Pairing preferences of the model mono-valence mono-atomic ions investigated by molecular simulation.
We carried out a series of potential of mean force calculations to study the pairing preferences of a series of model mono-atomic 1:1 ions with evenly varied sizes. The probabilities of forming the contact ion pair (CIP) and the single water separate ion pair (SIP) were presented in the two-dimensional plots with respect to the ion sizes. The pairing preferences reflected in these plots largely agree with the empirical rule of matching ion sizes in the small and big size regions. In the region that the ion sizes are close to the size of the water molecule; however, a significant deviation from this conventional rule is observed. Our further analysis indicated that this deviation originates from the competition between CIP and the water bridging SIP state. The competition is mainly an enthalpy modulated phenomenon in which the existing of the water bridging plays a significant role.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China.
Qiang
Q
Zhang
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China.
Ruiting
R
Zhang
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China.
Ying
Y
Zhao
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China.
HuanHuan
H
Li
College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
Yi Qin
YQ
Gao
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China.
Wei
W
Zhuang
D003198:Computer Simulation; D007477:Ions / Q000737:chemistry*; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D014867:Water / Q000737:chemistry*
D007477:Ions; D014867:Water