title: 2D Cocrystallization from H-Bonded Organic Ferroelectrics.
abstract: The synthesis of 2D H-bonded cocrystals from the room-temperature ferroelectric organics croconic acid (CA) and 3-hydroxyphenalenone (3-HPLN) is demonstrated through self-assembly on a substrate under ultrahigh vacuum. 2D cocrystal polymorphs of varied stoichiometry were identified with scanning tunneling microscopy, and one of the observed structural building blocks consists of two CA and two 3-HPLN molecules. Computational analysis with density functional theory confirmed that the experimental (CA)2(3-HPLN)2 tetramers are lower in energy than single-component structures due to the ability of the tetramers to pack efficiently in two dimensions, the promotion of favorable electrostatic interactions between tetramers, and the optimal number of intermolecular hydrogen bonds. The structures investigated, especially the experimentally found tetrameric building blocks, are not polar. However, it is demonstrated computationally that cocrystallization can, in principle, result in heterogeneous structures with dipole moments that exceed those of homogeneous structures and that 2D structures with select stoichiometries could favor metastable polar structures.
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.
authors.forename: Donna A
authors.initials: DA
authors.lastname: Kunkel
authors.affiliation: Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University , 30-060 Krakow, Poland.
authors.forename: James
authors.initials: J
authors.lastname: Hooper
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bradley
authors.affiliation: Department of Physics, California State University at San Bernardino , San Bernardino, California 92407, United States.
authors.forename: Lisa
authors.initials: L
authors.lastname: Schlueter
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.
authors.forename: Tom
authors.initials: T
authors.lastname: Rasmussen
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.
authors.forename: Paulo
authors.initials: P
authors.lastname: Costa
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.
authors.forename: Sumit
authors.initials: S
authors.lastname: Beniwal
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.|Nebraska Center for Materials and Nanoscience, University of Nebraska , Lincoln, Nebraska 68588-0298, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Ducharme
authors.affiliation: Department of Chemistry, State University of New York at Buffalo , Buffalo, New York 14260-3000, United States.
authors.forename: Eva
authors.initials: E
authors.lastname: Zurek
authors.affiliation: Department of Physics and Astronomy, University of Nebraska , Lincoln, Nebraska 68588-0299, United States.|Nebraska Center for Materials and Nanoscience, University of Nebraska , Lincoln, Nebraska 68588-0298, United States.
authors.forename: Axel
authors.initials: A
authors.lastname: Enders