Synthesis, Characterization, and Rotational Dynamics of Crystalline Molecular Compasses with N-Heterocyclic Rotators

• DOI: 10.1021/jo901261j
• Publication Date: 2009-10-22T12:57:33Z
• Authors: Braulio Rodriguez...; Ma. Eugenia Ochoa; Norberto Farfán; Rosa Santillan; Miguel A. García-...
• Keywords: Carbon-13 NMR satellite; Pyridazine; Deuterium NMR

We describe in this paper the synthesis, crystallization, and solid-state NMR dynamics of molecules intended to emulate structure function macroscopic compasses. The desired structures consist polar pyridine (2) pyridazine (3) groups as well their corresponding N-oxides (2O 3O), each linked axially two bulky triphenyl methyl by 1,4-triple bonds. are such that central heterocycles may rotate about dialkyne axle while being sterically shielded trityl groups. In addition synthesis samples with natural isotopic abundance, we preparation 2-d(2) 3-d(30), one labeled deuteria rotator other fully deuterated stator. Crystal 2 3 revealed packing motifs analogous those previously reported for prepared substituted phenylene rotators. While measurements (13)C CPMAS insufficient chemical shift dispersion a dynamic characterization rotation compounds (including 3-d(30)), use quadrupolar echo (2)H methods rotational site exchange barrier ca. 8.5 kcal/mol (35.5 kJ mol(-1)) group 2.