On the Molecular-Level Interactions Between Pyridine and Pittsburgh No. 8 Coal

The poly-cyclic units of Pittsburgh No. 8 coal (PIT), on the average, lie in short-range structural domains of ca. three layers. The species C14H9 is consistent with the average PCA unit in PIT, and its radius is ∼2.9 Å. The average distance between the PCA layers in the short-range domains of PIT is ∼3.9 Å. The addition of pyridine molecules to PIT does not alter structuring within the PCA units to an extent measured by wide-angle X-ray scattering experiments, and it appears that the interlayer structuring within the short-range structural domains in PIT is also not altered to a measurable extent. Rather, the quasi-stable adduct is formed between the three-layer domains of PIT and the pyridine molecules.