An equilibrium and kinetic study of water-soluble cadmium porphyrins
An equilibrium and kinetic study of water-soluble cadmium porphyrins
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水溶性镉卟啉的平衡和动力学研究
DOI：
10.1021/ic50204a060
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发表时间：
1980
影响因子：
4.6
通讯作者：
P. Hambright
中科院分区：
文献类型：
--
作者：
A. Shamim;P. Hambright
卟啉形成速率应取决于以 Kos 表示的静电参数。这可能合理化（表 II）为什么四阴性 TPPS4 与金属的反应比四阳性 TMpyP 更快 (4)。值得注意的是，八、四和二负电荷的尿卟啉、粪卟啉和氘卟啉在水中的Zn2+-卟啉形成速率的比率分别为10:5:1。 14 对于相同的卟啉电荷类型，水/吡啶介质中铁 (II)-卟啉的形成速率为 420:10:1。然而，对于在 DMF 溶液中研究的合成不带电荷内消旋卟啉 6 或改性不带电荷天然卟啉酯 23，金属化速率相当独立于卟啉的特性，表明它们的 Kos 和 fcNH 具有相似性价值观。预变形的 N-甲基卟啉 I17 吸收金属离子的速度比乙基卟啉 I 本身快 105 倍，这一事实证明 A-甲基卟啉具有更大的 KO 和 &NH。事实上，这种 N-烷基化卟啉比相应的未甲基化卟啉对 NH 解离具有更强的酸性。 20 此外，还报道了 2.2 (Zn/TPPS4)、24 2.4 (Zn/TAP)、11 和 1.3 (Cu/TPPS4) 21 的小氘同位素效应，这可能表明 NH 参与了活化复合物。
The porphyrin formation rates should depend on electrostatic parameters in terms of Kos. Thismight rationalize (Table II) why the tetranegative TPPS4reacts faster with metals than the tetrapositive TMpyP (4). It is noted that the ratios of the Zn2+-porphyrin formation rates in water of the octa-, tetra-, and dinegatively charged uro-, copro-, and deu-teroporphyrins are 10: 5: 1, respectively. 14 For the same por-phyrin charge types, the iron (II)-porphyrin formation rates in water/pyridine media are in the ratios 420: 10: 1. However, with syntheticuncharged meso-substituted porphyrins6 or modified uncharged natural porphyrin esters, 23 studied in DMF solutions, the metalation rates are fairly independent of the identity of the porphyrin, indicating a similarity in their Kos and fcNH values. Thefact that predeformed jV-methyletio-porphyrin I17 incorporates metal ions 105 times faster than etioporphyrin I itself argues for larger KO and &NH for the A-methylporphyrin. Such N-alkylated porphyrins have in fact been shown to be more acidic toward NH dissociation than the corresponding unmethylated porphyrin. 20 In addition, small deuterium isotope effects of 2.2 (Zn/TPPS4), 24 2.4 (Zn/TAP), 11 and 1.3 (Cu/TPPS4) 21 have been reported, a possible indication of NH involvement in the activated com-plex.