ACS Organic & Inorganic Au最新文献

Bipyridines and azaarenes are an important class of ligands that impart unique and tunable properties to transition metal complexes and catalysts. While some derivatives are commercially available, noncommercial analogues are often challenging to prepare and purify. Herein, we report a general nucleophilic aromatic substitution reaction that converts cationic trimethylaminated bipyridines into a series of functionalized bipyridines. Our method showcases a series of C–O, C–S, and C–F bond-forming reactions as well as a selective monodemethylation that converts the electron-deficient trimethylammonium to an electron-rich dimethylamine. The approach was further applied to diversification of pharmaceuticals and natural products and was applied to the total synthesis of Graveolinine and the preparation of Graveolinine derivatives.

Four dinuclear organometallic molecular wire complexes with diethynylmetalloporphyrin linkers 1^MM’, [5,15-bis{MCp*(dppe)ethynyl}-10,20-diarylporphinato]M’ (Cp* = η⁵-C₅Me₅; dppe = 1,2-bis(diphenylphosphino)ethane; M/M’ = Fe/Zn (1^FeZn), Ru/Zn (1^RuZn), Fe/Ni (1^FeNi), Ru/Ni (1^RuNi); aryl = 3,5-di-tert-butylphenyl), are synthesized and characterized by NMR, CV, UV–vis-NIR, and ESI-TOF mass spectrometry techniques. Electrochemical investigations combined with electronic absorption spectroscopic studies reveal strong interactions among the electron-donating, redox-active MCp*(dppe) termini and the metalloporphyrin moieties. The monocationic species of the four complexes obtained by chemical oxidation have been characterized as mixed-valence Class II/III or Class III compounds according to the Robin-Day classification despite the long molecular dimension (>1.5 nm), as demonstrated by their intense intervalence charge transfer bands (IVCT) in the near IR region. DFT calculations indicate large spin densities on the metalloporphyrin moieties. Furthermore, the wirelike performance can be finely tuned by coordination of appropriate nitrogen donors to the axial sites of the metalloporphyrin.

The electrochemical oxidation of amines to nitriles and imines represents a critical frontier in organic electrochemistry, offering a sustainable pathway to these valuable compounds. Nitriles and amines are pivotal in various industrial applications, including pharmaceuticals, agrochemicals, and materials science. This review encapsulates the recent advancements in the electrooxidation process, emphasizing mechanistic understanding, electrode material innovations, optimization of reaction conditions, and exploration of solvent and electrolyte systems. Additionally, the review addresses the operational parameters that significantly affect the electrooxidation process, such as current density, temperature, and electrode surface, offering insights into their optimization for enhanced performance. By providing a comprehensive view of the current state and prospects of amine electrooxidation to nitriles and imines, this review aims to inspire further development, innovation, and research in this promising area of green chemistry.

A combined direct and inverse photoemission study of coinage metal corroles suggests that the latter technique, in favorable cases, can provide some additional information relative to electrochemical measurements. Thus, whereas inverse photoemission spectroscopy (IPES) provides relative electron affinities for electron addition to different unoccupied orbitals, electrochemical reduction potentials shed light on the energetics of successive electron additions. While all three coinage metal triphenylcorrole (TPC) complexes exhibit similar ionization potentials, they exhibit dramatically different inverse photoemission spectra. For Cu[TPC], the lowest-energy IPES feature (0.74 eV) is found to be exceedingly close to the Fermi level; it is significantly higher for Ag[TPC] (1.65 eV) and much higher for Au[TPC] (2.40 eV). These differences qualitatively mirror those observed for electrochemical reduction potentials and are related to a partially metal-centered LUMO in the case of Cu- and Ag[TPC] and a fully corrole-based LUMO in the case of Au[TPC]; the latter orbital corresponds to the LUMO+1 in the case of Ag[TPC].

Under light irradiation, aryldiazo acetates can generate either singlet or triplet carbenes depending on the reaction conditions, but heteroaryl diazo compounds have remained underexplored in this context. Herein, we found that triazolyl diazoacetates exhibit higher reactivity than their aryl counterparts. They even react with dichloromethane (DCM), a common, inert solvent, for photoreactions involving diazo reagents, giving halogenated products. Theoretical studies show that all reactions involve carbenes but progress via different pathways depending on the solvent used.

Carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles are well-known for their wide range of applications in pharmaceutical and medicinal chemistry, but their high-yielding metal-free synthesis has always remained challenging, as no comprehensive protocol has been outlined to date. Owing to their structural and medicinal importance, herein, we synthesized various carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles and unsymmetrical 4,5′-bitriazoles with high yields and chemo-/regioselectivity from the library of 2,4-diketoesters and azides in a sequential one-pot manner through the combination of organocatalytic enolization, in situ [3 + 2]-cycloaddition, and hydrolysis reactions. The commercial availability of the starting materials/catalysts, diverse substrate scope, performance in a one-pot manner, chemo-/regioselectivity of organo-click reaction, quick synthesis of unsymmetrical 4,5′-bitriazoles, a large number of synthetic applications, and numerous medicinal applications of carbonyl-containing 1,2,3-triazoles are the key attractions of this metal-free organo-click work.

Labeling of peptides and proteins with fluorescent dyes is a key step in functionalizing these structures for a wide array of biological assays. However, coupling strategies of such dyes have not been optimized for the most common compounds, while this step is typically the most precious and costly of the whole synthesis. We searched for the best conditions for attachment of the most widely used fluorescent dyes such as 6-carboxyfluorescein, Rhodamine B, and BODIPY-FL to peptides, where amino terminal Cu(II) and Ni(II) binding site (ATCUN) peptides were used as a model system. Surprisingly, conventional methods of dye attachment proved to not be satisfactory and yielded poor efficiency results. We have discovered that when labeling primary amines on peptides, the uncommon synthesis of activated pentafluorophenol (PFP) esters is the most efficient strategy, expedited by microwave irradiation. Coupling to secondary amines is achieved most efficiently through conventional coupling reagents such as HATU and PyBOP. Furthermore, we have employed our fluorescently labeled ATCUN peptides in studies for Cu(II) and Ni(II) sensing, showing that changing the fluorophore does not significantly affect the fluorescence quenching process and discovering the optimal linker length between the ATCUN core and the dye, expanding the repertoire of fluorophores that can be used in this application.