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@ARTICLE{Rok:840549,
author = {Rok, M. and Szklarz, P. and Moskwa, M. and Kijewska, M. and
Baran, J. and Bator, G. and Medycki, W. and Zamponi, M.},
title = {{S}tructures and phase transitions in neat 4,4′-di- tert
-butyl-2,2′-bipyridyl and in its molecular complexes with
either bromanilic or iodanilic acid},
journal = {CrystEngComm},
volume = {19},
number = {45},
issn = {1466-8033},
address = {London},
publisher = {RSC},
reportid = {FZJ-2017-08056},
pages = {6883 - 6895},
year = {2017},
abstract = {Using the DSC method, structural phase transitions have
been found at 165 and 219 K for
4,4′-di-tert-butyl-2,2′-bipyridyl (dtBBP), whereas for
its complex with iodanilic acid (dtBBP·IA), its phase
transition is at 331 K. For the other molecular complex
described (with bromanilic acid, dtBBP·BRA), no phase
transitions have been observed between the liquid nitrogen
temperature and the temperature of crystal decomposition.
The crystal structures of the neat dtBBP have been
determined at 130, 190 and 250 K, whereas for its molecular
complex with bromanilic acid (BRA) is determined at 150 K
and for its complex with iodanilic acid (IA) determined at
293 and 345 K. The crystal structure of neat dtBBP is
characterized by layers of molecules, which are grouped by
their t-butyls. The structures of dtBBP·BRA and dtBBP·IA
are analogous to one another and consist of infinite chains
of alternating acid and base molecules linked by hydrogen
bonds. On the basis of the structural, dielectric and
spectroscopic results (infrared and Raman), the mechanisms
of the phase transitions have been proposed for dtBBP and
dtBBP·IA. The 1H NMR spin–lattice relaxation times for
all compounds under study, as well as the second moment for
the neat dtBBP in a wide temperature, have been measured.
The anomalies in the temperature dependent infrared spectra
together with the NMR results support the supposition that
for dtBBP the dynamics of tert-butyl groups is responsible
for the mechanism of the phase transitions found. The
dynamics of the molecules in the crystals presented is
related to the rotation both of the methyl and tert-butyl
groups.},
cin = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
(München) ; JCNS-FRM-II / Neutronenstreuung ; JCNS-1},
ddc = {540},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-1-20110106},
pnm = {6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)SPHERES-20140101},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000415884400016},
doi = {10.1039/C7CE01481C},
url = {https://juser.fz-juelich.de/record/840549},
}