Citation: Liu Zhi-Xian, Shi Shuang-Qun, Zhang Jian-Jun, Song Xin-Fang, Meng Min-Quan. Coordinating Properties of Nickel(II) tetra(4-N-benzylpyridyl) porphyrin in Aqueous Solution[J]. Acta Physico-Chimica Sinica, 1997, 13(07): 659-662. doi: 10.3866/PKU.WHXB19970718
English
Coordinating Properties of Nickel(II) tetra(4-N-benzylpyridyl) porphyrin in Aqueous Solution
Beer's law experiment, variable-temperature spectral experiment of UV-Vis absorption, 1H NMR, and measurement of magnetic moment were conducted for NiTMPyP in aqueous solution. It was found that Beer's law was obeyed in concentration range 8× 10-7-2×10-5.mol•dm-3.With the temperature increasing from 0 ℃ to 95 ℃, the isosbestic point appeared at 435 nm and the lowest downfield 1H NMR peak narrowed gradually and shifted to upfield. The magnetic moment is 2.07 BM in D2O at 30 ℃, but in the D2O-CD3COCD3 mixed solvent there was no evidence for the existance of paramagnetic species. These results show that NiTMPyP exists in aqueous solution as an equilibrium mixture of diamagnetic, four-coordinate nickel (Ⅱ) and paramagnetic, sir-coordinate nickel (Ⅱ) complexed by water molecules in the axial position. The thermodynamic parameters of the axial-coordinated reaction were △S?=-178.6 J•K-1•mol-1, △G298K?=-1.6 kJ•mol-1.
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Key words:
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Nickel(II) porphyrin
- / Coordinate property
- / Absorption spectrum
- / 1H NMR spectrum
- / Beer's law
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