Self-assembly represents probably the most flexible way to construct metastructured materials and devices from a wealth of colloidal building blocks with synthetically controllable sizes, shapes, and elemental compositions. In principle, surface capping is unavoidable during the synthesis of nanomaterials with well-defined geometry and stability. The ligand layer also endows inorganic building blocks with molecular recognition ability responsible for their assembly into desired structures. In the case of plasmonic nanounits, precise positioning of them in a nanomolecule or an ordered nanoarray provides a chance to shape their electrodynamic behaviors and thereby assists experimental demonstration of modern nanoplasmonics toward practical uses. Despite previous achievements in bottom-up nanofabrication, a big challenge exists toward strong coupling and facile charge transfer between adjacent nanounits in an assembly. This difficulty has impeded a functional development of plasmonic nanoassemblies. The weakened interparticle coupling originates from the electrostatic and steric barriers of ionic/molecular adsorbates to guarantee a good colloidal stability. Such a dilemma is rooted in fundamental colloidal science, which lacks an effective solution. During the past several years, a chemical tool termed Ag ion soldering (AIS) has been developed to overcome the above situation toward functional colloidal nanotechnology. In particular, a dimeric assembly of plasmonic nanoparticles has been taken as an ideal model to study plasmonic coupling and interparticle charge transfer. This Account starts with a demonstration of the chemical mechanism of AIS, followed by a verification of its workability in various self-assembly systems. A further use of AIS to realize postsynthetic coupling of DNA-directed nanoparticle clusters evidences its compatibility with DNA nanotechnology. Benefiting from the sub-nanometer interparticle gap achieved by AIS, a conductive pathway is established between two nanoparticles in an assembly. Accordingly, light-driven charge transfer between the conductively bridged plasmonic units is realized with highly tunable resonance frequencies. These situations have been demonstrated by thermal/photothermal sintering of silica-isolated nanoparticle dimers as well as gap-specific electroless gold/silver deposition. The regioselective silver deposition is then combined with galvanic replacement to obtain catalytically active nanofoci (plasmonic nanogaps). The resulting structures are useful for real time and on-site Raman spectroscopic tracking of chemical reactions in the plasmonic hotspots (nanogaps) as well as for study of plasmon-mediated/field-enhanced catalysis. The Account is concluded by a deeper insight into the chemical mechanism of AIS and its adaption to conformation-rich structures. Finally, AIS-enabled functional pursuits are suggested for self-assembled materials with strongly coupled and easily reshapable physicochemical properties.

中文翻译：

---

Ag离子焊接：用于亚纳米等离子等离子耦合的新兴工具。

自组装可能是从具有可综合控制的大小，形状和元素组成的胶体构建基块构建元结构化材料和设备的最灵活方法。原则上，在具有明确定义的几何形状和稳定性的纳米材料的合成过程中，表面封盖是不可避免的。配体层还赋予无机结构单元以分子识别能力，从而使其组装成所需的结构。在等离激元纳米单元的情况下，将它们精确定位在纳米分子或有序纳米阵列中提供了塑造其电动力学行为的机会，从而有助于将现代纳米等离激元用于实际应用的实验演示。尽管在自下而上的纳米加工方面取得了先前的成就，组件中相邻纳米单元之间的强耦合和便捷的电荷转移面临着巨大挑战。这种困难阻碍了等离子体纳米组件的功能发展。减弱的粒子间耦合源自离子/分子被吸附物的静电和空间屏障，以确保良好的胶体稳定性。这种困境根植于基本的胶体科学，而胶体科学缺乏有效的解决方案。在过去的几年中，已经开发出一种称为Ag离子焊接（AIS）的化学工具，以克服上述朝着功能胶体纳米技术发展的局面。特别地，等离激元纳米粒子的二聚体组装已被用作研究等离激元耦合和粒子间电荷转移的理想模型。该帐户首先说明了AIS的化学机理，然后验证其在各种自组装系统中的可使用性。AIS进一步用于实现DNA定向的纳米粒子簇的合成后偶联证明了其与DNA纳米技术的兼容性。受益于通过AIS实现的亚纳米粒子间间隙，在组件中的两个纳米粒子之间建立了导电路径。因此，以高度可调的谐振频率实现了在导电桥接的等离激元单元之间的光驱动电荷转移。通过二氧化硅隔离的纳米颗粒二聚体的热/光热烧结以及间隙特定的化学金/银沉积已证明了这些情况。然后将区域选择性的银沉积与电流置换相结合以获得催化活性纳米焦点（等离子体纳米间隙）。所得的结构可用于实时和现场拉曼光谱跟踪等离激元热点（nanogaps）中的化学反应，以及用于研究等离激元介导的/场增强的催化作用。该帐户是通过对AIS的化学机理及其对构象丰富的结构的适应性更深入的了解而得出的。最后，建议对具有强耦合且易于使用的物理化学性质的自组装材料进行AIS启用的功能追求。