Steric group enforced aromatic cyclic trimer conformer in tripodal moleculesElectronic supplementary information (ESI) available: X-ray crystallographic file in CIF format for 1, 3 and 5. Molecular structure of 1, optimized geometry, NMR spectra, and tables of XRD data. CCDC 1419799, 1051126 and 1051212. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ra05151g

A family of tripodal molecules ( 1-6 ) with/without steric ethyl groups at the central benzene scaffold and with furan/thiophene/pyridyl group at the 2-position of the benzimidazolyl unit was synthesised. Compounds 1-6 were characterized by elemental analysis and NMR spectroscopy. Compounds 1 , 3 , and 5 were further characterized by single crystal X-ray diffraction analysis. The molecular structures of 1 and 4 were optimized using density functional theory (DFT) calculations. X-ray and 1 H NMR studies reveal that the introduction of three ethyl groups into a central benzene scaffold of furan/thiophene/pyridyl substituted benzimidazolyl based tripodal molecules enhances the edge-to-face C-H π interactions, thereby favouring the aromatic cyclic trimer motif, in solution and the solid state. The unsubstituted central benzene scaffold allows the furan/thiophene substituted benzimidazolyl units in the tripodal molecules to move freely thereby weakening the edge-to-face C-H π interactions between the aromatic cyclic trimer motif. Molecular modelling calculations indicate that the energy minimized structures of the tripodal molecules adopt a symmetric cyclic aromatic motif conformation. A family of tripodal molecules ( 1-6 ) with/without steric ethyl groups at the central benzene scaffold and with furan/thiophene/pyridyl groups at the 2-position of the benzimidazolyl unit was synthesised.