The effects of strong Lewis-base reagents on supramolecular hydrogen bonding of meso-tetra(carboxyphenyl)porphyrins
The effects of strong Lewis-base reagents on supramolecular hydrogen bonding of meso-tetra(carboxyphenyl)porphyrins
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强路易斯碱试剂对内消旋四(羧苯基)卟啉超分子氢键的影响
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
I. Goldberg
中科院分区：
文献类型：
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作者：
S. Lipstman;Sankar Muniappan;S. George;I. Goldberg
中四（羧基苯基）卟啉的Pd-、Ru(CO)-和cu -配合物与强路易斯碱试剂（如吡啶、4-乙酰吡啶或二甲基亚砜）通过直接氢键反应，避免了通常观察到的二维或三维多卟啉阵列的形成。结晶产物的结构分析表明，这是由于这些试剂通过氢键与羧酸功能结合的优先亲和力，与卟啉单位的潜在自结合竞争。在铜卟啉衍生物中，给定卟啉的所有四个羧酸功能都与4-乙酰吡啶相互作用，形成离散的1:4卟啉配体五聚体组合。然后，在钌一氧化碳卟啉与吡啶或4-乙酰吡啶的加合物中，卟啉支架的两个反式相关羧基通过共同的（COOH）2环二聚体合成物直接与相邻的卟啉相互作用，生成一维氢键链。而其他羧基功能则将它们的质子提供给极性吡啶/乙酰吡啶配体分子，以防止卟啉沿垂直方向进一步横向结合。吡啶型部分在n原子上有一个电子孤对，可以作为有效的氢键受体，允许与羧酸形成局部氢键。另一方面，二甲基亚砜可以很容易地通过它的o位（携带两对孤电子）在四面体方向上参与两个氢键，因此可以作为相邻卟啉羧基之间的桥接助剂。相应的，它与钯配合物反应形成非均相卟啉-二甲基亚砜线性氢键链。沿着这些链，两个配体分子插入到相邻的两侧卟啉单元之间，并在其顺式相关的羧基苯基臂之间架起桥梁。不同的氢键基元影响不同的三维晶体填充特征，其中一些特征还表现为存在通过晶格传播的溶剂可接近的开放通道。
Reactions of Pd-, Ru(CO)- and Cu-complexes of meso-tetra(carboxyphenyl)porphyrin with strong Lewis base reagents (as pyridine, 4-acetylpyridine or dimetylsulfoxide) avoided the formation of commonly observed 2-D or 3-D multiporphyrin arrays by direct hydrogen bonding. Structural analysis of the crystalline products indicates that this is due to preferential affinity of these reagents to associate to the carboxylic acid functions via H-bonds, in competition with the potential self-association of the porphyrin units. In the copper–porphyrin derivative all four carboxylic acid functions of a given porphyrin interact with the 4-acetylpyridine species, creating discrete 1 : 4 porphyrin : ligand pentameric assemblies. Then, in adducts of the ruthenium carbon monoxide porphyrins with pyridine or 4-acetylpyridine, two trans-related carboxylic acid groups of the porphyrin scaffold interact directly with neighboring porphyrin species via the common (COOH)2 cyclic dimeric synthon to yield 1-D hydrogen bonded chains, while the other carboxylic functions donate their protons to molecules of the polar pyridine/acetylpyridine ligand that prevent further interporphyrin lateral binding along the perpendicular direction. The pyridyl-type moieties bear a single electron lone pair on the N-atom that can act as an effective hydrogen bond acceptor, allowing for a localized hydrogen bond with the carboxylic acid. On the other hand, the dimethylsulfoxide can involve readily through its O-site (bearing two lone pairs of electrons) in two hydrogen bonds in tetrahedral directions, and can thus serve as a bridging auxiliary between the carboxylic acid groups of neighboring porphyrins. Correspondingly, its reaction with the palladium complex leads to the formation of heterogeneous porphyrin–dimethylsulfoxide linear hydrogen bonded chains. Along these chains two ligand molecules are inserted between adjacent porphyrin units on both sides, and bridge between their cis-related carboxyphenyl arms. The different motifs of hydrogen-bonding effect different crystal packing features in three dimensions, some characterized also by the presence of solvent-accessible open channels that propagate through the lattice.