Ultrafast Proton Transfer Reaction in Phenol–(Ammonia)n Clusters: An Ab-Initio Molecular Dynamics Investigation.

Abstract

The ability of phenol to transfer the proton to surrounding ammonia molecules in a phenol-(ammonia)n cluster will depend on the relative orientation of the ammonia molecules and a critical field of about 285 MV cm-1 is essential along the O–H bond for the transfer process. Ab-initio MD simulations reveal that for a spontaneous proton transfer process, the phenol molecule must be embedded in a cluster consisting of at least eight ammonia molecules, even though several local minima with proton transferred can be observed for clusters consisting of 5-7 ammonia molecules. Further, phenol solvated in large clusters of ammonia, the proton transfer is spontaneous with the proton transfer event being instantaneous (about 20-120 fs). These simulations indicate that the rate-determining step for the proton transfer process is the organization of the solvent around the OH group and the proton transfer process in phenol-(ammonia)n clusters follows a curvilinear path which includes the O–H bond elongation and out-of-plane movement of the proton and can be referred to as a “Bend-to-Break” process.

Is Dissociation of HCl in DMSO Clusters Bistable?

“…The comparison suggests that out of 554 structures, only 22 structures have a similarity index less than 0.8, which indicates that in general, the gross structure of the cluster remains almost unaltered. any exceptions with the difference in the critical electric field at the MP2 level being higher by 49 MV cm −1 , 39 which is in good agreement with the present work. Therefore, electric field calculations are a very helpful tool to quickly test the efficiency of the level of theory used to model the interactions present in the system of interest, especially in the case of proton transfer reactions.…”