Redox-Active Carboranyl-Based Lewis Acids for Targeted N-H Bond Weakening

用于靶向 N-H 键弱化的氧化还原活性碳硼烷基路易斯酸

• 批准号: 2155239
• 负责人: Lior Sepunaru
• 金额: $ 50万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2155239&HistoricalAwards=false
• 关键词: Redox; Active; Carboranyl; Based; Lewis

With the support of the Chemical Synthesis Program of the Chemistry Division, Gabriel Menard of the Department of Chemistry at University of California – Santa Barbara will investigate the ability of a class of compounds, called carboranes, to activate N-H bonds in ammonia. This project is motivated by the need to develop energy storage technologies to facilitate the sustained growth of renewable energy (RE) production and distribution. For the practical use of RE, efficient energy storage is vital. This is because excess energy is obtained, for example, during periods when the sun is shining and must be stored in order to provide energy when the sun is not shining. An emerging storage technique involves use of ammonia. Ammonia, the second most produced chemical in the world, is a low-cost, energy-dense molecule with a high hydrogen content and an established global distribution infrastructure. However, its use in RE storage relies on its efficient conversion to hydrogen – a clean fuel – and nitrogen. This project will develop a set of molecules, called carboranes, that are capable of utilizing electrical energy to transform ammonia into hydrogen and nitrogen. The work focuses on the maximizing the ability of the carboranes to weaken the chemical bonds in ammonia, which prompts the fundamental steps involved in the conversion to hydrogen and nitrogen. The project will lead to the training of highly skilled chemists, including women and underrepresented minority scientists. In addition, Dr. Menard hosts monthly “Science Pub Night” event, where scientists from campus present their research to the public in an open and accessible way. This research aims to develop carborane reactivity for initiating the activation of the strong N–H bonds in ammonia for hydrogen release (or its equivalents). The underlying challenge in converting NH3 (ammonia) lies in activating the strong N–H bonds sufficiently to prompt subsequent N–N bond formation. A general strategy is being developed to systematically control N–H bond dissociation free energy by synthesizing proximal, redox-active, carborane (Cb)-appended Lewis acidic centers that allow for the decoupling and control of the thermochemical parameters by tuning the Cb cage electronics and Lewis acidic properties of these compounds. This will allow the systematic control and weakening of the N–H bonds of coordinated NH3 and target its partial splitting to hydrazine and hydrogen equivalents. The Specific Aims include: 1) the synthesis of Cb-appended, proximal Lewis acidic systems; 2) targeting the spontaneous release of H2 through thermochemical and structural control, and; 3) closing the cycle using an electrochemical reactor. The project involves a significant effort to recruit and retain a diverse group of students and an outreach component target non-traditional audiences for science education.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.

在化学系化学合成项目的支持下，加州大学圣塔芭芭拉分校化学系的 Gabriel Menard 将研究一类名为碳硼烷的化合物激活氨中 N-H 键的能力。该项目的动机是开发储能技术以促进可再生能源（RE）生产和分配的持续增长。对于可再生能源的实际应用，高效的储能至关重要。这是因为，例如，在阳光照射期间获得了多余的能量，并且必须将其存储起来，以便在阳光不照射时提供能量。一种新兴的储存技术涉及氨的使用。氨是世界上产量第二大的化学品，是一种低成本、高能量的分子，氢含量高，并拥有成熟的全球分销基础设施。然而，它在可再生能源存储中的使用依赖于其有效转化为氢气（一种清洁燃料）和氮气。该项目将开发一组称为碳硼烷的分子，它们能够利用电能将氨转化为氢气和氮气。这项工作的重点是最大限度地提高碳硼烷削弱氨中化学键的能力，从而促进转化为氢和氮的基本步骤。该项目将培训高技能化学家，包括女性和代表性不足的少数族裔科学家。此外，梅纳德博士每月举办“科学酒吧之夜”活动，校园里的科学家以开放且易于理解的方式向公众展示他们的研究成果。本研究旨在开发碳硼烷反应性，以引发氨中强 N-H 键的活化，从而释放氢气（或其等价物）。转化 NH3（氨）的根本挑战在于充分激活强 N-H 键以促进随后的 N-N 键形成。正在开发一种通用策略，通过合成近端、氧化还原活性、附加碳硼烷 (Cb) 的路易斯酸性中心来系统地控制 N-H 键解离自由能，通过调节这些化合物的 Cb 笼电子和路易斯酸性性质，可以解耦和控制热化学参数。这将允许系统控制和弱化配位 NH3 的 N-H 键，并将其部分分解为肼和氢当量。具体目标包括： 1) 合成附有 Cb 的近端路易斯酸性体系； 2) 通过热化学和结构控制来实现 H2 的自发释放； 3)使用电化学反应器关闭循环。该项目涉及招募和留住多元化学生群体的巨大努力，以及针对科学教育非传统受众的外展部分。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。