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Title: Langmuir Films of Anthracene Derivatives on Liquid Mercury II: Asymmetric Molecules

Abstract

The structure and phase sequence of liquid-mercury-supported Langmuir films (LFs) of anthrone and anthralin were studied by surface tensiometry and surface-specific synchrotron X-ray diffraction. In the low-coverage phase the molecules are both side-lying, rather than the flat-lying orientation found for anthracene and anthraquinone. In the high-coverage phase, the molecules are either standing up (anthrone) or remain side-lying (anthralin) on the mercury surface. In contrast with the symmetric anthracene and anthraquinone, both high-coverage phases exhibit long-range in-plane order. The order is different for the two compounds. The structural details, the role of molecular symmetry, the oxygen side groups, and the asymmetry-induced dipole moments are discussed.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930283
Report Number(s):
BNL-80987-2008-JA
TRN: US0806724
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry C; Journal Volume: 111
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ANTHRACENE; DIPOLE MOMENTS; EXHIBITS; FILMS; LIQUIDS; MERCURY; MOLECULES; ORIENTATION; OXYGEN; SURFACES; SYMMETRY; SYNCHROTRONS; X-RAY DIFFRACTION; national synchrotron light source

Citation Formats

Tamam,L., Kraack, H., Sloutskin, E., Ocko, B., Pershan, P., Ofer, E., and Deutsch, M.. Langmuir Films of Anthracene Derivatives on Liquid Mercury II: Asymmetric Molecules. United States: N. p., 2007. Web. doi:10.1021/jp063937g.
Tamam,L., Kraack, H., Sloutskin, E., Ocko, B., Pershan, P., Ofer, E., & Deutsch, M.. Langmuir Films of Anthracene Derivatives on Liquid Mercury II: Asymmetric Molecules. United States. doi:10.1021/jp063937g.
Tamam,L., Kraack, H., Sloutskin, E., Ocko, B., Pershan, P., Ofer, E., and Deutsch, M.. Mon . "Langmuir Films of Anthracene Derivatives on Liquid Mercury II: Asymmetric Molecules". United States. doi:10.1021/jp063937g.
@article{osti_930283,
title = {Langmuir Films of Anthracene Derivatives on Liquid Mercury II: Asymmetric Molecules},
author = {Tamam,L. and Kraack, H. and Sloutskin, E. and Ocko, B. and Pershan, P. and Ofer, E. and Deutsch, M.},
abstractNote = {The structure and phase sequence of liquid-mercury-supported Langmuir films (LFs) of anthrone and anthralin were studied by surface tensiometry and surface-specific synchrotron X-ray diffraction. In the low-coverage phase the molecules are both side-lying, rather than the flat-lying orientation found for anthracene and anthraquinone. In the high-coverage phase, the molecules are either standing up (anthrone) or remain side-lying (anthralin) on the mercury surface. In contrast with the symmetric anthracene and anthraquinone, both high-coverage phases exhibit long-range in-plane order. The order is different for the two compounds. The structural details, the role of molecular symmetry, the oxygen side groups, and the asymmetry-induced dipole moments are discussed.},
doi = {10.1021/jp063937g},
journal = {Journal of Physical Chemistry C},
number = ,
volume = 111,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The structure and phase sequence of liquid-mercury-supported Langmuir films (LFs) of two symmetric acenes, anthracene and anthraquinone, were studied by surface tensiometry and X-ray diffraction. At low coverage, both form a monolayer of surface-parallel, flat-lying, molecules. At high coverage, we find a monolayer of side-lying molecules, where the molecular plane is surface-normal, and the molecular long axis is surface-parallel. None of these phases exhibit long-range in-plane order.
  • Langmuir films (LFs) of biphenyl and anthracene derivatives on the surface of liquid mercury were studied by surface-specific X-ray and surface tension measurements. Phases of lying-down, side-lying and standing-up molecules were found, some of which exhibit long-range lateral order. The molecular symmetry and the position and nature of the side-, end-, and headgroups are shown to dominate the structural evolution of the LFs with surface coverage.
  • Homo- and heterochiral Langmuir films of a chiral derivative of stearic acid are studied in situ on the surface of liquid mercury as a function of surface coverage by surface tensiometry and surface-specific synchrotron X-ray diffraction and reflectivity. A transition from a phase of surface-parallel molecules to a phase of standing-up molecules is found. The former shows no surface-parallel long-range order. The standing-up phase of both homochiral and heterochiral compositions exhibit long-range order. However, the former has an oblique unit cell with parallel molecular planes, and the later has a centered rectangular unit cell with a herringbone molecular packing. Formore » both cases, the standing-up molecules are tilted by 44 from the surface normal and pack at a density of 19.5 Angstroms2/molecule in the plane normal to the molecular long axis. Important differences are found, and discussed, between this behavior and that of a Langmuir film of the nonchiral stearic acid on mercury.« less
  • The coverage dependent phase behavior of monolayers of alkyl thiols (CH{sub 3}(CH{sub 2}){sub n-1}SH, denoted as CnSH) on mercury was studied for chain lengths 9 {le} n {le} 22, using surface tensiometry and surface-specific X-ray scattering methods. At low coverage, a disordered single layer of surface-parallel molecules is found for all n. At high coverage, a monolayer of standing-up molecules is formed, exhibiting well-ordered phases, the structure of which is n- and coverage-dependent. The molecular chains pack in a centered rectangular unit cell, with an {approx}27{sup o} tilt from the surface normal toward nearest neighbors. The strong sulfur-mercury bond inducesmore » a noncentered unit cell for the headgroups, incorporating one mercury atom per two thiol molecules. The small but significant differences in structure of these films on gold and on mercury are discussed and assigned to the different structure of the subphase: long-range-ordered crystal for gold and short-range-ordered liquid for mercury.« less
  • No abstract prepared.