title: Electrostatic potentials and average electron densities of bioisosteres in methylsquarate and acetic acid.
abstract: BACKGROUND
  The bioisosterism in -CO2H and -C4HO3 is exploited using the quantum theory of atoms in molecules and molecular electrostatic potentials (ESP).
  
  
  CONCLUSIONS
  Bioisosteres in methylsquarate and acetic acid, in the neutral/anionic forms, have average electron densities that differ by less than 2% (i.e., ∼0.01 atomic units) while irrespective of the capping group. The topography of the ESP reveals similarities in the case of the neutral species but not in the anionic forms.
  
  
  CONCLUSIONS
  The nonclassical bioisosteres in methylsquarate and acetic acid have average electron densities that are similar and relatively insensitive to the ionization state (neutral or anionic) or its studied capping group (H, CH3, Cl or phenyl). The ESP reveals similarities in the topography of neutral molecules.
authors.affiliation: Department of Natural Science & Public Health, Zayed University, Abu Dhabi, PO Box 144534, UAE.
authors.forename: Alya A
authors.initials: AA
authors.lastname: Arabi
authors.affiliation: Department of Chemistry & Physics, Mount Saint Vincent University, Halifax, Nova Scotia, B3M 2J6, Canada.
authors.forename: Chérif F
authors.initials: CF
authors.lastname: Matta
mesh_terms: D000085:Acetates / Q000737:chemistry*; D003503:Cyclobutanes / Q000737:chemistry*; D004583:Electrons; D011789:Quantum Theory; D055672:Static Electricity; D013237:Stereoisomerism
chemical_list: D000085:Acetates; D003503:Cyclobutanes; C030042:squaric acid
keywords: acetic acid; bioisosteres; different cap groups; electrostatic potential; methylsquarate; neutral and anionic molecules; quantum theory of atoms in molecules