Birara Sunita, Saini Shalu, Majumder Moumita, Lama Prem, Tiwari Shree Prakash, Metre Ramesh K
Department of Chemistry, Indian Institute of Technology Jodhpur, Rajasthan-342030, India.
Department of Electrical Engineering, Indian Institute of Technology Jodhpur, Rajasthan-342030, India.
Dalton Trans. 2023 Dec 12;52(48):18429-18441. doi: 10.1039/d3dt02809g.
In this paper, we report the synthesis and characterization of a mononuclear zinc complex (1) containing a redox-active bis(4-antipyrinyl) derivative of the 3-cyanoformazanate ligand. Complex 1 was readily obtained by refluxing zinc acetate with 3-cyano-1,5-(4-antipyrinyl)formazan (LH) in a methanolic solution. Single-crystal X-ray diffraction analysis of complex 1 shows that the formazanate ligands bind to the zinc center in a five-member chelate "open" form the 1- and 4-positions of the 1,2,4,5-tetraazapentadienyl formazanate backbone leading to the formation of the mononuclear bis(formazanate) zinc complex exhibiting a distorted octahedral geometry. We also report the study of resistive-switching random access memory application of this solution-processable bis(formazanate) Zn(II) complex to facilitate the practical implementation of transition metal complex-based molecular memory devices. The complex demonstrated high conductance switching with a large ON-OFF ratio, good stability, and a long retention time. A trap-controlled space charge limited current mechanism is proposed for the observed resistive switching behavior of the device, wherein the role played by the [ZnL] complex that comprises the extended redox-active conjugated ligand backbone is revealed by corroborating electrochemical studies, spectrochemical experiments, and DFT calculations. In addition to providing significant insights into the molecular design of transition metal complexes for memory applications, this study also presents the utilization of ZnL towards the realization of non-volatile resistive random access memory (RRAM) devices with inorganic/organic hybrid active layers that are highly cost-effective and sustainable. These devices exhibited multilevel switching and low current operation, both of which are desirable for advanced memory applications.
在本文中，我们报道了一种单核锌配合物（1）的合成与表征，该配合物含有3-氰基甲脒酸配体的氧化还原活性双（4-安替吡啉基）衍生物。配合物1通过在甲醇溶液中使醋酸锌与3-氰基-1,5-（4-安替吡啉基）甲脒（LH）回流很容易得到。配合物1的单晶X射线衍射分析表明，甲脒酸配体以五元螯合“开放”形式与锌中心结合，即1,2,4,5-四氮杂戊二烯基甲脒酸主链的1位和4位，导致形成具有扭曲八面体几何构型的单核双（甲脒酸）锌配合物。我们还报道了这种可溶液加工的双（甲脒酸）Zn（II）配合物在电阻开关随机存取存储器应用方面的研究，以促进基于过渡金属配合物的分子存储器件的实际应用。该配合物表现出高电导切换，具有大的开-关比、良好的稳定性和长的保持时间。针对该器件观察到的电阻开关行为，提出了一种陷阱控制的空间电荷限制电流机制，其中通过电化学研究、光谱化学实验和密度泛函理论计算证实了包含扩展的氧化还原活性共轭配体主链的[ZnL]配合物所起的作用。除了为用于存储应用的过渡金属配合物的分子设计提供重要见解外，本研究还展示了ZnL在实现具有高性价比和可持续性的无机/有机混合活性层的非易失性电阻随机存取存储器（RRAM）器件方面的应用。这些器件表现出多级切换和低电流操作，这两者都是先进存储应用所需要的。
