Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications.

Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications.

Silica Jar-with-Lid as Chemo-Enzymatic Nano-Compartment for Enantioselective Synthesis inside Living Cells.

Nanodevices, harvesting the power of synthetic catalysts and enzymes to perform enantioselective synthesis inside cell, have never been reported. Here, we synthesized round bottom jar-like silica nanostructures (SiJARs) with a chemo-responsive metal-silicate lid. This was isolated as an intermediate structure during highly controlled solid-state nanocrystal-conversion at the arc-section of silica shell. Different catalytic noble metals (Pt, Pd, Ru) were selectively modified on the lid-section through galvanic reactions. And, lid aperture-opening was regulated by mild acidic conditions or intracellular environment which accommodated the metal nanocrystals and enzymes, and in turn created an open-mouth nanoreactor. Distinct from the free enzymes, SiJARs performed asymmetric aldol reactions with high activity and enantioselectivity (yield >99 %, ee=95 %) and also functioned as the artificial catalytic organelles inside living cells. This work bridges the enormous potential of sophisticated nanocrystal-conversion chemistry and advanced platforms for new-to-nature catalysis.

Magnetothermia-Induced Catalytic Hollow Nanoreactor for Bioorthogonal Organic Synthesis in Living Cells.

Nanoreactors, in which the reactions are remotely controlled by magnetic fields, are potentially valuable in bioorthogonal chemistry for future applications. Here, we develop a silica-confined magnetothermia-induced nanoreactor (MAG-NER) by selectively growing Pd nanocrystals on a preinstalled iron-oxide core inside a hollow silica nanoshell. The growth is achieved by magnetic induction. The interfacial catalytic site is activated by stimulating localized magnetothermia, and nanocompartmentalization is realized by the size-selective porous silica. Therefore, MAG-NER can be conveniently used in complex biomedia and can even be internalized to living cells, realizing an on-demand, high-performance intramolecular carbocyclization reaction by remote operation without compromising the cell viability. This work opens avenues for the design of advanced nanoreactors that complement and augment the existing bioorthogonal chemical tools.