Regioselectivity in nonsymmetric methyl pentyl Pillar[5]arene bound to non-symmetric axles

• Published in: Journal of molecular graphics & modelling Vol. 94; p. 107460
• Main Authors: Athare, Sulakshana V., Gejji, Shridhar P.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.2020
• Subjects: Density functional theory; Molecular electrostatic potential; Nonsymmetric pillararenes; QTAIM; σ Hole; Molecular electrostatic potential; Density functional theory; Nonsymmetric pillararenes; σ Hole; QTAIM
• ISSN: 1093-3263; 1873-4243
• DOI: 10.1016/j.jmgm.2019.107460

The present work illustrates regioselective binding of nonsymmetric axle BuX (X = F, Cl, Br, CN) and 5-bromovaleronitrile (BVN) to the non-symmetric methyl pentyl pillar[5]arene (MPP5). Theoretical calculations reveal that the guest encapsulation within MPP5 is spontaneous and the conformer showing X weakly bound to pentyl rim of MPP5 is favoured over its other conformer wherein it interacts with methyl rim of the host. The noncovalent interactions namely C–H---π, C–H---X and H–H prevail over C–H⋯O hydrogen bonding in the complexes of MPP5. The manifestations of these to vibrational spectra obtained from the present theory are discussed. The strength of host-guest binding further is shown to correlate well with weakening of the C-X bond through natural bond orbital analyses. [Display omitted] •Theoretical study on nonsymmetric axle and nonsymmetric pillar [5]arene complexes.•The binding of halo or pseudohalo group with pentyl rim of pillararene is favoured.•C–H---π, C–H---X and H–H prevail over C–H⋯O hydrogen bonding.•The host-guest binding strength correlates with σ* occupancy in C-X bond.