Conductive Dithiolene-Based Metal Organic Frameworks (MOFs) with Tunable Transport Properties

非技术摘要：金属有机骨架(MOF)是由有机分子连接的金属离子或团簇组成的晶态纳米多孔材料。由于其精确控制的纳米环境和可合成的可调性，MOF已成为一类具有可调性能的有前途的材料。然而，MOF的绝缘性限制了其在需要电荷传输的技术中的应用，如电子。该项目由国家科学基金会材料研究部的固态和材料化学计划支持，建立在Marinescu小组之前的研究基础上，该研究表明，一些二维扩展框架显示出高导电性。有了这一奖项，通过表征和改变电子环境以及研究这些MOF的整体性质，促进了对支配这些骨架的传输特性的因素的理解。这些框架的合成可调性允许对它们的配位环境进行良好的控制，这有助于结构-活性研究。该奖项的教育部分综合了与实验室研究的能源和材料应用相关的化学方面，覆盖了初中/高中学生和教师，以及博士后学者、研究生和本科生，重点是女性，这是科学界代表性较低的群体。技术摘要：这个项目得到了美国国家科学基金会材料研究部固体和材料化学计划的支持，研究了氧化还原活性配体的使用，如二硫代烯，作为一种促进通过MOF进行电荷传输的方法。Marinescu组以前的研究表明，基于苯六硫酸酯和2，3，6，7，10，11-三苯六硫酸酯配体的二维含钴MOF可以得到结晶度很高的二维MOF。这些包含金属和配体轨道的广泛离域的MOF表现出高的导电性，这个项目测试了PI的基本假设，即MOF的输运性质可以通过合成的自下而上的方法来调节，重点是调节配位球效应以及客体物种和掺杂到这些多孔结构中。研究了几个结构相似的框架，以了解促进和控制这些MOF导电性的潜在结构特征和机制。通过改变金属中心的同一性、氧化态和电荷补偿阳离子来调制这些被提议的MOF的电子环境。这些研究提供了有关当地环境和金属二硫烯骨架的本体性质如何影响其导电性的信息，这有助于制定产生导电MOF的设计原则。与该奖项相关的教育活动是多方面的，涉及洛杉矶的初中生/高中生和教师，以及南加州大学的研究生和本科生：(1)为本科阶段的女性领导一项指导方案，以增加女性对科学的参与；(2)为当地学校的教师举办暑期讲习班，在那里进行动手实验。最重要的是，参与这些努力的学生建立了一种长期的文化，为他们的科学和非科学社区做出贡献。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。

Non-technical abstract: Metal-organic frameworks (MOFs) are crystalline nanoporous materials composed of metal ions or clusters linked by organic molecules. Due to their precisely controlled nano-enviroments and synthetic tunability, MOFs have emerged as a promising class of materials with adjustable properties However, the insulating nature of MOFs has limited their use in technologies that require charge transport, such as electronics. This project, which is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, builds on previous research in the Marinescu group that has shown that some two-dimensional extended frameworks display high electrical conductivity. With this award, the understanding of the factors that govern the transport properties of these frameworks is advanced by characterizing and changing the electronic environment, as well as studying the bulk properties of these MOFs. The synthetic tunability of these frameworks allows for excellent control of their coordination environment, which facilitates structure-activity studies. The educational components of this award integrate aspects of chemistry related to energy and materials applications researched in the laboratory and reach middle/high school students and teachers, as well as postdoctoral scholars, graduate, and undergraduate students, with a focus on women, an underrepresented group in science.Technical abstract: With this project, which is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, the use of redox active ligands, such as dithiolenes, is investigated as a means to facilitate charge transport through MOFs. Previous research in the Marinescu group has demonstrated that two-dimensional cobalt-containing MOFs based on benzenehexathiolate and 2,3,6,7,10,11-triphenylenehexathiolate ligands can be produced with high degree of crystallinity. These MOFs that contain extensive delocalization of the metal and ligand orbitals exhibit high electrical conductivity, and this project tests the PI’s fundamental hypothesis that the transport properties of MOFs can be modulated through a synthetic, bottom-up approach with an emphasis on tuning the coordination sphere effects and incorporation of guest-species and dopants into these porous architectures. Several structurally analogous frameworks are investigated to understand the underlying structural features and mechanisms, which promote and control the conductivity of these MOFs. The electronic environment of these proposed MOFs are modulated by changing the identity of the metal center, its oxidation state, and charge compensating cations. The studies provide information on how the local environment and the bulk properties of the metal dithiolene frameworks affect their conductivity, which is instrumental in the development of design principles to generate conductive MOFs. The educational activities associated with this award are multifaceted and involve Los Angeles middle/high-school students and teachers, as well as graduate and undergraduate students from USC: the PI (1) leads a mentoring program for women at the undergraduate level to increase the participation of women in science; and (2) develops a summer workshop for teachers from local schools where hands-on experiments are performed. Most importantly, students involved in these efforts develop a long-lasting culture of contributing to their scientific and non-scientific communities.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.