Synthetic, Structural and Reactivity Studies on Supramolecules Obtained from Catechol Functionalized Macrocycles. Studies in Nb/S Chemistry

密歇根大学化学系的Dimitri CouCouvanis博士在化学部无机、生物无机和有机金属计划的支持下，对从儿茶酚功能化大环获得的超分子进行合成、结构和反应性研究。感兴趣的体系包括：邻苯二酚功能化的四氮杂大环配合物，能够在pH变化时进行分子内电子转移；超分子冠醚，其功能取决于分子的冠醚部分中结合的什么；以及光学活性的推进剂分子，其可用作能够在烯烃环氧化中不对称诱导的载体。还将合成包含存储电子和激活小分子的不同亚单位的分子‘反应物’，并描绘它们的反应模式。还将探讨Nb和Ta络合物中硫和硒配位配体的化学及其与杂烯、烯、炔、二氧化硫和分子氢的反应活性。分子结构涉及合成复杂的、多功能的系统，这些系统旨在转化结合的底物分子，很像酶在生命系统中的作用方式。金属大环是将金属离子结合到大环结构中的系统，就是这些所谓的超分子系统的例子。这些分子可以作为基本的分子器件，在光化学诱导电荷分离、光开关、催化氧化还原过程、电子存储或底物分子激活方面具有潜在的应用。

Dr. Dimitri Coucouvanis, Department of Chemistry, University of Michigan, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division to perform synthetic, structural and reactivity studies on supramolecules obtained from catechol functionalized macrocycles. The systems of interest include catechol-functionalized tetraazamacrocyclic complexes capable of undergoing intramolecular electron transfer upon changes in pH, supramolecular crown ethers which change their function depending on what is bound in the crown ether portion of the molecule, and optically active `propeller` molecules which could be useful as supports capable of asymmetric induction in the epoxidation of olefins. Molecular `reactors` which contain separate subunits for both the storage of electrons and the activation of small molecules will also be synthesized and their reactivity patterns delineated. The chemistry of coordinated sulfur and selenium ligands in niobium and tantalum complexes and their reactivity with heteroallenes, alkenes, alkynes, sulfur dioxide and molecular hydrogen will also be explored. Molecular architecture involves the synthesis of complex, multi-functional systems which are designed to transform a bound substrate molecule, much the way enzymes function in living systems. Metallomacrocycles, systems which incorporate metal ions into large ring structures, are examples of these so called `supramolecular` systems. These molecules may function as elementary molecular devices with potential applications in photochemically induced charge separation, photoswitching, catalytic redox processes, electron storage, or substrate molecule activation.