Phiromphu Nutchanikan, Juthathan Methasit, Chainok Kittipong, Theppitak Chatphorn, Thamyongkit Patchanita, Tuntulani Thawatchai, Leeladee Pannee
Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
Thammasat University Research Unit in Multifunctional Crystalline Materials and Applications (TU-McMa), Faculty of Science and Technology, Thammasat University, Pathum Thani, 12121, Thailand.
Sci Rep. 2025 May 6;15(1):15839. doi: 10.1038/s41598-025-00345-3.
In this study, the formation of acridine-based metal complexes from rearrangement of diphenylamine-2,2'-dicarboxaldehyde (2,2'-dpadc) in the presence of transition metal ions was investigated. As a result, two novel isomorphic nickel(II) complexes bearing acridine-based Schiff-base ligand NiL·CHCN (X = BF (1), ClO (2), L = (E)-N-(2-((acridin-4-ylmethylene)amino)ethyl)-N-(2-aminoethyl)ethane-1,2-diamine) were successfully synthesized via a one-pot condensation of 2,2'-dpadc and tris(2-aminoethyl)amine (TREN) with a satisfactory yield of approximately 60%. These complexes were fully characterized by X-ray crystallography, UV-vis spectroscopy and CHN elemental analysis. Additionally, their thermal stability (thermogravimetric analysis) and electrochemical properties were also determined. A plausible mechanism for the nickel(II)-mediated rearrangement of 2,2'-dpadc to form the acridine-based nickel(II) complex was proposed. To demonstrate their potential applications, complex 1 was explored in the realm of electrocatalysis. It exhibited moderate activity towards hydrogen evolution reaction (HER). During 1-h controlled-potential electrolysis (CPE) experiments, H production (16 micromole) was observed with faradaic efficiency of 40% when the reaction was conducted in a TBAPF/DMF solution at -2.1 V vs. Fc/Fc in the presence of acetic acid as a proton source. The facile synthesis of these acridine-based nickel(II) complexes reported herein may stimulate further development of novel acridine-based ligands and their corresponding metal complexes for a wide range of applications.
在本研究中，研究了在过渡金属离子存在下，二苯胺-2,2'-二甲醛（2,2'-dpadc）重排形成吖啶基金属配合物的过程。结果，通过2,2'-dpadc与三（2-氨基乙基）胺（TREN）的一锅缩合反应，成功合成了两种新型同构镍（II）配合物，其带有吖啶基席夫碱配体NiL·CHCN（X = BF（1），ClO（2），L = （E）-N-（2-（（吖啶-4-基亚甲基）氨基）乙基）-N-（2-氨基乙基）乙烷-1,2-二胺），产率约为60%，令人满意。这些配合物通过X射线晶体学、紫外可见光谱和CHN元素分析进行了全面表征。此外，还测定了它们的热稳定性（热重分析）和电化学性质。提出了一种合理的机制，用于镍（II）介导的2,2'-dpadc重排以形成吖啶基镍（II）配合物。为了证明它们的潜在应用，在电催化领域对配合物1进行了探索。它对析氢反应（HER）表现出中等活性。在1小时的控制电位电解（CPE）实验中，当反应在TBAPF/DMF溶液中于-2.1 V（相对于Fc/Fc）且存在乙酸作为质子源的条件下进行时，观察到产生了16微摩尔的氢气，法拉第效率为40%。本文报道的这些吖啶基镍（II）配合物的简便合成方法可能会刺激新型吖啶基配体及其相应金属配合物在广泛应用中的进一步发展。
