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Volumn 131, Issue 51, 2009, Pages 18269-18271

A pH activated configurational rotary switch: Controlling the E/Z isomerization in hydrazones

Author keywords

[No Author keywords available]

Indexed keywords

BISTABLE SWITCHES; CARBONYL GROUPS; CHEMICAL EQUATIONS; E CONFIGURATION; H NMR SPECTROSCOPY; HYDRAZONES; MOLECULAR SWITCHES; PYRIDINE RINGS; TREATMENT WITH TRIFLUOROACETIC ACID; TRIKETONE;

EID: 73249115315     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja909149z     Document Type: Article
Times cited : (137)

References (44)
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    • Molecular Switches; Feringa, B. L. Ed.; Wiley-VCH: Weinheim, Germany, 2001.
    • (2001) Molecular Switches
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    • For some examples, please see: a
    • For some examples, please see: (a) Badjić, J. D.; Stoddart, J. F. Science 2004, 303, 1845-1849.
    • (2004) Science , vol.303 , pp. 1845-1849
    • Badjić, J.D.1    Stoddart, J.F.2
  • 9
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    • Schilwa, M, Ed, Wiley-VCH: Weinheim, Germany
    • Molecular Motors; Schilwa, M., Ed.; Wiley-VCH: Weinheim, Germany, 2003.
    • (2003) Molecular Motors
  • 10
    • 73249123869 scopus 로고    scopus 로고
    • By configuration we mean cis-trans isomerism around double bonds. See ref 1b
    • By configuration we mean cis-trans isomerism around double bonds. See ref 1b.
  • 12
    • 84879890340 scopus 로고
    • Adam, R, Ed, Wiley-VCH: New York
    • Parmerter, S. M. In Organic Reactions; Adam, R., Ed.; Wiley-VCH: New York, 1959; Vol. 10, p 1.
    • (1959) Organic Reactions , vol.10 , pp. 1
    • Parmerter, S.M.1
  • 14
    • 33947484873 scopus 로고
    • (a) Yao, H. C. J. Org. Chem. 1964, 29, 2959-2963.
    • (1964) J. Org. Chem , vol.29 , pp. 2959-2963
    • Yao, H.C.1
  • 20
    • 0037715341 scopus 로고    scopus 로고
    • For examples of pH activated switches, see: (a) Dolain, C, Maurizot, V, Huc, I. Angew. Chem, Int. Ed. 2003, 42, 2738-2740
    • For examples of pH activated switches, see: (a) Dolain, C.; Maurizot, V.; Huc, I. Angew. Chem., Int. Ed. 2003, 42, 2738-2740.
  • 26
    • 73249151483 scopus 로고    scopus 로고
    • 3 to the solution. Upon the addition of 0.1 equiv of acid (TFA) only the appropriate amount of isomerization occurred. This rules out the catalytic equilibration process observed in other 1,2,3-tricarbonyl-2- arylhydrazone systems.
    • 3 to the solution. Upon the addition of 0.1 equiv of acid (TFA) only the appropriate amount of isomerization occurred. This rules out the catalytic equilibration process observed in other 1,2,3-tricarbonyl-2- arylhydrazone systems.
  • 27
    • 0006213897 scopus 로고
    • These types of hydrazones usually adopt planar structures. For other examples, see: a
    • These types of hydrazones usually adopt planar structures. For other examples, see: (a) Vickery, B.; Willey, G. R.; Drew, M. G. B. J. Chem. Soc., Perkin Trans. 2 1981, 155-160.
    • (1981) J. Chem. Soc., Perkin Trans. 2 , pp. 155-160
    • Vickery, B.1    Willey, G.R.2    Drew, M.G.B.3
  • 30
    • 73249145754 scopus 로고    scopus 로고
    • This isomer ratio remained constant even after heating the sample at 55 °C for 1 h
    • This isomer ratio remained constant even after heating the sample at 55 °C for 1 h.
  • 31
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    • Frisch, M. J.; et al. Gaussian 03, revision B.04; Gaussian Inc.; Wallingford, CT, 2004.
    • Frisch, M. J.; et al. Gaussian 03, revision B.04; Gaussian Inc.; Wallingford, CT, 2004.
  • 35
    • 73249146797 scopus 로고    scopus 로고
    • The reason for this is most probably the unfavorable interaction between proton H8 and the C=N nitrogen lone pair in the other conformation.
    • The reason for this is most probably the unfavorable interaction between proton H8 and the C=N nitrogen lone pair in the other conformation.
  • 36
    • 73249122362 scopus 로고    scopus 로고
    • 3H is used as the acid, only 1.0 equiv is needed to fully protonate the pyridine subunit.
    • 3H is used as the acid, only 1.0 equiv is needed to fully protonate the pyridine subunit.
  • 38
    • 73249143420 scopus 로고    scopus 로고
    • In ethyl-2-pyridylacetate this same proton resonates at 8.5 ppm and shifts to 8.7 ppm upon protonation with TFA. This indicates that the shift to 8.9 ppm in 1-E has to do with the aromatic ring current. In 1-Z proton H9 resonates at 8.6 ppm (vide infra), which is in agreement with the pyridine ring being further away from the naphthalene core. This is again in agreement with 1-E being the predominant configuration in solution.
    • In ethyl-2-pyridylacetate this same proton resonates at 8.5 ppm and shifts to 8.7 ppm upon protonation with TFA. This indicates that the shift to 8.9 ppm in 1-E has to do with the aromatic ring current. In 1-Z proton H9 resonates at 8.6 ppm (vide infra), which is in agreement with the pyridine ring being further away from the naphthalene core. This is again in agreement with 1-E being the predominant configuration in solution.
  • 39
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    • 3N.
    • 3N.
  • 40
    • 73249148802 scopus 로고    scopus 로고
    • This complete switching cycle was repeated 5 times in CD3CN, using TFA as acid and Et3N as the base, and the same switching behavior was observed over the 5 switching runs
    • 3N as the base, and the same switching behavior was observed over the 5 switching runs.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.