Novel cavitands containing electrochemically active 4,4′-bipyridinium subunits

Abstract

The synthesis and properties of a series of novel compounds containing one to five cavitand building blocks tethered by 4,4′-bipyridinium subunits is described.

References

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4. The reaction also produced small amounts of tribromo and dibromo derivatives that we are currently trying to prepare and isolate in larger yields.
5. Crystal data for 4: C₁₀₄H₁₁₂ F₂₄N₈O₁₂P₄, M= 2245.88, triclinic, space group P1̄, a= 17.9704(9), b= 18.3237(9), c= 19.771(1)Å, α= 67.629(1), β= 67.447(1), γ= 78.767(1)°, V= 5550.9(5)ų, T= 173(2) K, Z= 2. Data were collected at 173 K on a Siemens SMART PLATFORM equipped with a CCD area detector and a graphite monochromator utilizing Mo-Kα radiation (λ= 0.71073 Å). Cell parameters were refined using up to 8192 reflections. A hemisphere of data (1381 frames) was collected using the ω-scan method (0.3° frame width). The first 50 frames were remeasured at the end of data collection to monitor instrument and crystal stability (maximum correction on I was <1%). Absorption corrections by integration were applied based on measured indexed crystal faces. The structure was solved by the direct methods in SHELXTL5, and refined using full-matrix least-squares. The non-H atoms were treated anisotropically, whereas the methyl hydrogen atoms were calculated in ideal positions and were riding on their respective carbon atoms. Two of the R groups on the cation are disordered. They were refined in two parts each with their site occupation factors dependently refined. All four of the hexafluorophosphates are disordered and were refined with their geometries constrained to form perfect octahedra around the P atoms. The structure consists of the macrocycle cation, four hexafluorophosphates and a variety of solvent molecules most of which are disordered or partially present in the lattice. Some of the solvents identified and included in the refinement include MeCN, acetone, EtOH, MeOH and water. Because of the large lattice volumes occupied by disordered solvents, a precise formula weight could not be used but instead an approximate formula was used to reflect all that was refined. It should be noted that the refinement provided acceptable anisotropic models for the cation and four anions while all of the solvents were treated isotropically. A total of 1688 parameters, with 248 constraints, were refined in the final cycle of refinement using 14505 reflections with I > 2σ(I) to yield R₁ and wR₂ of 8.46 and 20.58%, respectively. Refinement was done using F². CCDC 182/1372. See http://www.rsc.org/suppdata/cc/1999/1887/ for crystallographic data in .cif format.See, for instance: A. Mirzoian and A. E. Kaifer, Eur. J. Chem., 1997, 3, 1052.