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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 a 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, roč.~72, č.~19, s.~7157-7166. ISSN~0022-3263.
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