Biomedical subjects

Aaron W McLean

Publications and source records attributed to Aaron W McLean.

3 recordsLinked to original sources

PubMed2004

sp-9-(o-Methylphenyl)fluorene.

While the barriers of rotation of the sp and ap rotamers of 9-(o-methylphenyl)fluorene, C(20)H(16), are sufficiently similar to permit them to equilibrate, both being observed (NMR) in solution, crystallization provides the sp rotamer, (I), exclusively. Although in the sp conformation the intramolecular distance between adjacent C atoms of the phenyl and fluorene rings is small [3.382 (4) A, within 0.02 A of the sum of the van der Waals radii], in the ap conformation the distance between the adjacent o-CH(3) group on the phenyl ring and C atom of the fluorene ring would be much closer, based on that exhibited in the crystalline ap progenitor 9-(o-methylphenyl)-9-fluorenol. The angle between the fluorene and 9-aryl planes of (I) is 75.82 (10) degrees.

Journal Article↗

PubMed2003

ap-9-(o-Methylphenyl)-9-fluorenol, a structure exhibiting several aryl-H...pi(arene) intermolecular interactions.

The title compound, C(20)H(16)O, (I), which crystallized exclusively as its ap rotamer, exhibits several intermolecular aryl-H.pi(arene) interactions, resulting in planar molecular arrays in which each molecule interacts with six adjacent molecules. Surprisingly, there were no O-H.O-H or O-H.pi(arene) interactions within hydrogen-bonding distances. Crystalline (I) melted sharply without molecular decomposition (NMR), but the cooled melt recrystallized only after several hours.

Journal Article↗

PubMed2003

ap-9-(meta-tert-butylphenyl)fluorene.

The title compound, C(23)H(22), (I), crystallizes in an ap conformationThe designations sp (synperiplanar) and ap (antiperiplanar) for these fluorene rotamers are in accordance with Rule E-6.6, IUPAC Tentative Rules, Section E, Fundamental Stereochemistry [J. Org. Chem. (1970), 35, 2861]. and its melt readily recrystallizes on cooling, in contrast to the corresponding 9-fluorenol compound, (II), which is sp and which melts without decomposition and fails to recrystallize over a long period. Both of these differences are ascribed to the intermolecular hydrogen bonding in (II), which is absent in (I) and which leads to distinctly different molecular packing in the two compounds.

Journal Article↗