Tuning the Lewis Acidity of Neutral Silanes Using Perfluorinated Aryl‐ and Alkoxy Substituents

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Tuning the Lewis Acidity of Neutral Silanes Using Perfluorinated Aryl- and Alkoxy Substituents

A set of Lewis acids was synthesized by installing perfluorotolyl- and perfluorocresolato ligands on neutral Si(IV) atoms. Additionally, a heteroleptic silane was synthesized using perfluoropinacolato and perfluorophenyl substituents. The obtained silanes were fully characterized and a Lewis acidity assessment was conducted by the Gutmann-Beckett and Childs method.


Abstract

The emerging field of Lewis acidic silanes demonstrates the versability of molecular silicon compounds for catalytic applications. Nevertheless, when compared to the multifunctional boron Lewis acid B(C6F5)3, silicon derivatives still lack in terms of reactivity. In this regard, we demonstrate the installation of perfluorotolyl groups (Tol F ) on neutral silicon atoms to obtain the respective tetra- and trisubstituted silanes Si(Tol F )4 and HSi(Tol F )3. These compounds were fully characterized including SC-XRD analysis but unexpectedly showed no significant Lewis acidity. By using strongly electron-withdrawing perfluorocresolato groups (OTol F ) the tetrasubstituted silane Si(OTol F )4 was obtained, bearing an 8 % increased Δδ(31P) shift when applying the Gutmann-Beckett method, compared to literature-known Si(OPh F )4. Ultimately the heteroleptic Si(Ph F )2pin F was successfully synthesized and fully characterized including SC-XRD analysis, introducing a highly Lewis acidic silicon atom holding two silicon-carbon bonds.

Hydrogen diffusion on (100), (111), (110) and (211) gold faces

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Hydrogen diffusion on (100), (111), (110) and (211) gold faces

The surface diffusion barriers of H increase in the following Au series: (110) < (111) < (100) < (211). The presence of low-coordinated Au atoms significantly reduces the surface adsorption barrier of H. A U-shaped dependence of the surface diffusion energy of H on the centres of the s- and d-bands of the gold atoms has been revealed.


Abstract

Calculations showed that hydrogen adsorption into subsurface sites is most likely to occur on Au (110) and (211) faces. The presence of low-coordinated Au atoms on significantly reduces the barrier of subsurface adsorption of H. The barriers of H surface diffusion increase in the following Au series: (110) < (111) < (100) < (211). An analysis of the dependence of the surface diffusion barriers on the electronic structure of gold atoms on the respective faces revealed a U-shaped dependence of the centers of the s- and d-bands. This dependence is the result of the filling of the s- and d-bands on different faces of the gold. The results obtained suggest that it is possible to use band centers to determine surface diffusion barriers.

Unusual formation of Ir(III) complexes with non‐symmetrical NacNac ligands: Synthesis, characterization, and evaluation of catalytic activity in transfer hydrogenation reduction reactions

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Unusual formation of Ir(III) complexes with non-symmetrical NacNac ligands: Synthesis, characterization, and evaluation of catalytic activity in transfer hydrogenation reduction reactions

This graphical abstract describes how a new type of trans-dichloro-Ir(III) complexes derived from non-symmetrical NacNac-type ligands were unexpectedly obtained as the main reaction product from the former ligands and the dimeric species [Ir(COD)Cl2]. Finally, an evaluation was made of the catalytic activity of all complexes in the transfer hydrogenation reaction of ketones and imines.


A new type of trans-dichloro-Ir(III) complexes derived from non-symmetrical NacNac-type ligands was unexpectedly obtained as the main reaction product from the former ligands and the dimeric species [Ir(COD)Cl2]. One equivalent of LH was reacted with an excess of [Ir(COD)Cl]2 in dichloromethane or toluene as solvent and at room temperature. The general formula of the product is [IrCl2(COD)L] and was isolated as a sole product instead of the expected Ir(I) compound [Ir(COD)L]; all the new Ir(III) were prepared in high yields as microcrystalline solids. They were all stable under laboratory atmosphere, lasting for weeks in solution and for months in solid state. The structure of each compound was examined by 1D and 2D nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). Complex 1k was selected for an X-ray diffraction study. Finally, an evaluation was made of the catalytic activity of all complexes in the transfer hydrogenation reaction of ketones and imines.

Hantzsch Ester Modified Asymmetric BODIPY Probe with Ultra‐high Sensitivity for Ultra‐fast Detection of Endogenous Hypochlorite in Living Cells

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Hantzsch Ester Modified Asymmetric BODIPY Probe with Ultra-high Sensitivity for Ultra-fast Detection of Endogenous Hypochlorite in Living Cells

Two Hantzsch ester derived fluorescent probes were constructed based on asymmetric BODIPY-matrix. These probes both exhibited significant fluorescence turn-on with ultra-high sensitivity (LoD < 1 nmol/L), response to hypochlorite (ClO–) in 5 s, and displayed excellent selectivity to ClO– and favourable quantum yield. Notably, MeDHP-BCl achieved the real-time visualization of endogenous ClO– in living cells for its lower cytotoxicity and more remarkable fluorescence increment after activation.


Comprehensive Summary

Hypochlorite (ClO–) is an important reactive oxygen species produced by the immune system to fight off invading pathogens, but its over-expression can interfere with normal physiological process and induce serious diseases. Although a variety of molecular probes have been reported for detecting ClO–, the development of advanced fluorescent tools with faster response and higher sensitivity to precisely monitor ClO– remains a challenge. In this work, two Hantzsch ester (a derivative of 1,4-dihydropyridine) derived fluorescent probes MeDHP-BCl and MeDHP-PhBCl were constructed based on asymmetric BODIPY-matrix. These probes exhibit significant fluorescence turn-on in the ultra-sensitive (detection limit < 1 nmol/L) and ultra-fast response (≤ 5 s) to ClO–. The reaction has been determined to be a highly selective N-chlorination of Hantzsch ester which cannot be activated by various common bioactive species, including nitric oxide (NO) that could oxidize Hantzsch ester under aerobic physiological conditions in most reports. MeDHP-PhBCl possessed a relatively longer fluorescence emission wavelength and higher quantum yield after activation, while more notably, MeDHP-BCl displayed lower cytotoxicity and more remarkable fluorescence increment in the response to ClO–, enabling selective and precise visualization of endogenous ClO– over-expression in living RAW264.7 cells.

Electron Transport through Hydrogen Bonded Single‐Molecule Junctions

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Electron Transport through Hydrogen Bonded Single-Molecule Junctions†


Comprehensive Summary

Hydrogen bonding is a vital driving force for organizing the hierarchy of molecular structure, especially in biologic field. Due to its directionality, selectivity and moderate strength, hydrogen bonding has been extensively introduced into the molecular recognition, sensing and electronic devices. Electric measurements at single-molecule level facilitate the investigation of hydrogen bonds and provide a comprehensive understanding of the electron transport properties governed by the hydrogen bonding, which is essential for the development of self-assembled electronic systems. This review provides a detailed overview of recent advancements in constructing single-molecule junctions utilizing intramolecular and intermolecular hydrogen bonding. We first introduce the methods utilized for characterizing the electric and dynamic properties of non-covalent interactions. Next, we discuss the mechanisms of electron transport, relevant influencing factors, and typical applications utilizing electrical signals based on single-molecule junctions. Finally, we propose our perspective on the existing challenges and prospective opportunities in utilizing hydrogen bonding for electronic device applications.

Recent Progress of Inorganic Hole‐Transport Materials for Perovskite Solar Cells

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Recent Progress of Inorganic Hole-Transport Materials for Perovskite Solar Cells†


Comprehensive Summary

Perovskite solar cells (PSCs) have achieved significant progress in the past decade and a certified power conversion efficiency (PCE) of 26.0% has been achieved. The widely used organic hole transport materials (HTMs) in PSCs are typically sensitive to the moisture environment and continuous light exposure. In contrast, the inorganic HTMs benefiting from their outstanding merits, such as excellent environmental stability, are considered as alternatives and have attracted much attention in PSCs. In this review, we provide a comprehensive summary of the fundamental properties and recent progress of inorganic HTMs in n-i-p and p-i-n structured PSCs. Additionally, we emphasize the importance of inorganic HTMs in the development of highly efficient and stable PSCs.

Dual Functional Diblock Amino Acid Copolymer Displaying Synergistic Effect with Curcumin against MRSA and Encapsulation of Curcumin

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Dual Functional Diblock Amino Acid Copolymer Displaying Synergistic Effect with Curcumin against MRSA and Encapsulation of Curcumin†

Dual functional diblock copolymer PLL20-b-PBLG20 was prepared by superfast and water-insensitive polymerization initiated by tetraalkylammonium carboxylate. In addition to direct antimicrobial activity, PLL20-b-PBLG20 also exerts a synergistic bactericidal effect against MRSA with curcumin, a plant extract with antibacterial property. Moreover, PLL20-b-PBLG20 successfully encapsulates curcumin to form nanoparticles via self-assembly. The combination of dual functional PLL20-b-PBLG20 and curcumin holds promise in combating MRSA infections.


Comprehensive Summary

The intensive use of antibiotics intensifies the development of bacterial resistance, which has become a serious problem globally. Methicillin-resistant Staphylococcus aureus (MRSA) has resulted in significant morbidity and mortality. Therefore, it is an urgent need to develop new antimicrobial drugs and administration methods. Herein, we report a dual functional diblock copolymer PLL20-b-PBLG20, which was prepared by superfast and water-insensitive polymerization on N-carboxyanhydrides (NCA) initiated by tetraalkylammonium carboxylate. In addition to direct antimicrobial activity, PLL20-b-PBLG20 also exerts a synergistic bactericidal effect against MRSA with curcumin, a plant extract with antibacterial property. Moreover, PLL20-b-PBLG20 successfully encapsulates curcumin to form nanoparticles via self-assembly. The combination of dual functional PLL20-b-PBLG20 and curcumin holds promise in combating MRSA infections.

Construction of Tumor Microenvironment‐Responsive Gene Carriers

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Construction of Tumor Microenvironment-Responsive Gene Carriers

(EK)10 prevents plasma protein adsorption, and MMP-2-responsive PLGLAG exposes Tat near tumors. A leucine zipper connects (EK)10-PLGLAG-Tat to ELP, creating the environmentally responsive gene carrier (ERGV). ERGV efficiently targets tumors by modifying surface charge in MMP-2 environments, ensuring safe and effective gene delivery.


Abstract

Peptide- and polypeptide-based self-assembling gene delivery systems have received considerable attention owing to their inherent biocompatibility and bioactivity. Gene carriers based on elastin-like polypeptides (ELPs) have been extensively studied because of their controllability and unique temperature responsiveness. The (EK)10-PLGLAG-Tat polypeptide sequence was selected for tumor gene delivery, with ELP serving as the hydrophobic core. In this sequence, a hydration layer can be formed on the surface of the carrier using the zwitterionic peptide segment (EK)10, which helps prevent the nonspecific adsorption of plasma proteins. Additionally, the MMP-2 enzyme-responsive PLGLAG peptide segment is responsible for exposing the cell-penetrating peptide Tat specifically near tumor cells, facilitating the penetration of tumor cells. To introduce (EK)10-PLGLAG-Tat into the self-assembling carrier while ensuring its bioactivity, a leucine zipper ZR/ZE with opposite charges was used to link it to the ELP. Because of its high specificity and low systemic toxicity, the carrier was named environmentally responsive gene carrier (ERGV). Experimental results demonstrated that the ERGV effectively removed (EK)10 in MMP-2 overexpressed environments, altering the surface charge from negative to positive and facilitating ssDNA delivery into tumor cells. These findings highlight the potential of ERGVs as a safe and efficient method for targeted gene delivery to tumors.

Physicochemical and Nonlinear Optical Properties of a Stilbazolium Family Single Crystal with Third Order Nonlinear Optical Activity

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Physicochemical and Nonlinear Optical Properties of a Stilbazolium Family Single Crystal with Third Order Nonlinear Optical Activity

A third-order nonlinear optical 4-[2-(4-dimethylamino-phenyl)-vinyl]-1-methyl-pyridinium 2-nitroaniline-4-sulfonate (DSNA) single crystal was successfully grown for the first time by incorporating a novel counter anion in the stilbazolium cation. Characterization results suggest that the DSNA crystal can be used for optoelectronic and optical limiting applications.


Abstract

A novel counter anion group was incorporated with the organic stilbazolium cation (C16H19N2 +) to yield a new third-harmonic-generation-active single crystal of 4-[2-(4-dimethylamino-phenyl)-vinyl]-1-methyl-pyridinium 2-nitroaniline-4-sulfonate (DSNA). The slow evaporation solution growth technique is employed to obtain DSNA crystals, whose nonlinear responses are analysed through a continuous wave laser Z scan experiment. The thermally induced strong reverse saturation absorption and self-defocusing behaviour of the DSNA crystal suggests that the material could be used as an optical limiting device. Optical characterization shows that the lower absorption edge falls in the visible region (530 nm), with a broad transparency range of 0.53 to 1 μm. Exploration of other optical constants, such as extinction coefficient (k=10−4), emission wavelength (602 nm – red light), optical (σopt=1010 Ωm−1) and electrical conductivity (σelc=1011 Ωm−1) also concludes that the DSNA crystal could be potentially employed in optoelectronic devices. The various bonds and their corresponding lengths and angles involved in the formation of DSNA ionic crystal are evaluated by means of single-crystal X-ray diffraction (SCXRD). Linear and nonlinear optical property findings undoubtedly affirm that the titular DSNA crystal is an effective nonlinear optical (NLO) crystal.

The Importance of Precise Reaction Condition Control for the Comparison of Photocatalyst Materials on the Example of Hydrogen Peroxide Formation over Polymeric Carbon Nitrides

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The Importance of Precise Reaction Condition Control for the Comparison of Photocatalyst Materials on the Example of Hydrogen Peroxide Formation over Polymeric Carbon Nitrides

Our study uses the photocatalytic production of hydrogen peroxide by various polymeric carbon nitride materials to demonstrate the importance of precisely adjusting various reaction conditions in the reactor, such as light intensity, oxygen flow, and wavelength. In addition, reaction parameters were chosen to achieve extremely high hydrogen peroxide concentrations.


Abstract

In our study, we aimed to show how different reaction parameters can affect production rates using photocatalytic hydrogen peroxide formation by different polymeric carbon nitrides (PCN). For this purpose, selected materials were first compared under the same reaction conditions and compared with TiO2 (P25). We also show that different light intensities can have a different influence on seemingly similar materials. Since hydrogen peroxide production in the presence of an electron donor proceeds mainly by reduction of oxygen, we also show an influence of the oxygen flow on the formation rates. Thus, with high oxygen fluxes and high intensities of irradiated light, we were able to achieve an H2O2 concentration of 125 mM after about 25 h. Finally, the two best PCN materials were selected to measure light intensity dependence at different wavelengths up to visible light. It was found that they behaved differently at the different wavelengths and thus it could be shown that an exact specification of the reaction parameters is indispensable for comparisons in the literature.