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ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 35, Number 5
JKCSEZ 35(5)
October 20, 1991 |
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Title |
Chemical Equilibrium between Metalloporphyrins (MTPP and M(o-Cl)TPP) and Basic Ligands(L). (M = Zn2+, Cu2+, Ni2+: TPP = tetraphenylporphyrin, (o-Cl)TPP = tetrakis (ortho-chlorophenyl)porphyrin: L = imidazole, pyridine, 1-methylimidazole, 2,6-lutidine)
Methalloporphyrin(MTPP 및 M(o-Cl)TPP)과 염기성리간드(L)간의 화학평형. (M = Zn2+, Cu2+, Ni2+:TPP = tetraphenylporphyrin, (o-Cl)TPP = tetrakis (ortho-chlorophenyl)porphyrin: L = imidazole, pyridine,1-methylimidazole, 2,6-lutidine) |
Author |
Yu Chul Park, Seong Su Kim, Hun Gil Na
박유철, 김성수, 나훈길 |
Keywords |
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Abstract |
유기용매(CH2Cl2, C6H6, CH3NO2, (CH3)2CO, CHCl3, DMF, DMSO)에서 Zn(Ⅱ)-, Cu(Ⅱ)- 및 Ni(Ⅱ)-tetrakis(o-chlorophenyl)porphyrin(o-ClTPP)과 Zn(Ⅱ)-, Cu(Ⅱ)- 및 Ni(Ⅱ)-tetraphenylporphyrin(TPP) 착물과 질소원자를 포함한 염기성 리간드(pyridine, imidazole, 1-methylimidazole 및 2,6-lutidine)간의 결합 반응성을 이온강도 0.01M에서 연구하였다. metalloporphyrin과 염기성 리간드간의 평형상수는 온도범위 15 ~ 35℃에서 분광광도법을 이용하여 결정하였으며, 이 때 M(Ⅱ)-TPP에서 관찰된 평형상수는 입체적 장애가 더 큰 M(Ⅱ)-(o-Cl)TPP에서 보다 큰 값을 나타내었다. M(Ⅱ)-TPP에서 logK값은 염기성 리간드의 pKa값이 커질수록 증가하였지만 입체적장애를 받는 M(Ⅱ)-(o-Cl)TPP에서 logK는 리간드의 pKa값에 비례하지 않았다. 열역학적 파라미터 분석결과 M(o-Cl)TPP의 안정도는 거의 반응엔트로피에 의존하였으나, M(Ⅱ)-TPPL의 안정도는 반응엔탈피와 반응엔트로피에 거의 비슷한 영향을 나타내었다. metalloporphyrin에 대한 용매의 배위능을 DMF, DMSO, CHCl3, (CH3)2CO에서 측정하였고, 이들 결과로부터 평형상수에 대한 용매효과를 논의하였다. The axial ligations of nitrogenous bases (pyridine, imidazole, 1-methylimidazole and 2,6-lutidine) to Zn(Ⅱ)-, Cu(Ⅱ)-, and Ni(Ⅱ)-tetrakis(o-chlorophenyl)porphyrin(o-ClTPP), and -tetraphenylporphyrin (TPP) were investigated in organic solvents (CH2Cl2, C6H6, CH3NO2, (CH3)2CO, CHCl3, DMF and DMSO) and at 0.01M of ionic strength. The equilibrium constants for the ligation reactions of methalloporphyrins were determined using spectrophotometric method at 15∼35℃. In case of M(Ⅱ)-TPP the equilibrium constants K were considerably larger than those of M(Ⅱ)-(o-Cl)TPP, depending on steric effect of the porphyrin. The linear relationships between logK of the axial ligation and pKa of nitrogenous base were shown in M(Ⅱ)-TPP, but not in M(Ⅱ)-(o-Cl)TPP. The stabilities of MTPP(L) were controlled by the reation enthalpy and entropy, while those of M(o-Cl)TPP almost by the reaction entropy. The coordinating power of solvent to the methalloporphyrin were also studied in CHCl3, (CH3)2CO, DMF and DMSO. From those results the solvent effects on the equilibrium constants were discussed. |
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512 - 519 |
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