Zhuo Hong-Yan, Su Hai-Feng, Cao Zhao-Zhen, Liu Wei, Wang Shu-Ao, Feng Lei, Zhuang Gui-Lin, Lin Shui-Chao, Kurmoo Mohamedally, Tung Chen-Ho, Sun Di, Zheng Lan-Sun
Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
Chemistry. 2016 Dec 5;22(49):17619-17626. doi: 10.1002/chem.201603797. Epub 2016 Oct 12.
Cu(CF COO) reacts with tert-butylacetylene (tBuC≡CH) in methanol in the presence of metallic copper powder to give two air-stable clusters, [Cu (tBuC≡C) (CF COO) ]⋅tBuC≡CH (1) and [Cu (tBuC≡C) (CF COO) (CH OH) ] (2). The assembly process involves in situ comproportionation reaction between Cu and Cu and the formation of two different clusters is controlled by reactants concentration. The clusters consist of Cu and Cu cores co-stabilized by strong by σ- and π-bonded tert-butylethynide and CF COO (together with methanol molecule in 2). Their stabilities in solution were confirmed using electrospray ionization mass spectrometry in which the cluster core remains intact for 1 in chloroform and acetone, and for 2 in acetonitrile. Strong thermochromic luminescence in the near infrared (NIR) region was observed in the solid-state. Of particular interest, the emission maximum of 1 is red-shifted from 710 nm at 298 K to 793 nm at 93 K, along with a 17-fold fluorescence enhancement. In contrast, 2 exhibits red shift from 298 to 123 K followed by blue shift from 123 to 93 K. The emission wavelength was correlated with the structural parameters using variable-temperature X-ray single-crystal analyses. The rich cuprophilic interaction plays a significant role in the formation of LMCT (tBuC≡C→Cu ) excited state mixed with cluster-centered ( CC) characters, which can be considerably influenced by temperature, leading to thermochromic luminescence. The present work provides 1) a new synthetic protocol for the high-nuclear Cu -alkynyl clusters; 2) a comprehensive insight into the mechanism of thermochromic luminescence; 3) unusual emissive materials with the characters of NIR and thermochromic luminescence simultaneously.
醋酸铜（Cu(CF₃COO)₂）在金属铜粉存在下于甲醇中与叔丁基乙炔（tBuC≡CH）反应，生成两种空气稳定的簇合物，[Cu₉(tBuC≡C)₆(CF₃COO)₃]⋅tBuC≡CH（1）和[Cu₉(tBuC≡C)₆(CF₃COO)₃(CH₃OH)]（2）。组装过程涉及Cu(I)和Cu(II)之间的原位氧化还原反应，两种不同簇合物的形成受反应物浓度控制。这些簇合物由Cu(I)和Cu(II)核组成，通过强σ键和π键结合的叔丁基乙炔基和CF₃COO⁻（在2中还有甲醇分子）共同稳定。使用电喷雾电离质谱法确认了它们在溶液中的稳定性，其中簇合物核心在氯仿和丙酮中对1保持完整，在乙腈中对2保持完整。在固态中观察到近红外（NIR）区域的强热致变色发光。特别值得注意的是，1的发射最大值从298K时的710nm红移至93K时的793nm，同时荧光增强了17倍。相比之下，2在298至123K表现出红移，随后在123至93K表现出蓝移。使用变温X射线单晶分析将发射波长与结构参数相关联。丰富的亲铜相互作用在形成混合了簇中心（CC）特征的LMCT（tBuC≡C→Cu(II)）激发态中起重要作用，其会受到温度的显著影响，导致热致变色发光。本工作提供了：1）一种用于高核Cu -炔基簇合物的新合成方案；2）对热致变色发光机制的全面洞察；3）同时具有近红外和热致变色发光特性的新型发光材料。
