The formation of heterometallic clusters usually involves a much more complex self-assembly process than that of homometallic clusters.Thus the tracking of their assembly mechanism is challenging.To achieve this task,...The formation of heterometallic clusters usually involves a much more complex self-assembly process than that of homometallic clusters.Thus the tracking of their assembly mechanism is challenging.To achieve this task,we designed one OH-containing Schiff base ligand of 1-[[(2-hydroxyethyl)imino]methyl]-2-naphthalenol(H_(2)L)with coordination pockets facile for selective coordination with CoII/NiII and 4f metal ions.Its reactions with the corresponding metal ions gave two new isostructural dodecanuclear complexes[Dy_(4)Co_(8)(μ_(3)-OH)_(8)(L)_(8)(OAc)_(4)(H_(2)O)_(4)]·3EtOH·3CH_(3)CN·H_(2)O(1)and[Dy_(4)Ni_(8)(μ_(3)-OH)_(8)(L)_(8)(OAc)_(4)(H_(2)O)_(4)]·3.5EtOH·0.5CH_(3)CN·5H_(2)O(2),which feature a vertex-sharing tetracubane cyclic skeleton with the four DyIII ions wrapped by the eight 3d metal ions.High-resolution electrospray mass spectrometry(HRESI-MS)tests showed that the skeletons of clusters 1 and 2 have high stability even under gradually increasing energy of the ion source.Most notably,the intermediates formed in the reaction courses for clusters 1 and 2 were tracked using time-dependent HRESI-MS,which gave different proposed assembly mechanisms for 1(H_(2)L→DyL→DyCoL→Dy_(2)CoL→Dy_(3)CoL→Dy_(4)CoL_(2)→Dy_(4)Co_(2)L_(3)→Dy_(4)Co_(4)L_(4)→Dy_(4)Co_(8)L_(8))and 2(H_(2)L→NiL→Dy_(2)NiL_(2)→Dy_(3)NiL_(2)→Dy_(4)NiL_(2)→Dy_(4)Ni_(2)L_(3)→Dy_(4)Ni_(4)L_(3)→Dy_(4)Ni_(6)L_(4)→Dy_(4)Ni_(8)L_(8)),respectively.This is the first time that different assembly mechanisms for isostructural heterometallic complexes are shown.Detailed magnetic studies revealed the absence of slow magnetic relaxation for 1 and the presence of slow magnetic relaxation for 2 with an energy barrier of 7.66 K and a pre-exponential factor of 1.45×10^(-6) s.The different magnetic performances of the two title complexes might be caused by the different metal ions of Co_((II))and Ni_((II)).展开更多
基金supported by the National Natural Science Foundation of China(grant no.12064002,22061004 and 21901050)the Guangxi Natural Science Foundation of China(grant no.2018GXNSFBA050031 and 2020GXNSFAA159132)+1 种基金the Guangxi Technology Base and Talent Subject(grant no.GUIKE AD19245002)the Key Project of Guangxi Normal University(grant no.2018ZD003).
文摘The formation of heterometallic clusters usually involves a much more complex self-assembly process than that of homometallic clusters.Thus the tracking of their assembly mechanism is challenging.To achieve this task,we designed one OH-containing Schiff base ligand of 1-[[(2-hydroxyethyl)imino]methyl]-2-naphthalenol(H_(2)L)with coordination pockets facile for selective coordination with CoII/NiII and 4f metal ions.Its reactions with the corresponding metal ions gave two new isostructural dodecanuclear complexes[Dy_(4)Co_(8)(μ_(3)-OH)_(8)(L)_(8)(OAc)_(4)(H_(2)O)_(4)]·3EtOH·3CH_(3)CN·H_(2)O(1)and[Dy_(4)Ni_(8)(μ_(3)-OH)_(8)(L)_(8)(OAc)_(4)(H_(2)O)_(4)]·3.5EtOH·0.5CH_(3)CN·5H_(2)O(2),which feature a vertex-sharing tetracubane cyclic skeleton with the four DyIII ions wrapped by the eight 3d metal ions.High-resolution electrospray mass spectrometry(HRESI-MS)tests showed that the skeletons of clusters 1 and 2 have high stability even under gradually increasing energy of the ion source.Most notably,the intermediates formed in the reaction courses for clusters 1 and 2 were tracked using time-dependent HRESI-MS,which gave different proposed assembly mechanisms for 1(H_(2)L→DyL→DyCoL→Dy_(2)CoL→Dy_(3)CoL→Dy_(4)CoL_(2)→Dy_(4)Co_(2)L_(3)→Dy_(4)Co_(4)L_(4)→Dy_(4)Co_(8)L_(8))and 2(H_(2)L→NiL→Dy_(2)NiL_(2)→Dy_(3)NiL_(2)→Dy_(4)NiL_(2)→Dy_(4)Ni_(2)L_(3)→Dy_(4)Ni_(4)L_(3)→Dy_(4)Ni_(6)L_(4)→Dy_(4)Ni_(8)L_(8)),respectively.This is the first time that different assembly mechanisms for isostructural heterometallic complexes are shown.Detailed magnetic studies revealed the absence of slow magnetic relaxation for 1 and the presence of slow magnetic relaxation for 2 with an energy barrier of 7.66 K and a pre-exponential factor of 1.45×10^(-6) s.The different magnetic performances of the two title complexes might be caused by the different metal ions of Co_((II))and Ni_((II)).
