Liu Jian-Hong, Tu Tao, Shen Yu-Luo, Tu Bo, Qian Dong-Jin
Department of Chemistry, Fudan University, 2005 Songhu Road, Shanghai 200438, China.
Langmuir. 2023 Apr 4;39(13):4777-4788. doi: 10.1021/acs.langmuir.3c00166. Epub 2023 Mar 22.
Metal-directed interfacial self-assembly of well-defined coordination polymer (CP) ultrathin films can control the metal complex arrangement and distribution at the molecular level, providing a convenient route for the design and fabrication of novel opto-electrical devices and heterogeneous catalysts. Here, we report the assembly of two series of CP multilayers with the transition-metal ions of Fe, Co, Zn and Tb as connectors and tripodal terpyridyl ligands of 4,4',4″-(1,3,5-triazine-2,4,6-triyl)tris(1-(4-([2,2':6',2″-terpyridin]-4'-yl)benzyl)pyridin-1-ium) (TerPyTa) and 4,4',4″-(benzene-1,3,5-triyl)tris(1-(4-([2,2':6',2″-terpyridin]-4'-yl)benzyl)pyridin-1-ium) (TerPyBen) as linkers at the air-water interface. The as-prepared Langmuir-Blodgett (LB) films display strong luminescence, with the emission wavelength and relative intensity dependent on both the metal ions and linkers; among them, the Zn-TerPyTa and Zn-TerPyBen CPs give off the strongest luminescent emission centered at about 370 nm with an emission lifetime of approximately 0.2-0.3 ns. The Tb-TerPyTa CPs can give off emission at approximately 490, 546, 586, and 622 nm, attributed to the D to F electron transitions of typical Tb ions. Finally, these CP LB films can act as efficient heterogeneous photocatalysts for the CO reduction to selectively produce CO. The catalytic efficiency can be optimized by adjusting the experimental conditions (light sensitizer, electron donor, and water content) and CP composition (metal ion and ligand) with an excellent yield of up to 248.1 mmol g. In particular, it is revealed that, under the same conditions, the catalytic efficiency of the Fe-TerPyTa CP LB film is nearly 2 to 3 orders of magnitude higher than that of the other metalated complexes investigated in the homogeneous system. UV-vis spectroscopy and cyclic voltammetry studies demonstrated that the dual active sites of Fe-terpyridine and TerPyTa units contribute to the enhanced catalytic activity. This work provides an effective method to introduce the earth-abundant metal complexes into CP films to construct efficient noble-metal-free photocatalysts for the CO reduction.
定义明确的配位聚合物（CP）超薄膜的金属导向界面自组装能够在分子水平上控制金属配合物的排列和分布，为新型光电器件和多相催化剂的设计与制造提供了一条便捷途径。在此，我们报道了以铁、钴、锌和铽等过渡金属离子作为连接体，以及以4,4',4″-(1,3,5-三嗪-2,4,6-三基)三(1-(4-([2,2':6',2″-三联吡啶]-4'-基)苄基)吡啶-1-鎓)(TerPyTa)和4,4',4″-(苯-1,3,5-三基)三(1-(4-([2,2':6',2″-三联吡啶]-4'-基)苄基)吡啶-1-鎓)(TerPyBen)作为连接基，在气-水界面组装两个系列的CP多层膜。所制备的朗缪尔-布洛杰特（LB）膜显示出强烈的发光，其发射波长和相对强度取决于金属离子和连接基；其中，Zn-TerPyTa和Zn-TerPyBen CP发出最强的发光，中心波长约为370 nm，发射寿命约为0.2 - 0.3 ns。Tb-TerPyTa CP在约490、546、586和622 nm处发光，这归因于典型铽离子的D到F电子跃迁。最后，这些CP LB膜可作为高效的多相光催化剂用于将CO还原以选择性地生成CO。通过调整实验条件（光敏剂、电子供体和含水量）以及CP组成（金属离子和配体），催化效率得以优化，产率高达248.1 mmol g，表现优异。特别地，研究表明，在相同条件下，Fe-TerPyTa CP LB膜的催化效率比在均相体系中研究的其他金属化配合物高出近2至3个数量级。紫外-可见光谱和循环伏安法研究表明，Fe-三联吡啶和TerPyTa单元的双活性位点有助于提高催化活性。这项工作提供了一种有效的方法，将储量丰富的金属配合物引入CP膜中，以构建用于CO还原的高效无贵金属光催化剂。
