Enantioselective Catalysis and Nitrogen Reduction Promoted by Visible Light With Abundant Dyes and Catalysts.

2016年，使用哈伯-博世工艺生产了约1.8亿吨NH3。哈伯-博世（Haber-Bosch，H-B）工艺需要高T、P、H2，并且其通过利用甲烷蒸汽重整（MSR）来生产H2而占全球年能耗的约2%。H-B目前排放约2吨CO2/吨NH3，加上通过逃逸甲烷泄漏产生的额外温室气体。光电化学氮还原反应（NRR）是一种很有前途的零碳制氨方法。此外，液态NH3是一种非常有前途的储存和运输可再生能源的介质。该提案将为电化学NRR开发新的地球丰富的纳米颗粒催化剂。我们还将结合已知的电化学，光化学和光电化学NRR催化剂，具有最高的感应电流或量子产率，并且是地球丰富的，易于制备。该提案将开发新的策略，将NRR催化剂与我们的有机发色团2，4，5，6-四（9 H-咔唑-9-基）乙腈，4CzIPN的新衍生物结合起来。4CzIPN是一种最近出现的用于光氧化还原和能量转移有机光反应的重要光催化剂。4CzIPN也正在有机发光二极管显示器中进行研究。我们将研究的衍生物包括NH 2-CzIPN，在5-咔唑基团的3-位上具有胺基; IMID-CzIPN，在IPN环的5-位上具有1-咪唑; BnzIMID-CzIPN，在IPN环的5-位上具有3-苄基-1-咪唑，以及NHC-CzIPN，相应的游离N-杂环卡宾。我们注意到NHC-CzIPN是含有CzIPN光催化剂的NHC配体的第一个实例。NRR催化剂和新的基于CzIPN的发色团将被纳入NRR光电阴极使用重氮盐电接枝，NHC配位到Mo，H-键合双官能N2活化，和咔唑电聚合。例如，基于CzIPN的第一种二硫杂环己烷光催化剂将使用已建立的异硫氰酸酯化学由NH 2-CzIPN在一个步骤中制备。这些二硫脲将被用来以一种新的双功能方式与氢键协同作用与N2协调钼光还原和激活N2。载体将是碳纤维或ITO纳米颗粒或纳米棒。新的电催化剂和活化模式也可以应用于由光催化剂提供动力的直接电化学NRR反应。NH 2-CzIPN还将制备新型手性二硫杂环戊二烯基光催化剂，并将其作为氢键有机光催化剂用于对映选择性的分子内和分子间-[2+2]-光环加成反应，包括DeMayo反应。同时，钴肟-NHC-CzIPN化合物将被开发为烯烃脱羧和亚胺交叉偶联反应的丰富的光催化剂。长期计划是开发一系列地球资源丰富的TM-CzIPN光催化剂。

Approximately 180 million tons of NH3 were produced in 2016 using the Haber-Bosch process. The Haber-Bosch (H-B) process requires high T, P, H2, and it accounts for ~2% of the worldwide annual energy consumption by utilizing methane steam reforming (MSR) to produce H2. H-B presently emits ~ 2 tons CO2/ton NH3, plus additional greenhouse gases through fugitive methane leaks. The photoelectrochemical nitrogen reduction reaction (NRR) is a promising carbon-zero method to produce NH3 fertilizer. As well, liquid NH3 is a highly promising medium to store and transport renewable energy. This proposal will develop new Earth-abundant nanoparticle catalysts for the electrochemical NRR. We will also incorporate known electrochemical, photochemical, and photoelectrochemical NRR catalysts with the highest faradic or quantum yields, and that are Earth-abundant and easy to prepare. The proposal will develop new strategies to incorporate the NRR catalysts with our new derivatives of the organic chromophore 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile, 4CzIPN. 4CzIPN is a recent, important photocatalyst for photoredox- and energy transfer organic photoreactions. 4CzIPN is also being investigated in organic light-emitting diode displays. The derivatives we will study include NH2-CzIPN, with an amine group at the 3-position of the 5-carbazole group; IMID-CzIPN, with 1-imidazole at the 5-position of the IPN ring; BnzIMID-CzIPN, with 3-benzyl-1-imidazolium at the 5-position of the IPN ring, and NHC-CzIPN, the corresponding free N-heterocyclic carbene. We note that NHC-CzIPN is the first example of an NHC ligand containing the CzIPN photocatalyst. The NRR catalysts and the new CzIPN-based chromophores will be incorporated into NRR photocathodes using diazonium electrografting, NHC coordination to Mo, H-bonding for bifunctional N2 activation, and carbazole electropolymerization. For example, the first dithiourea photocatalysts based upon CzIPN will be prepared in one step from NH2-CzIPN using established isothiocyanate chemistry. These dithioureas will be utilized to photoreduce and activate N2 in a new bifunctional manner with H-bonding acting synergistically with N2 coordination to Mo. The supports will be carbon fibre or ITO nanoparticles or nanorods. The new electrocatalysts and modes of activation can also be applied to the direct electrochemical NRR reaction powered by photovoltaics. New chiral dithiourea photocatalysts will also be prepared from NH2-CzIPN and utilized as H-bonding organic photocatalysts for enantioselective intra- and intermolecular-[2+2]-photocycloaddition reactions including the DeMayo reaction. As well, cobaloxime-NHC-CzIPN compounds will be developed as abundant photocatalysts for olefin decarboxylation and imine cross coupling reactions. The long-term plans are to develop a series of earth abundant TM-CzIPN photocatalysts.