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@article{1505558, author = {Církva, Vladimír and Jakubík, Petr and Strašák, Tomáš and Hrbáč, Jan and Sýkora, Jan and Císařová, Ivana and Vacek, Jan and Žádný, Jaroslav and Storch, Jan}, article_location = {WASHINGTON}, article_number = {4}, doi = {http://dx.doi.org/10.1021/acs.joc.8b02870}, keywords = {HELICAL MOLECULES; CRYSTAL PACKING; RESOLUTION; PHOTOCYCLIZATION; HELICENES}, language = {eng}, issn = {0022-3263}, journal = {Journal of Organic Chemistry}, title = {Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings}, url = {https://pubs.acs.org/doi/10.1021/acs.joc.8b02870}, volume = {84}, year = {2019} }
TY - JOUR ID - 1505558 AU - Církva, Vladimír - Jakubík, Petr - Strašák, Tomáš - Hrbáč, Jan - Sýkora, Jan - Císařová, Ivana - Vacek, Jan - Žádný, Jaroslav - Storch, Jan PY - 2019 TI - Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings JF - Journal of Organic Chemistry VL - 84 IS - 4 SP - 1980-1993 EP - 1980-1993 PB - AMER CHEMICAL SOC SN - 00223263 KW - HELICAL MOLECULES KW - CRYSTAL PACKING KW - RESOLUTION KW - PHOTOCYCLIZATION KW - HELICENES UR - https://pubs.acs.org/doi/10.1021/acs.joc.8b02870 L2 - https://pubs.acs.org/doi/10.1021/acs.joc.8b02870 N2 - The first racemization-stable helicene derivatives fluorinated at terminal rings, 1,2,3,4-tetrafluoro[6]helicene (6) and 1,2,3,4,13,14,15,16-octafluoro[6]helicene (15), were synthesized via the Wittig reaction followed by oxidative photocyclization in an overall yield of 41% of 6 and 76% of 15. The changed electronic structure in fluorinated helicenes was reflected in a slight shift of UV-vis absorption, fluorescence excitation, and emission spectra maxima when compared to unsubstituted [6]helicene. Cyclic voltammetry revealed a moderate decrease in the HOMO-LUMO gap with increasing fluorination. The specific rotation of tetrafluoro[6]helicene 6 enantiomers was found to be approximately 25% lower than that, of unsubstituted [6]helicene. The theoretical study of the racemization barrier suggested a reasonable shift toward higher energy with increasing fluorination. The increasing fluorination also significantly affected the intermolecular interactions in the crystal lattice. The observed CH center dot center dot center dot F interactions led to the formation of 1D-molecular chains in the crystal structures of both fluorinated helicenes. ER -
CÍRKVA, Vladimír, Petr JAKUBÍK, Tomáš STRAŠÁK, Jan HRBÁČ, Jan SÝKORA, Ivana CÍSAŘOVÁ, Jan VACEK, Jaroslav ŽÁDNÝ a Jan STORCH. Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings. \textit{Journal of Organic Chemistry}. WASHINGTON: AMER CHEMICAL SOC, roč.~84, č.~4, s.~1980-1993. ISSN~0022-3263. doi:10.1021/acs.joc.8b02870. 2019.
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