Inclusion complexes of selected amines with pillar[5]arenes: experimental and molecular dynamics study

Selected amines were allowed to form inclusion complexes with selected synthesized pillar[5]arenes. Formation of inclusion complexes were confirmed by MALDI–TOF, ESI–MS analyses and 1 H NMR spectroscopy. The complexation was supported by molecular dynamics calculations. Various pillar[5]arenes have been synthesized by BF 3 ·OE t2 (Lewis acid) catalyzed cyclization of 1,4-disubstitutedbenzenes with paraformaldehyde. Selected synthesized host macrocycles; DMpillar[5]arene ( 7 ), DPpillar[5]arene ( 8a ), DPGpillar[5]arene ( 8b ) were allowed to form inclusion complexes with N -containing guests; hexamethylenediamine ( GA ), di- n -octyl amine ( GB ) and diethyl amine ( GC ). Host–guest complex formation of the selected pillar[5]arenes with the N-containing guests has been confirmed by MALDI–TOF, ESI–MS analyses and 1 H NMR spectroscopy. ESI–MS revealed highly intense ion peaks that correspond to [pillar[5]arene@GA+Na] + for inclusion complexes of pillar[5]arenes with hexamethylenediamine ( GA ). ESI–MS confirmed formation of inclusion complexes between pillar[5]arenes with di- n -octyl amine ( GB ) and diethyl amine ( GC ) as evidenced by intense peaks that corresponds to [pillar[5]arene@GB+H] + and [pillar[5]arene@GC+H] + , respectively. Performed molecular dynamics (MD) simulations provided supportive results that indicate the formation of stable complexes between the three pillar[5]arene hosts and the guests included in this study. Hydrogen bonding and CH–π interactions were found amongst the factors that contribute significantly to the stability of these complexes.