Thermally Ultrarobust S = 1/2 Tetrazolinyl Radicals: Synthesis, Electronic Structure, Magnetism, and Nanoneedle Assemblies on Silicon Surface
Thermally Ultrarobust S = 1/2 Tetrazolinyl Radicals: Synthesis, Electronic Structure, Magnetism, and Nanoneedle Assemblies on Silicon Surface
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耐热超鲁棒 S = 1/2 四唑啉基自由基：硅表面上的合成、电子结构、磁性和纳米针组件
DOI：
10.1021/jacs.3c03402
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发表时间：
2023
影响因子：
15
通讯作者：
Rajca, Andrzej
中科院分区：
文献类型：
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作者：
Yang, Zhimin;Pink, Maren;Nowik-Boltyk, Ewa Malgorzata;Lu, Shutian;Junghoefer, Tobias;Rajca, Suchada;Stoll, Stefan;Casu, Maria Benedetta;Rajca, Andrzej
开壳有机分子，包括= 1/2自由基，可能为一些新兴技术提供增强的性能；然而，相对较少的合成到目前为止，具有强大的热稳定性和加工性。本文报道了s = 1/2联苯熔接四唑啉基自由基1和2的合成。基于它们的x射线结构和密度泛函理论（DFT）计算，两个自由基都具有接近完美的平面结构。根据热重分析（TGA）数据，radical1具有出色的热稳定性，在269°C时开始分解。两种自由基的氧化电位都很低（<0 V），电化学能隙（Ecell≈0.9 eV）也很低。用超导量子干涉装置（SQUID）磁强计表征了多晶1的磁性，揭示了交换耦合常数j′/k≈−22.0 k的一维als = 1/2反铁磁海森堡链。Radical1in甲苯玻璃具有很长的电子自旋相干时间，在40-80 K温度范围内Tm≈7 μs，这一特性有利于作为分子自旋量子比特的潜在应用。通过高分辨率x射线光电子能谱（XPS）证实，在超高真空（UHV）下，在硅衬底上形成完整的自由基组装。扫描电镜（SEM）图像显示自由基分子在衬底上形成纳米针状结构。通过x射线光电子能谱监测，纳米针在空气中至少稳定64小时。电子顺磁共振（EPR）研究表明，通过特高压蒸发制备的较厚组件根据一级动力学进行自由基衰变，在环境条件下具有50±4天的长半衰期。
Open-shell organic molecules, includingS= 1/2 radicals, may provide enhanced properties for several emerging technologies; however, relatively few synthesized to date possess robust thermal stability and processability. We report the synthesis ofS= 1/2 biphenylene-fused tetrazolinyl radicals1and2. Both radicals possess near-perfect planar structures based on their X-ray structures and density-functional theory (DFT) computations. Radical1possesses outstanding thermal stability as indicated by the onset of decomposition at 269 °C, based on thermogravimetric analysis (TGA) data. Both radicals possess very low oxidation potentials <0 V (vs. SCE) and their electrochemical energy gaps,Ecell≈ 0.9 eV, are rather low. Magnetic properties of polycrystalline1are characterized by superconducting quantum interference device (SQUID) magnetometry revealing a one-dimensionalS= 1/2 antiferromagnetic Heisenberg chain with exchange coupling constantJ′/k≈ −22.0 K. Radical1in toluene glass possesses a long electron spin coherence time,Tm≈ 7 μs in the 40–80 K temperature range, a property advantageous for potential applications as a molecular spin qubit. Radical1is evaporated under ultrahigh vacuum (UHV) forming assemblies of intact radicals on a silicon substrate, as confirmed by high-resolution X-ray photoelectron spectroscopy (XPS). Scanning electron microscope (SEM) images indicate that the radical molecules form nanoneedles on the substrate. The nanoneedles are stable for at least 64 hours under air as monitored by using X-ray photoelectron spectroscopy. Electron paramagnetic resonance (EPR) studies of the thicker assemblies, prepared by UHV evaporation, indicate radical decay according to first-order kinetics with a long half-life of 50 ± 4 days at ambient conditions.