Au_(24)Cd(SR)_(18)纳米团簇的非计量比和配体依赖的顺磁性  

Nonstoichiometric and ligand-dependent paramagnetism of Au24Cd(SR)18 nanoclusters

作　　者：Ambreen Ambreen 尤青 夏楠 闫楠 伍志鲲 Ambreen Ambreen;Qing You;Nan Xia;Nan Yan;Zhikun Wu(Key Laboratory of Materials Physics,Anhui Key Laboratory of Nanomaterials and Nanotechnology,Institute of Solid State Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;University of Science and Technology of China,Hefei 230601,China;Institute of Physical Science and Information Technology,Anhui University,Hefei 230601,China)

机构地区：[1]Key Laboratory of Materials Physics,Anhui Key Laboratory of Nanomaterials and Nanotechnology,Institute of Solid State Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China [2]University of Science and Technology of China,Hefei 230601,China [3]Institute of Physical Science and Information Technology,Anhui University,Hefei 230601,China

出　　处：《Science China Materials》2023年第12期4886-4890,共5页中国科学（材料科学）（英文版）

基　　金：supported by the National Natural Science Foundation of China(21925303,21829501,21771186,22171267,22171268,21222301,21171170 and 21528303);Anhui Provincial Natural Science Foundation(2008085MB31 and 2108085MB56);the Youth Innovation Promotion Association CAS(2023468);the HFIPS Director’s Fund(BJPY2019A02,YZJJ202102,YZJJ202306-TS and YZJJ-GGZX-2022-01);the Collaborative Innovation Program of Hefei Science Center,CAS(2020HSC-CIP005 and 2022HSC-CIP018).

摘　　要：近年来兴起的金属纳米团簇因其具有分子纯度和原子精确的组成与结构,为磁性研究提供了极好的机会.例如,目前报道的金属纳米团簇中的顺磁性可以基于超原子理论用未成对价电子很好地进行解释.到目前为止,金属纳米团簇的非计量比顺磁性尚未见报道.本研究首次揭示了Au_(24)Cd(PET)_(18)(PET:苯乙巯基配体)的顺磁性,且其强度仅为Au_(25)(PET)_(18)的约八分之一,而每个零价Au_(25)(PET)_(18)团簇都拥有一个未成对电子,这表明金属纳米团簇中存在着平均意义上的非整数未成对电子和非计量比顺磁性.进一步研究发现Au_(24)Cd(SR)_(18)(SR:巯基配体)的顺磁性依赖于配体.当配体更换为环己巯基(CHT)时,Au_(24)Cd-(CHT)_(18)的顺磁性消失了.这是由于柔性的CHT配体使得团簇容易靠近,进而发生相邻团簇之间的自旋耦合.而当配体更换为对叔丁基苯甲巯基(TBBM)时,Au_(24)Cd(TBBM)_(18)也显示了顺磁性,但与Au_(25)(PET)_(18)的顺磁性存在少许差异,归因于配体给电子能力的差异.我们排除了光照对团簇顺磁性的影响,证实了这种非计量比、配体依赖的顺磁性是团簇的固有性质.这些新颖发现有助于推进金属纳米团簇的磁性研究.Although bulk Au is diamagnetic[1],Au nanocrystals were found to have permanent magnetism[2–5],and in the past decades,the magnetic properties of Au nanocrystals have attracted extensive interest due to their potential applications in a wide range of fields[6–8].However,the exploration of magnetism origin and regulation for Au nanocrystals have been retarded by their multi-dispersity and unclear compositions and structures at the atomic scale,and even sometimes it is difficult to exclude the magnetism influence from the trace of impurities contained in Au nanocrystals[9].Fortunately,the recently emerging metal nanoclusters(ultrasmall metal nanoparticles)provide excellent opportunities for investigating the magnetism of metal nanoparticles due to their molecular purity and atomically precise compositions and structures[10–24],and the recently found paramagnetism was well explained by the unpaired valence electron on the basis of superatom theory[25–32].Given the fact that the metal charge state might be nonintegral[33],a question naturally arising is whether there is any nonstoichiometric paramagnetism corresponding to average nonintegral unpaired electron(s)in metal nanoclusters,which inspires our enthusiasm for study.Indeed,we recently confirmed the existence of nonstoichiometric paramagnetism and further revealed the ligand-dependent paramagnetism.Below we will show the details.

关 键 词：顺磁性 超原子 未成对电子 零价 纳米团簇 非整数 固有性质 磁性研究 

分 类 号：TB383.1[一般工业技术—材料科学与工程]