Microsolvation of dimethylphosphate: a molecular model for the interaction of cell membranes with waterElectronic supplementary information (ESI) available: Cartesian coordinates for all optimized geometries. See DOI: 10.1039/c2cp42778h

We present an exhaustive stochastic search of the quantum conformational spaces of the (CH 3 O) 2 PO 2 − + n H 2 O ( n = 1,2,3) systems. We uncover structural, conformational and energetic features of the problem. As in the isolated species, clusters containing the gauche - gauche ( gg ) conformation of dimethylphosphate (DMP − ) are energetically preferred, however, contributions from hydrated gauche - anti ( ga ) and anti - anti ( aa ) monomers cannot be neglected because such structures are quite common and because they are close in energy to those containing the gg monomer. At least seven distinct types of O H-O-H contacts lead to DMP − ↔ water interactions that are always stabilizing, but not strong enough to induce significant changes in the geometries of either DMP − or water units. Our results lead us to postulate DMP − to be a suitable model to study explicit and detailed aspects of microsolvation of cell membranes. Dimethylphosphate is a suitable model to study water ↔ cell membrane interactions at the molecular level.