修饰NADH模拟物的金属-有机三元环光催化制氢

将含有不同还原型烟酰烟腺嘌呤二核苷酸(NADH)活性中心模拟物的有机配体H₂L¹和H₂L²与钴离子配位自组装获得2例具有氧化还原活性且带有正电荷的金属-有机大环Co-L¹和Co-L²。选择阴离子型钌基光敏剂Ru(dcbpy)₃]^4-(dcbpy=2,2′-联吡啶-4,4′-二羧酸)作为光敏中心,金属-有机大环结构作为质子还原催化剂,通过静电作用力将光敏中心封装在其空腔内部以加速光诱导电子转移(PET)过程,构建了人工光合成体系并应用于光解水制氢研究。相比于未修饰NADH模拟物的金属-有机大环Co-L³以及未修饰NADH模拟物但配位环境相同的单核催化剂Co-L⁴,由Co-L¹和Co-L²构建的金属-有机大环主客体超分子体系的光催化产氢效率分别提高1.6和6倍,可能是由于NADH活性中心模拟物的引入以及主客体超分子体系的形成有利于光敏中心与催化中心之间的光致电子转移过程。

Metal-Organic Triangles with NADH Mimics for Photocatalytic Hydrogen Production

By incorporating two different reduced nicotinamide adenine dinucleotide(NADH)mimics within the ligand backbone,two positively charged cobalt-based metal-organic triangular hosts Co-L¹and Co-L²(H₂L¹-5′-(benzod]thiazol-2-yl)-N⁴,N^{′′′′′4"}-bis((E)-pyridin-2-ylmethylene)-1,1′:3′,1"-terphenyl]-4,4"-dicarbohydrazide,H₂L²=5′-(benzod]imidazol-2-yl)-N^′4,N^{′′′′′4"}-bis((E)-pyridin-2-ylmethylene)-1,1′:3′,1"-terphenyl]-4,4"-dicar bohydrazide)have been prepared in high yield and characterized as a redox vehicle for the construction of an artificial photosynthesis(AP)system.By taking advantage of electrostatic interaction to facilitate the formation of host-guest complexes,anionic ruthenium-based photosensitizerRu(dcbpy)₃]^4-(dcbpy=2,2′-bipyridine-4,4′-dicarboxylic acid)was encapsulated into the suitable cavity of hosts to improve photoinduced electron transfer(PET)processes and to promote photocatalytic hydrogen production.Compared with metal-organic triangular Co-L³without NADH mimics(H₂L³=5′-methyl-N^′4,N^{′′′′′4"}-bis((E)-pyridin-2-ylmethylene)-1,1′:3′,1"-terphenyl]-4,4"-dicarbohydrazide)and mononuclear catalyst Co-L⁴(HL⁴=(E)-N′-(pyridin-2-ylmethylene)benzohydrazide)containing the same coordination environment and without NADH mimics,photocatalytic hydrogen production efficiency of the host-guest supramolecular photosynthetic systems could increase 1.6 and 6 times,respectively.The higher catalytic activity is attributed to the formation of host-guest complex between catalyst Co-L¹and Co-L²and photosensitizerRu(dcbpy)₃]^4-and the introduction of NADH mimics benefiting the PET process between the catalyst and photosensitizer.