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Ide Y, Kuwahara T, Takeshita S, Fujishiro R, Suzuki M, Mori S, Shinokubo H, Nakamura M, Yoshino K, Ikeue T. Nickel (II) pyrrocorphin: Enhanced binding ability in a highly reduced porphyrin complex. J Inorg Biochem 2017; 178:115-124. [PMID: 29128496 DOI: 10.1016/j.jinorgbio.2017.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/25/2017] [Accepted: 10/29/2017] [Indexed: 02/07/2023]
Abstract
Pyrrocorphin is an air-sensitive porphyrinoid with a highly reduced hexahydroporphyrin core. In contrast, pyrrolidine-fused pyrrocorphin (Pyr) obtained by successive 1,3-dipolar cycloaddition reactions of azomethine ylide to 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin is less air-sensitive. In order to reveal the effect of highly reduced porphyrin rings on the physicochemical properties of their metal complexes, we have prepared diamagnetic (S=0) Ni(II) complex Ni(II)(Pyr). The addition of excess pyridine (Py) to the toluene solution of Ni(II)(Pyr) yielded five-coordinate Ni(II)(Pyr)(Py), which was then completely converted to six-coordinate paramagnetic (S=1) Ni(II)(Pyr)(Py)2. The latter was characterized by UV-Vis, 1H NMR, CV, SQUID, and X-ray crystallography as well as DFT calculations. As compared with analogous complexes of porphyrin (Por), chlorin (Chl), and isobacteriochlorin (Iso) reported by Herges and co-workers (R. Herges et al., Inorg. Chem. 2015), Ni(II)(Pyr)(Py)2 has longer equatorial NiN and shorter axial NiN bonds. The CV study has shown a large decrease in HOMO-LUMO gap as the reduction of porphyrin ring proceeds, which has further been confirmed by UV-Vis and DFT calculation. Titration studies using 1H NMR and UV-Vis have shown that the first binding constant of pyridine toward Ni(II)(Pyr) is ca. 4 times as large as that of Ni(II)(Iso) and ca 230 times as large as that of Ni(II)(Por). Thus, we have concluded that the binding constant of pyridine to Ni(II) porphyrinoid increases by the following order: Por<Chl<Iso<Pyr. The high affinity of pyridine binding in Ni(II)(Pyr) was discussed both from the structural and thermodynamic point of view.
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Affiliation(s)
- Yuki Ide
- Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Takamitsu Kuwahara
- Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Syo Takeshita
- Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Rei Fujishiro
- Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Masaaki Suzuki
- Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Shigeki Mori
- Advanced Research Support Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan
| | - Hiroshi Shinokubo
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Mikio Nakamura
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
| | - Katsumi Yoshino
- Shimane Institute for Industrial Technology, 1, Hokuryo, Matsue 690-0816, Japan
| | - Takahisa Ikeue
- Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Japan.
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Taniguchi M, Lindsey JS. Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins. Chem Rev 2016; 117:344-535. [DOI: 10.1021/acs.chemrev.5b00696] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Masahiko Taniguchi
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Jonathan S. Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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