π-Electron magnetic compounds on surfaces have emerged as a powerful platform to interrogate spin interactions at the atomic scale, with great potential in spintronics and quantum technologies. A key challenge is organizing these compounds over large length scales, while elucidating their resulting magnetic properties. Herein, we offer a relevant contribution toward this objective, which consists of using on-surface synthesis coupled with coordination chemistry to promote the self-assembly of π-electron magnetic porphyrin species. A porphyrin precursor equipped with carbonitrile moieties in a trans arrangement was prepared by solution synthesis and deposited on Au(111)/mica. Depending on the specific growth protocol, surface-promoted reactions led to the transformation of the precursor into non-magnetic Au-CN coordinated porphyrin monomers, covalent porphyrin dimers, and one-dimensional porphyrin polymers (based on porphyrin monomers or covalent porphyrin dimers), as revealed by scanning probe microscopy studies combined with theoretical calculations. Interestingly, the scanning tunneling microscopy tip could convert such closed-shell porphyrin units into open-shell species by the removal of some peripheral hydrogen atoms. The magnetic features (i.e., singlet or triplet ground state) of the porphyrin units comprising the polymers were investigated for polymers of different lengths. No magnetic exchange coupling between adjacent units was observed, suggesting protection of the magnetic entities.
- Klíčová slova
- STM, coordination chemistry, porphyrinoids, π-electron magnetism,
- Publikační typ
- časopisecké články MeSH
Artificial anion transporters offer a potential way to treat deficiencies in cellular anion transport of genetic origins. In contrast to the large variety of mobile anion carriers and self-assembled anion channels reported, unimolecular anion channels are less investigated. Herein, we present a unique example of a unimolecular anion channel based on a bambusuril (BU) macrocycle, a well-established anion receptor. The BU structure was expanded by appending various bile acid residues allowing a single molecule to span the membrane. Chloride transport mediated by BUs through lipid bilayers was investigated in liposomes and these studies revealed a surprisingly high dependence of the anion transport activity on the cholesterol content in the liposomal membrane.
- Klíčová slova
- Anion Channels, Anion transport, Bambusurils, Macrocycles, Supramolecular Chemistry,
- MeSH
- anionty * chemie MeSH
- cholesterol * chemie metabolismus MeSH
- iontový transport MeSH
- lipidové dvojvrstvy chemie metabolismus MeSH
- liposomy chemie metabolismus MeSH
- molekulární struktura MeSH
- žlučové kyseliny a soli * chemie metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- anionty * MeSH
- cholesterol * MeSH
- lipidové dvojvrstvy MeSH
- liposomy MeSH
- žlučové kyseliny a soli * MeSH
Nitrenes are known as key intermediates in various chemical reactions. Nitrene transfer reactions are particularly effective for synthesizing nitrogen-containing compounds, where metal catalysts play a crucial role in controlling nitrene reactivity and selectivity. In this study, we demonstrate the formation of a stable surface-supported dinitrene on Au(111) through UV irradiation of its diazide precursor, characterized by scanning probe techniques. The photoreaction mechanism is elucidated with wavelength-dependent experiments and time-dependent density functional theory calculations. Our findings present the first real-space visualization of a metal nitrene adsorbed on a surface, highlighting its potential in catalysis and surface functionalization.
- Klíčová slova
- Scanning Probe Microscopy, azide, metal surface, nitrene, photochemistry,
- Publikační typ
- časopisecké články MeSH
Triangulene and its homologues are promising building blocks for high-spin low-dimensional networks with long-range magnetic order. Despite the recent progress in the synthesis and characterization of coupled triangulenes, key parameters such as the number of organic linking units or their dihedral angles remain scarce, making further studies crucial for an essential understanding of their implications. Here, we investigate the synthesis and reactivity of two triangulene dimers linked by two (Dimer 1) or one (Dimer 2) para-biphenyl units, respectively, on a metal surface in an ultra-high vacuum environment. First-principles calculations and model Hamiltonians reveal how spin excitation and radical character depend on the rotation of the para-biphenyl units. Comprehensive scanning tunneling microscopy (STM) in combination with density functional theory (DFT) calculations confirm the successful formation of Dimer 1 on Au(111). Non-contact atomic force microscopy (nc-AFM) measurements resolve the twisted conformation of the linking para-biphenyl units for Dimer 1. On the contrary, the inherent flexibility of Dimer 2 induces the planarization of the para-biphenyl, resulting in the spontaneous formation of two additional five-membered rings per dimer connected by a single C-C bond (Dimers 2'). Furthermore, scanning tunneling spectroscopy (STS) measurements confirm the antiferromagnetic (S=0) coupling of the observed dimers, underscoring the critical influence of dihedral angles and structural flexibility of the linking units in π-electron magnetic nanostructures.
- Klíčová slova
- open-shell character, scanning tunneling microscopy, surface chemistry, triangulenes, π-electron magnetism,
- Publikační typ
- časopisecké články MeSH
Altering the reactivity model of a molecule can potentially eliminate limitations existing in its current paradigm. When it comes to the activation of Donor-Acceptor Cyclopropanes (DACs), Lewis acids have been the state-of-the-art. Although a variety of polarized 2π components have been successfully coupled with DACs for [3+2] cycloaddition, unpolarized alkenes prove to be a roadblock due to an inherent polarity mismatch with the Lewis acid-mediated 1,3-zwitterionic intermediate. Hereby, harnessing the distonic radical cation mode of cleavage by photoredox catalysis overcomes this mismatched reactivity of the zwitterionic intermediate, providing a unique route to highly substituted cyclopentanes and cyclopentenes. Expansion of this strategy to bicyclo[1.1.0]butanes enables access to bicyclo[3.1.1]heptanes (BCHs) through a facile [3σ+2σ] cycloaddition. Detailed mechanistic insights are also provided using dispersion-corrected density functional theory.
- Klíčová slova
- bicyclic structures, cycloaddition, cyclopentanes, photochemistry, radicals,
- Publikační typ
- časopisecké články MeSH
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by memory loss and behavioral and psychological symptoms of dementia (BPSD). Given that cholinergic neurons are predominantly affected in AD, current treatments primarily aim to enhance cholinergic neurotransmission. However, imbalances in other neurotransmitters, such as γ-aminobutyric acid (GABA), also contribute to AD symptomatology. In the presented research, using a combination of crystallography and computational methods we developed compound 6 as a dual modulator of GABAergic and cholinergic neurotransmission systems. Compound 6 demonstrated inhibition of BuChE (IC50=0.21 μM) and GABA transporter 1 (IC50=10.96 μM) and 3 (IC50=7.76 μM), along with a favorable drug-likeness profile. Subsequent in vivo studies revealed the effectiveness of 6 in enhancing memory retention and alleviating anxiety and depression symptoms in animal models, while also proving safe and bioavailable for oral administration. The innovative multi-target-directed ligand 6 offers a new approach to treating cognitive deficits and BPSD in AD.
- Klíčová slova
- Alzheimer's disease, GABA transporters, butyrylcholinesterase, inhibitors, multitarget drugs,
- MeSH
- Alzheimerova nemoc * farmakoterapie metabolismus MeSH
- cholinesterasové inhibitory chemie farmakologie terapeutické užití metabolismus MeSH
- fluoreny * chemie farmakologie terapeutické užití MeSH
- GABA * metabolismus chemie MeSH
- lidé MeSH
- molekulární struktura MeSH
- myši MeSH
- nervový přenos * účinky léků MeSH
- proteiny přenášející GABA přes plazmatickou membránu metabolismus chemie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cholinesterasové inhibitory MeSH
- fluorene MeSH Prohlížeč
- fluoreny * MeSH
- GABA * MeSH
- proteiny přenášející GABA přes plazmatickou membránu MeSH
The use of metal single atoms (SAs) as co-catalysts on semiconductors has emerged as a promising technology to enhance their photocatalytic hydrogen production performance. In this study, we describe the deposition of very low amounts of Pt SAs (<0.1 at %) on exfoliated graphitic carbon nitride (C3N4) by a direct Pt-deposition approach from highly dilute chloroplatinic acid precursors. We find that - using this technique-a remarkably low loading of highly dispersed Pt SAs (0.03 wt %) on C3N4 is sufficient to achieve a drastic decrease in the overall charge transfer resistance and a maximized photocatalytic efficiency. The resulting low-loaded Pt SAs/C3N4 provides a H2 production rate of 1.66 m mol/h/mg Pt, with a remarkable stability against agglomeration; even during prolonged photocatalytic reactions no sign of light-induced Pt agglomerations can be observed. We ascribe the high performance and stability to the site-selective, stable coordination of Pt within the C3N4 structure. Notably the H2 production rate of the low-loaded Pt SAs surpasses the activity of Pt SAs deposited by other techniques or nanoparticles at comparable or even higher loading - the optimized Pt SAs decorated C3N4 show ≈5.9 times higher rate than Pt NP decorated C3N4.
- Klíčová slova
- C3N4, H2 evolution, Pt single atoms, dark deposition, photocatalysis,
- Publikační typ
- časopisecké články MeSH
Wade's rules are a well-established tool for the description of the geometry of inorganic clusters. Among others, they state that a decrease or increase in charge is always accompanied by a change in the number of skeletal electron pairs (SEPs). This work reports the synthesis of the first cationic chalcogenaboranes closo-[12-X-2-IPr-1-EB11H10]BF4 (IPr=1,3-(2,6-iPr2C6H3)-imidazole-2-ylidene; X=H, I; E=S, Se 3 a/b, 4 a/b) featuring the same SEP count as their neutral precursors, EB11H11, but bearing a positive charge. This ionisation significantly enhances the activity towards the electrophiles. It unlocks reactivity with very weak bases and offers the control of the regioselectivity towards hard/soft bases by the modulation of LUMO. The localisation of the positive charge within the borane cluster has been confirmed experimentally, spectroscopically and theoretically.
- Klíčová slova
- Wade's rules, boranes, carbenes, cations,
- Publikační typ
- časopisecké články MeSH
This study presents the first successful demonstration of growing elemental bismuth (Bi) thin films via thermal atomic layer deposition (ALD) using Bi(NMe2)3 as the precursor and Sb(SiMe3)3 as the co-reactant. The films were deposited at a relatively low temperature of 100 °C, with a growth per cycle (GPC) of 0.31-0.34 Å/cycle. Island formation marked the initial growth stages, with surface coverage reaching around 80 % after 1000 cycles and full coverage between 2000 and 2500 cycles. Morphological analysis revealed that the Bi grains expanded and became more defined as the number of ALD cycles increased. This coalescence is further supported by X-ray diffraction (XRD) patterns, which show a preferential shift in growth orientation from the (012) plane to the (003) plane as the film thickness increases. X-ray photoemission spectroscopy (XPS) confirmed the presence of metallic Bi with minimal surface oxidation. Temperature-dependent sheet resistance measurements highlight the semimetallic nature of Bi, with a room temperature resistivity of ≈200 μΩcm for the 2500 cycles Bi. Temperature-dependent sheet resistance was also associated with a transition in carrier-type dominance from holes at higher temperatures to electrones at lower temperatures.
- Klíčová slova
- Atomic Layer Deposition, Hall resistance, Preferential growth, Surface Chemistry,
- Publikační typ
- časopisecké články MeSH
Bioorthogonal reactions that enable switching molecular functions by breaking chemical bonds have gained prominence, with the tetrazine-mediated cleavage of trans-cyclooctene caged compounds (click-to-release) being particularly noteworthy for its high versatility, biocompatibility, and fast reaction rates. Despite several recent advances, the development of highly reactive tetrazines enabling quantitative elimination from trans-cyclooctene linkers remains challenging. In this study, we present the synthesis and application of sulfo-tetrazines, a class of derivatives featuring phenolic hydroxyl groups with increased acidity constants (pKa). This unique property leads to accelerated elimination and complete release of the caged molecules within minutes. Moreover, the inclusion of sulfonate groups provides a valuable synthetic handle, enabling further derivatization into sulfonamides, modified with diverse substituents. Significantly, we demonstrate the utility of sulfo-tetrazines in efficiently activating fluorogenic compounds and prodrugs in living cells, offering exciting prospects for their application in bioorthogonal chemistry.
- Klíčová slova
- bioorthogonal chemistry, cleavage reactions, click chemistry, click-to-release, tetrazines,
- MeSH
- fluorescenční barviva chemie MeSH
- lidé MeSH
- molekulární struktura MeSH
- prekurzory léčiv chemie chemická syntéza MeSH
- syntetická chemie okamžité shody * MeSH
- tetrazoly chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fluorescenční barviva MeSH
- prekurzory léčiv MeSH
- tetrazoly MeSH
