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From Fundamental Chemistry to Biological Function: The Biological and Abiological Chemistry of Metal Persulfides and Related Species
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Abstract Guaianolide sesquiterpene natural products are of great biological and synthetic importance. Among them, phaeocaulisin A with a unique tetracyclic skeleton was isolated in 2013 and found to exhibit anticancer cell proliferation activity and anti-inflammatory activity. The first total synthesis of ( − )-phaeocaulisin A was achieved by Procter and coworkers in 2022. Two years later, we reported a total synthesis of ( ± )-phaeocaulisin A. The key steps of our total synthesis include a novel palladium-catalyzed cyclopropanol ring-opening carbonylative esterification to access a key γ-ketoester, a regio- and stereo-selective aldol cyclization to build the 7-membered carbocycle, and a cascade ketalization/lactonization to construct the tetracyclic skeleton. This Synpact article reflects our journey toward ( ± )-phaeocaulisin A, which also led to the discovery of an analogue with potent anticancer activity against triple negative or HER2+ breast cancer.more » « less
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Dr. Tobias Weidner (Ed.)Over the past few decades, the public recognition of the prevalence of certain classes of pollutants, such as perfluoroalkyl substances and nanoplastics, within the environment, has sparked growing concerns over their potential impact on environmental and human health. Within both environmental and biological systems, the adsorption and structural organization of pollutants at aqueous interfaces can greatly impact the chemical reactivity and transformation. Experimentally probing chemical behavior at interfaces can often pose a problem due to bulk solvated molecules convoluting molecular signatures from interfacial molecules. To solve this problem, there exist interface-specific nonlinear spectroscopy techniques that can directly probe both macroscopic planar interfaces and nanoplastic interfaces in aqueous environments. These techniques can provide essential information such as chemical adsorption, structure, and reactivity at interfaces. In this perspective, these techniques are presented with obvious advantages for studying the chemical properties of pollutants adsorbed to environmental and biological interfaces.more » « less
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After a brief introduction highlighting the challenges of fluorine chemistry and the latest developments in the field, this Perspective will discuss how a combination of fluorine and fluorous chemistry together with fluorinated reagents helped to bridge between organic, molecular, macromolecular, supramolecular and biological sciences to create functions in the laboratory of the corresponding author. The reactivity of fluoride as a leaving group is best illustrated by SNAr reactions when it helped to demonstrate single electron transfer-mediated side reactions and through molecular design replaced activated aryl fluorides with aryl chlorides in the synthesis of poly(etherketone)s. Subsequently it was demonstrated how Ni(II) sigma complexes provided an orthogonal approach to the Suzuki-type cross-coupling of arylfluorides, other halides and all aryl C–O based electrophiles. Fluorinated reagents facilitated cylotrimetrization vs cyclotetramerization of bis(methoxy)benzyl chloride and alcohol and the synthesis of the simplest molecular liquid crystals. Triflic acid, methyl triflate facilitated the most tolerant living polymerizations including of cyclic siloxanes, functional vinyl ethers and oxazolines to generate self-organizable dendronized polymers while fluorine, trifluoromethyl and trifluoromethoxy groups facilitated disassembly and reassembly of liquid crystal polyethers and poly(p-phenylenes). Fluorinated stereocenters accessed the first heterochiral recognition in side-chain liquid crystal poly(vinyl ether)s and their model compounds. Alkali metal triflates mediated self-organization of supramolecular nonfluorinated and fluorinated self-assembling minidendrons, dendrons, dendrimers and self-organizable dendronized polymers. The role of fluorinated alkyl groups and of alkali metal triflates in the self-assembly, disassembly and isomorphic replacement analysis, of supramolecular helical columns, of the assembly of helical cogwheel coat and of spherical supramolecular dendrimers forming Frank-Kasper periodic and quasiperiodic arrays was highlighted. A brief discussion of fluorinated amino acids, peptides and peptoids and their potential role in the self-assembly and functions resulted from dendritic dipeptides followed by a discussion of semifluorinated amphiphilic Janus dendrimers as models of biological membranes, including for cell fusion and fission, concludes this Perspective.more » « less
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It is increasingly realized that rational design is critical to advance potential applications and proactively preclude adverse consequences of carbon nanomaterials (CNMs). Central to this approach is the establishment of parametric relationships that correlate material properties to both their functional performance and inherent hazard. This work aims to decouple the causative mechanisms of material structure and surface chemistry as it relates to the electrochemical and biological activities of graphene oxide (GO). The results are evaluated in the context of established relationships between surface chemistry and oxygen functionalized multi-walled carbon nanotubes (O-MWCNTs), a carbon allotrope. Systematic manipulation of GO surface chemistry is achieved through thermal annealing (under inert conditions, 200–900 °C). To further elucidate the contribution of several properties, chemical reduction was also used as an approach to differentially modify the surface chemistry. Physicochemical properties of GO and reduced GO (rGO) samples were comprehensively characterized using multiple techniques (AFM, TGA, XPS, ATR-FTIR, Raman, and DLS). The results indicate that surface chemistry is a viable design handle to control both activities. Rather than a single direct property ( i.e. , relative presence of carbonyl-containing moieties), it is a balance of multiple consequential properties, (extent of dispersion, defect density, and electrical conductivity) in combination with the relative presence of carbonyl moieties that synergistically contribute to electrochemical and biological activities. The identification of these governing physicochemical properties aims to inform the establishment of design parameters to guide the rational and safe design of CNMs.more » « less
