Rational design of a nonbasic molecular receptor for selective NH4+/K+ complexation in the gas phase.

摘要: A new molecular receptor (1) for ammonium recognition has been designed and constructed by using only carbon atoms. This can co-exist in two different isoenergetic conformations but, upon complexation, the conformers are no longer isoenergetic, a basket-shaped conformation becomes clearly more stable. The pre-organised tetrahedral structure of this molecule favours complexation ions N-H⋅⋅⋅π interactions with four phenyl groups host. similar behaviour is not observed similar, but less pre-organised, reference molecule. ESI-MS competition experiments show that 1 able to bind NH(4)(+) over K(+) selectively. first example neutral shows remarkable NH(4)(+)/K(+) selectivity. DFT-calculations provide insight into nature host-guest both 1⋅NH(4)(+) 1⋅K(+) complexes as well mechanism involved multiple cation-π influence these on conformational stability selective binding