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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Halocuprate(I) zigzag chain structures with N-methylated DABCO cations - bright metal-centered luminescence and thermally activated color shifts
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Halocuprate(I) zigzag chain structures with N-methylated DABCO cations - bright metal-centered luminescence and thermally activated color shifts

机译：具有N-甲基化DABCO阳离子的Halocuprate（I）之字形链结构-以金属为中心的明亮发光和热激活的色移

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摘要

Two compounds 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane catena-tetra-mu-halo-dicuprate(I) with DABCOMe(2) Cu2X4 (1: X = Br, 2: X = I) were synthesized by hydrothermal reaction of copper(I) halides with the corresponding 1,4-diazoniabicyclo[2.2.2] octane (DABCO) dihydrohalides in an acetonitrile/methanol mixture. Both compounds crystallize monoclinically, 1 with a = 9.169(4) angstrom, b = 10.916(6) angstrom, c = 15.349(6) angstrom , beta = 93.93(2)degrees, V = 1533(1) angstrom(3), Z = 4, space group P2(1) (no. 14) and 2 with a = 15.826(9) angstrom, b = 9.476(5) angstrom, c = 22.90(2) angstrom, beta = 90.56(5)degrees, V = 3434(5) angstrom(3), Z = 8, space group P2(1) (no. 4), respectively (lattice constants refined from powder diffraction data measured at 293 K). The cations in both compounds are formed by in situ N-methylation of DABCOH(2)(2+) cations by methanol in a S(N)2 reaction. Both compounds contain an anionic copper(I) halide chain structure consisting of trans edge-sharing CuX4 tetrahedra. The chains are strongly kinked at every 2nd junction thus forming a zigzag structure. The shortest halide-halide distances are observed between the halide ions of adjacent tetrahedra which are approaching each other due to the kinking. This structure type shows a specific luminescence behavior. Under optical excitation, the compounds exhibit yellow (1) and green (2) emission with photoluminescence quantum yields of Phi(PL) = 52 and 4%, respectively, at ambient temperature. According to DFT and TDDFT calculations, the emission is assigned to be a phosphorescence essentially involving a metal centered transition between the HOMO consisting mainly of copper 3d and halide p orbitals and the LUMO consisting mainly of copper 4s and 4p orbitals. The temperature dependence of the emission spectra, decay times, and quantum yields has been investigated in detail, especially for 1. From the resulting trends it can be concluded that the emission for T <= 100 K stems from energetically lower lying copper halide segments. Such segments represent the structural motif of the halocuprate(I) chains. With increasing temperature energetically higher lying segments are populated which also emit, but open the pathway for thermally activated energy transfer to quenching defects.
机译：带有DABCOMe（2）Cu2X4的两种化合物1,4-二甲基-1,4-二氮杂双环[2.2.2]辛烷链-四-甲基-卤代-二异丙酸盐（I）（1：X = Br，2：X = I）卤化铜（I）与相应的1,4-二氮杂双环[2.2.2]辛烷（DABCO）二氢卤化物在乙腈/甲醇混合物中进行水热反应，合成了它们。两种化合物均单晶结晶，其a = 9.169（4）埃，b = 10.916（6）埃，c = 15.349（6）埃，β= 93.93（2）度，V = 1533（1）埃， Z = 4，空间组P2（1）/ n（编号14）和2，a = 15.826（9）埃，b = 9.476（5）埃，c = 22.90（2）埃，beta = 90.56（5）角度分别为V = 3434（5）埃（3），Z = 8，空间组P2（1）（第4号）（由293 K测量的粉末衍射数据提炼的晶格常数）。这两种化合物中的阳离子是通过甲醇在S（N）2反应中将DABCOH（2）（2+）阳离子原位N-甲基化而形成的。两种化合物均包含由跨边缘共享的CuX4四面体组成的阴离子卤化铜（I）链结构。链在每个第二个结处强烈扭结，从而形成锯齿形结构。观察到相邻的四面体的卤离子之间的最短卤化物-卤化物距离由于扭结而彼此接近。这种结构类型显示出特定的发光行为。在光激发下，这些化合物在环境温度下呈现黄色（1）和绿色（2）发射，光致发光量子产率分别为Phi（PL）= 52和4％。根据DFT和TDDFT计算，发射被指定为磷光，主要涉及主要由3d铜和卤化物p轨道组成的HOMO与主要由4s和4p铜轨道组成的LUMO之间的金属居中过渡。已经对发射光谱，衰减时间和量子产率的温度依赖性进行了详细研究，尤其是对于1。从结果趋势可以得出结论，T <= 100 K的发射源于能量较低的卤化铜片段。这样的片段代表了卤化铀（I）链的结构基序。随着温度的升高，高能位的链节被填充，这些链节也发射，但打开了将热活化能量转移至淬火缺陷的途径。

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