Efficient, Functional Group‐Tolerant, and Catalyst‐Free Nitrile Formation from Aldehydes

Solution combustion synthesis of zirconia-stabilized calcium oxide sorbents for CO2 capture

Emerging core-shell nanostructured catalysts of transition metal encapsulated by two-dimensional carbon materials for electrochemical applications

ZnCl2 Enabled Synthesis of Highly Crystalline and Emissive Carbon Dots with Exceptional Capability to Generate O2⋅–

Insight into product characteristics from microwave co-pyrolysis of low-rank coal and corncob: Unraveling the effects of metal catalysts

Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C-H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.

'Invited'Starting from critical dimensions below 10 nm, the continuation of CMOS scaling requires the Cu replacement as an IC interconnect material by a barrierless metal with lower resistivity and better electromigration performance than Cu, such as Co and Ru. In addition, narrow dimensions of interconnect features require implementation of bottom-up metal fill schemes to mitigate defects in metal structures. At the same time, significant technological improvements are required to mitigate the pattern overlays and litho-based edge placement errors when forming multilevel structures with a half-pitch at or below 10 nm. The transition from standard multiple litho-etch deposition schemes to bottom-up area-selective deposition (ASD) is a very promising way to enable self-alignment of multilevel structures. The approaches to achieve ASD can be classified in three categories: i) intrinsic selectivity, ii) selectivity enabled by passivation of the “non-growth area” and iii) selectivity enabled by activation of the “growth area”. Among selective deposition processes, electroless deposition (ELD) and atomic layer deposition (ALD) can be effectively used due to their chemical nature and surface sensitivity. This work explores all three categories of ASD approaches for BEOL technology application, utilizing the above listed techniques for Co and Ru deposition.Intrinsically selective metal deposition can be realized for very limited number of material combinations used in IC manufacturing. Part of this work focuses on various H-based plasma treatments, which allow forming appropriate surface functionalities enabling ASD. Among various material combinations, the focus was set on amorphous carbon (a-C) as “non-growth” surface and Si-based materials, such as SiCN, as “growth” surface. An interaction of various compounds of H-based plasma, namely: H ions and H radicals with a-C was investigated experimentally. In order to support experimental observations, molecular dynamic modeling of a-C interaction with H plasma was performed, which allowed to understand the mechanisms of a-C chemical modification by H ions and radicals. Effectivity of H plasma treatment on ALD selectivity was studied for the case of selective Ru ALD using (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl)Ru(0) (EBECHRu) precursor with O2 co-reactant. In addition, an initial study of Ru ASD integration into patterned structures of technological relevant dimensions was performed.Direct implementation of intrinsically selective processes into production is a rare case in microelectronic technology. In most of the cases, however, blocking layers can be used. This work explores self-assembled monolayers (SAMs) as blocking layers for ALD. Screening of various siloxane-SAM precursors was performed to study the impact of SAM’s functional group, length of alkyl chain and deposition conditions on surface density of SAM molecules and, specifically, passivation properties of SAM against Ru ALD. An additional study was performed in order to analyze modification of (3-trimethoxysilylpropyl)diethylenetriamine (DETA)-derived SAM under ALD conditions (250 °C and O2 co-reactant). In-situ XPS as well as molecular-dynamic modelling were employed to investigate the mechanisms of DETA modification. Lastly, a removal of DETA-derived SAM from Cu “growth area” selectively with respect to SiO2 “non-growth area” using acetic acid was investigated to mitigate defectivity.Further, surface functionalization by SAMs can also be used to form appropriate surface terminal groups for further attachment of a metal catalyst or metal seed, used in subsequent selective ELD deposition. ELD is based on redox reactions on the metal substrate; therefore, it can be used for intrinsically selective metal deposition on metal substrates or metal seeds. SAMs-enabled selectivity can be used for metal growth on a dielectric surface selectively with respect to another type of the dielectric material. In the case of ELD bottom-up growth in a trench, the metal catalyst should be selectively deposited at the trench bottom dielectric layer. In this work, the selectivity of Pd metal catalyst promoted by selective surface functionalization by SAMs was investigated. It has been shown that SAMs with amino functional groups form covalent bonds with Pd catalyst, which is commonly used as a seed for subsequent ELD of various metals including Co on the Pd seed. Since the electrical properties of interconnect material are of crucial importance, an additional study of ELD Co resistivity was performed, including in-depth analysis of Co recrystallization revealing Co grain size dependency on the film resistivity.In conclusion, area-selective metal deposition processes are an important part of future microelectronic technology. This work explores ASD of Ru and Co, as the most promising Cu replacement metals. For the deposition of these metals, surface sensitive techniques are used, namely ALD and ELD. For the cases, where intrinsic selectively of the deposition technique cannot be realized for the combination of materials used in the process flow, SAM-based passivation and SAM-based activation layers were investigated.

Chapter 2 - Synthesis and Purification of Multi-Walled and Single-Walled Carbon Nanotubes

Deuterium (D) labeling is of great value in organic synthesis, pharmaceutical industry, and materials science. However, the state‐of‐the‐art deuteration methods generally require noble metal catalysts, expensive deuterium sources, or harsh reaction conditions. Herein, noble metal‐free and ultrathin ZnIn2S4 (ZIS) is reported as an effective photocatalyst for visible light‐driven reductive deuteration of carbonyls to produce deuterated alcohols using heavy water (D2O) as the sole deuterium source. Defective two‐dimensional ZIS nanosheets (D‐ZIS) are prepared in a surfactant assisted bottom‐up route exhibited much enhanced performance than the pristine ZIS counterpart. A systematic study is carried out to elucidate the contributing factors and it is found that the in situ surfactant modification enabled D‐ZIS to expose more defect sites for charge carrier separation and active D‐species generation, as well as high specific surface area, all of which are beneficial for the desirable deuteration reaction. This work highlights the great potential in developing low‐cost semiconductor‐based photocatalysts for organic deuteration in D2O, circumventing expensive deuterium reagents and harsh conditions.

Carbonaceous feeds, such as oil, gas, and coal, can be catalytically converted to useful products. Many of these reactions are conducted under harsh conditions, where the metal catalysts will rapidly sinter and lose activity. Overcoating is a methodology which preserves catalyst integrity under reaction conditions by depositing protective layers around the catalysts. Recently, we show that overcoating the metal nanoparticles with alumina using atomic layer deposition (ALD) will reduce the sintering and coking while the lifetime and reactivity of catalyst increase dramatically compared to the catalyst without ALD overcoating. It is believed that nano-sized pore (less than 2 nm) was formed during the calcination of ALD overlayer at high temperature. However, the mechanism of pore formation is still poorly understood due to the limited characterization technique.Understanding the mechanism of the pore formation and further controlling the pore size are crucial for the development of the ALD overcoated catalyst. Recently, we demonstrated that small angle X-ray scattering (SAXS) can be used to characterize these ALD overcoated catalysts. From SAXS analysis, the thermal treatment resulted in the formation of ~ 3.5 nm pores. Moreover, the evolution of pore size was monitored by in situ SAXS technique. The pore size increases with increasing annealing temperature. In this proposal, we aim to investigate the mechanism of pore formation during the calcination using in situ SAXS as well as wide angle X-ray scattering, to understand how the ramping rate, gas used, nature of supports and overcoated materials affect the formation of the pore.

Coupling in situ generated intermediates with other substrates/intermediates is a viable approach for diversifying product outcomes of catalytic reactions involving two or multiple reactants. Cyclohexanone oxime is a key precursor for caprolactam synthesis (the monomer of Nylon‐6), yet its current production uses unsustainable carbon sources, noble metal catalysts, and harsh conditions. Herein, we report the first work to synthesize cyclohexanone oxime through electroreduction of phenol and hydroxylamine. The Faradaic efficiency reached 69.1 % over Cu catalyst, accompanied by a corresponding cyclohexanone oxime formation rate of 82.0 g h−1 gcat−1. In addition, the conversion of phenol was up to 97.5 %. In situ characterizations, control experiments, and theoretical calculations suggested the importance of balanced activation of water, phenol, and hydroxylamine substrates on the optimal metallic Cu catalyst for achieving high‐performance cyclohexanone oxime synthesis. Besides, a tandem catalytic route for the upgrading of lignin to caprolactam has been successfully developed through the integration of thermal catalysis, electrocatalysis, and Beckmann rearrangement, which achieved the synthesis of 0.40 g of caprolactam from 4.0 g of lignin raw material.

Nitrogen heterocyclic carbenes (NHCs) are emerging as effective substitutes for conventional thiol ligands in surface functionalization of nanoparticles (NPs), offering exceptional stability to NPs under harsh conditions. However, the highly reactive feature of NHCs limits their use in introducing chemically active groups onto the NP surface. Herein, we develop a general yet robust strategy for the efficient surface functionalization of NPs with copolymer ligands bearing various functional groups. The polymer ligands consist of a multiple NHCs block, utilized for surface binding on NPs, alongside a poly(reactive ester) block intended for incorporating functional groups. The multiple NHCs block enables NPs with excellent colloidal stability across a broader range of pH values (0-14), temperature variations (-78 °C-100 °C), and electrolyte concentrations (0-1000 mM). Through the in situ ammonolysis of the poly(reactive ester) block, various active functional groups can be individually or together introduced on the NP surface. We further demonstrate the chemical reactivity of these functionalized NPs, including addition polymerization, Diels-Alder and Schiff base reactions. This method is applicable to various types of NPs, including metal NPs, metal oxide NPs, and even upconversion NPs, thereby paving new pathways for the design and creation of nanoparticle-based functional materials.

The gradual and cost-effective integration of oximes and other functional groups into organic molecules is an important and competitive research area. Here, we present a method for directly thiooximating alkenes using thiophenols and tert-butyl nitroester (tBuONO) under visible light, without relying on photocatalysts or metal-based additives. The O-NO bond in tBuONO breaks upon light exposure, producing reactive tert-butoxy radical (tBuO•) and stable NO radicals. These species serve as both hydrogen-atom-transfer (HAT) reagents and precursors to oximes. A major advantage of this method is that it does not require photosensitizers, metal catalysts, or external heating. The reaction performs effectively with various arylalkenes and arylthiophenes, including those with significant steric hindrance and different electronic properties. Additionally, the conditions are mild, the substrate scope is broad, and the method exhibits good tolerance for various functional groups, along with operational simplicity. This allows for the synthesis of diverse α-arylthioacetyloximes in moderate to high yields. Importantly, this approach demonstrates practical value through scalability and successful late-stage modification of bioactive molecules.

Alkynylsilanes are one kind of essential synthetic block in organic chemistry. The established synthetic routes retain some drawbacks regarding harsh reaction conditions or expensive/rare metal catalysts. Herein, we report a method for iron-catalyzed, visible-light-induced alkynylation of hydrosilanes to produce value-added silicon compounds. Alkynes bearing functional groups with different steric properties and alkyl/aryl hydrosilanes were both suitable substrates. Mechanistic studies showed that chlorine radicals generated by iron-catalyzed ligand-to-metal charge transfer in the presence of lithium chloride promoted the formation of silyl radicals.

Proteases that can remain active under extreme conditions such as high temperature, pH, and salt concentration are widely applicable in the commercial sector. The majority of the proteases are rendered useless under harsh conditions in industries. Therefore, there is a need to search for new proteases that can tolerate and function in harsh conditions, thus improving their commercial value. In this study, 142 bacterial isolates were isolated from diverse alkaline soil habitats. The two highest protease-producing bacterial isolates were identified as Bacillus subtilis S1 and Bacillus amyloliquefaciens KSM12, respectively, based on 16S rRNA sequencing. Optimal protease production was detected at pH 8, 37 °C, 48 h, 5% (w/v) NaCl for Bacillus subtilis S1 (99.8 U/mL) and pH 9, 37 °C, 72 h, 10% (w/v) NaCl for Bacillus amyloliquefaciens KSM12 (94.6 U/mL). The molecular weight of these partially purified proteases was then assessed on SDS-PAGE (17 kDa for Bacillus subtilis S1 and 65 kDa for Bacillus amyloliquefaciens KSM12), respectively. The maximum protease activity for Bacillus subtilis S1 was detected at pH 8, 40 °C, and for Bacillus amyloliquefaciens KSM12 at pH 9, 60 °C. These results suggest that the proteases secreted by Bacillus subtilis S1 and Bacillus amyloliquefaciens KSM12 are suitable for industries working in a highly alkaline environment.

Copper(I) is able to catalyze Huisgen 1,3-dipolar cycloaddition in a "click" fashion. This copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction presents excellent chemoselectivity and occurs over a wide-range of reaction conditions. It shows tolerance to variation in both pH and solvent polarity, thereby facilitating the ligation of peptides and proteins to produce peptidomimetics and synthetic proteins. In addition, the only product formed is a 1,4-disubstituted-1,2,3-triazole moiety, in many aspects resembling the natural peptide bond, including hydrogen-bonding capability, planarity, distance between the 1 and 4 substituents, and conformational restriction of the peptide backbone; thus the triazole-backbone-modified peptide, in which a triazole replaces the amide bond, may be anticipated to present a secondary structure similar to that of its natural counterpart. This Focus Review describes the scope and applications of copper(I)-catalyzed alkyne–azide cycloaddition in synthetic peptide/protein chemistry.