The Story of 5d Metallocorroles: From Metal-Ligand Misfits to New Building Blocks for Cancer Phototherapeutics.
The Story of 5d Metallocorroles: From Metal-Ligand Misfits to New Building Blocks for Cancer Phototherapeutics.
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DOI：
10.1021/acs.accounts.1c00290
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发表时间：
2021-08-03
影响因子：
18.3
通讯作者：
Ghosh A
中科院分区：
文献类型：
--
作者：
Alemayehu AB;Thomas KE;Einrem RF;Ghosh A
卟啉化学是一门新兴学科：经过世纪的研究，该领域的多样性似乎无穷无尽。血红素蛋白质不断地用新的分子机制来迷惑我们，而新的卟啉类似物则以前所未有的光学、电子和金属结合特性来迷惑我们。在后一个领域中，corroles占据了特殊的位置，表现出独特而丰富的配位化学。5d metallocoroles可以说是蛋糕上的糖霜。新西兰化学家Penny Brothers用“错配”这个词来描述硼和卟啉之间的相互作用，硼是一种倾向于四面体配位的小原子，卟啉是经典的正方形平面配体。史蒂夫·乔布斯把那些不合群的人奉为以不同的方式看待事物并推动人类前进的人。这两种观点都启发了我们。5d金属错配体是失配的，因为它们将大的5d过渡金属离子封装在收缩的卟啉配体的紧密空腔内。考虑到它们结构中固有的空间错配，一些5d金属配合物的合成可以理解地是反复无常的，在高度特定的条件下进行并且提供低的产率。可以区分三种广泛的方法。(a)在金属-烷基方法中，将游离碱的可咯暴露于烷基锂，并将所得的锂代可咯用前过渡金属氯化物处理;该方法的一个变体避开烷基锂并部署过渡金属-烷基，从而消除作为烷烃的烷基基团并将金属插入可咯中。这种方法对于插入第4族、第5族以及在某种程度上第6族的过渡金属以及镧系元素和锕系元素很有用。(b)在我们的实验室中，我们经常对中间过渡元素（第6、7、8和9族）采用低价有机金属方法。这些试剂是低价金属-羰基或−烯烃络合物，在高温下失去一个或多个碳配体，提供配位不饱和的粘性金属片段，这些片段被咔咯氮捕获。(c)最后，金属醋酸盐方法提供了金和铂插入的选择方法（第10和11组）。本报告提供了这三种方法的第一手视角，重点介绍了后两种方法，这两种方法主要是在我们的实验室中开发的。在一般情况下，产品的特点与X射线晶体学，电化学，和各种光谱方法。物理化学数据，补充相对论DFT计算，提供了迷人的见解周期性的趋势和相对论效应。考虑到它们的错配特性，许多5d金属错配体的一个意想不到的特征是它们在热、化学和光化学刺激下的显著稳定性。它们中的许多还表现出100 μs量级的长三重态寿命，并有效地敏化单线态氧的形成。许多在环境条件下在近红外中显示磷光。此外，水溶性ReO和Au配合物对多种癌细胞系表现出令人印象深刻的光细胞毒性，有望作为癌症光治疗剂的潜在应用。因此，我们设想了一个光明的未来的化合物作为坚固的积木新一代的治疗和诊断（治疗诊断）剂。
Porphyrin chemistry is Shakespearean: over a century of study has not withered the field’s apparently infinite variety. Heme proteins continually astonish us with novel molecular mechanisms, while new porphyrin analogues bowl us over with unprecedented optical, electronic, and metal-binding properties. Within the latter domain, corroles occupy a special place, exhibiting a unique and rich coordination chemistry. The 5d metallocorroles are arguably the icing on that cake. New Zealand chemist Penny Brothers has used the word “misfit” to describe the interactions of boron, a small atom with a predilection for tetrahedral coordination, and porphyrins, classic square-planar ligands. Steve Jobs lionized misfits as those who see things differently and push humanity forward. Both perspectives have inspired us. The 5d metallocorroles are misfits in that they encapsulate a large 5d transition metal ion within the tight cavity of a contracted porphyrin ligand. Given the steric mismatch inherent in their structures, the syntheses of some 5d metallocorroles are understandably capricious, proceeding under highly specific conditions and affording poor yields. Three broad approaches may be distinguished. (a) In the metal–alkyl approach, a free-base corrole is exposed to an alkyllithium and the resulting lithio-corrole is treated with an early transition metal chloride; a variant of the method eschews alkyllithium and deploys a transition metal–alkyl instead, resulting in elimination of the alkyl group as an alkane and insertion of the metal into the corrole. This approach is useful for inserting transition metals from groups 4, 5, and, to some extent, 6, as well as lanthanides and actinides. (b) In our laboratory, we have often deployed a low-valent organometallic approach for the middle transition elements (groups 6, 7, 8, and 9). The reagents are low-valent metal–carbonyl or −olefin complexes, which lose one or more carbon ligands at high temperature, affording coordinatively unsaturated, sticky metal fragments that are trapped by the corrole nitrogens. (c) Finally, a metal acetate approach provides the method of choice for gold and platinum insertion (groups 10 and 11). This Account provides a first-hand perspective of the three approaches, focusing on the last two, which were largely developed in our laboratory. In general, the products were characterized with X-ray crystallography, electrochemistry, and a variety of spectroscopic methods. The physicochemical data, supplemented by relativistic DFT calculations, have provided fascinating insights into periodic trends and relativistic effects. An unexpected feature of many 5d metallocorroles, given their misfit character, is their remarkable stability under thermal, chemical, and photochemical stimulation. Many of them also exhibit long triplet lifetimes on the order of 100 μs and effectively sensitize singlet oxygen formation. Many exhibit phosphorescence in the near-infrared under ambient conditions. Furthermore, water-soluble ReO and Au corroles exhibit impressive photocytotoxicity against multiple cancer cell lines, promising potential applications as cancer phototherapeutics. We thus envision a bright future for the compounds as rugged building blocks for new generations of therapeutic and diagnostic (theranostic) agents.
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影响因子：
1.5
作者：
Capar, Can;Hansen, Lars-Kristian;Ghosh, Abhik
通讯作者：
Ghosh, Abhik
影响因子：
4.6
作者：
Alemayehu, Abraham B.;Gonzalez, Emmanuel;Ghosh, Abhik
通讯作者：
Ghosh, Abhik
影响因子：
16.6
作者：
Broering, Martin;Bregier, Frederique;Holthausen, Max C.
通讯作者：
Holthausen, Max C.
影响因子：
4.3
作者：
Alemayehu, Abraham B.;Vazquez-Lima, Hugo;Ghosh, Abhik
通讯作者：
Ghosh, Abhik
影响因子：
3.1
作者：
Borisov, Sergey M.;Einrem, Rune F.;Ghosh, Abhik
通讯作者：
Ghosh, Abhik