Torrent Joan, Puigjaner Cristina, Herchel Radovan, Mayans Júlia
Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, Universitat de Barcelona, Marti i Franques 1-11, Barcelona 08028, Spain.
Departament de Mineralogia, Cristal·lografia i Dipòsits Minerals and Unitat de Difracció de R-X, Centre Científic i Tecnològic de la Universitat de Barcelona (CCiTUB), Universitat de Barcelona, Solé i Sabarís 1-3, Barcelona 08028, Spain.
Inorg Chem. 2025 Mar 3;64(8):3735-3746. doi: 10.1021/acs.inorgchem.4c04542. Epub 2025 Feb 18.
The reaction between two equivalents of the Schiff base ligands ,'-bis(3-methoxysalicylidene)ethylenediamine (HL1) or enantiopure ,'-bis(3-methoxysalicylidene)cyclohexane-1,2-diamine (HL2) with one equivalent of Ce(NO)·6HO in the presence of a bulky counteranion leads to the formation of chiral metal-organic frameworks (MOFs) whose channels encapsulate the counteranion, leading to the formation of compounds with the structural formulas {[Ce(NO)(L1)]X·HO}, where X = ClO (), PF (), or BF (), and {[Ce(NO)(L2)]X·CHCN}, where X = ClO (), PF (), or BF (), as well as the isostructural reference compound {Nd(NO)(L1)]BF·CHCN} (). A combination of static and dynamic magnetic measurements demonstrates the good isolation of the Ce centers and a field-induced slow relaxation of the magnetization. Correlations between the temperature and field-dependent magnetic relaxation data and ultralow-frequency Raman spectroscopy reveal the presence of a vibronic barrier driving magnetic relaxation. Theoretical calculations have been performed to elucidate the nonparticipation of the electronic excited states in the main relaxation processes.
两当量的席夫碱配体，即1,2-双（3-甲氧基水杨醛）乙二胺（HL1）或对映体纯的1,2-双（3-甲氧基水杨醛）环己烷-1,2-二胺（HL2）与一当量的Ce(NO₃)₃·6H₂O在大体积抗衡阴离子存在下反应，导致形成手性金属有机框架（MOF），其通道包封抗衡阴离子，从而形成结构式为{[Ce(NO₃)(L1)]X·H₂O}的化合物，其中X = ClO₄⁻（1）、PF₆⁻（2）或BF₄⁻（3），以及{[Ce(NO₃)(L2)]X·CH₃CN}，其中X = ClO₄⁻（4）、PF₆⁻（5）或BF₄⁻（6），还有同构参考化合物{[Nd(NO₃)(L1)]BF₄·CH₃CN}（7）。静态和动态磁性测量相结合表明Ce中心具有良好的隔离性以及场诱导的磁化缓慢弛豫。温度和场依赖的磁弛豫数据与超低频拉曼光谱之间的相关性揭示了存在驱动磁弛豫的振动电子势垒。已进行理论计算以阐明电子激发态在主要弛豫过程中不参与。
