Alkali metal mediated resorcarene capsules: an ESI-FTICRMS study on gas-phase structure and cation binding of tetraethyl resorcarene and its per-methylated derivative

J Am Soc Mass Spectrom. 2002 Jul;13(7):851-61. doi: 10.1016/S1044-0305(02)00382-3.

Abstract

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) with additional ab initio calculations were used to examine the alkali metal cation binding selectivity (i.e., molecular recognition) and host properties of tetraethyl resorcarene (1) and its per-methylated derivative (2). The significance of intramolecular hydrogen bonding for the crown conformation was demonstrated. The presence of intramolecular flip-flop hydrogen bonding in 1 was confirmed both with calculations and in ND3-exchange experiments. All the alkali metal cations formed host-guest complexes by docking inside the cavity of the host. Complexation with the larger cations, especially Cs+, was favored. All the alkali metal cations also formed dimeric resorcarene capsules with 1. The capsules were directly H-bonded species, with no linking solvent molecules. ND3-exchange experiments and molecular modeling revealed the significance of direct intermolecular H-bonding for the crown conformation of 1 and stability of the capsule structure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkalies / chemistry*
  • Fourier Analysis
  • Hydrogen Bonding
  • Metals / chemistry
  • Methylation
  • Models, Molecular
  • Molecular Conformation
  • Polycyclic Compounds / chemical synthesis*
  • Spectrometry, Mass, Electrospray Ionization

Substances

  • Alkalies
  • Metals
  • Polycyclic Compounds