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

2016年，使用Haber-Bosch工艺生产了大约1.8亿吨NH3。Haber-Bosch （H-B）工艺对T、P、H2的要求很高，它利用甲烷蒸汽重整（MSR）生产H2，占全球年能耗的2%左右。H-B目前每吨NH3排放约2吨CO2，加上逸散性甲烷泄漏产生的额外温室气体。光化学氮还原反应（NRR）是一种很有前途的零碳生产氨肥料的方法。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。该方案将为电化学NRR开发新的地球富集纳米颗粒催化剂。我们还将纳入已知的具有最高的法进或量子产率的电化学、光化学和光电化学NRR催化剂，这些催化剂在地球上丰富且易于制备。该提案将开发新的策略，将NRR催化剂与我们的有机发色团的新衍生物2,4,5,6-四（9h -咔唑-9-基）异眼腈（4CzIPN）结合。4CzIPN是近年来出现的一种重要的光催化剂，用于光氧化还原和能量转移有机光反应。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NH2-CzIPN，在5-咔唑基团的3位上有一个胺基；IMID-CzIPN，在IPN环的5位有1-咪唑；BnzIMID-CzIPN，在IPN环的5位有3-苄基-1-咪唑，NHC-CzIPN是相应的游离n杂环碳。我们注意到NHC-CzIPN是含有CzIPN光催化剂的NHC配体的第一个例子。采用重氮电接枝、NHC与Mo配位、h键活化双功能态N2和咔唑电聚合的方法，将NRR催化剂和新的基于czipn的发色团结合到NRR光电阴极中。例如，基于CzIPN的第一个二硫脲光催化剂将使用已建立的异硫氰酸盐化学从NH2-CzIPN一步制备。这些双硫脲将以一种新的双功能方式光还原和激活N2，其氢键与N2配位与Mo协同作用。载体将是碳纤维或ITO纳米颗粒或纳米棒。新的电催化剂和激活方式也可以应用于由光伏电池供电的直接电化学NRR反应。以NH2-CzIPN为原料制备了新型手性双硫脲光催化剂，并将其作为h键有机光催化剂用于对映选择性分子内和分子间-[2+2]-光环加成反应，包括DeMayo反应。此外，钴胺肟- nhc - czipn化合物还可作为烯烃脱羧和亚胺交叉偶联反应的丰富光催化剂。长期计划是开发一系列地球富集的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.