Tautomerism-Induced Cis–Trans Isomerization of Pyridylethenyl N-Confused Porphyrin

Autor:	Ryuichi Sakashita, Yasutaka Oka, Motoki Toganoh, Hiroyuki Furuta, Hisanori Akimaru, Masatoshi Ishida, Tomoya Ishizuka, Shigeki Mori, Praseetha E. Kesavan
Rok vydání:	2017
Předmět:	010405 organic chemistry Organic Chemistry Aromaticity 010402 general chemistry Photochemistry 01 natural sciences Porphyrin Tautomer Cis trans isomerization 0104 chemical sciences chemistry.chemical_compound chemistry Intramolecular force Pyridine Isomerization Cis–trans isomerism
Zdroj:	The Journal of Organic Chemistry. 82:8686-8696
ISSN:	1520-6904 0022-3263
Popis:	Pyridylethenyl-substituted N-confused porphyrins (NCPs) were synthesized, and their cis–trans isomerization was studied. Among four possible isomers, trans-3H and cis-2H types of structures, of which aromaticity and absorption/emission properties differ largely, were isolated. The cis-isomer was largely stabilized by the intramolecular hydrogen bonding between the pyrrolic-NH and the pyridinic-N in the vicinity. The thermal cis–trans isomerization proceeded even at 30 °C, which was significantly accelerated by the pyridine added to the system. The kinetic studies revealed that the isomerization reaction was second-order and the activation energy of the thermal isomerization from cis to trans isomer was ΔG0⧧cis→trans = 35.7 kcal/mol at 298 K, which is significantly smaller than that of Ni complex (42.3 kcal/mol). An intermolecular proton transfer induced cis–trans isomerization mechanism was proposed.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::291069d0507581e8792e7ca44a690f21 https://doi.org/10.1021/acs.joc.7b01770 Zobrazit plný text záznamu