Molecular motions and hydrogen-bonding networks in (o-aminoanilinium)( crown ethers)[ PMo 12O 40] 4- Crystals

Daigoro Endo, Tomoyuki Akutagawa, Kazuya Kubo, Shin Ichiro Noro, Leroy Cronin, Takayoshi Nakamura

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Single crystals formed from hydrogen-bonding supramolecular cations of o-aminoanilinium (HOPD+)crown ethers, (HOPD +)([12]crown-4), (HOPD +)([15]crown-5), and (HOPD +)([18]crown-6), and one-electron-reduced [PMo 12O 40] 4- Keggin-type clusters were synthesized. The crystal structures and dielectric responses of the three new compounds (HOPD+)4([12]crown-4)4[PMo 12O 40] 4-.4CH 3CN (1), (HOPD+)4([15]crown-5) 4[PMo 12O 40] 4- (2), and (HOPD +)4([18]crown-6)4[PMo 12O 40] 4-. 8CH 3CN (3) were examined. The CH 3CN molecules in salts 1 and 3 were included in zero-dimensional pores and one-dimensional channels, respectively; higher thermal stability was observed in the former lattice because of its extended hydrogen-bonding network. Large frequency- and temperature-dependent dielectric responses were confirmed in salts 2 and 3, whereas the dielectric response of salt 1 was quite small. The fixed orientation of HOPD + because of the hydrogen-bonding network was consistent with the dielectric property of salt 1. In contrast, large magnitudes of dielectric responses in the temperature range above 280K were observed for salt 3. Thermal motions of CH 3CN molecules in the channel were the origin of such dielectric responses. In salt 2, the thermally activated coupled motion of the orthogonally arranged HOPD + pair along the CNH 3 +-axis with the potential energy barrier of ca. 80 kJ mol -1 resulted in large dielectric responses.

Original languageEnglish
Pages (from-to)305-315
Number of pages11
JournalBulletin of the Chemical Society of Japan
Volume85
Issue number3
DOIs
Publication statusPublished - 2012 Mar 26

ASJC Scopus subject areas

  • Chemistry(all)

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