On the cleavage process of the N-trifluoromethylsulfonyloxy-1,8-naphthalimide photoacid generator

Nanoscale Vertical Resolution in Optical Printing of Inorganic Nanoparticles

Direct optical printing of functional inorganics shows tremendous potential as it enables the creation of intricate two-dimensional (2D) patterns and affordable design and production of various devices. Although there have been recent advancements in printing processes using short-wavelength light or pulsed lasers, the precise control of the vertical thickness in printed 3D structures has received little attention. This control is vital to the diverse functionalities of inorganic thin films and their devices, as they rely heavily on their thicknesses. This lack of research is attributed to the technical intricacy and complexity involved in the lithographic processes. Herein, we present a generalized optical 3D printing process for inorganic nanoparticles using maskless digital light processing. We develop a range of photocurable inorganic nanoparticle inks encompassing metals, semiconductors, and oxides, combined with photolinkable ligands and photoacid generators, enabling the direct solidification of nanoparticles in the ink medium. Our process creates complex and large-area patterns with a vertical resolution of ∼50 nm, producing 50-nm-thick 2D films and several micrometer-thick 3D architectures with no layer height difference via layer-by-layer deposition. Through fabrication and operation of multilayered switching devices with Au electrodes and Ag-organic resistive layers, the feasibility of our process for cost-effective manufacturing of multilayered devices is demonstrated.

Charge Shielding-Oriented Design of Zinc-Based Nanoparticle Liquids for Controlled Nanofabrication

Metal-containing nanoparticles possess nanoscale sizes, but the exploitation of their nanofeatures in nanofabrication processes remains challenging. Herein, we report the realization of a class of zinc-based nanoparticle liquids and their potential for applications in controlled nanofabrication. Utilizing the metal-core charge shielding strategy, we prepared nanoparticles that display glass-to-liquid transition behavior with glass transition temperature far below room temperature (down to -50.9 °C). Theoretical calculations suggest the outer surface of these unusual nanoparticles is almost neutral, thus leading to interparticle interactions weak enough to give them liquefaction characteristics. Such features endow them with extraordinarily high dispersibility and excellent film-forming capabilities. Twenty-two types of nanoparticles synthesized by this strategy have all shown good lithographic properties in the mid-ultraviolet, electron beam, or extreme ultraviolet light, and these nanoparticle liquids have achieved controlled top-down nanofabrication with predesigned 18 or 16 nm patterns. This proposed strategy is synthetically scalable and structurally extensible and is expected to inspire the design of entirely new forms of nanomaterials.

Generalised optical printing of photocurable metal chalcogenides

Optical three-dimensional (3D) printing techniques have attracted tremendous attention owing to their applicability to mask-less additive manufacturing, which enables the cost-effective and straightforward creation of patterned architectures. However, despite their potential use as alternatives to traditional lithography, the printable materials obtained from these methods are strictly limited to photocurable resins, thereby restricting the functionality of the printed objects and their application areas. Herein, we report a generalised direct optical printing technique to obtain functional metal chalcogenides via digital light processing. We developed universally applicable photocurable chalcogenidometallate inks that could be directly used to create 2D patterns or micrometre-thick 2.5D architectures of various sizes and shapes. Our process is applicable to a diverse range of functional metal chalcogenides for compound semiconductors and 2D transition-metal dichalcogenides. We then demonstrated the feasibility of our technique by fabricating and evaluating a micro-scale thermoelectric generator bearing tens of patterned semiconductors. Our approach shows potential for simple and cost-effective architecturing of functional inorganic materials.

Optical 3D printing techniques are low-cost mask-less patterning methods, but their application is limited by the number of printable materials. Here, the authors report a generalized optical method to print 2D or micrometre-thick 2.5D architectures based on metal chalcogenides inks, showing the realization of micro-scale thermoelectric generators.

Independent Generation and Reactivity of 2'-Deoxyguanosin-N1-yl Radical

2'-Deoxyguanosin-N1-yl radical (dG(N₁-H)^•) is the thermodynamically favored one-electron oxidation product of 2'-deoxyguanosine (dG), the most readily oxidized native nucleoside. dG(N₁-H)^• is produced by the formal dehydration of a hydroxyl radical adduct of dG as well as by deprotonation of the corresponding radical cation. dG(N₁-H)^• were formed as a result of the indirect and direct effects of ionizing radiation, among other DNA damaging agents. dG(N₁-H)^• was generated photochemically (λ_max = 350 nm) from an N-aryloxy-naphthalimide precursor (3). The quantum yield for photochemical conversion of 3 is ∼0.03 and decreases significantly in the presence O₂, suggesting that bond scission occurs from a triplet excited state. dG is formed quantitatively in the presence of excess β-mercaptoethanol. In the absence of a reducing agent, dG(N₁-H)^• oxidizes 3, decreasing the dG yield to ∼50%. Addition of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) as a sacrificial reductant results in a quantitative yield of dG and two-electron oxidation products of 8-oxodGuo. N-Aryloxy-naphthalimide 3 is an efficient and high-yielding photochemical precursor of dG(N₁-H)^• that will facilitate mechanistic studies on the reactivity of this important reactive intermediate involved in DNA damage.

One/two-photon-sensitive photoacid generators based on benzene oligomer-containing D–π–A-type aryl dialkylsulfonium salts

D–π–A type photoacid generators with a benzene-oligomer as π-conjugated systems show high photoacid generation efficiency (Φ_H+max > 0.7) and good photoinitiated polymerization abilities by 365 nm and 780 nm excitation.

π-conjugated sulfonium-based photoacid generators: an integrated molecular approach for efficient one and two-photon polymerization

D–π–A type π-conjugated photoacid generators through the para-to-meta substitution strategy show high efficiency in photoinitiated cationic polymerization reactions at 405 nm and 800 nm excitation.