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Chemical, Electrochemical and Physical Properties of Metallosupramolecular Architectures with Neutral and Radical Bridging Ligands and the Influence of Non-Covalent Interactions

具有中性和自由基桥连配体的金属超分子结构的化学、电化学和物理性质以及非共价相互作用的影响

基本信息

批准号：
1808779
负责人：
Kim Dunbar
金额：
$ 64万
依托单位：
Texas A&M University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808779&HistoricalAwards=false
关键词：
Chemical Electrochemical Physical Properties Metallosupramolecular

项目摘要

From common refrigerator magnets to tiny magnetic particles on which data are recorded in hard drives, magnets are pervasive in everyday life. The reduction in size of magnetic particles over the past several decades has led to significant increase in the storage capacity but the limit is being reached. Professor Dunbar's group at Texas A&M University Main Campus explores new types of chemical structures that display magnetic behavior at the nanoscale level. Through systematic investigation of the structure-property relationships of these magnetic compounds, the team aims to gain a better fundamental understanding of the factors that contribute to superior magnetic properties and provide insight to inform design of the next generation magnets for computing or electronic storage devices. The versatility of skills required to work on this project is an excellent opportunity for students, including members of underrepresented groups, to learn chemical synthesis as well as numerous methods of characterization. The Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division supports Prof. Dunbar's group to synthesize and study the properties of multinuclear transition and lanthanide metal supramolecular architectures with neutral and radical bridging ligands. Whereas more commonly used closed-shell (diamagnetic) bridging ligands engage in superexchange (indirect) interactions between the metal spins, radical bridging ligands facilitate direct exchange interactions which results in much stronger magnetic coupling. For transition metal complexes, this situation results in modest coupling and in lanthanide complexes these interactions are very weak. Magnetic coupling in both transition metal complexes and lanthanide rare earth complexes is greatly improved by using a radical bridging ligand that can engage in direct exchange with the metal ions. In order to further improve upon these systems, the Dunbar group seeks to generate new classes of radical-bridged magnetic complexes using supramolecular strategies. This project focuses on using N-heterocyclic neutral ligands that feature interactions between anions and electron deficient aromatic rings, namely the anion-pi interaction. The neutral ligand can undergo a reversible one-electron reduction at accessible potentials to form a stable radical. Computatonal studies are performed to identify the most synthetically feasible targets and guide the direction of research as it progresses. Spontaneous self-assembly of paramagnetic metal ions with the ligands gives multinuclear supramolecular complexes in high yields due to anion and solvent templates. A plethora of techniques (including single-crystal X-ray crystallography, SQUID magnetometry, electrochemistry, and electron paramagnetic resonance) is used to study the rich electronic, redox, and magnetic properties of these supramolecular architectures. By comparing the properties of the complexes with a variety of ligands with different electron donating ability and coordinating geometry, this research aims to unveil the structural and electronic factors that contribute to superior magnetic coupling.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.

从普通的冰箱磁铁到硬盘中记录数据的微小磁性颗粒，磁铁在日常生活中无处不在。在过去的几十年中，磁性颗粒尺寸的减小导致了存储容量的显着增加，但正在达到极限。德克萨斯农工大学主校区的邓巴教授的研究小组探索了在纳米级水平上显示磁性行为的新型化学结构。通过对这些磁性化合物的结构-性质关系的系统研究，该团队旨在更好地了解有助于上级磁性的因素，并为计算或电子存储设备的下一代磁体的设计提供见解。该项目所需技能的多功能性是学生，包括代表性不足的群体的成员，学习化学合成以及表征的许多方法的绝佳机会。NSF化学部的大分子，超分子和纳米化学计划支持Dunbar教授的小组合成和研究具有中性和自由基桥接配体的多核过渡和镧系金属超分子结构的性质。虽然更常用的闭合壳层（抗磁性）桥接配体参与金属自旋之间的超交换（间接）相互作用，但自由基桥接配体促进直接交换相互作用，这导致更强的磁耦合。对于过渡金属络合物，这种情况导致适度的耦合，而在镧系元素络合物中，这些相互作用非常弱。过渡金属配合物和镧系稀土配合物中的磁耦合通过使用可以与金属离子直接交换的自由基桥连配体而大大改善。为了进一步改进这些系统，Dunbar小组试图使用超分子策略产生新类别的自由基桥接磁性复合物。该项目的重点是使用N-杂环中性配体，其特征在于阴离子和缺电子芳环之间的相互作用，即阴离子-π相互作用。中性配体可以在可及电位下进行可逆的单电子还原以形成稳定的自由基。计算研究是为了确定最综合可行的目标，并指导研究方向，因为它的进展。顺磁性金属离子与配体的自发自组装由于阴离子和溶剂模板而以高产率得到多核超分子配合物。大量的技术（包括单晶X射线晶体学，SQUID磁力学，电化学和电子顺磁共振）被用来研究这些超分子结构的丰富的电子，氧化还原和磁性。通过比较具有不同供电子能力和配位几何形状的各种配体的配合物的性质，本研究旨在揭示有助于上级磁耦合的结构和电子因素。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（20）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

A Co8 metallacycle stabilized by double anion-π interactions

DOI：
10.1039/c9cc04151f
发表时间：
2019-10-21
期刊：
CHEMICAL COMMUNICATIONS
影响因子：
4.9
作者：
Alexandropoulos, Dimitris, I;Dolinar, Brian S.;Dunbar, Kim R.
通讯作者：
Dunbar, Kim R.

Hexagonal Bipyramidal Dy(III) Complexes as a Structural Archetype for Single-Molecule Magnets

六方双锥 Dy(III) 配合物作为单分子磁体的结构原型

DOI：
10.1021/acs.inorgchem.8b03206
发表时间：
2019
期刊：
Inorganic Chemistry
影响因子：
4.6
作者：
Li Jing;Gomez Coca Silvia;Dolinar Brian S;Yan Li;Yu Fei;Kong Ming;Zhang Yi Quan;Song You;Dunbar Kim R
通讯作者：
Dunbar Kim R

Quinoxaline radical-bridged transition metal complexes with very strong antiferromagnetic coupling

具有极强反铁磁耦合的喹喔啉自由基桥接过渡金属配合物