scholarly journals Surface engineering of a Cu-based heterogeneous catalyst for efficient azide-alkyne click cycloaddition

2021 ◽  
Author(s):  
Gianvito Vilé ◽  
Jiaxu Liu ◽  
Zhenmei Zhang
Keyword(s):  
Heterogeneous Catalyst ◽  
Active Site ◽  
Surface Engineering ◽  
Building Blocks ◽  
Atomic Scale ◽  
Regioselective Synthesis

In this work, we disclose that atomic-scale engineering of the active site in copper-based catalysts can effectively tune the material performance for the regioselective synthesis of triazoles, important building blocks...

Triflate-functionalized calix[6]arenes as versatile building-blocks: application to the synthesis of an inherently chiral Zn(ii) complex

2016 ◽  
Vol 14 (6) ◽  
pp. 1950-1957 ◽  
Author(s):  
Sara Zahim ◽  
Roy Lavendomme ◽  
Olivia Reinaud ◽  
Michel Luhmer ◽  
Gwilherm Evano ◽  
...  
Keyword(s):  
Building Blocks ◽  
Regioselective Synthesis ◽  
Inherently Chiral

The regioselective synthesis of two calix[6]arenes bearing triflate groups is described. These compounds constitute versatile molecular platforms that allow the elaboration of sophisticated calixarene-based systems selectively functionalized at the large and/or at the small rim.

Atomic scale surface engineering of micro- to nano-sized pharmaceutical particles for drug delivery applications

Nanoscale ◽  
2017 ◽  
Vol 9 (32) ◽  
pp. 11410-11417 ◽  
Author(s):  
D. Zhang ◽  
M. J. Quayle ◽  
G. Petersson ◽  
J. R. van Ommen ◽  
S. Folestad
Keyword(s):  
Drug Delivery ◽  
Atomic Layer Deposition ◽  
Surface Engineering ◽  
Atomic Layer ◽  
Atomic Scale ◽  
Ambient Conditions ◽  
Surface Layers ◽  
Layer Deposition ◽  
Atomic Surface ◽  
Scale Surface

Few atomic surface layers via atomic layer deposition under near ambient conditions significantly altered dissolution and dispersion of pharmaceutical particles.

scholarly journals Dynamism and Cooperativity Essential for Efficient Catalysis in Aspergillus Niger Monoamine Oxidase

2019 ◽  
Author(s):  
Christian Curado-Carballada ◽  
Ferran Feixas ◽  
Sílvia Osuna
Keyword(s):  
Aspergillus Niger ◽  
Monoamine Oxidase ◽  
Active Site ◽  
Conformational Dynamics ◽  
Catalytic Efficiency ◽  
Building Blocks ◽  
Chiral Amine ◽  
Evolutionary Pathway ◽  
Accelerated Molecular Dynamics ◽  
Open States

<p><b> </b><i>Aspergillus niger </i>Monoamine Oxidase (MAO-N) is a homodimeric enzyme responsible for the oxidation of amines into the corresponding imine. Laboratory evolved variants of MAO-N in combination with a non-selective chemical reductant represents a powerful strategy for the deracemisation of chiral amine mixtures and, thus, is of interest for obtaining chiral amine building blocks. MAO-N presents a rich conformational dynamics with a flexible ß-hairpin region that can adopt closed, partially closed and open states. Despite the ß-hairpin conformational dynamics is altered along the laboratory evolutionary pathway of MAO-N, the connection between the ß-hairpin conformational dynamics and active site catalysis still remains unclear. In this work, we use accelerated molecular dynamics to elucidate the potential interplay between the ß-hairpin conformational dynamics and catalytic activity in MAO-N wild type and its evolved D5 variant. Our study reveals a delicate communication between both MAO-N subunits that impacts the active site architecture, and thus its catalytic efficiency. In both MAO-N WT and the laboratory evolved D5 variant, the ß-hairpin conformation in one of the monomers affects the productive binding of the substrate in the active site of the other subunit. However, both MAO-N WT and D5 variants show a quite different behaviour due to the distal mutations introduced experimentally with Directed Evolution. </p>

Atomic Scale Determination of Enzyme Flexibility and Active Site Stability through Static Modes: Case of Dihydrofolate Reductase

2011 ◽  
Vol 115 (7) ◽  
pp. 1616-1622 ◽  
Author(s):  
Marie Brut ◽  
Alain Estève ◽  
Georges Landa ◽  
Guillaume Renvez ◽  
Mehdi Djafari Rouhani ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Active Site ◽  
Atomic Scale

scholarly journals Apertureless scanning near-field optical microscopy of sparsely labeled tobacco mosaic viruses and the intermediate filament desmin

2013 ◽  
Vol 4 ◽  
pp. 510-516 ◽  
Author(s):  
Alexander Harder ◽  
Mareike Dieding ◽  
Volker Walhorn ◽  
Sven Degenhard ◽  
Andreas Brodehl ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Fluorescence Imaging ◽  
Intermediate Filament ◽  
Dipolar Coupling ◽  
Incident Light ◽  
Near Field ◽  
Building Blocks ◽  
Atomic Scale ◽  
Intermediate Filament Protein ◽  
Wide Range

Both fluorescence imaging and atomic force microscopy (AFM) are highly versatile and extensively used in applications ranging from nanotechnology to life sciences. In fluorescence microscopy luminescent dyes serve as position markers. Moreover, they can be used as active reporters of their local vicinity. The dipolar coupling of the tip with the incident light and the fluorophore give rise to a local field and fluorescence enhancement. AFM topographic imaging allows for resolutions down to the atomic scale. It can be operated in vacuum, under ambient conditions and in liquids. This makes it ideal for the investigation of a wide range of different samples. Furthermore an illuminated AFM cantilever tip apex exposes strongly confined non-propagating electromagnetic fields that can serve as a coupling agent for single dye molecules. Thus, combining both techniques by means of apertureless scanning near-field optical microscopy (aSNOM) enables concurrent high resolution topography and fluorescence imaging. Commonly, among the various (apertureless) SNOM approaches metallic or metallized probes are used. Here, we report on our custom-built aSNOM setup, which uses commercially available monolithic silicon AFM cantilevers. The field enhancement confined to the tip apex facilitates an optical resolution down to 20 nm. Furthermore, the use of standard mass-produced AFM cantilevers spares elaborate probe production or modification processes. We investigated tobacco mosaic viruses and the intermediate filament protein desmin. Both are mixed complexes of building blocks, which are fluorescently labeled to a low degree. The simultaneous recording of topography and fluorescence data allows for the exact localization of distinct building blocks within the superordinate structures.

Processing Complex and Uniform Nanoparticles for Microelectronic and Photonic Applications

2001 ◽  
Vol 704 ◽  
Author(s):  
Nobuyuki Kambe
Keyword(s):  
Refractive Index ◽  
Chemical Reaction ◽  
Surface Engineering ◽  
Building Blocks ◽  
Size Distributions ◽  
Direct Deposition ◽  
Device Structures ◽  
Inorganic Nanocomposites ◽  
Planar Lightwave ◽  
Reaction Processes

AbstractTwo major challenges that exist in order to utilize nanoparticles as building blocks for microelectronic and photonic applications are presented. The first challenge is how to make uniform nanoparticles in industrial-scale. The second challenge is how to convert these nano-building blocks to application forms such as device structures or coatings. In this paper, materials and processing guidelines to provide the solutions for these challenges are described on the basis of (a) laser-driven chemical reaction processes to generate a versatile range of nanoparticles having extremely narrow size distributions, and (b) unique organic-inorganic nanocomposites using surface engineering over nanoparticles. As promising applications, direct deposition of nanoparticles and nanocomposites are discussed in conjunction with planar lightwave devices, photonic nanocomposites for the refractive index engineering, and planarization processes for electronic chips.

Visions of Atomic-Scale Tomography

2012 ◽  
Vol 20 (3) ◽  
pp. 12-16 ◽  
Author(s):  
Thomas F. Kelly ◽  
Michael K. Miller ◽  
Krishna Rajan ◽  
Simon P. Ringer
Keyword(s):  
High Precision ◽  
Building Block ◽  
Building Blocks ◽  
Atomic Scale ◽  
Human Knowledge ◽  
Length Scales ◽  
Analytical Information

A microscope, by definition, provides structural and analytical information about objects that are too small to see with the unaided eye. From the very first microscope, efforts to improve its capabilities and push them to ever-finer length scales have been pursued. In this context, it would seem that the concept of an ultimate microscope would have received much attention by now; but has it really ever been defined? Human knowledge extends to structures on a scale much finer than atoms, so it might seem that a proton-scale microscope or a quark-scale microscope would be the ultimate. However, we argue that an atomic-scale microscope is the ultimate for the following reason: the smallest building block for either synthetic structures or natural structures is the atom. Indeed, humans and nature both engineer structures with atoms, not quarks. So far as we know, all building blocks (atoms) of a given type are identical; it is the assembly of the building blocks that makes a useful structure (see Figure 1). Thus, would a microscope that determines the position and identity of every atom in a structure with high precision and for large volumes be the ultimate microscope? We argue, yes. In this article, we consider how it could be built, and we ponder the answer to the equally important follow-on questions: who would care if it is built, and what could be achieved with it?

scholarly journals Practical and Regioselective Synthesis of C4-Alkylated Pyridines

2021 ◽  
Author(s):  
jin choi ◽  
Gabriele Laudadio ◽  
Edouard Godineau ◽  
Phil Baran
Keyword(s):  
Carboxylic Acid ◽  
Late Stage ◽  
Building Blocks ◽  
Regioselective Synthesis ◽  
Heterocyclic Chemistry ◽  
Blocking Group ◽  
Functionalized Materials

The direct position-selective C–4 alkylation of pyridines has been a longstanding challenge in heterocyclic chemistry, particularly from pyridine itself. Historically this has been addressed using pre-functionalized materials to avoid overalkylation and mixtures of regioisomers. This study reports the invention of a simple maleate-derived blocking group for pyridines that enables exquisite control for Minisci-type decarboxylative alkylation at C–4 that allows for inexpensive access to these valuable building blocks. The method is employed on a variety of different pyridines and carboxylic acid alkyl donors, is operationally simple, scalable, and is applied to access known structures in a rapid and inexpensive fashion. Finally, this work points to an interesting strategic departure for the use of Minisci chemistry at the earliest possible stage (native pyridine) rather than current dogma that almost exclusively employs Minisci as a late-stage functionalization technique.

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