Oppelt Kerstin T, Wöß Eva, Stiftinger Martin, Schöfberger Wolfgang, Buchberger Wolfgang, Knör Günther
Institute of Inorganic Chemistry, and ‡Institute of Analytical Chemistry, Johannes Kepler University Linz (JKU) , A-4040 Linz, Austria.
Inorg Chem. 2013 Oct 21;52(20):11910-22. doi: 10.1021/ic401611v. Epub 2013 Sep 27.
An efficient photocatalytic two-electron reduction and protonation of nicotine amide adenine dinucleotide (NAD(+)), as well as the synthetic nucleotide co-factor analogue N-benzyl-3-carbamoyl-pyridinium (BNAD(+)), powered by photons in the long-wavelength region of visible light (λirr > 610 nm), is demonstrated for the first time. This functional artificial photosynthetic counterpart of the complete energy-trapping and solar-to-fuel conversion primary processes occurring in natural photosystem I (PS I) is achieved with a robust water-soluble tin(IV) complex of meso-tetrakis(N-methylpyridinium)-chlorin acting as the light-harvesting sensitizer (threshold wavelength of λthr = 660 nm). In buffered aqueous solution, this chlorophyll-like compound photocatalytically recycles a rhodium hydride complex of the type Cp*Rh(bpy)H, which is able to mediate regioselective hydride transfer processes. Different one- and two-electron donors are tested for the reductive quenching of the irradiated tin complex to initiate the secondary dark reactions leading to nucleotide co-factor reduction. Very promising conversion efficiencies, quantum yields, and excellent photosensitizer stabilities are observed. As an example of a catalytic dark reaction utilizing the reduction equivalents of accumulated NADH, an enzymatic process for the selective transformation of aldehydes with alcohol dehydrogenase (ADH) coupled to the primary photoreactions of the system is also demonstrated. A tentative reaction mechanism for the transfer of two electrons and one proton from the reductively quenched tin chlorin sensitizer to the rhodium co-catalyst, acting as a reversible hydride carrier, is proposed.
首次证明了在可见光长波长区域（λirr > 610 nm）的光子驱动下，烟酰胺腺嘌呤二核苷酸（NAD(+)）以及合成核苷酸辅因子类似物N-苄基-3-氨基甲酰基吡啶鎓（BNAD(+)）能够进行高效的光催化双电子还原和质子化。通过使用一种稳定的水溶性中-四（N-甲基吡啶鎓）-二氢卟吩锡（IV）配合物作为光捕获敏化剂（阈值波长λthr = 660 nm），实现了天然光系统I（PS I）中完整的能量捕获和太阳能到燃料转化初级过程的功能性人工光合作用对应物。在缓冲水溶液中，这种类叶绿素化合物光催化循环一种Cp*Rh(bpy)H型的氢化铑配合物，该配合物能够介导区域选择性氢化物转移过程。测试了不同的单电子和双电子供体对辐照锡配合物的还原猝灭，以引发导致核苷酸辅因子还原的二级暗反应。观察到了非常有前景的转化效率、量子产率以及优异的光敏剂稳定性。作为利用积累的NADH还原当量进行催化暗反应的一个例子，还展示了一个将醛与乙醇脱氢酶（ADH）选择性转化的酶促过程与系统的初级光反应相耦合。提出了一个从还原猝灭的二氢卟吩锡敏化剂向作为可逆氢化物载体的铑共催化剂转移两个电子和一个质子的初步反应机理。
