Making the Golden Connection: Reversible Mechanochemical and Vapochemical Switching of Luminescence from Bimetallic Gold-Silver Clusters Associated through Aurophilic Interactions
Making the Golden Connection: Reversible Mechanochemical and Vapochemical Switching of Luminescence from Bimetallic Gold-Silver Clusters Associated through Aurophilic Interactions
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DOI：
10.1021/ja206845s
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发表时间：
2011-10-19
影响因子：
15
通讯作者：
Naumov, Pance
中科院分区：
文献类型：
--
作者：
Lasanta, Tania;Elena Olmos, M.;Naumov, Pance
为了在寻求具有可调谐发射的强发光材料的背景下开发新的结构，我们利用了稳健的金簇[Au 2Ag 2（R-I/R-II）（4）]（R-I = 4-C6 F4 I，R-II = 2-C6 F4 I）通过亲金相互作用进行自组装的倾向。与从头的方法，结合的协调和卤素键合潜力的芳香族杂全卤代配体，我们已经产生了一个家庭的显着发光的发光材料，提供的理由来解决的相关性，相对影响，和协同作用的两个相互作用的基础physics。通过聚合绿光发射（λ（em）（max）= 540 nm）单体[Au 2Ag 2 R4 II（tfa）（2）]（2-）（TFA =三氟乙酸盐）转化为发红光的（λ（em）（max）= 660 nm）聚合物[Au 2Ag 2 R4 II（MeCN）（2）]（n），我们在此证明，这些材料中的团簇缔合程度可以简单地通过施加机械化学和/或化学反应来有效地和可逆地切换。或通过固态中的蒸气化学刺激以及通过溶液中的溶剂化化学，反应与强烈的、容易察觉的光致发光的剧烈切换一致。我们证明了相关平衡中的关键事件是亚稳态黄色发光体（λ（em）（max）= 580 nm）的演变，在配体RH的情况下，其结构测定揭示了二聚体非溶剂化拓扑结构[Au 2Ag 2 R4 II]（2）。综合起来看，这些结果揭示了亲金性驱动的Au 2Ag 2团簇自组装的两阶段过程（R-I/R-II）（4）]（1）绿色发光单体的初始缔合以形成亚稳态黄色发光二聚体和去溶剂化，然后（2）二聚体的溶解和它们的自组装以形成具有离域前沿轨道和减小的能隙的红色发光线性结构。[Au 2 Ag 2 R4 II（tfa）（2）]（2-）的绿色发射（λ（em）（max）= 540 nm）超过了迄今为止在[Au 2 Ag 2]基结构中观察到的最高能量，从而将相关结构发射的光谱片段从绿色区域扩展到140 nm以外的深红色区域。方案1.全卤代配体RI和RH的结构以及基于亲金相互作用（AI），亲金属相互作用（MI）和卤素键（XB）的联合作用推测的键合基序[GRAPHICS]。
Aiming at the development of new architectures within the context of the quest for strongly luminescent materials with tunable emission, we utilized the propensity of the robust bimetallic clusters [Au2Ag2(R-I/R-II)(4)] (R-I = 4-C6F4I, R-II = 2-C6F4I) for self-assembly through aurophilic interactions. With a de novo approach that combines the coordination and halogen-bonding potential of aromatic heteroperhalogenated ligands, we have generated a family of remarkably luminescent bimetallic materials that provide grounds to address the relevance, relative effects, and synergistic action of the two interactions in the underlying photophysics. By polymerizing the green-emitting (lambda(em)(max) = 540 nm) monomer [Au2Ag2R4II(tfa)(2)](2-) (tfa = trifluoroacetate) to a red-emitting (lambda(em)(max) = 660 nm) polymer [Au2Ag2R4II(MeCN)(2)](n), we demonstrate herein that the degree of cluster association in these materials can be effectively and reversibly switched simply by applying mechanochemical and/or vapochemical stimuli in the solid state as well as by solvatochemistry in solution, the reactions being coincident with a dramatic switching of the intense, readily perceptible photoluminescence. We demonstrate that the key event in the related equilibrium is the evolution of a metastable yellow emitter (lambda(em)(max) = 580 nm) for which the structure determination in the case of the ligand RH revealed a dimeric nonsolvated topology [Au2Ag2R4II](2). Taken together, these results reveal a two-stage scenario for the aurophilic-driven self-assembly of the bimetallic clusters [Au2Ag2(R-I/R-II)(4)] (1) initial association of the green-emitting monomers to form metastable yellow-emitting dimers and desolvation followed by (2) resolvation of the dimers and their self-assembly to form a red-emitting linear architecture with delocalized frontier orbitals and a reduced energy gap. The green emission from [Au2Ag2R4II(tfa)(2)](2-) (lambda(em)(max) = 540 nm) exceeds the highest energy observed for [Au2Ag2]-based structures to date, thereby expanding the spectral slice for emission from related structures beyond 140 nm, from the green region to the deep-red region. Scheme 1. Structures of the Perhalogenated Ligands RI and RH and Bonding Motifs Conjectured on the Basis of the Combined Action of Aurophilic Interactions (AIs), Metallophilic Interactions (MIs), and Halogen Bonds (XBs)[GRAPHICS].