Competition as a design concept: Polymorphism in self-assembled monolayers of biphenyl-based thiols

Piotr Cyganik, Manfred Buck, Thomas Strunskus, Andrei Shaporenko, James D. E. T. Wilton-Ely, Michael Zharnikov, Christof Woell

Research output: Contribution to journalReview articlepeer-review

85 Citations (Scopus)

Abstract

Self-assembled monolayers (SAMs) of two omega-(4'-methylbiphenyl-4-yl) alkanethiols (CH3(C6H4)(2)-(CH2)(n) SH, BPn, n = 4, 6) on Au(111) substrates, prepared from solution at room temperature and subsequently annealed at temperatures up to 493 K under a nitrogen atmosphere, were studied using scanning tunneling microscopy (STM), high-resolution X-ray photoelectron spectroscopy (HRXPS), and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). In striking contrast to BP n SAMs with n = odd, for which only one phase is observed, the even-numbered BP n SAMs exhibit polymorphism. Irreversible phase transitions occur which involve three phases differing substantially in density and stability. Upon annealing, BP4 and BP6 transform into a beta-phase, which is characterized by an exceptionally high structural quality with virtually defect-free domains exceeding 500 nm in diameter. Exchange experiments, monitored by contact angle measurement, reveal that the, beta-phase exhibits a dramatically improved stability. The fundamental differences in the phase behavior of even-and odd-numbered BP n SAMs are discussed in terms of two design strategies based on cooperative and competitive effects.

Original languageEnglish
Pages (from-to)13868-13878
Number of pages11
JournalJournal of the American Chemical Society
Volume128
Issue number42
DOIs
Publication statusPublished - 25 Oct 2006

Keywords

  • SCANNING-TUNNELING-MICROSCOPY
  • ALKANETHIOL MONOLAYERS
  • MOLECULAR ELECTRONICS
  • N-ALKANETHIOLS
  • THIOAROMATIC MONOLAYERS
  • BENZENETHIOL ADSORPTION
  • CYCLIC VOLTAMMETRY
  • INTERNAL-ROTATION
  • AU(111)
  • GOLD

Fingerprint

Dive into the research topics of 'Competition as a design concept: Polymorphism in self-assembled monolayers of biphenyl-based thiols'. Together they form a unique fingerprint.

Cite this