limitations to the utilization of organic spin‐based systems are their high reactivity, instability, and propensity for dimerization. Herein, we report the synthesis, characterization, and magnetic and electronic studies of three ambient stable radical ions (1 a.+, 1 b.+, and 1 c.+). The radical ions 1 b.+ and 1 c.+ with BPh4− and BF4− counter anions, respectively, were synthesized in excellent yields by means of anion metathesis of 1 a.+ with Br− as its counter anion. Notably, synthesis of 1 a.+ was achieved in an ecofriendly, solvent‐free protocol. The radical ions were characterized by means of single‐crystal X‐ray diffraction studies, which revealed the discrete nature of the radical ions and extensive hydrogen‐bonding interactions within the radical ions and with the counter anions. Thus, radical ions can be organized to form infinite supramolecular arrays using weak noncovalent interactions. In addition, the Br−, BF4−, and BPh4− anions formed diverse types of anion–π interactions with the naphthalene and imide rings of the radical ions. The radical ions were characterized by means of X‐band electron paramagnetic resonance (EPR) spectroscopy in solution and in the solid state. Magnetic studies revealed their paramagnetic nature in the range of 10 to 300 K. The radical ions exhibited high resistivity approaching the gigaohm (GΩ) scale. In addition, the radical ions exhibited panchromism.

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Section: Introductionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Ionic Assembly, Anion–π, Magnetic, and Electronic Attributes of Ambient Stable Naphthalenediimide Radical Ions

Kumar

Malik

Shukla

et al. 2019

Chemistry A European J

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“…These can as well offer deeper understanding of the various multielectron‐based processes in biological systems. Also, important are the multifaceted organic radicals and radical ions that are the usual by‐products of multielectron‐based processes …”

Section: Resultsmentioning

confidence: 99%

Molecular and Supramolecular Multiredox Systems

2020

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The design and synthesis of molecular and supramolecular multiredox systems have been summarized. These systems are of great importance as they can be employed in the next generation of materials for energy storage, energy transport, and solar fuel production. Nature provides guiding pathways and insights to judiciously incorporate and tune the various molecular and supramolecular design aspects that result in the formation of complex and efficient systems. In this review, we have classified molecular multiredox systems into organic and organic‐inorganic hybrid systems. The organic multiredox systems are further classified into multielectron acceptors, multielectron donors and ambipolar molecules. Synthetic chemists have integrated different electron donating and electron withdrawing groups to realize these complex molecular systems. Further, we have reviewed supramolecular multiredox systems, redox‐active host‐guest recognition, including mechanically interlocked systems. Finally, the review provides a discussion on the diverse applications, e. g. in artificial photosynthesis, water splitting, dynamic random access memory, etc. that can be realized from these artificial molecular or supramolecular multiredox systems.

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“…[7] Stable radicals are of particular interest to the scienti c community for their potential applications in catalysis, [8][9] [10] organic light-emitting diodes (OLEDs) [11] [12] [13] and other materials applications. [14][15] [16] [17] In recent years, organic radicals have received increasing interest due to their involvement in the fast growing eld of photocatalysis. [18] [19] During photoinduced electron transfer (PET) processess, an electron transfer occurs between the excited state of an organic photocatalyst (PC) and an electrochemically matching substrate, resulting in the formation of an organic radical.…”

Section: Introductionmentioning

confidence: 99%

Stable Helicene Radicals: Synthesis, Structure, Physical Properties, and Photocatalysis

Shaikh

Hossain

Moutet

et al. 2020

Preprint

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Stable organic radicals have gained considerable attention in the fields of catalysis and material sciences. In particular, helical molecules are of great interest in the development and application of novel organic radicals in optoelectronic and spintronic materials. Here we report the syntheses of highly stable neutral quinolinoacridine radicals by chemical reduction of their quinolinoacridinium cation analogs. The crystal structures of these [4]helicene radicals were determined by X-ray diffraction. Electron paramagnetic resonance (EPR) measurements, supported by density functional theory (DFT) calculations, indicate that the unpaired electron is mostly localized, showing more than 40% of spin density located at the central carbon of the [4]helicene radicals. Quantitative conversion from neutral radical to cation is observed upon exposure to air, monitored via UV-vis spectroscopy. The successful photoreductive dehalogenation of aryl halides occurs in the presence of 10 mol% of [4]helicene radical under blue light.

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Recent Advances in Organic Radicals and Their Magnetism

Cited by 97 publications

References 163 publications

Ionic Assembly, Anion–π, Magnetic, and Electronic Attributes of Ambient Stable Naphthalenediimide Radical Ions

Ionic Assembly, Anion–π, Magnetic, and Electronic Attributes of Ambient Stable Naphthalenediimide Radical Ions

Molecular and Supramolecular Multiredox Systems

Stable Helicene Radicals: Synthesis, Structure, Physical Properties, and Photocatalysis

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