Distinctly different 3D assemblies of ∼1.6 nm Au nanoparticles are constructed based on weak and strong coordination strategies. Reduction of KAuCl4 with NaBH4 in the presence of newly-synthesized 4-(4-phenylmethanethiol)-2,2′:6′,2′′-terpyridine (1) yields functionalized Au nanoparticles which assemble in situ into large 3D aggregates via weak coordination between alkali metal ions and terpyridine attached to separated particles. These assemblies are disassembled into individual nanoparticles via addition of DMF solvent and further reassembled into highly dispersed 3D spherical nanostructures via addition of Co2+ (strong coordination with 1). Wide and small angle XRD measurements show that the assemblies are formed from small Au nanoparticles, consistent with TEM results. It is significant that the large aggregates formed in situ can be directly transformed into nearly monodispersed 3D spherical assemblies via strong coordination (with Co2+), presenting the first example of a direct transformation of one 3D nanonetwork into another distinctly different 3D nanonetwork. The controlled assembly and disassembly processes are accompanied by distinct shifts in the surface plasmon resonance.
基于弱配位和强配位策略构建了截然不同的 ∼1.6 nm Au 纳米颗粒 3D 组装体。在新合成的 4-(4-苯基
甲硫醇)-2,2':6',2''-三联
吡啶 (1) 存在下用 NaBH4 还原 KAuCl4,生成功能化的 Au 纳米粒子,该纳米粒子通过弱相互作用原位组装成大型 3D 聚集体碱
金属离子和附着在分离颗粒上的三联
吡啶之间的配位。通过添加
DMF 溶剂,这些组件被分解成单个纳米颗粒,并通过添加 Co2+(与 1 强配位)进一步重新组装成高度分散的 3D 球形纳米结构。广角和小角度 XRD 测量表明,组件是由小型
金纳米粒子形成的,与
TEM 结果一致。值得注意的是,原位形成的大聚集体可以通过强配位(与 Co2+)直接转化为几乎单分散的 3D 球形组件,这是第一个将一个 3D 纳米网络直接转化为另一个截然不同的 3D 纳米网络的例子。受控的组装和拆卸过程伴随着表面等离子共振的明显变化。