Tamaki Yusuke, Tokuda Kazuma, Yamazaki Yasuomi, Saito Daiki, Ueda Yutaro, Ishitani Osamu
Department of Chemistry, Tokyo Institute of Technology, Tokyo, Japan.
Front Chem. 2019 May 14;7:327. doi: 10.3389/fchem.2019.00327. eCollection 2019.
Ruthenium(II) picolinate complex, [Ru(dmb)(pic)] (; dmb = 4,4'-dimethyl-2,2'-bipyridine; Hpic = picolinic acid) was newly synthesized as a potential redox photosensitizer with a wider wavelength range of visible-light absorption compared with [Ru(NN)] (NN = diimine ligand), which is the most widely used redox photosensitizer. Based on our investigation of its photophysical and electrochemical properties, was found to display certain advantageous characteristics of wide-band absorption of visible light (λ < 670 nm) and stronger reduction ability in a one-electron reduced state ( = -1.86 V vs. Ag/AgNO), which should function favorably in photon-absorption and electron transfer to the catalyst, respectively. Performing photocatalysis using as a redox photosensitizer combined with a Re(I) catalyst reduced CO to CO under red-light irradiation (λ > 600 nm). TON reached 235 and Φ was 8.0%. Under these conditions, [Ru(dmb)] () is not capable of working as a redox photosensitizer because it does not absorb light at λ > 560 nm. Even in irradiation conditions where both and absorb light (λ > 500 nm), using demonstrated faster CO formation (TOF = 6.7 min) and larger TON (2347) than (TOF = 3.6 min; TON = 2100). These results indicate that is a superior redox photosensitizer over a wider wavelength range of visible-light absorption.
新合成了吡啶甲酸钌（II）配合物[Ru(dmb)(pic)]（dmb = 4,4'-二甲基-2,2'-联吡啶；Hpic = 吡啶甲酸），作为一种潜在的氧化还原光敏剂，与最广泛使用的氧化还原光敏剂[Ru(NN)]（NN = 二亚胺配体）相比，其可见光吸收波长范围更宽。基于对其光物理和电化学性质的研究，发现该配合物具有可见光宽带吸收（λ < 670 nm）和单电子还原态下较强还原能力（相对于Ag/AgNO为 -1.86 V）的某些有利特性，这分别在光子吸收和向催化剂的电子转移中应能良好发挥作用。使用[Ru(dmb)(pic)]作为氧化还原光敏剂与Re(I)催化剂相结合，在红光照射（λ > 600 nm）下进行光催化将CO还原为CO。TON达到235，Φ为8.0%。在这些条件下，[Ru(dmb)]不能作为氧化还原光敏剂，因为它在λ > 560 nm处不吸收光。即使在[Ru(dmb)(pic)]和[Ru(dmb)]都吸收光的照射条件下（λ > 500 nm），使用[Ru(dmb)(pic)]显示出比[Ru(dmb)]更快的CO生成速率（TOF = 6.7 min）和更大的TON（2347）（TOF = 3.6 min；TON = 2100）。这些结果表明，[Ru(dmb)(pic)]在更宽的可见光吸收波长范围内是一种优越的氧化还原光敏剂。
