scholarly journals Accelerated synthesis of energetic precursor cage compounds using confined volume systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hilary M. Brown ◽  
Karan R. Doppalapudi ◽  
Patrick W. Fedick
Keyword(s):  
Solution Phase ◽  
Rapid Screening ◽  
Bulk Solution ◽  
Cage Structure ◽  
Reaction Conditions ◽  
Cage Compounds ◽  
Cage Compound ◽  
Reaction Acceleration ◽  
Energetic Compound ◽  
Reducing Costs

AbstractConfined volume systems, such as microdroplets, Leidenfrost droplets, or thin films, can accelerate chemical reactions. Acceleration occurs due to the evaporation of solvent, the increase in reactant concentration, and the higher surface-to-volume ratios amongst other phenomena. Performing reactions in confined volume systems derived from mass spectrometry ionization sources or Leidenfrost droplets allows for reaction conditions to be changed quickly for rapid screening in a time efficient and cost-saving manner. Compared to solution phase reactions, confined volume systems also reduce waste by screening reaction conditions in smaller volumes prior to scaling. Herein, the condensation of glyoxal with benzylamine (BA) to form hexabenzylhexaazaisowurtzitane (HBIW), an intermediate to the highly desired energetic compound 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), was explored. Five confined volume systems were compared to evaluate which technique was ideal for forming this complex cage structure. Substituted amines were also explored as BA replacements to screen alternative cage structure intermediates and evaluate how these accelerated techniques could apply to novel reactions, discover alternative reagents to form the cage compound, and improve synthetic routes for the preparation of CL-20. Ultimately, reaction acceleration is ideal for predicting the success of novel reactions prior to scaling up and determining if the expected products form, all while saving time and reducing costs. Acceleration factors and conversion ratios for each reaction were assessed by comparing the amount of product formed to the traditional bulk solution phase synthesis.

scholarly journals Chemie polyfunktioneller Liganden, 60 [1]. Über Käfigverbindungen mit den Heteroelementen Arsen und Selen / Chemistry of Polyfunctional Ligands, 60 [1]. On Cage Compounds with the Heteroelements Arsenic and Selenium

1980 ◽  
Vol 35 (12) ◽  
pp. 1514-1517 ◽  
Author(s):  
Jochen Eilermann ◽  
Martin Lietz
Keyword(s):  
Molar Ratio ◽  
Cage Compounds ◽  
Cage Compound

Abstract The reaction of 1,1,1-tris(diiodoarsinomethyl)ethane, CH3C(CH2Asl2)3 (1) with NaAs(C6H5)2 in the molar ratio of 1:3 gives 4-methyl-1,2,6-triarsa-tricyclo[2,2,1,02,6]-heptane, CH3C(CH2As)3 (2). The previously synthesized CH3C(CH2AsS)3 (4) can be desulphurated with triphenylphosphine to yield also 2. The reaction of 1 with NaSeH gives the new cage compound 6-methyl-1,3,4-triarsa-2,8-diselena-tricyclo[3,3,1,03 ,4]-nonane, CH3C(CH2As)3Se2 (5).

Development of Boron Cage Compound Nanocomposite Elastomers

2009 ◽  
Vol 1239 ◽  
Author(s):  
Eric Allen Eastwood ◽  
Daniel Edward Bowen ◽  
Mark W. Lee
Keyword(s):  
Vinyl Acetate ◽  
Physical Property ◽  
Ethyl Acrylate ◽  
Thermomechanical Properties ◽  
Advanced Materials ◽  
Cage Compounds ◽  
Cage Compound ◽  
Wide Range ◽  
High Boron ◽  
Poly Ethylene

AbstractA wide variety of nanofillers of varying compositions have been used to create polymer nanocomposites, including tubes, wires, fibers, sheets, and particles. A new class of compounds has been identified for use as nanofillers, boron cage compounds. Boron cage compounds are discrete, icosahedral closed cage molecules of high boron content and examples include carboranes and dodecaborate salts. Several chemically modified boron cage compounds have been incorporated into polyolefin elastomers, such as poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), poly(ethylene-co-ethyl acrylate), and poly(ethylene-co-octene), among others. The resulting thermal and thermomechanical properties were evaluated in order to determine when plasticization and reinforcement occur to better understand the chemical structure/physical property relationships. Materials with a wide range of properties were produced, however under certain conditions, advanced materials were created with high boron contents, improved thermal stability, mechanical strength, and significant reinforcement.

scholarly journals Non-centrosymmetric superconductor Th$$_4$$Be$$_{{33}}$$Pt$$_{{16}}$$ and heavy-fermion U$$_4$$Be$$_{{33}}$$Pt$$_{{16}}$$ cage compounds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Koželj ◽  
M. Juckel ◽  
A. Amon ◽  
Yu. Prots ◽  
A. Ormeci ◽  
...  
Keyword(s):  
Specific Heat ◽  
Electronic Band Structure ◽  
Upper Critical Field ◽  
Cage Compounds ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Cage Compound ◽  
Type Ii Superconductor ◽  
Structure Calculations ◽  
Specific Heat Coefficient

AbstractUnconventional superconductivity in non-centrosymmetric superconductors has attracted a considerable amount of attention. While several lanthanide-based materials have been reported previously, the number of actinide-based systems remains small. In this work, we present the discovery of a novel cubic complex non-centrosymmetric superconductor $${\text {Th}}_4{\text {Be}}_{{33}}{\text {Pt}}_{{16}}$$ Th 4 Be 33 Pt 16 ($$I{\bar{4}}3d$$ I 4 ¯ 3 d space group). This intermetallic cage compound displays superconductivity below $$T_{\text {c}} = 0.90 \pm 0.04$$ T c = 0.90 ± 0.04  K, as evidenced by specific heat and resistivity data. $${\text {Th}}_4{\text {Be}}_{{33}}{\text {Pt}}_{{16}}$$ Th 4 Be 33 Pt 16 is a type-II superconductor, which has an upper critical field $${\text {H}}_{{\text {c}}2} = 0.27$$ H c 2 = 0.27  T and a moderate Sommerfeld coefficient $$\gamma _{\text {n}} = 16.3 \pm 0.8$$ γ n = 16.3 ± 0.8  mJ $${\text {mol}}^{-1}_{\text {Th}}$$ mol Th - 1  $${\text {K}}^{-2}$$ K - 2 . A non-zero density of states at the Fermi level is evident from metallic behavior in the normal state, as well as from electronic band structure calculations. The isostructural $${\text {U}}_4{\text {Be}}_{{33}}{\text {Pt}}_{{16}}$$ U 4 Be 33 Pt 16 compound is a paramagnet with a moderately enhanced electronic mass, as indicated by the electronic specific heat coefficient $$\gamma _{\text {n}} = 200$$ γ n = 200  mJ $${\text {mol}}^{-1}_{\text {U}}$$ mol U - 1  $${\text {K}}^{-2}$$ K - 2 and Kadowaki–Woods ratio $$A/\gamma ^2 = 1.1 \times 10^{-5}$$ A / γ 2 = 1.1 × 10 - 5  $$\upmu $$ μ  $$\Omega $$ Ω  cm $${\text {K}}^2$$ K 2 $${\text {mol}}_{\text {U}}^2$$ mol U 2  (mJ)$$^{-2}$$ - 2 . Both $${\text {Th}}_4{\text {Be}}_{{33}}{\text {Pt}}_{{16}}$$ Th 4 Be 33 Pt 16 and $${\text {U}}_4{\text {Be}}_{{33}}{\text {Pt}}_{{16}}$$ U 4 Be 33 Pt 16 are crystallographically complex, each hosting 212 atoms per unit cell.

scholarly journals Restricted intramolecular rotation of fluorescent molecular rotors at the periphery of aqueous microdroplets in oil

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jooyoun Kang ◽  
SangMoon Lhee ◽  
Jae Kyoo Lee ◽  
Richard N. Zare ◽  
Hong Gil Nam
Keyword(s):  
Fluorescence Intensity ◽  
Solution Viscosity ◽  
Bulk Solution ◽  
Molecular Rotor ◽  
Reaction Conditions ◽  
Dominant Mechanism ◽  
Alexa Fluor ◽  
Fluorescent Molecular Rotors ◽  
Phase Chemistry ◽  
Intramolecular Rotation

Abstract Fluorescent molecular rotor dyes, including Cy3, Cy5, and Alexa Fluor 555, dissolved in micron-sized aqueous droplets (microdroplets) in oil were excited, and the fluorescence intensity was recorded as function of time. We observed lengthening of the fluorescence lifetime of these dyes at the water–oil periphery, which extended several microns inward. This behavior shows that intramolecular rotation is restricted at and near the microdroplet interface. Lengthened lifetimes were observed in water microdroplets but not in microdroplets composed of organic solvents. This lifetime change was relatively insensitive to added glycerol up to 60%, suggesting that solution viscosity is not the dominant mechanism. These restricted intramolecular rotations at and near the microdroplet periphery are consistent with the reduced entropy observed in chemical reactions in microdroplets compared to the same reaction conditions in bulk solution and helps us further understand why microdroplet chemistry differs so markedly from bulk-phase chemistry.

scholarly journals Solution-Phase Fmoc-Based Peptide Synthesis for DNA-Encoded Chemical Libraries: Reaction Conditions, Protecting Group Strategies, and Pitfalls

2020 ◽  
Vol 22 (12) ◽  
pp. 833-843
Author(s):  
Olivier B. C. Monty ◽  
Nicholas Simmons ◽  
Srinivas Chamakuri ◽  
Martin M. Matzuk ◽  
Damian W. Young
Keyword(s):  
Peptide Synthesis ◽  
Solution Phase ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Chemical Libraries

scholarly journals Natural Charge-Transfer Analysis: Eliminating Spurious Charge-Transfer States in Time-Dependent Density Functional Theory via Diabatization, with Application to Projection-Based Embedding

2021 ◽  
Author(s):  
Kevin Carter-Fenk ◽  
Christopher J. Mundy ◽  
John Herbert
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Density Functional ◽  
Solution Phase ◽  
Time Dependent ◽  
Bulk Solution ◽  
Excitation Energies ◽  
Functional Theory ◽  
Natural Charge ◽  
Dependent Density

<p>For many types of vertical excitation energies, linear-response time-dependent density functional theory (LR-TDDFT) offers a useful degree of accuracy combined with unrivaled computational efficiency, although charge-transfer excitation energies are often systematically and dramatically underestimated, especially for large systems and those that contain explicit solvent. As a result, low-energy electronic spectra of solution-phase chromophores often contain tens to hundreds of spurious charge-transfer states, making LR-TDDFT needlessly expensive in bulk solution. Intensity borrowing by these spurious states can affect intensities of the valence excitations, altering electronic bandshapes. At higher excitation energies, it is difficult to distinguish spurious charge-transfer states from genuine charge-transfer-to-solvent (CTTS) excitations. In this work, we introduce an automated diabatization that enables fast and effective screening of the CTTS acceptor space in bulk solution. Our procedure introduces ``natural charge-transfer orbitals'' that provide a means to isolate orbitals that are most likely to participate in a CTTS excitation. Projection of these orbitals onto solvent-centered virtual orbitals provides a criterion for defining the most important solvent molecules in a given excitation and be used as an automated subspace selection algorithm for projection-based embedding of a high-level description of the CTTS state in a lower-level description of its environment. We apply this method to an <i>ab initio</i> molecular dynamics trajectory of I<sup>-</sup>(aq) and report the lowest-energy CTTS band in the absorption spectrum. Our results are in excellent agreement with experiment and only one-third of the water molecules in the I<sup>-</sup>(H<sub>2</sub>O)<sub>96</sub> simulation cell need to be described with LR-TDDFT in order to obtain excitation energies that are converged to <0.1 eV. The tools introduced herein will improve the accuracy, efficiency, and usability of LR-TDDFT in solution-phase environments.</p>

scholarly journals Natural Charge-Transfer Analysis: Eliminating Spurious Charge-Transfer States in Time-Dependent Density Functional Theory via Diabatization, with Application to Projection-Based Embedding

2021 ◽  
Author(s):  
Kevin Carter-Fenk ◽  
Christopher J. Mundy ◽  
John Herbert
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Density Functional ◽  
Solution Phase ◽  
Time Dependent ◽  
Bulk Solution ◽  
Excitation Energies ◽  
Functional Theory ◽  
Natural Charge ◽  
Dependent Density

<p>For many types of vertical excitation energies, linear-response time-dependent density functional theory (LR-TDDFT) offers a useful degree of accuracy combined with unrivaled computational efficiency, although charge-transfer excitation energies are often systematically and dramatically underestimated, especially for large systems and those that contain explicit solvent. As a result, low-energy electronic spectra of solution-phase chromophores often contain tens to hundreds of spurious charge-transfer states, making LR-TDDFT needlessly expensive in bulk solution. Intensity borrowing by these spurious states can affect intensities of the valence excitations, altering electronic bandshapes. At higher excitation energies, it is difficult to distinguish spurious charge-transfer states from genuine charge-transfer-to-solvent (CTTS) excitations. In this work, we introduce an automated diabatization that enables fast and effective screening of the CTTS acceptor space in bulk solution. Our procedure introduces ``natural charge-transfer orbitals'' that provide a means to isolate orbitals that are most likely to participate in a CTTS excitation. Projection of these orbitals onto solvent-centered virtual orbitals provides a criterion for defining the most important solvent molecules in a given excitation and be used as an automated subspace selection algorithm for projection-based embedding of a high-level description of the CTTS state in a lower-level description of its environment. We apply this method to an <i>ab initio</i> molecular dynamics trajectory of I<sup>-</sup>(aq) and report the lowest-energy CTTS band in the absorption spectrum. Our results are in excellent agreement with experiment and only one-third of the water molecules in the I<sup>-</sup>(H<sub>2</sub>O)<sub>96</sub> simulation cell need to be described with LR-TDDFT in order to obtain excitation energies that are converged to <0.1 eV. The tools introduced herein will improve the accuracy, efficiency, and usability of LR-TDDFT in solution-phase environments.</p>

scholarly journals Serotype-Specific Identification of Polioviruses by PCR Using Primers Containing Mixed-Base or Deoxyinosine Residues at Positions of Codon Degeneracy

1998 ◽  
Vol 36 (2) ◽  
pp. 352-357 ◽  
Author(s):  
David R. Kilpatrick ◽  
Baldev Nottay ◽  
Chen-Fu Yang ◽  
Su-Ju Yang ◽  
Edson Da Silva ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
High Rate ◽  
Rapid Screening ◽  
Reaction Conditions ◽  
Specific Primers ◽  
Specific Identification ◽  
Primer Sets ◽  
Reference Strains ◽  
Codon Degeneracy

We have developed a method for determining the serotypes of poliovirus isolates by PCR. Three sets of serotype-specific antisense PCR-initiating primers (primers seroPV1A, seroPV2A, and seroPV3A) were designed to pair with codons of VP1 amino acid sequences that are conserved within but that differ across serotypes. The sense polarity primers (primers seroPV1S, seroPV2S, and seroPV3S) matched codons of more conserved capsid sequences. The primers contain mixed-base and deoxyinosine residues to compensate for the high rate of degeneracy of the targeted codons. The serotypes of all polioviruses tested (48 vaccine-related isolates and 110 diverse wild isolates) were correctly identified by PCR with the serotype-specific primers. None of the genomic sequences of 49 nonpolio enterovirus reference strains were amplified under equivalent reaction conditions with any of the three primer sets. These primers are useful for the rapid screening of poliovirus isolates and for determining the compositions of cultures containing mixtures of poliovirus serotypes.

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