Solvent-Free Synthesis of Luminescent Copper(I) Coordination Polymers with Thiourea Derivatives

This communication reports the solvent-free synthesis of a series of copper­(I) cyanide (CuCN) -based coordination polymers showing interesting luminescence properties and specific three-dimensional structures. The new compounds have been achieved by directly grinding CuCN together with thiourea (tu), N-methylthiourea (mtu), N-phenylthiourea (ptu), N,N′-diphenylthiourea (dptu), and 2,4-difluorophenylthiourea (fptu). The resulting compounds are [(CuCN)2(tu)]n, [(CuCN)5(mtu)3]n, [(CuCN)3(mtu)2]n, [CuCN­(ptu)]n, [CuCN­(dptu)]n, and [(CuCN)3(fptu)2]n. “Seeding” crystallization was successful for [(CuCN)2(tu)]n, [CuCN­(ptu)]n, [CuCN­(dptu)]n, and [(CuCN)3(fptu)2]n, and their structures have been resolved using X-ray single crystal diffraction. Owing to the microcrystalline powdered nature of compounds [(CuCN)5(mtu)3]n and [(CuCN)3(mtu)2]n, their characterization was mainly based on solid-state NMR, via 13C cross polarization magic angle spinning for ligand coordination and 1H magic angle spinning for the weak interactions involving hydrogen atoms. Other solid-state techniques (infrared spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and thermogravimetric analysis) completed the characterization. Finally, the luminescence properties were explored by recording emission and excitation spectra and by evaluating the luminescence quantum yields and lifetimes. Such in-depth study gives promising results for the potential application as luminescent sensors of such compounds.本通讯报道了一系列基于氰化亚铜(I)（copper(I) cyanide，CuCN）的配位聚合物的无溶剂合成方法，该类配位聚合物展现出引人关注的发光特性与特异性三维结构。 上述新型化合物通过将氰化亚铜(I)与硫脲（thiourea，tu）、N-甲基硫脲（N-methylthiourea，mtu）、N-苯基硫脲（N-phenylthiourea，ptu）、N,N′-二苯基硫脲（N,N′-diphenylthiourea，dptu）以及2,4-二氟苯基硫脲（2,4-difluorophenylthiourea，fptu）直接研磨制得，所得产物分别为[(CuCN)₂(tu)]ₙ、[(CuCN)₅(mtu)₃]ₙ、[(CuCN)₃(mtu)₂]ₙ、[CuCN(ptu)]ₙ、[CuCN(dptu)]ₙ以及[(CuCN)₃(fptu)₂]ₙ。 针对[(CuCN)₂(tu)]ₙ、[CuCN(ptu)]ₙ、[CuCN(dptu)]ₙ以及[(CuCN)₃(fptu)₂]ₙ的"晶种诱导"结晶实验取得成功，其晶体结构通过X射线单晶衍射（X-ray single crystal diffraction）解析得到。由于[(CuCN)₅(mtu)₃]ₙ与[(CuCN)₃(mtu)₂]ₙ均为微晶粉末状态，其表征主要依托固态核磁共振（solid-state NMR）技术：采用¹³C交叉极化魔角旋转（cross polarization magic angle spinning）分析配体配位情况，以¹H魔角旋转（magic angle spinning）探究涉及氢原子的弱相互作用。其余固态表征手段包括红外光谱、X射线粉末衍射（X-ray powder diffraction）、差示扫描量热法（differential scanning calorimetry）与热重分析（thermogravimetric analysis），共同完善了相关表征工作。 最后，通过采集发射与激发光谱、测定发光量子产率（luminescence quantum yields）及发光寿命（luminescence lifetimes），对该系列化合物的发光性能开展了系统探究。本项深入研究表明，此类配位聚合物在发光传感器领域具备潜在应用价值，研究结果颇具前景。