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

2020 ◽  
Author(s):  
Aslam Shaikh ◽  
Md Mubarak Hossain ◽  
Jules Moutet ◽  
Jose Veleta ◽  
Jan Bloch ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reduction ◽  
Organic Radicals ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Neutral Radical ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic ◽  
Helical Molecules

Abstract 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.

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

2020 ◽  
Author(s):  
Aslam Shaikh ◽  
Md Mubarak Hossain ◽  
Jules Moutet ◽  
Jose M Veleta ◽  
jan bloch ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reduction ◽  
Organic Radicals ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Neutral Radical ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic ◽  
Helical Molecules

<p>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.<b></b></p>

scholarly journals Persistent, Highly Localized, and Tunable [4]Helicene Radicals

2020 ◽  
Author(s):  
Aslam Shaikh ◽  
Jules Moutet ◽  
Jose M Veleta ◽  
Md Mubarak Hossain ◽  
jan bloch ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reduction ◽  
Organic Radicals ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Structural Modifications ◽  
X Ray Crystallography ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic ◽  
Helical Molecules

<p><a>Persistent organic radicals have gained considerable attention in the </a>fields of catalysis and material sciences. In particular, helical molecules are of great interest for the development and application of novel organic radicals in optoelectronic and spintronic materials. Here we report the syntheses of easily tunable and stable neutral quinolinoacridine radicals under anaerobic conditions by chemical reduction of their quinolinoacridinium cation analogs. The structures of these [4]helicene radicals were determined by X-ray crystallography. Density functional theory (DFT) calculations, supported by Electron paramagnetic resonance (EPR) measurements, indicate that over 40% of spin density is located at the central carbon of the [4]helicene radicals regardless of their structural modifications. The localization of the charge promotes a reversible oxidation to the cation upon exposure to air. This unusual reactivity toward molecular oxygen was monitored via UV-Vis spectroscopy.</p>

scholarly journals Persistent, Highly Localized, and Tunable [4]Helicene Radicals

2020 ◽  
Author(s):  
Aslam Shaikh ◽  
Jules Moutet ◽  
Jose M Veleta ◽  
Md Mubarak Hossain ◽  
jan bloch ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reduction ◽  
Organic Radicals ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Structural Modifications ◽  
X Ray Crystallography ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic ◽  
Helical Molecules

<p><a>Persistent organic radicals have gained considerable attention in the </a>fields of catalysis and material sciences. In particular, helical molecules are of great interest for the development and application of novel organic radicals in optoelectronic and spintronic materials. Here we report the syntheses of easily tunable and stable neutral quinolinoacridine radicals under anaerobic conditions by chemical reduction of their quinolinoacridinium cation analogs. The structures of these [4]helicene radicals were determined by X-ray crystallography. Density functional theory (DFT) calculations, supported by Electron paramagnetic resonance (EPR) measurements, indicate that over 40% of spin density is located at the central carbon of the [4]helicene radicals regardless of their structural modifications. The localization of the charge promotes a reversible oxidation to the cation upon exposure to air. This unusual reactivity toward molecular oxygen was monitored via UV-Vis spectroscopy.</p>

scholarly journals [CpNi(diselenolene)] Neutral Radical Complexes:  Electron Paramagnetic Resonance and Density Functional Theory Investigations

2008 ◽  
Vol 112 (17) ◽  
pp. 4067-4073 ◽  
Author(s):  
Philippe Grosshans ◽  
Prashant Adkine ◽  
Helena Sidorenkova ◽  
Mitsushiro Nomura ◽  
Marc Fourmigué ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electron Paramagnetic Resonance ◽  
Density Functional ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Neutral Radical ◽  
Electron Paramagnetic

The Interplay of manganese and nitrate in hydroxyapatite nanoparticles as revealed by pulsed EPR and DFT

2015 ◽  
Vol 17 (31) ◽  
pp. 20331-20337 ◽  
Author(s):  
Marat Gafurov ◽  
Timur Biktagirov ◽  
Georgy Mamin ◽  
Elena Klimashina ◽  
Valery Putlayev ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Hydroxyapatite Nanoparticles ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Pulsed Epr ◽  
Pulsed Electron Paramagnetic Resonance ◽  
Electron Paramagnetic ◽  
Oppositely Charged

The interplay of oppositely charged substitutions in the structure of hydroxyapatite nanopowders is investigated by pulsed electron paramagnetic resonance and ab initio density functional theory calculations.

scholarly journals DFT Protocol for EPR Prediction of Paramagnetic Cu(II) Complexes and Application to Protein Binding Sites

2018 ◽  
Vol 4 (4) ◽  
pp. 55 ◽  
Author(s):  
Giuseppe Sciortino ◽  
Giuseppe Lubinu ◽  
Jean-Didier Maréchal ◽  
Eugenio Garribba
Keyword(s):  
Binding Sites ◽  
Density Functional ◽  
Computational Procedure ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Protein Binding Sites ◽  
The Mean ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

With the aim to provide a general protocol to interpret electron paramagnetic resonance (EPR) spectra of paramagnetic copper(II) coordination compounds, density functional theory (DFT) calculations of spin Hamiltonian parameters g and A for fourteen Cu(II) complexes with different charges, donor sets, and geometry were carried out using ORCA software. The performance of eleven functionals was tested, and on the basis of the mean absolute percent deviation (MAPD) and standard deviation (SD), the ranking of the functionals for Az is: B3LYP > B3PW91 ~ B3P86 > PBE0 > CAM-B3LYP > TPSSh > BH and HLYP > B2PLYP > MPW1PW91 > ω-B97x-D >> M06; and for gz is: PBE0 > BH and HLYP > B2PLYP > ω-B97x-D > B3PW91~B3LYP~B3P86 > CAM-B3LYP > TPSSh~MPW1PW91 >> M06. With B3LYP the MAPD with respect to A z exp t l is 8.6% with a SD of 4.2%, while with PBE0 the MAPD with respect to g z exp t l is 2.9% with a SD of 1.1%. The results of the validation confirm the fundamental role of the second order spin-orbit contribution to Az. The computational procedure was applied to predict the values of gz and Az of the adducts formed by Cu(II) with albumin and two fragments of prion protein, 106–126 and 180–193.

Distribution of the unpaired electron in neutral bis(phthalocyaninato) yttrium double-deckers: An experimental and theoretical combinative investigation

2018 ◽  
Vol 22 (01n03) ◽  
pp. 165-172 ◽  
Author(s):  
Xin Chen ◽  
Yuxiang Chen ◽  
Ming Bai ◽  
Chiming Wang ◽  
Dongdong Qi ◽  
...  
Keyword(s):  
Unpaired Electron ◽  
Density Functional ◽  
Population Distribution ◽  
Experimental Methods ◽  
Molecular Structures ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Double Decker ◽  
Tetrapyrrole Chromophores ◽  
Electron Paramagnetic

The location of the unpaired electron in neutral bis(phthalocyaninato) yttrium double-decker complexes, with different substituents, has been studied on the basis of both experimental methods and density functional theory (DFT) calculations over the molecular structures, atomic charges, electronic absorption, infrared spectra, and electron paramagnetic resonance. The results reveal the location of the unpaired electron mainly on the carbon atoms of both tetrapyrrole chromophores with the population distribution obviously affected by the peripheral substituents.

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