三明治型卟啉、酞菁类金属配合物的合成及性质研究

【作者】 边永忠；

【导师】 姜建壮；

【作者基本信息】 山东大学 ， 无机化学， 2005， 博士

【摘要】 卟啉和酞菁都是非常重要的染料分子,它们都属于环状四吡咯化合物,其中的四个吡咯或异吲哚氮原子可以和金属元素络合而形成多种多样的配合物。当配位的中心金属离子半径较大时（例如稀土元素,锕系元素等）,倾向于形成八配位的三明治型二层或三层配合物。在三明治型配合物中,由于两个或三个共轭大环配体之间距离很近,所以具有非常强的分子内p-p相互作用,使得这类配合物具有非常特殊的功能性质和应用前景,例如可以作为电致变色显示材料、场效应晶体管材料、气体传感材料以及光合作用反应中心特殊对的结构和谱学模型等。本文的研究内容包括以下三个方面: 1、混杂卟啉萘菁稀土三明治型配合物RE（OEP）（Nc）及RE₂（OEP）₂（Nc）的合成及性质研究 对于在其中一个四吡咯配体上带有一个未成对电子的三明治型配合物来说,一个基本的问题是空穴在分子内的离域程度。要进一步阐明这个问题,需要合成并研究含有不同大环配体的不对称三明治型配合物,而且其中的不同配体之间必须具有差别很大的光化学和氧化还原性质。2,3-萘菁由于在酞菁环的外围又并上了四个苯环,具有比一般酞菁或卟啉更为扩展的p共轭体系。实验和理论计算表明,其HOMO-LUMO能级差变小,具有比酞菁更小的电离能和更低的氧化电势,而且其特征Q带比酞菁显著红移。以往对含有萘菁配体的三明治型配合物的研究主要集中在对称的Lu的配合物上,不对称萘菁三明治型配合物还少有报道。作者合成了一系列新颖的三明治型萘菁卟啉配合物M^Ⅲ（Nc）（OEP）（M=Y,La-Lu except Pm）和M₂^Ⅲ（Nc）（OEP）₂（M=Nd,Eu）,对所合成的二层及三层配合物都进行了充分的表征,包括:元素分析（EA）、质谱（MS）、电子自旋共振光谱（EPR）、核磁共振光谱（¹H NMR）、紫外-可见及近红外吸收光谱（UV-Vis and NIR）、红外光谱（IR）以及拉曼光谱（Raman）。并对所有二层配合物M^Ⅲ（Nc）（OEP）（M=Y,La-Lu except Pm）的晶体及分子结构、电化学性质以及在氧化或还原状态下的电子吸收光谱进行了系统研究。结果表明,在该类配合物中存在强烈的π-π相互作用;在三价稀土元素的双层配合物中,未成对电子是离域在两个大环配体之上的。更多还原

【Abstract】 Phthalocyanines and porphyrins are two important classes of pigments which have found their applications in various disciplines. Both series belong to a cyclic tetrapyrrole family in which the four isoindole or pyrrole nitrogen atoms are able to complex with a range of metal ions. With large metal centers which favor octa-coordination (e.g. rare earths, actinides, group 4 transition metals, and main group elements such as In, Sn, As, Sb, and Bi), sandwich-type complexes in the form of double- and triple-deckers can be formed. Due to the intramolecular π-π interactions and the intrinsic nature of the metal centers, these novel complexes display characteristic features, which cannot be found in their non-sandwich counterparts, enabling them to be used in different areas. They are versatile materials for electrochromic displays, field effect transistors, gas sensors and as structural and spectroscopic models for the special pair found in the bacterial photosynthetic reaction centers.1. Synthesis, Structure, Spectroscopic Properties, and Electrochemistry of Rare Earth Sandwich Compounds with Mixed 2,3-Naphthalocyaninato and Octaethylporphyrinato LigandsFor sandwich complexes with an unpaired electron in one of the tetrapyrrole ligands, one of the fundamental questions is related to the extent of hole delocalization. To have a better understanding on this issue, there is a need of more examples of heteroleptic complexes in which the individual chromophoric ligands exhibit very different optical and redox properties. 2,3-Naphthalocyanine is a phthalocyanine derivative having a more extended π system. As shown by experiments and theoretical calculations, the linear benzoannulation destabilizes the HOMO level leading to a smaller HOMO-LUMO gap. As a result, 2,3-naphthalocyanine has a lower ionization energy and oxidation potential than the phthalocyanine analogue, and its characteristic Q band is also significantly red-shifted.Although naphthalocyaninate-containing sandwich compounds have been known for some time, studies have been focused on the homoleptic complexes, mainly of lutetium(III). Heteroleptic naphthalocyaninato complexes remain extremely rare. We have developed a straightforward and simple methodology to prepare a new series of complexes Mm(Nc)(OEP) (M = Y, La-Lu except Ce and Pm) and Min2(Nc)(OEP)2 (M = Nd, Eu). These rare heteroleptic complexes have been fully characterized by elemental analyses and a wide range of spectroscopic methods, including Mass, EPR, UV-Vis, NIR, NMR, IR and Raman. The molecular structures of all of double-deckers and one triple-decker have also been determined, and the structural parameters have been systematically analyzed and compared. According to the spectroscopic, electrochemical and structural studies, all the complexes exhibit significant jt-jt interactions, for the double-deckers, the hole or the unpaired electron is delocalized over both macrocyclic ligands.2. Tuning the Valence of the Cerium Center in (Na)phthalocyaninato and Porphyrinato Cerium Double-Deckers by Changing the Nature of the Tetrapyrrole LigandsAmong the whole rare earth series, cerium is the only exception. Having an electronic configuration of [Xe]4f15d16s2, this lanthanide may also utilize the electron in the extended 4f orbital in reactions leading to an additional +4 oxidation state. For all the bis(porphyrinato) complexes [Ce(Por)2] and the mixed double-deckers [Ce(Pc)(Por)j reported so far, it is believed that the cerium center is tetravalent and both tetrapyrrole rings are dianionic. Compared with the porphyrin analogues, bis(phthalocyaninato) cerium complexes have been little studied and the exact valence of the metal center remains elusive. While the spectroscopic properties of cerium double-decker [Ce{Nc(fBu)4}2] suggests the presence of a trivalent cerium center. To resolve and clarify this controversial issue, we have prepared a series of cerium double-deckers using a range of tetrapyrrole ligands with very different electronic properties, and systematically examined their structural, electrochemical and spectroscopic properties, including the X-ray absorption near-edge structure(XANES) of the cerium center. The results demonstrate that the valent state of the cerium center varies from III to IV depending on the electronic nature of the two tetrapyrrole ligands.3. Design, synthesis and characterization of chiral sandwich-typephthalocyaninato metal complexesThere has been a growing interest in optically active tetrapyrrole derivatives because of their biological relevance and various potential applications. While chiral porphyrins, ranging from synthetic to naturally occurring analogues, have been extensively studied over the past few decades, the phthalocyanine counterparts have only been reported recently. Because of the unique structure, sandwich-like rare earth complexes with certain tetrapyrrole ligands can exhibit chirality. We have designed and synthesized three series of chiral sandwich-type phthalocyaninato metal complexes as follows: Pb[Pc(a-OR)4] [R = C5Hn, C7H15, Q0H7], [Mm(Pc){Pc(a-OC5Hn)4}] (M = Y, Sm-Lu) and (Pc)M(Pc)M[Pc(a-OC5Hn)4] (M = Sm, Gd, Lu). These new complexes have been fully characterized by elemental analyses and a wide range of spectroscopic methods, their electrochemical properties have been studied systematically. The molecular structures of Pb[Pc(a-0 CsHnM, [Mul(Pc){Pc(a-OC5Hii)4}] (M = Sm, Eu and Er) and (Pc)M(Pc)M[Pc(a-OC5Hn)4] (M = Gd, Lu) have been determined by single-crystal X-ray diffraction analysis. According to the spectroscopic, electrochemical and structural studies, all these molecules are intrinsically chiral possessing a C4 or Cs symmetry.更多还原