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Solvent and acidity effects on the UV-visible spectra and protonation-deprotonation of free-base octaethylcorrole

Zhongping Ou

School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, P.R. China

Corresponding author, fax: +86 511-88791800.

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Hongxia Sun

School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, P.R. China

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Weihua Zhu

School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, P.R. China

student member in good standing

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Zulin Da

School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, P.R. China

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, and

Karl M. Kadish

Department of Chemistry, University of Houston, Houston, TX 77204-5003, USA

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https://doi.org/10.1142/S1088424608000029Cited by:18 (Source: Crossref)

Abstract

The UV-visible spectrum of free-base octaethylcorrole, (OECor)H₃, was recorded in thirteen different nonaqueous solvents as well as in a mixed acetonitrile/acid solvent containing one of seven different acids. Spectra were also measured in seven different solutions of neat concentrated acid and in CH₃CN containing piperidine or tetrabutylammonium hydroxide as an added base. The overall data was analyzed as a function of solvent acidity or basicity parameters and the number of protons on the central nitrogens of the macrocycle, the predominant form of the corrole in these solutions being respresented as (OECor)H₃, [(OECor)H₄]⁺, [(OECor)H₂]⁻ or [(OECor)H]²⁻ where OECor = trianion of octaethylcorrole. The mono-protonated corrole, [(OECor)H₄]⁺, is formed in concentrated acetic acid or in CH₃CN containing 0.10 M trifluoroacetic acid, H₂SO₄, HCl, H₃PO₄ or HClO₄. The mono-deprotonated corrole, [(OECor)H₂]⁻, is generated in piperidine while doubly deprotonated [(OECor)H]²⁻ exists in solutions of tetrabutylammonium hydroxide. An addition of protons to the macrocycle of [(OECor)H₄]⁺ also occurs in the presence of concentrated strong acids and this results in a loss of the characteristic Soret band of the corrole leading presumably to [(OECor)H₅]²⁺ where the second proton has been added to a meso-position of the macrocycle. The UV-visible spectral changes upon formation of [(OECor)H₄]⁺, [(OECor)H₂]⁻ or [(OECor)H]²⁻ in CH₃CN were monitored during a titration with the relevent acid or base and equilibrium constants for protonation or deprotonation of (OECor)H3 were determined using standard equations. The measured logK values are compared to protonation and deprotonation constants obtained for two related corroles and two related porphyrins under the same experimental conditions.

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References

J. Shenet al., Inorg. Chem. 45, 2251 (2006), DOI: 10.1021/ic051729h. Web of Science, Google Scholar
Z. Ouet al., Inorg. Chem. 46, 2275 (2007). Google Scholar
J. P. Gisselbrechtet al., J. Electroanal. Chem. 170 (2001), DOI: 10.1016/S0022-0728(01)00477-6. Google Scholar
A. Mahammedet al., Tetrahedron Lett. 44, 2077 (2003), DOI: 10.1016/S0040-4039(03)00174-6. Web of Science, Google Scholar
R. Grigget al., J. Chem. Soc., Perkin Trans. 2 407 (1973), DOI: 10.1039/p29730000407. Google Scholar
M. J. Broadhurst, R. Grigg and G. Shelton, J.C.S. Perkin I 143 (1972), DOI: 10.1039/p19720000143. Google Scholar
J. Shenet al., J. Porphyrins Phthalocyanines 11, 269 (2007), DOI: 10.1142/S1088424607000321. Link, Web of Science, Google Scholar
P. Hambright, The Porphyrin Handbook 3, eds. K. M. Kadish, K. M. Smith and R. Guilard (Acedemic Press, Boston, 2000) pp. 129–210. Google Scholar
Y. Murakamiet al., Bull. Chem. Soc. Jpn. 54, 163 (1981), DOI: 10.1246/bcsj.54.163. Web of Science, Google Scholar
E. Vogelet al., Angew. Chem. Int. Ed. Engl. 33, 731 (1994), DOI: 10.1002/anie.199407311. Web of Science, Google Scholar
D. T. Gryko and B. Koszarna, Org. Biomol. Chem. 1, 350 (2003), DOI: 10.1039/b208950e. Web of Science, Google Scholar
P. E. Elliset al., J. Am. Chem. Soc. 102, 1889 (1980), DOI: 10.1021/ja00526a022. Web of Science, Google Scholar
T. Ding, J. D. Harvey and C. J. Ziegler, J. Porphyrins Phthalocyanines 9, 22 (2005), DOI: 10.1142/S1088424605000058. Link, Web of Science, Google Scholar
R. Paolesseet al., Chem. Commun. 1307 (1999), DOI: 10.1039/a903247i. Google Scholar
R. Paolesseet al., J. Porphyrins Phthalocyanines 7, 25 (2003), DOI: 10.1142/S1088424603000057. Link, Web of Science, Google Scholar
C. Erben, S. Will and K. M. Kadish, The Porphyrin Handbook 2, eds. K. M. Kadish, K. M. Smith and R. Guilard (Academic Press, Boston, 2000) pp. 233–300. Google Scholar
U. Mayer, V. Gutmann and W. Gerger, Monatsh. Chem. 106, 1235 (1975), DOI: 10.1007/BF00913599. Web of Science, Google Scholar
R. W. Taft and M. J. Kamlet, J. Am. Chem. Soc. 98, 2886 (1976), DOI: 10.1021/ja00426a036. Web of Science, Google Scholar
M. J. Kamletet al., J. Org. Chem. 48, 2877 (1983), DOI: 10.1021/jo00165a018. Web of Science, Google Scholar
V. Gutmann and E. Wychera, Inorg. Nucl. Chem. Lett. 2, 257 (1966), DOI: 10.1016/0020-1650(66)80056-9. Web of Science, Google Scholar
V. Gutmann, Coord. Chem. Rev. 18, 225 (1976), DOI: 10.1016/S0010-8545(00)82045-7. Web of Science, Google Scholar
M. J. Kamlet and R. W. Taft, J. Am. Chem. Soc. 99, 377 (1976). Web of Science, Google Scholar