138308-89-1Relevant articles and documents
Rigid Core Anthracene and Anthraquinone Linked Nitronyl and Iminoyl Nitroxide Biradicals
Akpinar, Handan,Schlueter, John A.,All?o Cassaro, Rafael A.,Friedman, Jonathan R.,Lahti, Paul M.
, p. 4051 - 4059 (2016)
The first syntheses of bis(nitronyl nitroxide) and bis(iminoyl nitroxide) (diNN, diIN) biradicals linked through rigid acene core conjugating anthracene (A) and anthraquinone (AQ) units are reported. Computational modeling predicts weak intramolecular exchange in AQ-linked systems, but A-linked biradicals to have ground state multiplicities consistent with the Borden-Davidson disjointness model. Solution electron spin resonance spectra showed inter-radical exchange-coupled triplet states, except for 2,6-AQ biradicals showing isolated spin spectra. Crystallography of the A-linked biradicals shows a key role for inter-radical contacts for molecular packing. DiINs showed lower-dimensional dyad packing with disorder at the radical units: the conformationally more symmetrical diNNs gave staircase one-dimensional or brickwork two-dimensional lattices. Core anthracene unit stacking was only seen in two systems with bromine on the central anthracene ring: the (large) bromine occupies alternate side placement in dyad stacks for the diIN, chain stacks for the diNN. Magnetism of 2,7-A-linked systems showed predominant ferromagnetic intramolecular triplet-singlet splitting of 24-28 K for diNNs and 8 K for diINs, plus weak antiferromagnetic (AFM) interactions from intermolecular contacts. The 2,6-A-linked biradicals showed AFM exchange between spins. Both A and AQ cores offer possibilities for electronic material development, with a combination of multiple radical spins and π-electron-rich acene cores.
Design, synthesis and characterization of self-assembled As 2L3 and Sb2L3 cryptands
Fontenot, Sean A.,Cangelosi, Virginia M.,Pitt, Melanie A. W.,Sather, Aaron C.,Zakharov, Lev N.,Berryman, Orion B.,Johnson, Darren W.
, p. 12125 - 12131 (2012/03/11)
The syntheses and X-ray crystal structures of six new self-assembled supramolecular As and Sb-containing cryptands are described. Analysis in the context of previously reported As2L3 and Sb 2L3 cryptands reveals that small differences in ligand geometries result in significant differences in the helicity of the complexes and the stereochemistry of the metal coordination within the assembled complexes. Additionally, a new synthetic route is described which involves exposure of reactants to vacuum to help facilitate self-assembly.
Bimolecular formation of radicals by hydrogen transfer. 14: The uncatalyzed transfer hydrogenation of α-methylstyrene by 2,6-disubstituted 9,10-dihydroanthracenes
Keller, Friedrich,Ruechardt, Christoph
scheme or table, p. 642 - 648 (2011/10/09)
2,6-Dimethoxy- (4a), 2,6-bis(dimethylamino)- (4b), 2,6-dichloro- (4c) and 2,6-dimethoxycarbonyl-9,10-dihydroanthracene (4d) were prepared by conventional methods and used as hydrogen transfer donors to α-methylstyrene (5) between 290-350°C. The mechanism
