Communications Chemistry最新文献

Validating thermodynamic models is essential in experimental geosciences for exploring increasingly complex systems and developing analytical protocols. However, investigating solid-fluid equilibria in mm³-sized experimental capsules poses several challenges, particularly in sulfur-bearing chemical systems. These include maintaining bulk fluid composition and performing quantitative analysis with extremely low amounts of synthesized fluid. We present an innovative methodology for measuring ultra-low amounts of sulfur volatiles (H₂S and SO₂) generated during experimental runs at high pressure and temperature conditions of 3 GPa and 700 °C. Using solid sulfides (FeS + FeS₂) and water as reactants, we performed redox-controlled syntheses employing a piston cylinder apparatus. We demonstrate that ex-situ measurements of these fluids by quadrupole mass spectrometry ensure accurate and precise analysis, confirming predicted thermodynamic compositions. This methodology allows in-depht investigation of sulfide solid-fluid equilibria, shedding light on sulfur volatiles behavior and geochemical cycles under high P-T conditions characteristic of the Earth's interior.

Psoralen-conjugated triplex-forming oligonucleotides (Ps-TFOs) have been employed for the photodynamic regulation of gene expression by the photo-cross-linking of psoralen with the target DNA. However, stable triplex formation requires a consecutive purine base sequence in one strand of the target DNA duplexes. The pyrimidine-base interruption in the consecutive purine base sequence drastically decreases the thermodynamic stability of the corresponding triplex, which hampers the TFO application. Here, we propose a design of the Ps-TFO for stable triplex formation with target DNA sequences containing pyrimidine-base interruptions under physiological conditions. This Ps-TFO, named 1'(one)-psoralen-conjugated triplex-forming oligonucleotide (OPTO), incorporates a synthesized nucleoside mimic 1'-psoralen-conjugated deoxyribose to increase the thermodynamic stability of the corresponding triplex by the intercalation of psoralen. The triplex-forming abilities of the OPTO were successfully demonstrated in combination with LNA and 5-methylcytosine, indicating that the use of OPTO will expand the range of the target sequences of TFO for photodynamic gene regulation.

Cyclic lipopeptides (CLPs) produced by the genus Bacillus are amphiphiles composed of hydrophilic amino acid and hydrophobic fatty acid moieties and are biosynthesised by non-ribosomal peptide synthetases (NRPSs). CLPs are produced as a mixture of homologues with different fatty acid moieties, whose length affects CLP activity. Iturin family lipopeptides are a family of CLPs comprising cyclic heptapeptides and β-amino fatty acids and have antimicrobial activity. There is little research on how the length of the fatty acid moiety of iturin family lipopeptides is determined. Here, we demonstrated that the acyl ligase (AL) domain determines the length of the fatty acid moiety in vivo. In addition, enzyme assays revealed how mutations in the substrate-binding pocket of the AL domain affected substrate specificity in vitro. Our findings have implications for the design of fatty acyl moieties for CLP synthesis using NRPS.

Translation of mRNA into protein is a fundamental process and tightly controlled during development. Several mechanisms acting on the mRNA level regulate when and where an mRNA is expressed. To explore the effects of conditional and transient gene expression in a developing organism, it is vital to experimentally enable abrogation and restoration of translation. We recently developed the FlashCaps technology allowing preparation of translationally muted mRNAs and their controlled activation by light. Here, we validate its functionality in vivo. We demonstrate that translation of FlashCap-eGFP-mRNA can be triggered in zebrafish embryos with spatiotemporal control. The injected FlashCap-mRNA is stable for hours and remains muted. Light-mediated activation up to 24 h post fertilization produces visible amounts of eGFP and can be restricted to distinct parts of the embryo. This methodology extends the toolbox for vertebrate models by enabling researchers to locally activate mRNA translation at different timepoints during development.

Iminophosphoranes with the general formula (R₃P═NR') have great potential in synthetic chemistry as valuable precursors/intermediates in organic synthesis or as building blocks for various organic compounds. However, the synthetic approaches and conditions to prepare iminophosphoranes are still poorly understood, limiting the utility of this chemistry for organic materials. In this article, a simple and efficient synthesis of previously unattainable poly(arylene iminophosphoranes) is reported. The azide-phosphine Staudinger polycondensation is used, and the reaction conditions are carefully studied, including consideration of light and air, the influence of solvent and temperature, and investigation of the electronic and steric effects of multiazides. The newly defined reaction conditions appear to be highly versatile, allowing the use of both electron-rich and electron-deficient arylazides for reaction with phosphines to synthesize a library of poly(arylene iminophosphorane) networks that exhibit exceptional thermal and oxidative stability. Interestingly, despite the ylidic-form of the iminophosphorane linkage as shown by theoretical calculations, these newly developed poly(arylene-iminophosphorane) networks exhibit semiconducting properties, such as absorption band edges up to 800 nm and optical band gaps in the range of 1.70 to 2.40 eV. Finally, we demonstrate the broad applicability of these polymers by processing them into glassy films, creating foam-like structures and synthesizing metallo-polymer hybrids.

The discovery of fullerene following the synthesis of graphene marked a paradigm shift in chemistry. Here, we report the discovery of biycycloborane, arising from the synthesis of borophane (hydrogen boride). Uniquely, this synthesis method involves a decomposition mechanism rather than traditional atom-by-atom assembly, marking an unique approach to constructing complex borane structures. The mass spectrometry unveiled that the stable molecule has a mass of 178 in atomic mass unit with a stoichiometry of B₁₄H₂₆. Optical spectra and simulations further evidenced its bicyclic structure, featuring fulvene-like heptagons or octagons. This borane molecule, analogous to cyclic hydrocarbons, adopts a unit configuration with a three-center two-electron (3c-2e) bonding, akin to diborane. The B₁₄H₂₆ molecule has been historically anticipated as a distant descendant of the dodecahedron borane, but it was born from the hydrogen boride sheet with a non-symmorphic symmetry. The discovery of biycycloborane expands the frontiers of boron chemistry, promising advancements in boron-based nanomaterials and beyond.

The transcription factor p53 is exquisitely sensitive and selective to a broad variety of cellular environments. Several studies have reported that oxidative stress weakens the p53-DNA binding affinity for certain promoters depending on the oxidation mechanism. Despite this body of work, the precise mechanisms by which the physiologically relevant DNA-p53 tetramer complex senses cellular stresses caused by H₂O₂ are still unknown. Here, we employed native mass spectrometry (MS) and ion mobility (IM)-MS coupled to chemical labelling and H₂O₂-induced oxidation to examine the mechanism of redox regulation of the p53-p21 complex. Our approach has found that two reactive cysteines in p53 protect against H₂O₂-induced oxidation by forming reversible sulfenates.

Deubiquitinating enzymes (DUBs) are key regulators of cellular homoeostasis, and their dysregulation is associated with several human diseases. The ovarian tumour protease (OTU) family of DUBs are biochemically well-characterised and of therapeutic interest, yet only a few tool compounds exist to study their cellular function and therapeutic potential. Here we present a chemoproteomics fragment screening platform for identifying novel DUB-specific hit matter, that combines activity-based protein profiling with high-throughput chemistry direct-to-biology optimisation to enable rapid elaboration of initial fragment hits against OTU DUBs. Applying these approaches, we identify an enantioselective covalent fragment for OTUD7B, and validate it using chemoproteomics and biochemical DUB activity assays.

Explainable Artificial Intelligence (XAI) is an emerging field in AI that aims to address the opaque nature of machine learning models. Furthermore, it has been shown that XAI can be used to extract input-output relationships, making them a useful tool in chemistry to understand structure-property relationships. However, one of the main limitations of XAI methods is that they are developed for technically oriented users. We propose the XpertAI framework that integrates XAI methods with large language models (LLMs) accessing scientific literature to generate accessible natural language explanations of raw chemical data automatically. We conducted 5 case studies to evaluate the performance of XpertAI. Our results show that XpertAI combines the strengths of LLMs and XAI tools in generating specific, scientific, and interpretable explanations.

All-solid-state (ASS) batteries are a promising solution to achieve carbon neutrality. ASS lithium-sulfur (Li-S) batteries stand out due to their improved safety, achieved by replacing organic solvents, which are prone to leakage and fire, with solid electrolytes. In addition, these batteries offer the benefits of higher capacity and the absence of rare metals. However, the low electronic conductivity of sulfur poses a major challenge for ASS Li-S batteries. To address this challenge, sulfur is often combined with porous carbon. Despite this standard practice, the local structure of sulfur in these composites remains unclear. Based on small-angle X-ray scattering and pair distribution function analysis, we discovered that sulfur in carbon-sulfur composites formed via melt diffusion is amorphous and primarily comprises S₈ ring-shaped structures. The carbon-sulfur composite demonstrated a high specific capacity of 1625 mAh g^-1 (97% of the theoretical specific capacity of sulfur). This remarkable performance is attributed to the extensive contact area between carbon and sulfur, which results in an excellent interface formed through melt diffusion. The insights gained into the local structure of sulfur and the analytical approaches employed enhanced our understanding of electrochemical reactions in ASS Li-S batteries, thereby aiding in the optimization of material design.