Polymeric precipitation inhibitor differently affects cocrystal surface and bulk solution phase transformations

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.

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

10.26434/chemrxiv.14485368.v1 ◽

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

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 ab initio molecular dynamics trajectory of I-(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-(H2O)96 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.

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

10.26434/chemrxiv.14485368 ◽

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

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 ab initio molecular dynamics trajectory of I-(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-(H2O)96 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.

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Severe Plastic Deformation and Phase Transformations in High Entropy Alloys: A Review

Crystals ◽

10.3390/cryst12010054 ◽

2021 ◽

Vol 12 (1) ◽

pp. 54

Author(s):

Boris B. Straumal ◽

Roman Kulagin ◽

Brigitte Baretzky ◽

Natalia Yu. Anisimova ◽

Mikhail V. Kiselevskiy ◽

...

Keyword(s):

Solid Solution ◽

Plastic Deformation ◽

Severe Plastic Deformation ◽

Phase Transformations ◽

Single Phase ◽

Materials Science ◽

Bulk Solution ◽

Second Phase ◽

High Entropy Alloys ◽

High Entropy

This review discusses an area of expertise that is at the intersection of three large parts of materials science. These are phase transformations, severe plastic deformation (SPD), and high-entropy alloys (HEA). First, SPD makes it possible to determine the borders of single-phase regions of existence of a multicomponent solid solution in HEAs. An important feature of SPD is that using these technologies, it is possible to obtain second-phase nanoparticles included in a matrix with a grain size of several tens of nanometers. Such materials have a very high specific density of internal boundaries. These boundaries serve as pathways for accelerated diffusion. As a result of the annealing of HEAs subjected to SPD, it is possible to accurately determine the border temperature of a single-phase solid solution area on the multicomponent phase diagram of the HEA. Secondly, SPD itself induces phase transformations in HEAs. Among these transformations is the decomposition of a single-phase solid solution with the formation of nanoparticles of the second phase, the formation of high-pressure phases, amorphization, as well as spinodal decomposition. Thirdly, during SPD, a large number of new grain boundaries (GBs) are formed due to the crystallites refinement. Segregation layers exist at these new GBs. The concentration of the components in GBs differs from that in the bulk solid solution. As a result of the formation of a large number of new GBs, atoms leave the bulk solution and form segregation layers. Thus, the composition of the solid solution in the volume also changes. All these processes make it possible to purposefully influence the composition, structure and useful properties of HEAs, especially for medical applications.

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The mechanism of porosity formation during solvent-mediated phase transformations

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2010.0469 ◽

2010 ◽

Vol 467 (2129) ◽

pp. 1408-1426 ◽

Cited By ~ 24

Author(s):

Christophe Raufaste ◽

Bjørn Jamtveit ◽

Timm John ◽

Paul Meakin ◽

Dag Kristian Dysthe

Keyword(s):

Solid Solution ◽

Pore Structure ◽

Phase Transformations ◽

Solid Phase ◽

Ex Situ ◽

Bulk Solution ◽

Product Phase ◽

Long Time ◽

Transformation Mechanisms

Solvent-mediated solid–solid phase transformations often result in the formation of a porous medium, which may be stable on long time scales or undergo ripening and consolidation. We have studied replacement processes in the KBr–KCl–H 2 O system using both in situ and ex situ experiments. The replacement of a KBr crystal by a K(Br,Cl) solid solution in the presence of an aqueous solution is facilitated by the generation of a surprisingly stable, highly anisotropic and connected pore structure that pervades the product phase. This pore structure ensures efficient solute transport from the bulk solution to the reacting KBr and K(Br,Cl) surfaces. The compositional profile of the K(Br,Cl) solid solution exhibits striking discontinuities across disc-like cavities in the product phase. Similar transformation mechanisms are probably important in controlling phase-transformation processes and rates in a variety of natural and man-made systems.

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Solid- and Solution Phase Transformations in Novel Hybrid Iodoplumbate Derivatives Templated by Solvated Yttrium Complexes

Inorganic Chemistry ◽

10.1021/ic8010376 ◽

2008 ◽

Vol 47 (20) ◽

pp. 9333-9343 ◽

Cited By ~ 43

Author(s):

Shashank Mishra ◽

Erwann Jeanneau ◽

Stéphane Daniele ◽

Gilles Ledoux ◽

Prakash N. Swamy

Keyword(s):

Phase Transformations ◽

Solution Phase ◽

Yttrium Complexes

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Excited-State Dynamics of an Environment-Sensitive Push–Pull Diketopyrrolopyrrole: Major Differences between the Bulk Solution Phase and the Dodecane/Water Interface

The Journal of Physical Chemistry B ◽

10.1021/jp506062j ◽

2014 ◽

Vol 118 (33) ◽

pp. 9952-9963 ◽

Cited By ~ 30

Author(s):

Sabine Richert ◽

Sandra Mosquera Vazquez ◽

Marek Grzybowski ◽

Daniel T. Gryko ◽

Alexander Kyrychenko ◽

...

Keyword(s):

Excited State ◽

Solution Phase ◽

Bulk Solution ◽

Water Interface ◽

Excited State Dynamics

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Transition alpha structure in beta-isomorphous Nb-Hf alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126068 ◽

1987 ◽

Vol 45 ◽

pp. 232-233

Author(s):

R.W. Carpenter ◽

Changhai Li ◽

David J. Smith

Keyword(s):

Solid Solution ◽

Solution Phase ◽

Miscibility Gap ◽

Large Strains ◽

Solid Solution Phase ◽

Two Phase ◽

Diffuse Intensity ◽

Metastable Form ◽

The Matrix ◽

Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

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The use of high-resolution FESEM to study solid-state phase transformations and reactions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172875 ◽

1994 ◽

Vol 52 ◽

pp. 1028-1029

Author(s):

P. G. Kotula ◽

D. D. Erickson ◽

C. B. Carter

Keyword(s):

Solid State ◽

High Resolution ◽

Phase Transformations ◽

High Efficiency ◽

Sol Gel ◽

Quantitative Information ◽

Solid State Reactions ◽

Critical Dimensions ◽

Backscattered Electrons ◽

Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

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