Spin delocalization on curved surface π-system: Corannulene with iminonitroxide

Nishida, Shinsuke; Kobayashi, Tadahiro; Fukui, Kozo; Ueda, Akira; Sato, Kazunobu; Shiomi, Daisuke; Takui, Takeji; Nakasuji, Kazuhiro

doi:10.1016/j.poly.2005.03.041

Cited by 20 publications

(4 citation statements)

References 26 publications

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“…Quite recently, a bowl-shaped neutral radical incorporating a corannulene system has been designed and synthesized for the first time as a stable solid in air. In this case, it has been established that an appreciable amount of spin delocalization extends onto the corannulene unit’s curved surface . Corannulene chemistry has also started to become a very intriguing research subject in the field of metal complexes with π-electron curved surface ligands …”

Section: Introductionmentioning

confidence: 99%

Electrochemical and Theoretical Investigation of Corannulene Reduction Processes

et al. 2009

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The voltammetric generation of corannulene anions was investigated over a large range of experimental conditions comprising either "traditional" electrochemical solvents, such as dimethylformamide, acetonitrile, and tetrahydrofuran, or "unconventional" solvents, such as liquid ammonia, liquid methylamine, or liquid dimethylamine, and several different supporting electrolytes. Strong ion pairing effects were found to dominate the electrochemical generation of corannulene higher anions, and through the suitable choice of the solvent/electrolyte system, we observed, for the first time, the reversible electrochemical generation of up to the triply reduced corannulene. The standard potentials obtained experimentally compared rather well with the theoretical values calculated by ab initio and density functional methods, in which solvation and ion pairing effect were explicitly taken into account. In particular, the calculations considered the effect of the electrolyte cation size on ion pairing in order to rationalize the occurrence of the third reduction within the experimental potential window.

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Section: Introductionmentioning

confidence: 99%

Electrochemical and Theoretical Investigation of Corannulene Reduction Processes

et al. 2009

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“…In this study, a small inclusion amount of PhNN (Scheme b) in TPP nanochannels was achieved by means of coinclusion with spacers according to the synthetic process reported in ref . In addition, a small inclusion amount of 4-phenyliminonitroxide (PhIN; − Scheme c) radical was also attained in the TPP nanochannels by a similar synthetic process. Temperature-dependent ESR measurements were used to determine the g and hyperfine (A) tensors for PhNN and PhIN in TPP nanochannels, and their molecular orientation and dynamics were clarified in detail by spectral reproduction using EasySpin. , In particular, the g and A tensors for PhIN have rarely been reported, let alone the molecular dynamics in confined spaces.…”

Section: Introductionmentioning

confidence: 80%

Electron Spin Resonance Study of Molecular Orientation and Dynamics of Phenyl Imino and Nitronyl Nitroxide Radicals in Organic 1D Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene

et al. 2018

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Imino and nitronyl nitroxide (IN and NN, respectively) radicals such as phenyliminonitroxide (PhIN) and phenylnitronylnitroxide (PhNN), respectively, were dispersed in the organic 1D nanochannels of tris( o-phenylenedioxy)cyclotriphosphazene (TPP). Electron spin resonance (ESR) measurements were conducted on these inclusion compounds (ICs) in the temperature range 4.2-300 K. The modulated-septet ESR spectra of TPP ICs using PhIN observed in the range 165-258 K were reproduced with the EasySpin program package using a model in which some of the PhIN molecules underwent uniaxial rotational diffusion in the TPP nanochannels around the molecular long axis corresponding to the principal y-axis of the g tensor. However, for the TPP IC using PhNN, complicated ESR spectra were observed, which were not consistent with the modulated quintet observed in solution or in the fast-motion limit in solids. These spectra were reproduced by the superposition of a quintet originating from rotational diffusion of PhNN molecules and a septet based on rotational diffusion of PhIN molecules generated in the synthetic process. The rotational diffusion activation energies of PhIN and PhNN in the TPP nanochannels were estimated to be 19 and 45 kJ mol using an Arrhenius plot, respectively. These were consistent with that for NN radicals in the 1D nanochannels of 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine (CLPOT) (37-54 kJ mol) with a larger pore diameter than TPP reported in our previous study, or with that for 4-substituted-2,2,6,6-tetramethyl-1-piperidinyloxyl (4-X-TEMPO) in TPP nanochannels (5-26 kJ mol) with regard to molecular size or host-guest or guest-guest interactions. These results indicate that not only the NN group but also IN may be used for the clarification of chemical or biological structures of nanomaterials such as nanosized cavities.

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“…Regarding dual P/SC functional elements alternative to anthracene, there are the silole luminophore,74, 75 and pyrene,10c, f as well as metallo‐porphyrins76 or metallo‐phtalocyanines,77 and even corannulene78 or fullerene79 derivatives.…”

Section: Resultsmentioning

confidence: 99%

Reaching Optimal Light‐Induced Intramolecular Spin Alignment within Photomagnetic Molecular Device Prototypes

Ciofini

Adamo

Teki

et al. 2008

Chemistry A European J

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Ground-state (GS) and excited-state (ES) properties of novel photomagnetic molecular devices (PMMDs) are investigated by means of density functional theory. These organic PMMDs undergo a ferromagnetic alignment of their intramolecular spins in the lowest ES. They are comprised of: 1) an anthracene unit (An) as both the photosensitizer (P) and a transient spin carrier (SC) in the triplet ES ((3)An*); 2) imino-nitroxyl (IN) or oxoverdazyl (OV) stable radical(s) as the dangling SC(s); and 3) bridge(s) (B) connecting peripheral SC(s) to the An core at positions 9 and 10. Improving the efficiency of the PMMDs involves strengthening the ES intramolecular exchange coupling (J(ES)) between transient and persistent SCs, hence the choice of 2-pyrimidinyl (pm) as B elements to replace the original p-phenylene (ph). Dissymmetry of the pm connectors leads to [SC-B-P-B-SC] regio-isomers int. and ext., depending on whether the pyrimidinic nitrogen atoms point towards the An core or the peripheral SCs, respectively. For the int. regio-isomers we show that the photoinduced spin alignment is significantly improved because the J(ES)/k(B) value is increased by a factor of more than two compared with the ph-based analogue (J(ES)/k(B)>+400 K). Most importantly, we show that the optimal J(ES)/k(B) value ( approximately +600 K) could be reached in the event of an unexpected saddle-shaped structural distortion of the lowest ES. Accounting for this intriguing behavior requires dissection of the combined effects of 1) borderline intramolecular steric hindrance about key An-pm linkages, which translates into the flatness of the potential energy surface; 2) spin density disruption due to the presence of radicals; and 3) possibly intervening photochemistry, with An acting as a light-triggered electron donor while pm, IN, and OV behave as electron acceptors. Finally, potentialities attached to the [(SC)-pm-An-pm](int) pattern are disclosed.

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Spin delocalization on curved surface π-system: Corannulene with iminonitroxide

Cited by 20 publications

References 26 publications

Electrochemical and Theoretical Investigation of Corannulene Reduction Processes

Electrochemical and Theoretical Investigation of Corannulene Reduction Processes

Electron Spin Resonance Study of Molecular Orientation and Dynamics of Phenyl Imino and Nitronyl Nitroxide Radicals in Organic 1D Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene

Reaching Optimal Light‐Induced Intramolecular Spin Alignment within Photomagnetic Molecular Device Prototypes

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