Metalloporphenes: Synthesis and Characterization

在化学系化学结构、动力学机制-B（CSDM-B）项目的支持下，位于博尔德的科罗拉多大学化学系的Josef Michl教授正在开发一种新的超薄聚合物系列，其设计厚度为一个原子，并具有有趣的光电性能。 本研究的目标是探索这些含金属离子的聚合物的特性，并利用它们开发光电器件，如纳米电子晶体管。 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。 该小组也有能力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。这种新的聚合物称为金属卟啉，由卟啉大环在所有四个侧面上融合成平面正方形阵列，类似于苯环融合成石墨烯。 大环的中心可以含有两个质子（“游离碱卟啉”）或二价金属阳离子（“金属卟啉”），并且金属原子可以携带两个、一个或没有轴向配体，使得大量精细可调的衍生物是可能的。 使用水亚相中含有的氧化剂，在Langmuir-Blodgett槽中，在受控的表面压力下，通过在水表面上氧化聚合锌卟啉双层来合成游离碱玢。 该项目目前的重点是解开的动力学和规则聚合物的形成机制，其单晶域具有至少120 nm的相干长度，从预组织的单体双层，同时损失的锌阳离子。 一系列的技术将被用来监测动力学的逐渐消失的特征光谱签名的起始锌卟啉，如其紫外-可见（Soret带）和CH伸缩吸收及其XPS信号，作为表面张力、氧化剂性质和浓度、溶液pH、底物氘代的函数，人们期望对卟啉形成机理的理解将有助于开发出能够产生含有更大单晶畴且缺陷更少的更大金属卟啉片的程序。 这些材料可以用作画布，在其上绘制平版印刷图案，甚至可能是电路，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NSF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.