Metalloporphenes: Synthesis and Characterization

在化学部化学结构、动力学和机理b （CSDM-B）项目的支持下，科罗拉多大学博尔德分校化学系的Josef Michl教授正在开发一种新的超薄聚合物家族，这种聚合物被设计为单原子厚度，并具有有趣的光电特性。本研究的目的是探索这些含金属离子聚合物的特性，并利用它们开发光电子器件，如纳米电子学的晶体管。该项目位于有机、无机和材料化学的界面，因此非常适合各级科学家的教育。这个群体也处于有利地位，可以为科学领域代表性不足的学生提供最高水平的教育和培训。涉及K-12学生的外展活动也将是该项目的一部分。这种新型聚合物被称为金属卟啉，由卟啉大环在四面融合成一个平面正方形阵列，类似于苯环被融合成石墨烯。大环的中心可以包含两个质子（“自由碱卟烯”）或一个二价金属阳离子（“金属卟烯”），金属原子可以携带两个、一个或没有轴向配体，这样就有可能产生大量精细可调的衍生物。在Langmuir-Blodgett槽中，在可控的表面压力下，利用水相中含有的氧化剂，在水面上氧化聚合了一层双层卟啉锌，合成了游离基卟啉。该项目目前的重点是揭开动力学和形成规则聚合物的机制，其单晶域具有至少120纳米的相干长度，从预组织的双分子层单体，同时失去锌阳离子。本文将采用一系列技术监测起始卟啉锌的紫外可见（Soret波段）和CH拉伸吸收及其XPS信号等特征光谱特征随表面张力、氧化剂性质和浓度、溶液pH、底物氘化等的逐渐消失动力学。预计对卟烯形成机制的理解将有助于开发出含有更大单晶域和更少缺陷的更大面积的金属卟烯。然后，这些可以用作画布，在画布上可以绘制平版印刷图案，甚至可能绘制电路，其中包含不同的金属离子，因此在不同的区域具有不同的特性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Structure, Dynamics & Mechanisms-B (CSDM-B) Program of the Chemistry Division, Professor Josef Michl of the Department of Chemistry at the University of Colorado at Boulder is developing a new family of ultra-thin polymers that are designed to be one-atom thick and to possess interesting optoelectronic properties. The goal of this research is to explore the characteristics of these metal ion containing polymers and to exploit them for the development of optoelectronic devices, such as transistors for nanoelectronics. The project lies at the interface of organic, inorganic, and materials chemistry, and is therefore well suited to the education of scientists at all levels. This group is also well-positioned to provide the highest level of education and training for students underrepresented in science. Outreach activities involving K-12 students will also be part of the project.The new polymers, called metalloporphenes, consist of porphyrin macrocycles fused on all four sides into a planar square array similarly as benzene rings are fused into graphene. The centers of the macrocycles may contain two protons (“free base porphene”) or a divalent metal cation (“metalloporphene”), and the metal atom may carry two, one, or no axial ligands, such that a vast number of finely tunable derivatives are possible. Free-base porphene has been synthesized by oxidative polymerization of a bilayer of zinc porphyrin on the surface of water in a Langmuir-Blodgett trough under controlled surface pressure, using an oxidant contained in the aqueous subphase. The current focus of the project is the unravelling of the kinetics and the mechanism of the formation of a regular polymer, whose single crystalline domains have a coherence length of at least 120 nm, from the preorganized bilayer of monomers, with a simultaneous loss of the zinc cations. A series of techniques will be used to monitor the kinetics of the gradual disappearance of the characteristic spectral signatures of the starting zinc porphyrin, such as its UV-visible (Soret band) and CH stretching absorption and its XPS signals, as a function of surface tension, oxidant nature and concentration, solution pH, substrate deuteriation, etc. It is expected that an understanding of the mechanism of porphene formation will contribute to the development of procedures that will yield larger patches of metalloporphenes containing larger single crystalline domains with fewer defects. These may then be amenable to use as a canvas on which lithographic patterns and possibly even circuitry can be drawn, containing different metal ions and thus different properties in different regions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.