Is Molecular Chirality Connected to Supramolecular Chirality? The Particular Case of Chiral 2‑Pyridyl Alcohols

Ten
structurally related racemic 2-pyridylmethyl alcohols containing
an o-carborane core (1,2-closo-C2B10H10; rac-1a) or m-carborane (1,7-closo-C2B10H10; rac-2a) or p-carborane (1,7-closo-C2B10H10; rac-3a) and their enantiopure forms (R- and S-1a or R- and S-2a or R- and S-3a), as well as an iodo derivative of rac-3a (rac-4a) and a non-carborane derivative
(C6H5; rac-5)
have been studied by single crystal X-ray crystallography. All racemic
and enantiopure structures show O–H···N hydrogen
bonded homochiral 21-helical networks, except that for rac-3a, which forms O–H···N
hydrogen bonded trimers. A comparison of these X-ray structures with
that for others found in the Cambridge Structural Database for chiral
2-pyridyl alcoholseither in racemic or enantiopure formsthat
form O–H···N hydrogen bonded homochiral 21-helical networks reveals a possible relationship between
the torsion angle of the hydrogen bond donor and acceptor groups in
these molecules and the hydrogen bonded supramolecular helices formed
in the solid state.