Receptor-containing polynuclear mixed-metal complexes of gold(I)âcopper(I) 1â3 based on a [Au3Cu2(CCPh)6}Au3PPh2âC6H4âPPh2}3]2+ (Au6Cu2) core with benzo-15-crown-5, oligoether and urea binding sites were designed and synthesized, respectively. These complexes exhibited remarkably strong red emission at ca. 619â630 nm in dichloromethane solution at room temperature upon photoexcitation at λ > 400 nm, with the emission quantum yield in the range 0.59â0.85. The cation-binding properties of 1 and 2 and the anion-binding properties of 3 were studied using UV-vis, emission and 1H NMR techniques. Complex 1, with six benzo-15-crown-5 pendants, was found to show a higher binding preference for K+, with a selectivity trend of K+ â« Cs+ > Na+ > Li+. The addition of metal ions (Li+, Na+, K+ and Cs+) to complex 1 led to a modest emission enhancement with a concomitant slight blue shift in energy and well-defined isoemissive points, which is attributed to the rigidity of the structure and the inhibited PET (photo-induced electron transfer) process from the oxygen to the aggregate as a result of the binding of the metal ion. The six urea receptor groups on complex 3 were found to form multiple hydrogen bonding interactions with anions, with the positive charge providing additional electrostatic interaction for anion-binding. The anion selectivity of 3 follows the trend Fâ > Clâ â H2PO4â > Brâ and the highest affinity towards Fâ is attributed to the stronger basicity of Fâ, as well as its good size match with the cavity of the urea pocket.
分别设计并合成了以[Au3Cu2(CCPh)6}Au3PPh2â
C6H4âPPh2}3]2+(Au6Cu2)为核心、具有苯并-15-
冠醚-5、寡聚醚和
脲结合位点的含受体多核混合
金属
金(I)â
铜(I)1â3配合物。这些配合物在约 619â630 纳米波长的波长范围内显示出明显的红色发射。在室温下的
二氯甲烷溶液中,当光激发波长δ" > 400 nm时,这些复合物在约 619â630 nm处显示出明显的强红色发射,发射量子产率在 0.59â0.85 之间。利用紫外可见光、发射和 1H NMR 技术研究了 1 和 2 的阳离子结合特性以及 3 的阴离子结合特性。研究发现,含有六个苯并-15-
冠醚-5 下垂物的络合物 1 对 K+ 具有更高的结合偏好,其选择性趋势为 K+ â"Cs+ > Na+ > Li+。在复合物 1 中加入
金属离子(Li+、Na+、K+ 和 Cs+)后,发射率会适度提高,同时能量会发生轻微的蓝移,并出现明确的等离点,这归因于结构的刚性以及
金属离子的结合抑制了从氧到聚集体的 PET(光诱导电子转移)过程。研究发现,复合物 3 上的六个
脲受体基团与阴离子形成了多种氢键相互作用,正电荷为阴离子结合提供了额外的静电作用。复合物 3 对阴离子的选择性呈 Fâ > Clâ â H2PO4â > Brâ 的趋势,对 Fâ 的亲和力最高,这是因为 Fâ 的碱性较强,而且其大小与
脲口袋的空腔相匹配。