Structural and Magnetic Modulation of a Purely Organic Open Framework by Selective Guest Inclusion

Abstract

Seek and hide! An organometallic ruthenium arene anticancer complex with ruthenium (pink ball) chelated by ethylenediamine (blue) is selective for guanine bases on DNA and can bury the noncoordinated phenyl ring of its arene ligand (yellow) between bases in the double helix.

Polychlorinated trityl radicals for dynamic nuclear polarization: the role of chlorine nuclei

“…Namely, these radicals have been successfully used as robust open-shell organic 75 synthons for the preparation of multidimensional networks showing magnetic ordering at low temperatures. 5 The three phenyl rings assume a propeller-like conformation, with dihedral angles between the phenyl rings, as determined from the crystal structures, similarly to the ones reported for 80 OX63. 6 This high out-of-plane torsion of the phenyl rings causes in these radicals a decrease in the conjugation of the π-electron system and hence affects the spin density distribution.…”

“…Substituted PTM radicals were synthesized as previosuly described. 7 OX63 is a commercial (Oxford Molecular Biotools) non-chlorinated trityl radical 5 with carboxilate groups as sodium salts in the para position. A Bruker Elexsys X-band instrument equipped with a rectangular standard cavity (TE 102) was used to record the EPR room temperature spectra.…”

“…2.0029 and 2.0021 respectively) are lower than for 3 and 4 (with six carboxylic substituents, 2.0041 and 2.0034 respectively). 19 As a reference the g-value of OX63 in H 2 O:DMSO 1:1 is 2.0031 and the EPR linewidth is 0.2 G. Thanks to the presence of large number of symmetry related 5 carbons it is possible to measure the hyperfine couplings to carbon-13 nuclei at natural abundance, observed as satellite lines. The coupling to the central carbon could not be observed.…”

“…This is probably due to fast relaxation because of the slow tumbling rate of the molecule in this viscous solvent 10 under the used experimental conditions. 20 The largest observed coupling arise from the phenyl 13 C bridgehead (ipso), followed by the phenyl 13 C in ortho (2,6) with respect to the central carbon atom, followed by the coupling with the phenyl 13 C in para (4) and meta (3,5) positions. Hyperfine 15 couplings were accurately determined by simulation of the experimental spectra.…”

“…27 They noticed that transitions implying │∆m│>1 were important in these systems. 5 For a cylindrically symmetric system in which the quadrupolar and Zeeman axes of chlorine were collinear, the transition frequencies would include simple additive combinations of the Zeeman multiple quantum terms and the quadrupolar frequencies. striking supramolecular effects that may shed light on the details of the initial polarization transfer step with different substrates.…”