scholarly journals Record-high stability and compactness of multiply-charged clusters aided by selected terminal groups

2020 ◽  
Vol 22 (9) ◽  
pp. 4880-4883 ◽  
Author(s):  
Ming Min Zhong ◽  
Hong Fang ◽  
Puru Jena
Keyword(s):  
Gas Phase ◽  
High Stability ◽  
Building Blocks ◽  
Bulk Materials ◽  
Multiply Charged ◽  
Charged Clusters ◽  
Potential Applications ◽  
Weakly Coordinating

Multiply-charged clusters with compact sizes that are stable in the gas phase are important due to their potential applications as weakly-coordinating ions and building blocks of bulk materials.

scholarly journals Super-electrophiles of Tri- and Tetra-Anions Stabilized by Selected Terminal Groups and Their Role in Binding Noble Gas atoms

2021 ◽  
Author(s):  
MingMin Zhong ◽  
Hong Fang ◽  
Deepika Deepika ◽  
Purusottam Jena
Keyword(s):  
Gas Phase ◽  
Noble Gas ◽  
Atomic Clusters ◽  
Weakly Coordinating Anions ◽  
Multiply Charged ◽  
Potential Applications ◽  
Weakly Coordinating

Stabilization of multiply-charged atomic clusters in the gas phase has been a topic of great interest not only because of their potential applications as weakly-coordinating anions, but also for their...

scholarly journals A Structurally Variable Hinged Tetrahedron Framework from DNA Origami

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
David M. Smith ◽  
Verena Schüller ◽  
Carsten Forthmann ◽  
Robert Schreiber ◽  
Philip Tinnefeld ◽  
...  
Keyword(s):  
Self Assembly ◽  
Gel Electrophoresis ◽  
Imaging Techniques ◽  
Building Blocks ◽  
Dna Origami ◽  
Microscopy Technique ◽  
Wire Frame ◽  
Wide Range ◽  
Potential Applications ◽  
Linker Molecules

Nanometer-sized polyhedral wire-frame objects hold a wide range of potential applications both as structural scaffolds as well as a basis for synthetic nanocontainers. The utilization of DNA as basic building blocks for such structures allows the exploitation of bottom-up self-assembly in order to achieve molecular programmability through the pairing of complementary bases. In this work, we report on a hollow but rigid tetrahedron framework of 75 nm strut length constructed with the DNA origami method. Flexible hinges at each of their four joints provide a means for structural variability of the object. Through the opening of gaps along the struts, four variants can be created as confirmed by both gel electrophoresis and direct imaging techniques. The intrinsic site addressability provided by this technique allows the unique targeted attachment of dye and/or linker molecules at any point on the structure's surface, which we prove through the superresolution fluorescence microscopy technique DNA PAINT.

scholarly journals Insights into the deactivation of 5-bromouracil after ultraviolet excitation

2017 ◽  
Vol 375 (2092) ◽  
pp. 20160202 ◽  
Author(s):  
Francesca Peccati ◽  
Sebastian Mai ◽  
Leticia González
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Surface Hopping ◽  
Ultraviolet Excitation ◽  
Quantum Chemistry Calculations ◽  
Electronic Structure Methods ◽  
Dna Strands ◽  
Potential Applications ◽  
Adiabatic Dynamics ◽  
Dynamics Simulations

5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after ultraviolet irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and non-adiabatic dynamics simulations. It is found that, after irradiation to the bright ππ * state, three main relaxation pathways are, in principle, possible: relaxation back to the ground state, intersystem crossing (ISC) and C–Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground-state relaxation should be the predominant deactivation pathway in the gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS (multi-reference configuration interaction including single excitations) was used in surface hopping simulations to compute the ultrafast ISC dynamics, which mostly involves the 1 n O π * and 3 ππ * states. This article is part of the themed issue ‘Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces’.

Laser electrodispersion as a new chlorine-free method for the production of highly effective metal-containing supported catalysts

2012 ◽  
Vol 84 (3) ◽  
pp. 495-508 ◽  
Author(s):  
Ekaterina S. Lokteva ◽  
Anton A. Peristyy ◽  
Natalia E. Kavalerskaya ◽  
Elena V. Golubina ◽  
Lada V. Yashina ◽  
...  
Keyword(s):  
Gas Phase ◽  
High Stability ◽  
Heterogeneous Catalysts ◽  
Supported Catalysts ◽  
Promising Technique ◽  
Wet Impregnation ◽  
Oxide Supports ◽  
Highly Active ◽  
Specific Catalytic Activity ◽  
Free Metal

Laser electrodispersion (LED) of metals is a promising technique for the preparation of heterogeneous catalysts as an alternative to wet impregnation of supports with the corresponding salt solutions. The LED technique can be used to deposit highly active chloride- and nitrate-free metal nanoparticles onto carbon or oxide supports. We report preparation and properties of new Ni-, Pd-, and Au-containing alumina-supported catalysts with low metal loadings (10–3–10–4 % mass) and their comparison with the previously studied carbon (Sibunit) supported systems. The catalysts demonstrate high stability and extremely high specific catalytic activity (by 2–3 orders of magnitude higher than for traditional catalysts) in the gas-phase hydrodechlorination (HDC) of chlorobenzene (CB).

Highly regioselective surface acetylation of cellulose and shaped cellulose constructs in the gas-phase

2021 ◽  
Author(s):  
Tetyana Koso ◽  
Marco Beaumont ◽  
Blaise Tardy ◽  
Daniel Rico del Cerro ◽  
Samuel Eyley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Liquid Crystalline ◽  
Computational Modelling ◽  
Building Blocks ◽  
Cellulosic Materials ◽  
Gas Phase Chemistry ◽  
Liquid Crystalline Phases ◽  
Phase Chemistry ◽  
Cholesteric Liquid Crystalline ◽  
Surface Acetylation

Gas-phase acylation of cellulose is an attractive method for modifying the surface properties of cellulosics. However, little is known concerning the regioselectivity of the chemistry, in terms of which cellulose positions are preferentially acylated and if acylation can be restricted to the surface, preserving crystallinities/morphologies. Consequently, we reexplore simple gas-phase acetylation of modern-day cellulosic building blocks – cellulose nanocrystals, pulps, regenerated fibre and aerogels. The gas-phase acetylation is shown to be highly regioselective for the C6-OH, is further supported with computational modelling. This contrasts with liquid-state acetylation, highlighting that the gas-phase chemistry is much more controllable, yet with similar kinetics to the uncatalyzed liquid-phase reactions. Furthermore, this method preserves both the native crystalline structure of cellulose and the supramolecular morphologies of even delicate cellulosic constructs (aerogel exhibiting retention of chiral cholesteric liquid crystalline phases). Therefore, we are convinced that this methodology will lead to more rapid adoption of precisely tailored and cellulosic materials

Substantially Transparent Pt, Pd, Rh, And Re Films: Preparation and Properties

1987 ◽  
Vol 111 ◽  
Author(s):  
D. E. Aspnes ◽  
A. Heller
Keyword(s):  
Light Transmission ◽  
Building Blocks ◽  
Poor Quality ◽  
Model Calculations ◽  
Transmission Electron ◽  
Metal Volume ◽  
Potential Applications ◽  
Metallic Catalyst ◽  
Anomalous Transparency ◽  
Best Fit

AbstractFilms of Pt, Pd, Rh, and Re with metal volume fractions of 0.3 to 0.5 have been prepared by mass-transport-limited photoelectrodeposition onto (001) p-InP photocathodes from ∼5 × 10−5 M solutions of the metal ions in 1 M HClO4. These films exhibit their normal catalytic activities (e.g., in hydrogen evolution) and have normal crystal structures, yet are substantially more transparent than equivalent dense films of the same metal loading per unit area. Effective-medium analysis of the spectroellipsometrically measured dielectric functions of these films shows that the anomalous transparency is due to microstructure: depolarization factors and metal packing fractions obtained by best-fit model calculations indicate dendritic (Rh), particulate (Pt, Pd), or platelet (Re) forms that are poorly interconnected in directions parallel to the surface, and whose dimensions are all small compared to the wavelength of light. Transmission electron micrographs confirm these results and reveal that these films consist of primary building blocks of ca. 5 nm crystallites that are organized into relatively loosely packed secondary structures. Potential applications of these films include the formation of efficient metallic-catalyst-coated photoelectrodes on poor-quality semiconductors.

scholarly journals Cyclic cis-1,3-Diamines Derived from Bicyclic Hydrazines: Synthesis and Applications

Synlett ◽  
2020 ◽  
Author(s):  
Erica Benedetti ◽  
Laurent Micouin ◽  
Claire Fleurisson
Keyword(s):  
Bond Cleavage ◽  
Building Blocks ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Chemical Similarity ◽  
Active Compounds ◽  
General Overview ◽  
Biological Interest ◽  
Potential Applications ◽  
Rna Binders

AbstractCyclic cis-1,3-diamines are versatile building blocks frequently found in natural molecules or biologically active compounds. In comparison with widely studied 1,2-diamines, and despite their chemical similarity, 1,3-diamines have been investigated less intensively probably because of a lack of general synthetic procedures giving access to these compounds with good levels of chemo-, regio-, and stereocontrol. In this Account we will give a general overview of the biological interest of cyclic cis-1,3-diamines. We will then describe the synthesis and potential applications of these compounds with a particular focus on the work realized in our laboratory.1 Introduction2 Biological Relevance of the cis-1,3-Diamine Motif3 Classical Synthetic Strategies towards cis-1,3-Diamines4 N–N Bond Cleavage of Bicyclic Hydrazines: A Versatile Method to Access cis-1,3-Diamines4.1 Preparation of Five-Membered Cyclic cis-1,3-Diamino Alcohols4.2 Access to Fluorinated 1,3-cis-Diaminocyclopentanes4.3 Synthesis of cis-1,3-Diaminocyclohexitols4.4 Formation of Cyclic cis-3,5-Diaminopiperidines5 Applications of Cyclic cis-1,3-Diamines5.1 Small-Molecular RNA Binders5.2 Fluorinated 1,3-Diamino Cyclopentanes as NMR Probes6 Concluding Remarks

scholarly journals Recent Progress in the Synthesis and Characterization of Diarylethene-based MOFs

2014 ◽  
Vol 70 (a1) ◽  
pp. C1223-C1223
Author(s):  
Jason Benedict ◽  
Ian Walton ◽  
Dan Patel ◽  
Jordan Cox
Keyword(s):  
Chemical Properties ◽  
Building Blocks ◽  
Synthesis And Characterization ◽  
Next Generation ◽  
Design Synthesis ◽  
Thermally Induced ◽  
Potential Applications ◽  
External Stimuli ◽  
Physical And Chemical

Metal-organic Frameworks (MOFs) remain an extremely active area of research given the wide variety of potential applications and the enormous diversity of structures that can be created from their constituent building blocks. While MOFs are typically employed as passive materials, next-generation materials will exhibit structural and/or electronic changes in response to applied external stimuli including light, charge, and pH. Herein we present recent results in which advanced photochromic diarylethenes are combined with MOFs through covalent and non-covalent methods to create photo-responsive permanently porous crystalline materials. This presentation will describe the design, synthesis, and characterization of next-generation photo-switchable diarylethene based ligands which are subsequently used to photo-responsive MOFs. These UBMOF crystals are, by design, isostructural with previously reported non-photoresponsive frameworks which enables a systematic comparison of their physical and chemical properties. While the photoswitching of the isolated ligand in solution is fully reversible, the cycloreversion reaction is suppressed in the UBMOF single crystalline phase. Spectroscopic evidence for thermally induced cycloreversion will be presented, as well as a detailed analysis addressing the limits of X-ray diffraction techniques applied to these systems.

Tetracarboxyl-Functionalized Ionic Liquid: Synthesis and Catalytic Properties

2015 ◽  
Vol 68 (10) ◽  
pp. 1513 ◽  
Author(s):  
Miaona Feng ◽  
Guoying Zhao ◽  
Hongling Gao ◽  
Suojiang Zhang
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Ionic Liquids ◽  
Propionic Acid ◽  
Propylene Carbonate ◽  
Propylene Oxide ◽  
High Stability ◽  
Ammonium Acetate ◽  
Catalytic Properties ◽  
Potential Applications

Novel tetracarboxyl-functionalized 2,2′-biimidazolium-based ionic liquids (ILs) with different anions were synthesized in two steps from readily available and sustainable starting materials including ammonium acetate, glyoxal, and halogenated propionic acid. The functionalized IL exhibited higher catalytic activity towards the cycloaddition of CO2 to terminal epoxides. With propylene oxide as a substrate, the optimum yield of propylene carbonate reached 82.7 % at an initial CO2 pressure of 2.0 MPa for 4 h at 140°C. Moreover, the functionalized IL catalyst displayed a high stability and can be reused for at least five cycles without obvious loss of catalytic activity. The results provide a simple and economical way to synthesize multi-functionalized imidazolium-based ILs with versatile potential applications.

Sign in / Sign up

Export Citation Format

Share Document