Low temperature properties of acetonitrile confined in MCM-41

Shigeharu Kittaka, Takafumi Iwashita, Akihiro Serizawa, Miki Kranishi, Shuichi Takahara, Yasushige Kuroda, Toshinori Mori, Toshio Yamaguchi

Research output: Contribution to journalArticle

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Abstract

The effect of confinement on the phase changes and dynamics of acetonitrile in mesoporous MCM-41 was studied by use of adsorption, FT-IR, DSC, and quasi-elastic neutron scattering (QENS) measurements. Acetonitrile molecules in a monolayer interact strongly with surface hydroxyls to be registered and perturb the triple bond in the C≡N group. Adsorbed molecules above the monolayer through to the central part of the cylindrical pores are capillary condensed molecules (cc-acetonitrile), but they do not show the hysteresis loop in adsorption-desorption isotherms, i.e., second order capillary condensation. FT-IR measurements indicated that the condensed phase is very similar to the bulk liquid. The cc-acetonitrile freezes at temperatures that depend on the pore size of the MCM-41 down to 29.1 Å (C14), below which it is not frozen. In addition, phase changes between α-type and β-type acetonitriles were observed below the melting points. Application of the Gibbs-Thomson equation, assuming the unfrozen layer thickness to be 0.7 nm, gave the interface free energy differences between the interfaces, i.e., Δγ1/α = 22.4 mJ m-2 for the liquid/pore surface (ps) and α-type/ps, and Δγα/β = 3.17 mJ m-2 for α-type/ps and β-type/ps, respectively. QENS experiments substantiate the differing behaviors of monolayer acetonitrile and cc-acetonitrile. The monolayer acetonitrile molecules are anchored so as not to translate. The two Lorentzian analysis of QENS spectra for cc-acetonitriles showed translational motion but markedly slowed. However, the activation energy for cc-acetonitrile in MCM-41 (C18) is 7.0 kJ mol -1 compared to the bulk value of 12.7 kJ mol-1. The relaxation times for tumbling rotational diffusion of cc-acetonitrile are similar to bulk values.

Original languageEnglish
Pages (from-to)23162-23169
Number of pages8
JournalJournal of Physical Chemistry B
Volume109
Issue number49
DOIs
Publication statusPublished - Dec 15 2005

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Low temperature properties
Multicarrier modulation
Acetonitrile
acetonitrile
Elastic scattering
Acetonitriles
Monolayers
porosity
Neutron scattering
Molecules
elastic scattering
neutron scattering
molecules
MCM-41
Adsorption
Barreling
Liquids
Hysteresis loops
adsorption
translational motion

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Kittaka, S., Iwashita, T., Serizawa, A., Kranishi, M., Takahara, S., Kuroda, Y., ... Yamaguchi, T. (2005). Low temperature properties of acetonitrile confined in MCM-41. Journal of Physical Chemistry B, 109(49), 23162-23169. https://doi.org/10.1021/jp052476g

Low temperature properties of acetonitrile confined in MCM-41. / Kittaka, Shigeharu; Iwashita, Takafumi; Serizawa, Akihiro; Kranishi, Miki; Takahara, Shuichi; Kuroda, Yasushige; Mori, Toshinori; Yamaguchi, Toshio.

In: Journal of Physical Chemistry B, Vol. 109, No. 49, 15.12.2005, p. 23162-23169.

Research output: Contribution to journalArticle

Kittaka, S, Iwashita, T, Serizawa, A, Kranishi, M, Takahara, S, Kuroda, Y, Mori, T & Yamaguchi, T 2005, 'Low temperature properties of acetonitrile confined in MCM-41', Journal of Physical Chemistry B, vol. 109, no. 49, pp. 23162-23169. https://doi.org/10.1021/jp052476g
Kittaka S, Iwashita T, Serizawa A, Kranishi M, Takahara S, Kuroda Y et al. Low temperature properties of acetonitrile confined in MCM-41. Journal of Physical Chemistry B. 2005 Dec 15;109(49):23162-23169. https://doi.org/10.1021/jp052476g
Kittaka, Shigeharu ; Iwashita, Takafumi ; Serizawa, Akihiro ; Kranishi, Miki ; Takahara, Shuichi ; Kuroda, Yasushige ; Mori, Toshinori ; Yamaguchi, Toshio. / Low temperature properties of acetonitrile confined in MCM-41. In: Journal of Physical Chemistry B. 2005 ; Vol. 109, No. 49. pp. 23162-23169.
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