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Arrays of Dipolar Molecular Rotors in Tris(o-phenylenedioxy)cyclotriphosphazene

  • Ke Zhao
  • Paul I. Dron
  • Jiří Kaleta
  • Charles T. Rogers
  • Josef MichlEmail author
Chapter
Part of the Topics in Current Chemistry book series (TOPCURRCHEM, volume 354)

Abstract

Regular two-dimensional or three-dimensional arrays of mutually interacting dipolar molecular rotors represent a worthy synthetic objective. Their dielectric properties, including possible collective behavior, will be a sensitive function of the location of the rotors, the orientation of their axes, and the size of their dipoles. Host–guest chemistry is one possible approach to gaining fine control over these factors. We describe the progress that has been achieved in recent years using tris(o-phenylenedioxy)cyclotriphosphazene as a host and a series of rod-shaped dipolar molecular rotors as guests. Structures of both surface and bulk inclusion compounds have been established primarily by solid-state nuclear magnetic resonance (NMR) and powder X-ray diffraction (XRD) techniques. Low-temperature dielectric spectroscopy revealed rotational barriers as low as 1.5 kcal/mol, but no definitive evidence for collective behavior has been obtained so far.

Keywords

Dielectric spectroscopy Hexagonal TPP Inclusion compounds Molecular rotors Powder X-ray diffraction Solid-state NMR 

Abbreviations

(ss)NMR

(Solid-state) nuclear magnetic resonance

2-D

Two-dimensional

3-D

Three-dimensional

B97-D3/SVP//PM6

Density functional theory calculation with the B97-D3 functional and SVP basis set at a geometry optimized with the PM6 method

Boc

tert-Butoxycarbonyl

Bu

n-Butyl

CP MAS

Cross-polarization with magic angle spinning

DMF

Dimethylformamide

DSC

Differential scanning calorimetry

Et

Ethyl

Hex

n-Hexyl

Me

Methyl

TBACl

Tetra(n-butyl)ammonium chloride

TBAF

Tetra(n-butyl)ammonium fluoride

THF

Tetrahydrofuran

TIPS

Tris(isopropyl)silyl

TMS

Trimethylsilyl

TMSA

Trimethylsilylacetylene

TPP

Tris(o-phenylenedioxy)cyclotriphosphazene

Ts

p-Toluenesulfonyl

Xmol%Y@TPP

Inclusion compound containing X% of guest Y in TPP as host

XRD

Powder X-ray diffraction

Notes

Acknowledgement

This material is based upon work supported in Prague by the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007–2013) ERC grant agreement no. 227756 and by the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic RVO: 61388963, and in Boulder by the National Science Foundation under Grant No. CHE 0848663. We are grateful to Dr. Martina Čižková for taking the TEM image shown in Fig. 5.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Ke Zhao
    • 1
  • Paul I. Dron
    • 2
  • Jiří Kaleta
    • 3
  • Charles T. Rogers
    • 1
  • Josef Michl
    • 2
    • 3
    Email author
  1. 1.Department of PhysicsUniversity of ColoradoBoulderUSA
  2. 2.Department of Chemistry and BiochemistryUniversity of ColoradoBoulderUSA
  3. 3.Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech RepublicPrague 6Czech Republic

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