The interacting effect of fused indanedione (IND) groups and antipodal Br β-substituents on the electroreduction of free-base and transition metal tetraphenylporphyrins (TPPs) are elucidated through the use of cyclic voltammetry. A systematic study of the reduction potentials for mono- and di-fused derivatives of MTPP(IND)(R)₂ and MTPP(IND)₂(R)₂ where R = Br or H and M = CuII, NiII, ZnII or H₂ is carried out in pyridine containing 0.1 M tetrabutylammonium perchlorate (TBAP) as supporting electrolyte and demonstrates how the overall electrochemical properties of these compounds can be tuned by systematic changes in the number of meso-βfused IND groups on the molecule and the presence or absence of electron-withdrawing Br β-substituents. Under these solution conditions, two reversible one-electron reductions are seen for H₂TPP, while three reversible reductions are obtained for H₂TPP(IND) or H₂TPP(IND)Br₂ and four for H₂TPP(IND)₂Br₂. Multiple reductions also occur for the other investigated mono- and di-fused metalloporphyrins. Plots of measured E1/2 values for the two ring-centered reductions of compounds in a given series vs. the number of fused IND groups are linear and with slopes varying in magnitude between 15 and 230 mV/IND depending upon the product of the electron transfer (anion radical or dianion), the specific central metal ion and the presence or absence of Br substituents on the pyrrole ring opposite the fused IND group(s). It is anticipated that the information from this study can be used for predicting the reduction potentials for yet to be synthesized compounds where a specific redox reactivity is desired.

中文翻译：

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稠合茚满二酮（IND）基团和对映β-取代基对不对称金属卟啉电化学性质的影响

稠合茚满二酮 (IND) 基团和对映溴的相互作用β-通过使用循环伏安法阐明了游离碱和过渡金属四苯基卟啉 (TPP) 电还原的取代基。_{对 MTPP(IND)(R) 2}和 MTPP(IND) ₂ (R) ₂其中 R = Br 或 H 和 M = Cu的单稠合和稠合衍生物的还原电位的系统研究二， 你二, 锌二或 H ₂在含有 0.1 M 高氯酸四丁基铵 (TBAP) 作为支持电解质的吡啶中进行，并展示了如何通过系统改变这些化合物的数量来调整这些化合物的整体电化学性质。中观-β分子上的稠合IND基团和吸电子溴的存在与否β-取代基。_{在这些溶液条件下，H 2} TPP出现两个可逆的单电子还原，而 H ₂ TPP(IND) 或 H ₂ TPP(IND)Br _{2出现三个可逆还原，H 2} TPP(IND ) ₂出现四个可逆还原溴₂。其他研究的单融合和扩散金属卟啉也发生了多次还原。测量图乙1/2给定系列中化合物的两个环中心还原的值对比. 融合 IND 基团的数量是线性的，并且斜率在 15 和 230 mV/IND 之间变化，具体取决于电子转移的产物（阴离子自由基或双阴离子）、特定的中心金属离子和 Br 取代基的存在与否与稠合 IND 基团相对的吡咯环。预计该研究的信息可用于预测尚未合成的化合物的还原电位，其中需要特定的氧化还原反应性。