Dynamics of guest molecules in PHTP inclusion compounds as probed by solid-state NMR and fluorescence spectroscopy

G. Srinivasan; J. A. Villanueva-Garibay; K. Müller; D. Oelkrug; B. Milian Medina; D. Beljonne; J. Cornil; M. Wykes; L. Viani; J. Gierschner; R. Martinez-Alvarez; M. Jazdzyk; M. Hanack; H.-J. Egelhaaf

doi:10.1039/B820604J

Dynamics of guest molecules in PHTP inclusion compounds as probed by solid-state NMR and fluorescence spectroscopy

G. Srinivasan,^a J. A. Villanueva-Garibay,^a K. Müller,*^ab D. Oelkrug,^c B. Milian Medina,^de D. Beljonne,^d J. Cornil,^d M. Wykes,^d L. Viani,^d J. Gierschner,*^cdf R. Martinez-Alvarez,^g M. Jazdzyk,^g M. Hanack^g and H.-J. Egelhaaf †*^ch

Author affiliations

* Corresponding authors

^a Institute for Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart, Germany

^b Dipartimento di Ingegneria dei Materiali e Tecnologie Industriali, Universitá degli Studi di Trento, via Mesiano 77, I-38100, Italy and INSTM, Trento, UdR Trento, Italy
E-mail: k.mueller@ipc.uni-stuttgart.de, klaus.mueller@ing.unitn.it

^c Institute for Physical Chemistry, University of Tübingen, Auf der Morgenstelle 8, Tübingen, Germany

^d Laboratory for Chemistry of Novel Materials, University of Mons-Hainaut, Place du Parc 20, Mons, Belgium

^e Institute for Molecular Science, University of Valencia, P.O. Box 22085, Valencia, Spain

^f IMDEA Nanoscience, Madrid, Spain
E-mail: johannes.gierschner@imdea.org

^g Institute for Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, Tübingen, Germany

^h Christian-Doppler Laboratory for Surface-Optical Methods, Johannes-Kepler-University, Altenbergerstr. 69, Linz, Austria
E-mail: hegelhaaf@konarka.com

Abstract

Partially deuterated 1,4-distyrylbenzene (2PV) is included into the pseudohexagonal nanochannels of perhydrotriphenylene (PHTP). The overall and intramolecular mobility of 2PV is investigated over a wide temperature range by ¹³C, ²H NMR as well as fluorescence spectroscopy. Simulations of the ²H NMR spectral shapes reveal an overall wobble motion of 2PV in the channels with an amplitude of about 4° at T = 220 K and 10° at T = 410 K. Above T = 320 K the wobble motion is superimposed by localized 180° flips of the terminal phenyl rings with a frequency of 10⁶ Hz at T = 340 K. The activation energies of both types of motions are around 40 kJ mol⁻¹ which imply a strong sterical hindrance by the surrounding PHTP channels. The experimental vibrational structure of the fluorescence excitation spectra of 2PV is analyzed in terms of small amplitude ring torsional motions, which provide information about the spatial constraints on 2PV by the surrounding PHTP host matrix. Combining the results from NMR and fluorescence spectroscopy as well as of time-dependent density functional calculations yields the complete potential surfaces of the phenyl ring torsions. These results, which suggest that intramolecular mobility of 2PV is only reduced but not completely suppressed by the matrix, are corroborated by MD simulations. Unrealistically high potential barriers for phenyl ring flips are obtained from MD simulations using rigid PHTP matrices which demonstrate the importance of large amplitude motions of the PHTP host lattice for the mobility of the guest molecules.

Physical Chemistry Chemical Physics

Dynamics of guest molecules in PHTP inclusion compounds as probed by solid-state NMR and fluorescence spectroscopy

Abstract

Article information

Download Citation

Permissions

Dynamics of guest molecules in PHTP inclusion compounds as probed by solid-state NMR and fluorescence spectroscopy

Social activity

Search articles by author

Spotlight

Advertisements