TY - JOUR
T1 - Cation–π interactions in competition with cation microhydration
T2 - a theoretical study of alkali metal cation–pyrene complexes
AU - Pašalić, Hasan
AU - Aquino, Adelia J.A.
AU - Tunega, Daniel
AU - Haberhauer, Georg
AU - Gerzabek, Martin H.
AU - Lischka, Hans
N1 - Funding Information:
Open access funding provided by University of Natural Resources and Life Sciences Vienna (BOKU). This work was supported by the Austrian Science Fund, project no. P20893-N19, and the Deutsche Forschungsgemeinschaft (SPP 1315), project no. GE1676/1-1. Computer time at the Vienna Scientific Cluster, project no. 70544, is gratefully acknowledged.
Publisher Copyright:
© 2017, The Author(s).
PY - 2017/4/1
Y1 - 2017/4/1
N2 - Cation–π interactions were systematically investigated for the adsorption of H+ and alkali metal cations M+ to pyrene by means of Møller–Plesset perturbation theory (MP2) and density functional theory (DFT). The main aims were to determine the preferred adsorption sites and how the microhydration shell influences the adsorption process. The preferred adsorption sites were characterized in terms of structural parameters and energetic stability. Stability analysis of the M+–pyrene complexes revealed that the binding strength and the barrier to transitions between neighboring sites generally decreased with increasing cation size from Li+ to Cs+. Such transitions were practically barrierless (<<1 kcal/mol) for the large Rb+ and Cs+ ions. Further, the influence of the first hydration shell on the adsorption behavior was investigated for Li+ and K+ as representatives of small and large (alkali metal) cations, respectively. While the isolated complexes possessed only one minimum, two minima—corresponding to an inner and an outer complex—were observed for microhydrated complexes. The small Li+ ion formed a stable hydration shell and preferentially interacted with water rather than pyrene. In contrast, K+ favored cation–π over cation–water interactions. It was found that the mechanism for complex formation depends on the balance between cation–π interactions, cation–water complexation, and the hydrogen bonding of water to the π-system.
AB - Cation–π interactions were systematically investigated for the adsorption of H+ and alkali metal cations M+ to pyrene by means of Møller–Plesset perturbation theory (MP2) and density functional theory (DFT). The main aims were to determine the preferred adsorption sites and how the microhydration shell influences the adsorption process. The preferred adsorption sites were characterized in terms of structural parameters and energetic stability. Stability analysis of the M+–pyrene complexes revealed that the binding strength and the barrier to transitions between neighboring sites generally decreased with increasing cation size from Li+ to Cs+. Such transitions were practically barrierless (<<1 kcal/mol) for the large Rb+ and Cs+ ions. Further, the influence of the first hydration shell on the adsorption behavior was investigated for Li+ and K+ as representatives of small and large (alkali metal) cations, respectively. While the isolated complexes possessed only one minimum, two minima—corresponding to an inner and an outer complex—were observed for microhydrated complexes. The small Li+ ion formed a stable hydration shell and preferentially interacted with water rather than pyrene. In contrast, K+ favored cation–π over cation–water interactions. It was found that the mechanism for complex formation depends on the balance between cation–π interactions, cation–water complexation, and the hydrogen bonding of water to the π-system.
KW - Alkali metal cation–pyrene
KW - Cation–π interactions
KW - DFT
KW - Microhydration
UR - http://www.scopus.com/inward/record.url?scp=85015979815&partnerID=8YFLogxK
U2 - 10.1007/s00894-017-3302-3
DO - 10.1007/s00894-017-3302-3
M3 - Article
C2 - 28337678
AN - SCOPUS:85015979815
VL - 23
JO - Journal of Molecular Modeling
JF - Journal of Molecular Modeling
SN - 1610-2940
IS - 4
M1 - 131
ER -