Fajardo Javier, Schwan Josef, Kramer Wesley W, Takase Michael K, Winkler Jay R, Gray Harry B
Beckman Institute, California Institute of Technology (Caltech), Pasadena, California 91125, United States.
Inorg Chem. 2021 Mar 15;60(6):3481-3491. doi: 10.1021/acs.inorgchem.0c02912. Epub 2020 Dec 6.
Homoleptic tungsten(0) arylisocyanides possess photophysical and photochemical properties that rival those of archetypal ruthenium(II) and iridium(III) polypyridine complexes. Previous studies established that extending the π-system of 2,6-diisopropylphenylisocyanide (CNDipp) by coupling aryl substituents to the isocyanide functionality results in W(CNDippAr) oligoarylisocyanide complexes with greatly enhanced metal-to-ligand charge transfer (MLCT) excited-state properties relative to those of W(CNDipp). Extending electronic modifications to delineate additional design principles for this class of photosensitizers, herein we report a series of W(CNAr) compounds with naphthalene-based fused-ring (CN-1-(2-Pr)-Naph) and CNDipp-based alkynyl-bridged (CNDippAr) arylisocyanide ligands. Systematic variation of the secondary aromatic system in the CNDippAr platform provides a straightforward method to modulate the photophysical properties of W(CNDippAr) complexes, allowing access to an extended range of absorption/luminescence profiles and highly reducing excited states, while maintaining the high molar absorptivity MLCT absorption bands, high photoluminescence quantum yields, and long excited-state lifetimes of previous W(CNAr) complexes. Notably, W(CN-1-(2-Pr)-Naph) exhibits the longest excited-state lifetime of all W(CNAr) complexes explored thus far, highlighting the potential benefits of utilizing fused-ring arylisocyanide ligands in the construction of tungsten(0) photoreductants.
全配体芳基异腈钨(0)配合物具有与典型的钌(II)和铱(III)多吡啶配合物相媲美的光物理和光化学性质。先前的研究表明，通过将芳基取代基与异腈官能团偶联来扩展2,6 - 二异丙基苯基异腈(CNDipp)的π体系，会得到W(CNDippAr)寡聚芳基异腈配合物，相对于W(CNDipp)配合物，其金属到配体的电荷转移(MLCT)激发态性质得到了极大增强。为了进一步扩展电子修饰以阐明这类光敏剂的其他设计原则，在此我们报道了一系列含有萘基稠环(CN - 1-(2 - Pr)-Naph)和基于CNDipp的炔基桥连(CNDippAr)芳基异腈配体的W(CNAr)化合物。在CNDippAr平台中对二级芳族体系进行系统变化，提供了一种直接的方法来调节W(CNDippAr)配合物的光物理性质，从而能够获得更广泛的吸收/发光光谱以及具有高还原性的激发态，同时保持先前W(CNAr)配合物的高摩尔吸光率MLCT吸收带、高光致发光量子产率和长激发态寿命。值得注意的是，W(CN - 1-(2 - Pr)-Naph)在迄今为止所研究的所有W(CNAr)配合物中表现出最长的激发态寿命，突出了在构建钨(0)光还原剂中使用稠环芳基异腈配体的潜在优势。
