Spin-State Switching and Conductivity in Metal Complexes with Non-Innocent Ligands

在这个由化学系化学结构、动力学和机制B计划资助的项目中，由佛罗里达州立大学化学和生物化学系的Mykhailo Shatruk教授和佛罗里达州立大学物理系的Stephen O Hill教授领导的合作研究小组将研究刺激响应分子。这些分子是由能够引起金属中心的磁性状态改变的有机基团(配体)围绕过渡金属离子形成的。分子固体中的磁性状态转换在很大程度上还没有被探索，并具有发展成为刺激响应材料的潜力，可以用于新的传感器和催化系统。该项目还将探索使用这些分子来制备结合了磁态转换和导电性的固体。这种多功能材料可用于下一代电子设备和光控开关的设计。该项目将为研究生和本科生提供多样化的研究经验，包括来自物理学代表性不足的群体的学生。推广工作包括组织全国范围内的磁学和磁共振光谱学本科生暑期课程。该项目的目标是合成和广泛表征基于Fe(II)离子与非无害(氧化还原活性)有机配体结合的自旋态开关材料。由外球部分和配位配体之间的可逆电子转移引起的自旋态转变的机制在很大程度上还没有被探索。建立导致这种自旋态转换现象的条件可能会打开一类新的刺激响应分子，能够将温度、压力或光诱导的外球电子转移转化为系统磁性和结构状态的戏剧性变化。该团队将系统地探索此类络合物的设计和合成，然后通过X射线结构分析、磁性测量和各种类型的磁共振光谱对其进行详细表征。我们将研究络合物在各种外部扰动下的行为，以确定导致自旋态转换的条件。这些刺激响应分子将与阴离子有机自由基共结晶，得到结合了自旋态转换和电导的杂化多功能材料。金属中心的自旋组态的变化通常会导致在整个结构中传播的显著的原子位移。将磁性金属中心的这种结构扰动转化为有机亚结构，并通过自旋态转换来调节电导率的可能性尤其吸引人，如果它可以被光照射刺激的话。除了发现一类新的刺激响应性络合物和材料外，该项目预期的发现也将对催化和生物无机化学领域具有价值。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In this project funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, a collaborative research team led by Professor Mykhailo Shatruk of the Department of Chemistry and Biochemistry and Professor Stephen O Hill of the Department of Physics at Florida State University will study stimuli-responsive molecules. These molecules are formed by surrounding transition metal ions by organic groups (ligands) capable of inducing a change in the magnetic state at the metal center. Magnetic state switching in molecular solids is largely unexplored and holds potential to develop into stimuli-responsive materials that could be used in new sensors and catalytic systems. The project will also explore the use of these molecules for the preparation of solids that combine magnetic state switching with electrical conductivity. Such multifunctional materials can be useful for the design of next-generation electronic devices and light-activated switches. The project will provide diverse research experiences to graduate and undergraduate students, including students from groups underrepresented in physical sciences. The outreach efforts include organizing nationwide undergraduate summer schools in magnetism and magnetic resonance spectroscopy.This project targets the synthesis and extensive characterization of spin-state switching materials based on the combination of Fe(II) ions with non-innocent (redox-active) organic ligands. The mechanism of the spin-state transition induced by a reversible electron transfer between an outer-sphere moiety and the coordinated ligand is largely unexplored. Establishing conditions that lead to such spin-state switching phenomena may open a new class of stimuli-responsive molecules, capable of translating temperature-, pressure-, or light-induced outer-sphere electron transfer into dramatic changes in the magnetic and structural states of the system. The team will systematically explore the design and synthesis of such complexes, followed by their detailed characterization by X-ray structural analysis, magnetic property measurements, and various types of magnetic resonance spectroscopy. The behavior of complexes will be studied under various external perturbations to establish the conditions that lead to spin-state switching. These stimuli-responsive molecules will be co-crystallized with anionic organic radicals to obtain hybrid multifunctional materials that combine spin-state switching with electrical conductivity. Changes in the spin configuration at the metal center typically lead to significant atomic displacements that propagate through the entire structure. The possibility to translate such structural perturbations at the magnetically active metal center to the organic substructure and modulate conductivity via spin-state switching is especially appealing if it can be stimulated by light irradiation. Beyond the discovery of a new class of stimuli-responsive complexes and materials, the findings expected from this project will be also of value to the areas of catalysis and bioinorganic chemistry.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.