The Chemistry of Cu3N and Cu3PdN Nanocrystals

The precursor conversion chemistry and surface chemistry of Cu3 N and Cu3 PdN nanocrystals are unknown or contested. Here, we first obtain phase-pure, colloidally stable nanocubes. Second, we elucidate the pathway by which copper(II) nitrate and oleylamine form Cu3 N. We find that oleylamine is both a reductant and a nitrogen source. Oleylamine is oxidized by nitrate to a primary aldimine, which reacts further with excess oleylamine to a secondary aldimine, eliminating ammonia. Ammonia reacts with Cu(I) to form Cu3 N. Third, we investigated the surface chemistry and find a mixed ligand shell of aliphatic amines and carboxylates (formed in situ). While the carboxylates appear tightly bound, the amines are easily desorbed from the surface. Finally, we show that doping with palladium decreases the band gap and the material becomes semi-metallic. These results bring insight into the chemistry of metal nitrides and might help the development of other metal nitride nanocrystals

The Chemistry of Cu3N and Cu3PdN Nanocrystals

The precursor conversion chemistry and surface chemistry of Cu3 N and Cu3 PdN nanocrystals are unknown or contested. Here, we first obtain phase-pure, colloidally stable nanocubes. Second, we elucidate the pathway by which copper(II) nitrate and oleylamine form Cu3 N. We find that oleylamine is both a reductant and a nitrogen source. Oleylamine is oxidized by nitrate to a primary aldimine, which reacts further with excess oleylamine to a secondary aldimine, eliminating ammonia. Ammonia reacts with Cu(I) to form Cu3 N. Third, we investigated the surface chemistry and find a mixed ligand shell of aliphatic amines and carboxylates (formed in situ). While the carboxylates appear tightly bound, the amines are easily desorbed from the surface. Finally, we show that doping with palladium decreases the band gap and the material becomes semi-metallic. These results bring insight into the chemistry of metal nitrides and might help the development of other metal nitride nanocrystals

Lewis versus Brønsted Acid Activation of a Mn(IV) Catalyst for Alkene Oxidation

Lewis acid (LA) activation by coordination to metal oxido species has emerged as a new strategy in catalytic oxidations. Despite the many reports of enhancement of performance in oxidation catalysis, direct evidence for LA-catalyst interactions under catalytically relevant conditions is lacking. Here, we show, using the oxidation of alkenes with H2O2 and the catalyst [Mn2(μ-O)3(tmtacn)2](PF6)2 (1), that Lewis acids commonly used to enhance catalytic activity, e.g., Sc(OTf)3, in fact undergo hydrolysis with adventitious water to release a strong Brønsted acid. The formation of Brønsted acids in situ is demonstrated using a combination of resonance Raman, UV/vis absorption spectroscopy, cyclic voltammetry, isotope labeling, and DFT calculations. The involvement of Brønsted acids in LA enhanced systems shown here holds implications for the conclusions reached in regard to the relevance of direct LA-metal oxido interactions under catalytic conditions

Supplementary data for the article: Steen, J. D.; Stepanovic, S.; Parvizian, M.; De Boer, J. W.; Hage, R.; Chen, J.; Swart, M.; Gruden, M.; Browne, W. R. Lewis versus Brønsted Acid Activation of a Mn(IV) Catalyst for Alkene Oxidation. Inorganic Chemistry 2019, 58 (21), 14924–14930. https://doi.org/10.1021/acs.inorgchem.9b02737

Supplementary material for: [https://doi.org/10.1021/acs.inorgchem.9b02737]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3691

Supplementary data for the article: Steen, J. D.; Stepanovic, S.; Parvizian, M.; De Boer, J. W.; Hage, R.; Chen, J.; Swart, M.; Gruden, M.; Browne, W. R. Lewis versus Brønsted Acid Activation of a Mn(IV) Catalyst for Alkene Oxidation. Inorganic Chemistry 2019, 58 (21), 14924–14930. https://doi.org/10.1021/acs.inorgchem.9b02737

Supplementary material for: [https://doi.org/10.1021/acs.inorgchem.9b02737]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3691

Exploring metal nitride synthesis from precursors to structural insights

Metal nitride nanocrystals are a versatile class of nanomaterials with a wide range of optical properties, depending on their chemical composition. These properties can vary from those typical of traditional semiconductor nanocrystals, often referred to as quantum dots, to more metallic character, featuring plasmon resonance. However, the synthesis of colloidal metal nitride nanocrystals presents unique challenges due to the less developed precursor chemistry compared to other nanocrystal systems, such as metal, metal chalcogenide, or metal phosphide nanocrystals. This thesis begins with a comprehensive literature review of current synthetic methods for producing metal nitride nanocrystals, with a primary focus on chemical conversion reactions, laying the foundation for our research. Our investigation focuses on copper nitride (Cu3N), a well-studied metal nitride synthesized via wet chemistry. We explore the precursor conversion process and the complexities of surface chemistry associated with Cu3N. Building upon the insights gained from Cu3N chemistry, we investigate various wet chemical approaches aimed at developing methodologies for producing colloidally stable metal nitrides at relatively low temperatures. Recognizing that some nitride formations require higher temperatures to achieve crystalline materials, we delve into the realm of solid-state chemistry. Our work provides an in-depth examination of solid-state-based synthesis methods, particularly focusing on titanium nitride metal nitrides. Finally, we turn our attention to the surface chemistry for nanocrystals, with a specific focus on the use of silane as a versatile ligand. Throughout this thesis, we aim to comprehensively cover synthetic strategies, chemical complexities, and surface chemistry aspects associated with metal nitride nanocrystals. The insights provided in this work are intended to serve as a valuable guide for the further development and applications of colloidal nitride nanocrystals in various fields of nanoscience and technology

Molten Salt-Assisted synthesis of Titanium Nitride

Titanium nitride is an exciting plasmonic material, with optical properties similar to gold. However, synthesizing TiN nanocrystals is highly challenging and typically requires solid-state reactions at very high temperatures (800-1000°C). Here, we achieve the synthesis of TiN nanocrystals at temperatures as low as 350°C, in just three hours. The strategy comprises molten salt, Mg as reductant and Ca3N2 as nitride source. This brings TiN from the realm of solid-state chemistry into the field of solution-based synthesis in regular, borosilicate glassware

Design and Synthesis of Luminescent Lanthanide-Based Bimodal Nanoprobes for Dual Magnetic Resonance (MR) and Optical Imaging

Current biomedical imaging techniques are crucial for the diagnosis of various diseases. Each imaging technique uses specific probes that, although each one has its own merits, do not encompass all the functionalities required for comprehensive imaging (sensitivity, non-invasiveness, etc.). Bimodal imaging methods are therefore rapidly becoming an important topic in advanced healthcare. This bimodality can be achieved by successive image acquisitions involving different and independent probes, one for each mode, with the risk of artifacts. It can be also achieved simultaneously by using a single probe combining a complete set of physical and chemical characteristics, in order to record complementary views of the same biological object at the same time. In this scenario, and focusing on bimodal magnetic resonance imaging (MRI) and optical imaging (OI), probes can be engineered by the attachment, more or less covalently, of a contrast agent (CA) to an organic or inorganic dye, or by designing single objects containing both the optical emitter and MRI-active dipole. If in the first type of system, there is frequent concern that at some point the dye may dissociate from the magnetic dipole, it may not in the second type. This review aims to present a summary of current activity relating to this kind of dual probes, with a special emphasis on lanthanide-based luminescent nano-objects