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@article{747531,
author = {Dvořáková, Hana and Lang, Jan and Vlach, Jiří and Sýkora, Jan and Čajan, Michal and Himl, Michal and Pojarová, Michaela and Stibor, Ivan and Lhoták, Pavel},
article_location = {Columbus, OH, USA},
article_number = {19},
keywords = {ALTERNATE CONFORMATION; CONE INTERCONVERSION; INFINITE CHANNELS; SOLID-STATE; X-RAY; COMPLEXATION; THIACALIXARENES; CONFORMERS; H-1-NMR; NMR},
language = {eng},
issn = {0022-3263},
journal = {Journal of Organic Chemistry},
title = {Partially O-Alkylated thiacalix[4]arenes: Synthesis, molecular and crystal structures, conformational behavior},
volume = {72},
year = {2007}
}
TY - JOUR
ID - 747531
AU - Dvořáková, Hana - Lang, Jan - Vlach, Jiří - Sýkora, Jan - Čajan, Michal - Himl, Michal - Pojarová, Michaela - Stibor, Ivan - Lhoták, Pavel
PY - 2007
TI - Partially O-Alkylated thiacalix[4]arenes: Synthesis, molecular and crystal structures, conformational behavior
JF - Journal of Organic Chemistry
VL - 72
IS - 19
SP - 7157-7166
EP - 7157-7166
PB - the American Chemical Society
SN - 00223263
KW - ALTERNATE CONFORMATION
KW - CONE INTERCONVERSION
KW - INFINITE CHANNELS
KW - SOLID-STATE
KW - X-RAY
KW - COMPLEXATION
KW - THIACALIXARENES
KW - CONFORMERS
KW - H-1-NMR
KW - NMR
N2 - NMR spectroscopy, X-ray diffraction analysis, and quantum chemical calculations were used for conformational behavior study of partially alkylated thiacalix[4]arenes bearing methyl (1), ethyl (2), or propyl (3) groups at the lower rim. The conformational properties are governed by two basic effects: (i) stabilization by intramolecular hydrogen bonds, and (ii) sterical requirements of the alkoxy groups at the lower rim. While the monosubstituted derivatives la and 3a adopt the cone conformation in solution, distally disubstituted compounds 1b, 1'b, 2b, 2'b, 3b, and 3'b exhibit several. interesting conformational features. They prefer pinched cone conformation in solution, and, except for 3'b, they form also 1,2-alternate conformation, which is flexible and undergoes rather fast transition between two identical structures. The crystal structures of the compounds 1b, 2b, 2'b, and 3b revealed yet quite rare 1,2-alternate conformation forming molecular channels held together by pi-pi interactions. Different channels-with hexagonal symmetry, 0.26 nm wide-are formed in the crystal structure of the pinched cone conformation of 3b. An uncommon hydrogen bonding pattern was found in dimethoxy and dipropoxy derivatives 1'b and 3'b that adopt distorted cone conformations in crystal. Trialkoxy-substituted compounds 1c and 3c adopt the partial cone conformation in solution. A higher mobility of methyl derivative 1c enables also existence of the cone conformer.
ER -
DVOŘÁKOVÁ, Hana, Jan LANG, Jiří VLACH, Jan SÝKORA, Michal ČAJAN, Michal HIML, Michaela POJAROVÁ, Ivan STIBOR and Pavel LHOTÁK. Partially O-Alkylated thiacalix[4]arenes: Synthesis, molecular and crystal structures, conformational behavior. \textit{Journal of Organic Chemistry}. Columbus, OH, USA: the American Chemical Society, 2007, vol.~72, No~19, p.~7157-7166. ISSN~0022-3263.
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