Structural characteristics of formic acid dodecamers,

Exploratory ab initio and density functional theory calculations are used to locate low-energy minima on the potential energy surface of the formic acid dodecamer ( HCOOH ) 12 . The lowest-energy structures are folded rings, some with a crown-like structure, stabilized by π – π interactions. There are many more C – H ⋯ O interactions than in smaller oligomers. Unlike in tetramers and pentamers, ring structures with one or more monomers in the E (cis) conformation are not significant for dodecamers.