Syntheses, structures, and magnetic properties of a series of dimer lanthanide complexes with 5-isoquinoline-substituted nitronyl nitroxide

Three lanthanide-radical cyclic dimers with the formula [Ln(hfac)₃(NIT-5-IQN)]₂, derived from a new isoquinolyl-substituted nitronyl nitroxide ligand (NIT-5-IQN) (<b>L</b>) and Ln(hfac)₃ (Ln(III) = Tb (<b>1</b>), Gd (<b>2</b>) and Yb(<b>3</b>); NIT-5-IQN = 2-(5-isoquinoly)-4,4,5,5 -tetramethyl-imidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonato anion), were synthesized and characterized structurally and magnetically. Single-crystal structural analyses reveal that complexes <b>1</b>－<b>3</b> exhibit isomorphism, in which the NIT-5-IQN molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N–O group and the nitrogen atom from the isoquinoline unit to form a ring-like dimer. Magnetic studies reveal the antiferromagnetic interactions between the Ln(III) ions and nitronyl nitroxide radicals in complexes <b>1－3</b>. Alternating current (AC) magnetic susceptibilities demonstrate that complex <b>1</b> displays frequency-dependent signals at low temperature, while room-temperature photoluminescence spectra of complex <b>1</b> exhibit strong characteristic emissions in the visible region. A series of lanthanide-radical dimers with the formula [Ln(hfac)₃(NIT-5-IQN)]₂, derived from a new isoquinolyl-substituted nitronyl nitroxide ligand (NIT-5-IQN) (<b>L</b>) and Ln(hfac)₃ (Ln(III) = Tb (<b>1</b>), Gd (<b>2</b>) and Yb(<b>3</b>); NIT-5-IQN = 2-(5-isoquinoly)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonato anion), were synthesized and characterized structurally and magnetically. Single-crystal structural analyses reveal that complexes <b>1</b>－<b>3</b> exhibit isomorphism. Magnetic studies reveal that the antiferromagnetic interactions between the Ln(III) ions and nitronyl nitroxide radicals in complexes <b>1－3</b>. Alternating current (AC) magnetic susceptibilities demonstrate that complex <b>1</b> displays frequency-dependent signals at low temperature, while room-temperature photoluminescence spectra of complex <b>1</b> exhibit strong characteristic emissions in the visible region.

以新型异喹啉取代硝酰基氮氧自由基配体（NIT-5-IQN，记为配体L）与Ln(hfac)₃（其中Ln(III)分别为Tb（化合物1）、Gd（化合物2）和Yb（化合物3）；NIT-5-IQN即2-(5-异喹啉基)-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物；hfac为六氟乙酰丙酮根阴离子）为原料，合成了3种通式为[Ln(hfac)₃(NIT-5-IQN)]₂的镧系-自由基环二聚体，并对其进行了结构与磁性表征。单晶结构分析表明，化合物1-3具有同构性：NIT-5-IQN分子作为桥联配体，通过N-O基团的氧原子与异喹啉单元中的氮原子连接两个Ln(III)离子，形成环状二聚体结构。磁性研究揭示，化合物1-3中Ln(III)离子与硝酰基氮氧自由基之间存在反铁磁相互作用。交流（AC）磁化率测试显示，化合物1在低温下表现出频率依赖的磁信号；而化合物1的室温光致发光光谱在可见光区展现出强烈的特征发射。另有一系列通式为[Ln(hfac)₃(NIT-5-IQN)]₂的镧系-自由基二聚体，以新型异喹啉取代硝酰基氮氧自由基配体（NIT-5-IQN，记为配体L）与Ln(hfac)₃（其中Ln(III)分别为Tb（化合物1）、Gd（化合物2）和Yb（化合物3）；NIT-5-IQN即2-(5-异喹啉基)-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物；hfac为六氟乙酰丙酮根阴离子）为原料合成并完成结构与磁性表征。单晶结构分析显示，化合物1-3具有同构性。磁性研究表明，化合物1-3中的Ln(III)离子与硝酰基氮氧自由基之间存在反铁磁相互作用。交流（AC）磁化率测试证实，化合物1在低温下呈现频率依赖的磁信号；其室温光致发光光谱在可见光区表现出强烈的特征发射。