Synthesis and Preferred All-syn Conformation of C3-Symmetrical N-(Hetero)arylmethyl Triindoles

A new series of C-3-symmetrical N-(hetero)arylmethyl triindoles has been synthesized in a straightforward procedure. The structure and conformation in the solid state have been determined for three derivatives (3, 4, and 6) by X-ray crystallographic analysis. In all three cases. the molecules adopt a tripodal conformation with all of the flexible arms directed towards the same side. thereby delimiting an inner cavity. Compound 6 crystallizes and forms C-3-symmetric climeric cage-like complexes. Guest molecules of chloroform and water are confined within the resulting cavities with stabilization by different intermolecular interactions; this highlights the potential of these compounds in the construction of supramolecular systems. A computational analysis has been performed to predict the most stable conformers. As a general trend, a preference for a conformation with all branches directed to the same side has been predicted. Comparison between theoretical and experimental results indicates that the computational level selected for the present study, B3LYP/6-31G*, is able to reproduce both the minimum energy conformations and the rotation barriers about the N-CH2 bond.