Formation of interesting organic supramolecular structures in the solid-state self-assembly of triphenol adducts

Utilization of the interplay of dimensionality (1D, 2D, 3D), orientation of functional groups of the building blocks, influence of rigid/flexible linking groups, and weak interactions provides an interesting route for the creation of novel supramolecular architectures in the crystal lattice. Molecular complexes of triphenol 1 with aza compounds such as pyrazine (pyz), 1,10-phenanthroline (phen), 4,4'-bipyridyl (bpy), trans-1,2-bis(4-pyridyl)ethylene (bpy-ethe), and 1,2-bis(4-pyridyl)ethane (bpy-etha) have been investigated using X-ray diffraction techniques. The rigid 3D triphenol 1 self-assembles to form a distorted ladder, which organizes into columns via O-H center dot center dot center dot O hydrogen bonds. Self-assembly of complexes 1 center dot pyz and 1 center dot bpy-ethe result in ladder-type structures with pyz and bpy-ethe molecules forming the rungs of the ladder. The molecular components in complex 1 center dot phen aggregate into 1D hydrogen-bonded chains. A 4-fold self-clathration was observed in the crystal lattice of 1 center dot bpy. Owing to the expanded lattice of the complex 1 center dot bpy-etha, one of the reactant molecules of bpy-etha fills the spaces as guest molecules. The nature of the aza groups helps to enhance the overall volume of the crystal lattice thus leading to the formation of various supramolecular assemblies.