Jayaraj K, Gold A, Ball L M, White P S
Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Inorg Chem. 2000;39(16):3652-64. doi: 10.1021/ic000112r.
This report describes the synthesis and characterization of a series of octaethylporphyrin derivatives in which the porphyrin pi-network is connected to phenyl, 3-fluoranthenyl, or 1-pyrenyl aromatic systems through a meso amino or amido nitrogen. Metal-free bases and zinc(II) and iron(III) complexes have been obtained. These compounds represent the first examples of linkages between porphyrins and extended pi-networks through a nitrogen atom directly attached to a porphyrin meso position. 1H NMR studies of the metal-free bases and zinc complexes showed that in the amido-linked adducts, the plane containing the aryl substituent was oriented perpendicular to the plane of the porphyrin. Linkage through the secondary amino nitrogen, however, allowed the aryl plane to rotate toward coplanarity with the porphyrin plane, resulting in conjugation of the highest occupied aryl and porphyrin molecular orbitals through the nitrogen lone pair. In developing routes to the amino-linked compounds, the facile formation of fused azaaryl chlorins via an oxidative intramolecular cycloaddition was observed. An aryl carbon ortho to the meso linkage attacked the beta-carbon of an adjacent pyrrole ring, accompanied by 1,2-migration of a pyrrole beta-ethyl substituent and a two-electron oxidation of the initially formed macrocycle. The resulting structures are analogous to benzochlorins. The electronic spectra of the metal-free bases are characterized by intense, long-wavelength bands in the visible region. Molecular structures of the chloroferric complexes of the azabenzofluorantheno- and azabenzpyrenoporphyrin macrocycles (derived from fusion of the fluoranthenyl and pyrenyl substituents, respectively) were obtained by X-ray diffraction. The porphyrin moiety in the azabenzofluoranthenoporphyrin adopted a gable structure, with a 22 degrees fold along a diagonal including the pyrrole-ring C4 and C16 alpha-carbons. By contrast, the azabenzpyrenoporphyrin was virtually planar.
本报告描述了一系列八乙基卟啉衍生物的合成与表征，其中卟啉π网络通过中位氨基或酰胺氮与苯基、3-荧蒽基或1-芘基芳香体系相连。已获得无金属碱以及锌（II）和铁（III）配合物。这些化合物代表了卟啉与扩展π网络之间通过直接连接到卟啉中位位置的氮原子形成连接的首个实例。对无金属碱和锌配合物的¹H NMR研究表明，在酰胺连接的加合物中，含有芳基取代基的平面垂直于卟啉平面取向。然而，通过仲氨基氮连接时，芳基平面能够朝着与卟啉平面共面的方向旋转，导致最高占据的芳基和卟啉分子轨道通过氮孤对共轭。在开发氨基连接化合物的合成路线时，观察到通过氧化分子内环加成容易形成稠合氮杂芳基二氢卟吩。与中位连接相邻的芳基碳进攻相邻吡咯环的β-碳，同时伴随着吡咯β-乙基取代基的1,2-迁移以及最初形成的大环的双电子氧化。所得结构类似于苯并二氢卟吩。无金属碱的电子光谱在可见光区域具有强烈的长波长吸收带。通过X射线衍射获得了氮杂苯并荧蒽卟啉和氮杂苯并芘卟啉大环（分别源自荧蒽基和芘基取代基的稠合）的氯铁配合物的分子结构。氮杂苯并荧蒽卟啉中的卟啉部分呈现出山墙结构，沿包含吡咯环C4和C16α-碳的对角线折叠22度。相比之下，氮杂苯并芘卟啉几乎是平面的。
