Self-assembled monolayers of single-molecule magnets [Tb{Pc′(SR) 8} 2] on gold

Ulrich Glebe, Tobias Weidner, Joe E. Baio, Denise Schach, Clemens Bruhn, Axel Buchholz, Winfried Plass, Stephan Walleck, Thorsten Glaser, Ulrich Siemeling*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

15 Citations (Scopus)

Abstract

The magnetic properties of the bis(phthalocyaninato)terbium complexes [Tb{Pc′(SR) 8} 2] (1) containing eight b-positioned long-chain alkylthio substituents SR (a: R = n-C 8H 17, b: R = n-C 12H 25) were studied by SQUID measurements, which revealed that both compounds are single-molecule magnets with an effective energy barrier for spin reversal significantly higher than that found for pristine bis(phthalocyaninato)terbium [Tb(Pc) 2]. Thin films on gold were fabricated from 1a and 1b by chemisorption from solution and were characterised by near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS). In the case of 1a, atomic force microscopy (AFM) was used in addition. The results are in accord with the formation of self-assembled monolayers which contain the macrocyclic rings mainly in an approximately horizontal orientation. The chemisorption is primarily due to the peripheral SR substituents, giving rise to coordinatively bound thioether units, whose alkyl chains are in an almost parallel orientation with respect to the surface. In the case of 1b, covalently attached thiolate units were also observed, indicating that the chemisorption process can lead to carbon-sulfur bond cleavage. In addition, the crystal structure of 1a was determined.

Original languageEnglish
JournalChemPlusChem
Volume77
Issue10
Pages (from-to)889-897
Number of pages9
ISSN2192-6506
DOIs
Publication statusPublished - Oct 2012
Externally publishedYes

Keywords

  • Magnetic properties
  • Monolayers
  • NEXAFS spectroscopy
  • Self-assembly
  • X-ray photoelectron spectroscopy

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