Cocrystal Engineering of Pharmaceutical Solids: Therapeutic Potentials and Challenges

CrystEngComm ◽  
2021 ◽  
Author(s):  
Si Nga Wong ◽  
Yu Chee Sonia Chen ◽  
Bianfei Xuan ◽  
Changquan Calvin Sun ◽  
Shing Fung Chow
Keyword(s):  
Crystal Lattice ◽  
Pharmaceutical Solids ◽  
Covalent Bonds ◽  
Crystalline Materials

Cocrystals are an emerging class of crystalline materials composed of two or more different molecules in the same crystal lattice that are physically connected by non-ionic and non-covalent bonds. Formulating...

Seeded Growth of Single-Crystal Two-Dimensional Covalent Organic Frameworks

2017 ◽  
Author(s):  
Austin M. Evans ◽  
Lucas R. Parent ◽  
Nathan C. Flanders ◽  
Ryan P. Bisbey ◽  
Edon Vitaku ◽  
...  
Keyword(s):  
Molecular Transport ◽  
Controlled Synthesis ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Seeded Growth ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Step Procedure ◽  
Structures And Properties ◽  
2D Polymer

<div> <div> <div> <p>Polymerizing monomers into periodic two-dimensional (2D) networks provides structurally precise, atomically thin macromolecular sheets linked by robust, covalent bonds. These materials exhibit desirable mechanical, optoelectrotronic, and molecular transport properties derived from their designed structure and permanent porosity. 2D covalent organic frameworks (COFs) offer broad monomer scope, but are generally isolated as polycrystalline, insoluble powders with limited processability. Here we overcome this limitation by controlling 2D COF formation using a two- step procedure. In the first step, 2D COF nanoparticle seeds are prepared with approximate diameters of 30 nm. Next, monomers are slowly added to suppress new nucleation while promoting epitaxial growth on the existing seeds to sizes of several microns. The resulting COF nanoparticles are of exceptional and unprecedented quality, isolated as single crystalline materials with micron-scale domain sizes. These findings advance the controlled synthesis of 2D layered COFs and will enable a broad exploration of synthetic 2D polymer structures and properties. </p> </div> </div> </div>

Seeded Growth of Single-Crystal Two-Dimensional Covalent Organic Frameworks

2017 ◽  
Author(s):  
Austin M. Evans ◽  
Lucas R. Parent ◽  
Nathan C. Flanders ◽  
Ryan P. Bisbey ◽  
Edon Vitaku ◽  
...  
Keyword(s):  
Molecular Transport ◽  
Controlled Synthesis ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Seeded Growth ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Step Procedure ◽  
Structures And Properties ◽  
2D Polymer

<div> <div> <div> <p>Polymerizing monomers into periodic two-dimensional (2D) networks provides structurally precise, atomically thin macromolecular sheets linked by robust, covalent bonds. These materials exhibit desirable mechanical, optoelectrotronic, and molecular transport properties derived from their designed structure and permanent porosity. 2D covalent organic frameworks (COFs) offer broad monomer scope, but are generally isolated as polycrystalline, insoluble powders with limited processability. Here we overcome this limitation by controlling 2D COF formation using a two- step procedure. In the first step, 2D COF nanoparticle seeds are prepared with approximate diameters of 30 nm. Next, monomers are slowly added to suppress new nucleation while promoting epitaxial growth on the existing seeds to sizes of several microns. The resulting COF nanoparticles are of exceptional and unprecedented quality, isolated as single crystalline materials with micron-scale domain sizes. These findings advance the controlled synthesis of 2D layered COFs and will enable a broad exploration of synthetic 2D polymer structures and properties. </p> </div> </div> </div>

scholarly journals Vibrational Spectroscopy for Cocrystals Screening. A Comparative Study

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3263 ◽  
Author(s):  
Marisa Rodrigues ◽  
João Lopes ◽  
Mafalda Sarraguça
Keyword(s):  
Vibrational Spectroscopy ◽  
Near Infrared ◽  
Screening Method ◽  
Growing Up ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Drug Products ◽  
Infrared And Raman Spectroscopy ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

A recurrent problem faced by the pharmaceutical industry when formulating drug products concerns poorly soluble drugs, which, despite having desirable pharmacological activity, present limited bioavailability. Cocrystallization is growing up as a possible approach to tackle this problem. Cocrystals are crystalline materials comprising at least two components, solid at room temperature, and held together by non-covalent bonds. The increasing interest in these compounds is steadily demanding faster, simpler, and more reliable methods for the task of screening new cocrystals. This work aims at comparing the performance of three vibrational spectroscopy techniques (mid infrared, near infrared, and Raman spectroscopy) for cocrystals screening. Presented results are based on hydrochlorothiazide, a poorly soluble drug belonging to class IV of the Biopharmaceutical Classification System. The implemented cocrystal screening procedure tested six coformers (all considered safe for human administration) added according to a drug:coformer ratio of 1:1 and 1:2 and seven solvents with different polarity. The screening method chosen was based on slurry cocrystallization performed by sonication (ultrasound assisted) in a 96-well plate. Results show that all evaluated vibrational spectroscopy techniques provided important information regarding cocrystal formation, including information on the groups involved in the cocrystallization and purity, and can be used for the screening task.

Seeded Growth of Single-Crystal Two-Dimensional Covalent Organic Frameworks

2017 ◽  
Author(s):  
Austin M. Evans ◽  
Lucas R. Parent ◽  
Nathan C. Flanders ◽  
Ryan P. Bisbey ◽  
Edon Vitaku ◽  
...  
Keyword(s):  
Molecular Transport ◽  
Controlled Synthesis ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Seeded Growth ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Step Procedure ◽  
Structures And Properties ◽  
2D Polymer

<div> <div> <div> <p>Polymerizing monomers into periodic two-dimensional (2D) networks provides structurally precise, atomically thin macromolecular sheets linked by robust, covalent bonds. These materials exhibit desirable mechanical, optoelectrotronic, and molecular transport properties derived from their designed structure and permanent porosity. 2D covalent organic frameworks (COFs) offer broad monomer scope, but are generally isolated as polycrystalline, insoluble powders with limited processability. Here we overcome this limitation by controlling 2D COF formation using a two- step procedure. In the first step, 2D COF nanoparticle seeds are prepared with approximate diameters of 30 nm. Next, monomers are slowly added to suppress new nucleation while promoting epitaxial growth on the existing seeds to sizes of several microns. The resulting COF nanoparticles are of exceptional and unprecedented quality, isolated as single crystalline materials with micron-scale domain sizes. These findings advance the controlled synthesis of 2D layered COFs and will enable a broad exploration of synthetic 2D polymer structures and properties. </p> </div> </div> </div>

Liquids and Solids

2021 ◽  
pp. 152-176
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Crystal Structure ◽  
Crystal Lattice ◽  
Vapour Pressure ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Covalent Bonds ◽  
Chemical Structures ◽  
Structures And Properties ◽  
Ratio Rule ◽  
Unit Cell Dimensions

Liquids and Solids introduce basic physical properties of liquids and solids. An overview of the liquid state is presented, with reference to polar covalent bonds and dipole moment. The effects of temperature on the vapour pressure of a liquid are described, including the Clausius-Clapeyron equation, which can be used to calculate the vapour pressure of a liquid at various temperatures. The chapter reviews the types of solids including their chemical structures and properties. The crystal lattice system and the unit cell relationships for the seven types of crystal lattice structures and the four substructures are examined. Guidelines for determining the number of atoms in a unit cell, including calculations involving unit cell dimensions, are explained. The ionic crystal structure, radius ratio rule for the ionic compounds and determination of crystal structure by X-ray diffraction and Bragg’s equation are covered.

scholarly journals Amorphous Pharmaceutical Solids.

2004 ◽  
Vol 4 (3) ◽  
pp. 35-39 ◽  
Author(s):  
Edina Vranić
Keyword(s):  
Amorphous Materials ◽  
Pharmaceutical Research ◽  
Structural Disorder ◽  
Thermal Fluctuations ◽  
Amorphous Solids ◽  
Dosage Forms ◽  
Current Interest ◽  
Pharmaceutical Solids ◽  
Pharmaceutical Dosage Forms ◽  
Crystalline Materials

Amorphous forms are, by definition, non-crystalline materials which possess no long-range order. Their structure can be thought of as being similar to that of a frozen liquid with the thermal fluctuations present in a liquid frozen out, leaving only “static” structural disorder. The amorphous solids have always been an essential part of pharmaceutical research, but the current interest has been raised by two developments: a growing attention to pharmaceutical solids in general, especially polymorphs and solvates and a revived interest in the science of glasses and the glass transition.Amorphous substances may be formed both intentionally and unintentionally during normal pharmaceutical manufactoring operations. The properties of amorphous materials can be exploited to improve the performance of pharmaceutical dosage forms, but these properties can also give rise to unwanted effects that need to be understood and managed in order for the systems to perform as required.

A Facile Synthesis of HKUST-1 MOF through Reductive Electrosynthesis Method

2021 ◽  
Vol 874 ◽  
pp. 3-12
Author(s):  
Siti Unvaresi M. Beladona ◽  
Achmad Rochliadi ◽  
Aep Patah
Keyword(s):  
Room Temperature ◽  
Electrochemical Sensing ◽  
Synthetic Method ◽  
High Porosity ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Open Metal Sites ◽  
Metal Organic ◽  
Conductive Substrates ◽  
Tunable Structure

Metal-organic frameworks (MOFs) are porous crystalline materials that consist of metal ions bind to organic ligands as linkers by coordination covalent bonds. MOF properties, such as the presence of open metal sites, large surface area, high porosity, high thermal stability, tunable structure, and feasibility in modification are controlled and determined by metal cations, organic linkers, and applied synthetic method. Reductive electrosynthesis is a popular and interesting MOF synthetic method on the surface of conductive substrates. This method is based on electroreduction of oxoanions to generate hydroxide anions that lead to selective deposition of MOFs on conductive surfaces to form a thin MOFs film. The applied potentials during electrosynthesis affect the properties and applications of the produced MOFs. Here, Cu-based MOFs with the type of CuBTC (H3BTC: 1,3,5-benzenetricarboxylic acid) known as HKUST-1 films were synthesized using different cathodic potentials and time, at room temperature, on the surface of brass. The reductive electrosynthesis was found to be fast and mild for preparing HKUST-1. This method allows direct surface modification which in turn affect the HKUST-1 applications as electrode material for electrochemical sensing such as glucose.

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Resolution, Contrast and Interpretation of HVEM Images of Crystals

1973 ◽  
Vol 31 ◽  
pp. 228-229
Author(s):  
L. E. Thomas ◽  
J. S. Lally ◽  
R. M. Fisher
Keyword(s):  
High Voltage ◽  
Chromatic Aberration ◽  
Crystalline Materials ◽  
Resolution Parameter ◽  
Instrument Resolution ◽  
Imaging Conditions ◽  
Beam Excitation ◽  
Optimum Imaging

In addition to improved penetration at high voltage, the characteristics of HVEM images of crystalline materials are changed markedly as a result of many-beam excitation effects. This leads to changes in optimum imaging conditions for dislocations, planar faults, precipitates and other features.Resolution - Because of longer focal lengths and correspondingly larger aberrations, the usual instrument resolution parameter, CS174 λ 374 changes by only a factor of 2 from 100 kV to 1 MV. Since 90% of this change occurs below 500 kV any improvement in “classical” resolution in the MVEM is insignificant. However, as is widely recognized, an improvement in resolution for “thick” specimens (i.e. more than 1000 Å) due to reduced chromatic aberration is very large.

TEM studies of amorphization processes and amorphous structures

1988 ◽  
Vol 46 ◽  
pp. 448-449
Author(s):  
T. E. Mitchell ◽  
R. B. Schwarz
Keyword(s):  
Amorphous Materials ◽  
Fission Products ◽  
Rapid Quenching ◽  
Surface Films ◽  
List Type ◽  
Oxide Glasses ◽  
Crystalline Materials ◽  
Amorphous Structures ◽  
Amorphous Surface ◽  
Interfacial Films

Traditional oxide glasses occur naturally as obsidian and can be made easily by suitable cooling histories. In the past 30 years, a variety of techniques have been discovered which amorphize normally crystalline materials such as metals. These include [1-3]:Rapid quenching from the vapor phase.Rapid quenching from the liquid phase.Electrodeposition of certain alloys, e.g. Fe-P.Oxidation of crystals to produce amorphous surface oxide layers.Interdiffusion of two pure crystalline metals.Hydrogen-induced vitrification of an intermetal1ic.Mechanical alloying and ball-milling of intermetal lie compounds.Irradiation processes of all kinds using ions, electrons, neutrons, and fission products.We offer here some general comments on the use of TEM to study these materials and give some particular examples of such studies.Thin specimens can be prepared from bulk homogeneous materials in the usual way. Most often, however, amorphous materials are in the form of surface films or interfacial films with different chemistry from the substrates.

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