Hydrogen-Bond-Assisted, Crossed Dipole π-Stacking in 1,4-Bis(phenylethynyl)benzene

2,5-Bis(2-hydroxyethoxy)-1,4-bis(phenylethynyl)benzene (BHE-PE2.5) was synthesized and characterized by X-ray single-crystal diffraction analysis:  formula = C26H22O4, M = 398.44, orthorhombic unit cell, Pbcn, a = 22.5520(9) Å, b = 12.9259(4) Å, c =
7.2463(2) Å, α = β = γ = 90.00(0)°, V = 2112.33(12) Å3, Z = 4, R1 = 0.1194, wR2 = 0.1455. The molecules are somewhat deplanarized,
with a 19.8° interplane torsion between phenyl rings. They form π-stacks with a centroid−centroid distance of 3.62 Å along the stack axis,
a cant angle of the central phenyl ring of 13.2° relative to the π-stack c-axis, and a 99.2° rotation of each molecule along the π-stack,
yielding crossed-dipole stacks in which the molecular long axes alternate nearly perpendicularly to one another. This unusual crossed
dipole pattern is induced by a network of hydrogen bonds that assembles the BHE-PE2.5 molecules into the stacks and further associates
the stacks into two-dimensional sheets.