1176903-74-4Relevant academic research and scientific papers
Cooperative Magnetism in Crystalline N-Aryl-Substituted Verdazyl Radicals: First-Principles Predictions and Experimental Results
Eusterwiemann, Steffen,Dresselhaus, Thomas,Doerenkamp, Carsten,Janka, Oliver,Niehaus, Oliver,Massolle, Anja,Daniliuc, Constantin G.,Eckert, Hellmut,P?ttgen, Rainer,Neugebauer, Johannes,Studer, Armido
, p. 6069 - 6082 (2017)
We report on a series of eight diaryl-6-oxo-verdazyl radicals containing a tert-butyl group at the C(3) position with regard to their crystal structure and magnetic properties by means of magnetic susceptibility measurements in combination with quantum chemical calculations using a first-principles bottom-up approach. The latter method allows for a qualitative prediction and detailed analysis of the correlation between the solid-state architecture and magnetic properties. Although the perturbation in the molecular structure by varying the substituent on the N-aryl ring may appear small, the effects upon the structural parameters controlling intermolecular magnetic coupling interactions are strong, resulting in a wide spectrum of cooperative magnetic behavior. The non-substituted 1,5-diphenyl-tert-butyl-6-oxo-verdazyl radical features a ferromagnetic one-dimensional spin ladder type magnetic network—an extremely rarely observed phenomenon for verdazyl radicals. By varying substituents at the phenyl group, different non-isostructural compounds were obtained with widely different magnetic motifs ranging from linear and zigzag one-dimensional chains to potentially two-dimensional networks, from which we predict magnetic susceptibility data that are in qualitative agreement with experiments and reveal a large sensitivity to packing effects of the molecules. The present study advances the fundamental understanding between solid-state structure and magnetism in organically based radical systems.
N^N Pt(II) Bisacetylide Complexes with Oxoverdazyl Radical Ligands: Preparation, Photophysical Properties, and Magnetic Exchange Interaction between the Two Radical Ligands
Gurzadyan, Gagik G.,Lee, Jin Yong,Li, Xiaoxin,Lim, Jong Hyeon,Meng, Yinshan,Sukhanov, Andrei A.,Sun, Haoling,Voronkova, Violeta K.,Yang, Wenbo,Zhao, Jianzhang
supporting information, p. 12471 - 12485 (2020/09/15)
To study the effect of a stable radical on the photophysical properties of a phosphorescent Pt(II) coordination framework and the intramolecular magnetic interaction between radical ligands in the N^N Pt(II) bisacetylide complexes, we prepared a series of
An oxo-verdazyl radical for a symmetrical non-aqueous redox flow battery
Cekic-Laskovic, Isidora,Grünebaum, Mariano,Korshunov, Aleksandr,Milner, Matthew James,Studer, Armido,Winter, Martin
supporting information, p. 22280 - 22291 (2020/11/11)
Verdazyl free radical compounds are promising candidates for symmetrical all-organic redox flow batteries (RFBs) due to their redox stability, the ease with which their chemical structure can be varied, and their unique bipolar nature. The present work re
Intersystem Crossing in Naphthalenediimide–Oxoverdazyl Dyads: Synthesis and Study of the Photophysical Properties
Hussain, Mushraf,Taddei, Maria,Bussotti, Laura,Foggi, Paolo,Zhao, Jianzhang,Liu, Qingyun,Di Donato, Mariangela
supporting information, p. 15615 - 15627 (2019/11/19)
Oxoverdazyl (Vz) radical units were covalently linked to the naphthalenediimide (NDI) chromophore to study the effect of the radical on the photophysical properties, especially the radical enhanced intersystem crossing (REISC), which is a promising approach to develop heavy-atom-free triplet photosensitizers. Rigid phenyl or ethynylphenyl linkers between the two moieties were used, thus REISC and formation of doublet (D1, total spin quantum number S=1/2) and quartet states (Q1, S=3/2) are anticipated. The photophysical properties of the dyads were studied with steady-state and femtosecond/nanosecond transient absorption (TA) spectroscopies and DFT computations. Femtosecond transient absorption spectra show a fast electron transfer (1→D0 decay, and the slow decay component (2.0 μs; 20 %) to the Q1→D0 ISC. DFT computations indicated ferromagnetic interactions between the radical and chromophore (J=0.07–0.13 eV). Reversible formation of the radical anion of the NDI moiety by photoreduction of the radical-NDI dyads in the presence of sacrificial electron donor triethanolamine (TEOA) is achieved. This work is useful for design of new triplet photosensitizers based on the REISC effect.
Towards reliable references for electron paramagnetic resonance parameters based on quantum chemistry: The case of verdazyl radicals
Massolle, Anja,Dresselhaus, Thomas,Eusterwiemann, Steffen,Doerenkamp, Carsten,Eckert, Hellmut,Studer, Armido,Neugebauer, Johannes
, p. 7661 - 7675 (2018/03/25)
We present an efficient and accurate computational procedure to calculate properties measurable by EPR spectroscopy. We simulate a molecular dynamics (MD) trajectory by employing the quantum mechanically derived force field (QMDFF) [S. Grimme, J. Chem. Theory Comput., 2014, 10, 4497] and sample the trajectory at different time steps. For each snapshot EPR properties are calculated with a hybrid density functional theory (DFT) method. EPR spectra are simulated based on the averaged results. We applied the strategy to a number of previously published and novel verdazyl radicals, for which we recorded EPR spectra. The resulting simulated spectra are compatible with experiment already before employing an additional fitting step, in contrast to those from single point electronic-structure calculations. After the refinement, the experimental data are excellently reproduced, and the fitted EPR parameters do not deviate much from the calculated ones. This provides confidence in ascribing a direct physical meaning to the refined data in terms of experimental EPR parameters rather than merely considering them as mathematical fit parameters. We also find that couplings to hydrogen nuclei have a significant influence on the spectra of verdazyl radicals.
