High‐Nuclear Organometallic Copper(I)–Alkynide Clusters: Thermochromic Near‐Infrared Luminescence and Solution Stability

Abstract

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.

Ether‐Soluble Cu53 Nanoclusters as an Effective Precursor of High‐Quality CuI Films for Optoelectronic Applications

“…Unfortunately, compared to Ag and Au systems, the lower Cu I /Cu 0 half‐cell potential (0.52 V) makes Cu 0 ‐containing Cu nanoclusters highly air‐sensitive, often seriously hindering the synthesis of high‐nuclearity Cu I /Cu 0 clusters . The synthetic strategy of alkynyl‐protected Cu clusters can be grouped into two categories: 1) the reaction of Cu powder and Cu 2+ which prefers to achieve Cu I clusters, such as Cu 14 , Cu 15 , Cu 16 , Cu 17 , Cu 18 , Cu 24 , Cu 33 , Cu 48 , Cu 62 , Cu 92 ; and 2) the direct reduction of Cu + complexes, which is likely to generate Cu 0 ‐containing clusters, one notable example being Cu 20 . However, it remains challenging to develop a general method for the synthesis of stable high‐nuclearity Cu I /Cu 0 clusters.…”

“…After being stored at 4 °C, red block crystals (Supporting Information, Figure S2) were grown from the solution in 4 days. We believe that in the synthesis, Cu powder reduces Cu 2+ complexes through reverse disproportionation to yield intermediate Cu I cluster(s), which are subsequently reduced by Ph 2 SiH 2 to produce the Cu I /Cu 0 clusters . The cooperation of Cu powder and Ph 2 SiH 2 makes it more convenient to achieve high‐nuclearity Cu I /Cu 0 clusters.…”

Synthesis, crystal structures and photoelectric properties of copper(I) alkynyl nanoclusters

“…如图 3(e)所示, 他们 [53] 又用具有线性碳链的炔基配体 RC≡C⁻ (R: n-C 4 H 9 , n-C 5 H 11 , n-C 6 H 13 ) 合成了 3 个 结 构 相 似 的 26 核 炔 铜 (I) 团簇 [Cu 26 (hfac) [50][51][52][53][54] [46] 用 归中反应对反应条件进行了细微控制, 合成了两种由 t BuC≡C⁻和 NO 3 ⁻共同保护的 14 核 和 15 核炔 Cu(I)团簇(图 4(c)和(d)). 同年, Mak 课题组 [37] 也合成了 2 个 15 核和 28 核炔 图 4 含 O 、 S 配体和炔 配体共保护的铜 (I) 团簇的晶体结构示意图 [37,46,55,56] [37,46,55,56] Liu 课题组在铜团簇方面做了多年的系统研究, 特别是用二硫代磷酸酯配体和炔配 体共同构筑铜氢簇 [57] , 与 hfac⁻、 CH 3 COO⁻和 NO 3 ⁻等含 O 酸根离子与炔配体共同保护铜 (I)团簇的策略类似. 他们 [58] 课题组 [65] 在 2014 年得到了[Au 12+n Cu 32 (SR) 30+n ] 4-(n = 0, 2, 4, 6), 含有部分 0 价 Au 和 Cu.…”

Ethynyl π-coordinated and non-coordinated mononuclear Cu(i) halide diphosphine complexes: synthesis and photophysical studies

“…The alkynyl ligand possesses a linear geometry, a conjugated p-electron structure, and an ability to coordinate with the Cu center by Z 1 (end-on) and Z 2 (side on) modes to construct Cu(I) alkynyl complexes, which have gained tremendous attention due to their diverse structures, intriguing luminescence and catalytic activity. 32 In general, alkynyls are coordinated by Z 1 (end-on) and (or) Z 2 (side on) modes with more than two Cu(I) centers to form Cu(I) alkynyl clusters, [33][34][35] Cu(I) alkynyl phosphine [36][37][38] and imine clusters, 39 but dinuclear, 40 and especially mononuclear alkynyl phosphine Cu(I) complexes in which the alkynyl is coordinated with Cu(I) by a Z 2 (side on) mode are not reported to date.…”