title: High-Nuclear Organometallic Copper(I)-Alkynide Clusters: Thermochromic Near-Infrared Luminescence and Solution Stability.
abstract: Cu(CF3COO)2reacts with tert-butylacetylene (tBuC≡CH) in methanol in the presence of metallic copper powder to give two air-stable clusters, [CuI15(tBuC≡C)10(CF3COO)5]⋅tBuC≡CH (1) and [CuI16(tBuC≡C)12(CF3COO)4(CH3OH)2] (2). The assembly process involves in situ comproportionation reaction between Cu2+and Cu0and the formation of two different clusters is controlled by reactants concentration. The clusters consist of Cu15and Cu16cores co-stabilized by strong by σ- and π-bonded tert-butylethynide and CF3COO-(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 of3LMCT (tBuC≡C→Cux) excited state mixed with cluster-centered (3CC) 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 CuI-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.
authors.affiliation: Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Zhuo
authors.affiliation: 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.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Su
authors.affiliation: Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
authors.forename: Zhao-Zhen
authors.initials: ZZ
authors.lastname: Cao
authors.affiliation: School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, Jiangsu, 215123, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, Jiangsu, 215123, P. R. China.
authors.forename: Shu-Ao
authors.initials: SA
authors.lastname: Wang
authors.affiliation: Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.affiliation: College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou, 310032, P. R. China.
authors.forename: Gui-Lin
authors.initials: GL
authors.lastname: Zhuang
authors.affiliation: 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.
authors.forename: Shui-Chao
authors.initials: SC
authors.lastname: Lin
authors.affiliation: Institut de Chimie de Strasbourg, Université de Strasbourg, CNRS-UMR 7177, 4 rue Blaise Pascal, 67008, Strasbourg Cedex, France.
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo
authors.affiliation: Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
authors.forename: Chen-Ho
authors.initials: CH
authors.lastname: Tung
authors.affiliation: Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
authors.forename: Di
authors.identifier: http://orcid.org/0000-0001-5966-1207
authors.initials: D
authors.lastname: Sun
authors.affiliation: 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.
authors.forename: Lan-Sun
authors.initials: LS
authors.lastname: Zheng
keywords: alkynes; cluster compounds; copper; photoluminescence; thermochromism