Zhang Yu, Huang Lian, Miao Hao, Wan Hong Xiang, Mei Hua, Liu Ying, Xu Yan
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009 (P.R. China).
Chemistry. 2015 Feb 16;21(8):3234-41. doi: 10.1002/chem.201405178. Epub 2014 Dec 8.
Two Ln26 @CO3 (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs) formulated as [Dy26 Cu3 (Nic)24 (CH3 COO)8 (CO3 )11 (OH)26 (H2 O)14 ]Cl ⋅3 H2 O (1; HNic=nicotinic acid) and [Tb26 NaAg3 (Nic)27 (CH3 COO)6 (CO3 )11 (OH)26 Cl(H2 O)15 ]⋅7.5 H2 O (2) have been successfully synthesized by hydrothermal methods and characterized by IR, thermogravimetric analysis (TGA), elemental analysis, and single X-ray diffraction. Compound 1 crystallizes in the monoclinic space group Cc with a=35.775(12) Å, b=33.346(11) Å, c=24.424(8) Å, β=93.993(5)°, V=29065(16) Å(3) , whereas 2 crystallizes in the triclinic space group P$\bar 1$ with a=20.4929(19) Å, b=24.671(2) Å, c=29.727(3) Å, α=81.9990(10)°, β=88.0830(10)°, γ=89.9940(10)°, V=14875(2) Å(3) . Structural analysis indicates the framework of 1 is a 3D perovskite-like structure constructed out of CO3 @Dy26 building units and Cu(+) centers by means of nicotinic acid ligand bridging. In 2, however, nanosized CO3 @Tb26 units and Ag3 Cl centers are connected by Nic(-) bridges to give rise to a 2D structure. It is worth mentioning that this kind of 4d-4f cluster-based MOF is quite rare as most of the reported analogous compounds are 3d-4f ones. Additionally, the solid-state emission spectra of pure compound 2 at room temperature suggest an efficient energy transfer from the ligand Nic(-) to Tb(3+) ions, which we called the "antenna effect". Compound 2 shows a good two-photon absorption (TPA) with a TPA coefficient of 0.06947 cm GM(-1) (1 GM=10(-50) cm(4) s photon(-1) ), which indicates that compound 2 might be a good choice for third-order nonlinear optical materials.
通过水热法成功合成了两种基于Ln₂₆@CO₃（Ln = Dy和Tb）簇的镧系-过渡金属有机框架（Ln MOF），其化学式分别为[Dy₂₆Cu₃(Nic)₂₄(CH₃COO)₈(CO₃)₁₁(OH)₂₆(H₂O)₁₄]Cl·3H₂O（1；HNic = 烟酸）和[Tb₂₆NaAg₃(Nic)₂₇(CH₃COO)₆(CO₃)₁₁(OH)₂₆Cl(H₂O)₁₅]·7.5H₂O（2），并通过红外光谱、热重分析（TGA）、元素分析和单晶X射线衍射对其进行了表征。化合物1结晶于单斜空间群Cc，a = 35.775(12) Å，b = 33.346(11) Å，c = 24.424(8) Å，β = 93.993(5)°，V = 29065(16) ų，而化合物2结晶于三斜空间群P$\bar 1$，a = 20.4929(19) Å，b = 24.671(2) Å，c = 29.727(3) Å，α = 81.9990(10)°，β = 88.0830(10)°，γ = 89.9940(10)°，V = 14875(2) ų。结构分析表明，1的框架是一种由CO₃@Dy₂₆结构单元和Cu(+)中心通过烟酸配体桥连构建而成的三维钙钛矿型结构。然而，在2中，纳米尺寸的CO₃@Tb₂₆单元和Ag₃Cl中心通过Nic(-)桥相连，形成二维结构。值得一提的是，这种基于4d - 4f簇的MOF非常罕见，因为大多数报道的类似化合物是3d - 4f的。此外，纯化合物2在室温下的固态发射光谱表明存在从配体Nic(-)到Tb(3+)离子的有效能量转移，我们将其称为“天线效应”。化合物2表现出良好的双光子吸收（TPA），TPA系数为0.06947 cm GM⁻¹（1 GM = 10⁻⁵⁰ cm⁴ s photon⁻¹），这表明化合物2可能是三阶非线性光学材料的一个不错选择。
