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Tytuł:
Chiral surface networks of 3-HPLN : a molecular analog of rounded triangle assembly
Autorzy:
Beniwal, Sumit
Kunkel, Donna
Simpson, Scott
Enders, Axel
Zurek, Eva
Hooper, James
Opis:
The self-assembly of 3-hydroxyphenalenone (3-HPLN) on the Ag(111) surface has been studied with scanning tunnelingmicroscopyand fi rst-principlescomputations.Theprochiral3-HPLNmoleculeformszipper-likechains when deposited on the Ag(111) surface, representing a 2D analog of their arrangement in bulk crystals. Upon annealing, local chiral trimer motifs form and serve as building blocks in extended 2D supramolecular networks not observed in 3D crystals. The extended network is porous and is held together via weak van der Waals interactions. The dispersion forces between trimers suggest that their handedness is overall racemic, but the asymmetric packing of 3-HPLN trimers around the pores leads to a chiral network. The offset alignment of neighboring 3-HPLN molecules in the unit cell resembles the offset between neighboring particles that are seen in the most ef fi cient packings of rounded triangles. Computations illustrate that charge is transferred from the Ag(111) surface to the lowest unoccupied orbital of 3-HPLN, and a number of networks (including a honeycomb, as well as an alternative close-packed arrangement) are investigated.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Kagome lattice of pi-pi stacked 3-hydroxyphenalenone on Cu(111)
Autorzy:
Hooper, James
Zeng, X.
Enders, Axel
Chen, S.
Zurek, Eva
Kunkel, Donna
Beniwal, Sumit
Simpson, Scott
Opis:
We have identified a structurally complex double-layer of 3-hydroxy- phenalenone on Cu(111), which exhibits Kagome lattice symmetry. A key feature is the perpendicular attachment of p – p stacked mole- cular dimers on top of molecules that are flat-lying on the substrate, representing a rare example of a three-dimensional arrangement of molecules on a two-dimensional surface.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Rhodizonic acid on noble metals : surface reactivity and coordination chemistry
Autorzy:
Hooper, James
Enders, Axel
Cousins, Kimberley
Morrow, Katie L.
Zurek, Eva
Kunkel, Donna A.
Beniwal, Sumit
Ducharme, Stephen
Smith, Douglas C.
Simpson, Scott
Opis:
A study of the two-dimensional crystallization of rhodizonic acid on the crystalline surfaces of gold and copper is presented. Rhodizonic acid, a cyclic oxocarbon related to the ferroelectric croconic acid and the antiferroelectric squaric acid, has not been synthesized in bulk crystalline form yet. Capitalizing on surface-assisted molecular self- assembly, a two-dimensional analogue to the well-known solution-based coordination chemistry, two-dimensional structures of rhodizonic acid were stabilized under ultrahigh vacuum on Au(111) and Cu(111) surfaces. Scanning tunneling microscopy, coupled with fi rst-principles calculations, reveals that on the less reactive Au surface, extended two- dimensional islands of rhodizonic acid are formed, in which the molecules interact via hydrogen bonding and dispersion forces. However, the rhodizonic acid deprotonates into rhodizonate on Cu substrates upon annealing, forming magic clusters and metal − organic coordination networks with substrate adatoms. The networks show a 2:1 distribution of rhodizonate coordinated with 3 and 6 Cu atoms, respectively. The stabilization of crystalline structures of rhodizonic acid, structures not reported before, and their transition into metal − organic networks demonstrate the potential of surface chemistry to synthesize new and potential useful organic nanomaterials.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Self-assembly of strongly dipolar molecules on metal surfaces
Autorzy:
Hooper, James
Miller, Daniel P.
Enders, Axel
Braunstein, Pierre
Routaboul, Lucie
Skomski, Ralph
Zurek, Eva
Doudin, Bernard
Kunkel, Donna A.
Beniwal, Sumit
Dowben, Peter
Simpson, Scott
Opis:
The role of dipole-dipole interactions in the self-assembly of dipolar organic molecules on surfaces is investigated. As a model system, strongly dipolar model molecules, p-benzoquinonemonoimine zwitterions (ZI) of type C6H2(⋯ NHR)2(⋯ O)2 on crystalline coinage metal surfaces were investigated with scanning tunneling microscopy and first principles calculations. Depending on the substrate, the molecules assemble into small clusters, nano gratings, and stripes, as well as in two-dimensional islands. The alignment of the molecular dipoles in those assemblies only rarely assumes the lowest electrostatic energy configuration. Based on calculations of the electrostatic energy for various experimentally observed molecular arrangements and under consideration of computed dipole moments of adsorbed molecules, the electrostatic energy minimization is ruled out as the driving force in the self-assembly. The structures observed are mainly the result of a competition between chemical interactions and substrate effects. The substrate’s role in the self-assembly is to (i) reduce and realign the molecular dipole through charge donation and back donation involving both the molecular HOMO and LUMO, (ii) dictate the epitaxial orientation of the adsorbates, specifically so on Cu(111), and (iii) inhibit attractive forces between neighboring chains in the system ZI/Cu(111), which results in regularly spaced molecular gratings.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Wyświetlanie 1-10 z 12

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