A new bernissartiid crocodyliform from the Lower Cretaceous Wessex Formation (Wealden Group, Barremian) of the Isle of Wight, southern England

Concentration-dependent Ac4GalNAz incorporation (24 h incubation). (DOCX 322 kb

Простір публічних комунікацій сучасних релігійних організацій

Porous aluminum oxide (PAO) is a nanoporous material used for various (bio)­technological applications, and tailoring its surface properties via covalent modification is a way to expand and refine its application. Specific and complex chemical modification of the PAO surface requires a stepwise approach in which a secondary reaction on a stable initial modification is necessary to achieve the desired terminal molecular architecture and reactivity. We here show that the straightforward initial modification of the bare PAO surface with bromo-terminated phosphonic acid allows for the subsequent preparation of PAO with a wide scope of terminal reactive groups, making it suitable for (bio)­functionalization. Starting from the initial bromo-terminated PAO, we prepared PAO surfaces presenting various terminal functional groups, such as azide, alkyne, alkene, thiol, isothiocyanate, and <i>N</i>-hydroxysuccinimide (NHS). We also show that this wide scope of easily accessible tailored reactive PAO surfaces can be used for subsequent modification with (bio)­molecules, including carbohydrate derivatives and fluorescently labeled proteins

Photochemical Grafting and Patterning of Organic Monolayers on Indium Tin Oxide Substrates

Covalently attached organic layers on indium tin oxide (ITO) surfaces were prepared by the photochemical grafting with 1-alkenes. The surface modification was monitored with static water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. Hydrophobic methyl-terminated ITO surfaces can be obtained via the grafting of tetradec-1-ene, whereas the attachment of ω-functionalized 1-alkenes leads to functionalized ITO surfaces. The use of a CCGe­(CH₃)₃ terminus allows for facile tagging of the surface with an azido group via a one-pot deprotection/click reaction, resulting in bio/electronically active interfaces. The combination of nonaggressive chemicals (alkenes), mild reaction conditions (room temperature), and a light-induced grafting that facilitates the direct patterning of organic layers makes this simple approach highly promising for the development of ITO-based (bio)­electronic devices

Sulfur-Phenolate Exchange as a Mild, Fast, and High-Yielding Method toward the Synthesis of Sulfonamides

Sulfonamides have many important biological applications, yet their synthesis often involves long reaction times under dry and non-ambient conditions. Here we report the synthesis of a large range of sulfonamides at room temperature using 4-nitrophenyl benzylsulfonate as a starting material. Sulfonamides were prepared from a wide range of aliphatic, linear, and cyclic amines, anilines, and N-methylanilines. The yields and reaction times observed here were comparable to or better than those reported previously, establishing sulfur-phenolate exchange as a viable alternative

Simulation of XPS C1s Spectra of Organic Monolayers by Quantum Chemical Methods

Several simple methods are presented and evaluated to simulate the X-ray photoelectron spectra (XPS) of organic monolayers and polymeric layers by density functional theory (DFT) and second-order Møller–Plesset theory (MP2) in combination with a series of basis sets. The simulated carbon (C1s) XPS spectra as obtained via B3LYP/6-311G­(d,p) or M11/6-311G­(d,p) calculations are in good agreement (average mean error <0.3 eV) with the experimental spectra, and good estimates of C1s spectra can be obtained via <i>E</i>_C1s(exp) = 0.9698<i>E</i>_C1s(theory) + 20.34 (in eV) (B3LYP/6-311G­(d,p)). As a result, the simulated C1s XPS spectra can elucidate the binding energies of the different carbon species within an organic layer and, in this way, greatly aid the assignment of complicated C1s XPS spectra. The paper gives a wide range of examples, including haloalkanes, esters, (thio-)­ethers, leaving groups, clickable functionalities, and bioactive moieties

Structure and Long-Term Stability of Alkylphosphonic Acid Monolayers on SS316L Stainless Steel

Surface modification of stainless steel (SS316L) to improve surface properties or durability is an important avenue of research, as SS316L is widely used in industry and science. We studied, therefore, the formation and stability of a series of organic monolayers on SS316L under industrially relevant conditions. These included acidic (pH 3), basic (pH 11), neutral (Milli-Q water), and physiological conditions [10 mM phosphate-buffered saline (PBS)], as well as dry heating (120 °C). SS316L was modified with alkylphosphonic acids of chain length (CH₂)_<i>n</i> with <i>n</i> varying between 3 and 18. While alkylphosphonic acids of all chain lengths formed self-assembled monolayers with hydrophobic properties, only monolayers of chain lengths 12–18 formed ordered monolayers, as evidenced by static water contact angle (SCA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and infrared reflection absorption spectroscopy (IRRAS). A long-term stability study revealed the excellent stability of monolayers with chain lengths 12–18 for up to 30 days in acid, neutral, and physiological solutions, and for up to 7 days under dry heating. Under strong basic conditions a partial breakdown of the monolayer was observed, especially for the shorter chain lengths. Finally, the effect of multivalent surface attachment on monolayer stability was explored by means of a series of divalent bisphosphonic acids

Clickable Polylactic Acids by Fast Organocatalytic Ring-Opening Polymerization in Continuous Flow

The use of microreactor technology for the ring-opening polymerization of l-lactide catalyzed by 1,5,7-triaza­bicyclo[4.4.0]­dec-5-ene allows for rapid optimization of reaction parameters (reaction temperature and residence time). At moderate catalyst loading, good control over the polymerization is demonstrated by high conversion of monomer (>95%) and low polydispersity (<1.3) at residence times as low as 2 s. This metal-free, organocatalytic route yields well-defined poly­(lactic acid) in continuous flow and by using bicyclononyne- and tetrazine-containing initiators gives access to poly­(lactic acid) amenable to click chemistry

Generic Top-Functionalization of Patterned Antifouling Zwitterionic Polymers on Indium Tin Oxide

This paper presents a novel surface engineering approach that combines photochemical grafting and surface-initiated atom transfer radical polymerization (SI-ATRP) to attach zwitterionic polymer brushes onto indium tin oxide (ITO) substrates. The photochemically grafted hydroxyl-terminated organic layer serves as an excellent platform for initiator attachment, and the zwitterionic polymer generated via subsequent SI-ATRP exhibits very good antifouling properties. Patterned polymer coatings can be obtained when the surface with covalently attached initiator was subjected to photomasked UV-irradiation, in which the C–Br bond that is present in the initiator was broken upon exposure to UV light. A further, highly versatile top-functionalization of the zwitterionic polymer brush was achieved by a strain-promoted alkyne–azide cycloaddition, without compromising its antifouling property. The attached bioligand (here: biotin) enables the specific immobilization of target proteins in a spatially confined fashion, pointing to future applications of this approach in the design of micropatterned sensing platforms on ITO substrates

Toward the Rational Design of More Efficient Mo₂C Catalysts for Hydrodeoxygenation–Mechanism and Descriptor Identification

Viable alternatives to scarce and expensive noble-metal-based catalysts are transition-metal carbides such as Mo and W carbides. It has been shown that these are active and selective catalysts in the hydrodeoxygenation of renewable lipid-based feedstocks. However, the reaction mechanism and the structure–activity relationship of these transition-metal carbides have not yet been fully clarified. In this work, the reaction mechanism of butyric acid hydrodeoxygenation (HDO) over molybdenum carbide (Mo2C) has been studied comprehensively by means of density functional theory coupled with microkinetic modeling. We identified the rate-determining step to be butanol dissociation: C4H9*OH + * → C4H9* + *OH. Then we further explored the possibility to facilitate this step upon heteroatom doping and found that Zr- and Nb-doped Mo2C are the most promising catalysts with enhanced HDO catalytic activity. Linear-scaling relationships were established between the electronic and geometrical descriptors of the dopants and the catalytic performance of various doped Mo2C catalysts. It was demonstrated that descriptors such as dopants’ d-band filling and atomic radius play key roles in governing the catalytic activity. This fundamental understanding delivers practical strategies for the rational design of Mo2C-based transition-metal carbide catalysts with improved HDO performance

High-Density Modification of H‑Terminated Si(111) Surfaces Using Short-Chain Alkynes

H–Si­(111)-terminated surfaces were alkenylated via two routes: through a novel one-step gas-phase hydrosilylation reaction with short alkynes (C₃ to C₆) and for comparison via a two-step chlorination and Grignard alkenylation process. All modified surfaces were characterized by static water contact angles and X-ray photoelectron spectroscopy (XPS). Propenyl- and butenyl-coated Si(111) surfaces display a significantly higher packing density than conventional C₁₀–C₁₈ alkyne-derived monolayers, showing the potential of this approach. In addition, propyne chemisorption proceeds via either of two approaches: the standard hydrosilylation at the terminal carbon (<i>lin</i>) at temperatures above 90 °C and an unprecedented reaction at the second carbon (<i>iso</i>) at temperatures below 90 °C. Molecular modeling revealed that the packing energy of a monolayer bonded at the second carbon is significantly more favorable, which drives <i>iso</i>-attachment, with a dense packing of surface-bound <i>iso</i>-propenyl chains at 40% surface coverage, in line with the experiments at <90 °C. The highest density monolayers are obtained at 130 °C and show a linear attachment of 1-propenyl chains with 92% surface coverage