Melt-Quenched Porous Organic Cage Glasses

The discrete molecular nature of porous organic cages (POCs) has allowed us to direct the formation of crystalline materials by crystal engineering. It has also been possible to create porous amorphous solids by deliberately disrupting the crystalline packing, either with chemical modification or by processing. More recently, organic cages were used to form isotropic porous liquids. However, the connection between solid and liquid states of POCs, and the glass state, are almost completely unexplored. Here, we investigate the melting and glass-forming behaviour of a range of organic cages, including both shape-persistent POCs formed by imine condensation, and reduced and synthetically post-modified amine POCs that are more flexible and lack shape-persistence. The organic cages exhibited melting and quenching of the resultant liquids provides molecular glasses. One of these molecular glasses exhibited improved gas uptake for both CO2 and CH4 compared to the starting amorphous cage. In addition, foaming of the liquid in one case resulted in a more stable and less soluble glass, which demonstrates the potential for an alternative approach to forming materials such as membranes without solution processing.

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Trapping liquid drugs inside crystals

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314090159 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C984-C984

Author(s):

Alessia Bacchi ◽

Davide Capucci ◽

Paolo Pelagatti

Keyword(s):

Human Health ◽

Crystal Engineering ◽

Room Temperature ◽

The Body ◽

New Materials ◽

Active Molecule ◽

Crystalline Materials ◽

Pharmaceutical Ingredients ◽

Solid Dosage ◽

Intellectual Properties

The objective of this work is to embed liquid or volatile pharmaceuticals inside crystalline materials, in order to tune their delivery properties in medicine or agrochemistry, and to explore new regulatory and intellectual properties issues. Liquid or volatile formulations of active pharmaceutical ingredients (APIs) are intrinsically less stable and durable than solid forms; in fact most drugs are formulated as solid dosage because they tend to be stable, reproducible, and amenable to purification. Most drugs and agrochemicals are manufactured and distributed as crystalline materials, and their action involves the delivery of the active molecule by a solubilization process either in the body or on the environment. However some important compounds for the human health or for the environment occur as liquids at room temperature. The formation of co-crystals has been demonstrated as a means of tuning solubility properties of solid phases, and therefore it is widely investigated by companies and by solid state scientists especially in the fields of pharmaceuticals, agrochemicals, pigments, dyestuffs, foods, and explosives. In spite of this extremely high interest towards co-crystallization as a tool to alter solubility, practically no emphasis has been paid to using it as a means to stabilize volatile or labile or low-melting products. In this work we trap and stabilize volatile and liquid APIs and agrochemicals in crystalline matrices by engineering suitable co-crystals. These new materials alter the physic state of the active ingredients allowing to expand the phase space accessible to manufacturing and delivery. We have defined a benchmark of molecules relevant to human health and environment that have been combined with suitable partners according to the well known methods of crystal engineering in order to obtain cocrystals. The first successful results will be discussed; the Figure shows a cocrystal of propofol, a worldwide use anesthetic.

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Dropwise cooling crystallization of ammonium perchlorate in gas–liquid two-phase suspension systems

CrystEngComm ◽

10.1039/c8ce01389f ◽

2018 ◽

Vol 20 (43) ◽

pp. 6932-6939 ◽

Cited By ~ 4

Author(s):

Wei Liu ◽

Yong Xie ◽

Qiang Xie ◽

Kexiong Fang ◽

Xuan Zhang ◽

...

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Crystal Engineering ◽

Smooth Surface ◽

Narrow Particle Size Distribution ◽

Two Phase ◽

Crystalline Materials ◽

Suspension Systems ◽

Crystallization Method ◽

Cooling Crystallization

A dropwise cooling crystallization method was proposed to prepare AP crystals with a uniform shape, a narrow particle size distribution and a smooth surface, which is also a reference for the crystallization of other crystalline materials in crystal engineering.

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Crystal Engineering for Catalysis

Annual Review of Chemical and Biomolecular Engineering ◽

10.1146/annurev-chembioeng-060817-083953 ◽

2018 ◽

Vol 9 (1) ◽

pp. 283-309 ◽

Cited By ~ 19

Author(s):

Jeffrey D. Rimer ◽

Aseem Chawla ◽

Thuy T. Le

Keyword(s):

Crystal Engineering ◽

Active Sites ◽

Heterogeneous Catalysts ◽

Computational Design ◽

Crystal Nucleation ◽

Synthesis Methods ◽

Crystalline Materials ◽

Simultaneous Control ◽

Metal Organic ◽

Controlled Environments

Crystal engineering relies upon the ability to predictively control intermolecular interactions during the assembly of crystalline materials in a manner that leads to a desired (and predetermined) set of properties. Economics, scalability, and ease of design must be leveraged with techniques that manipulate the thermodynamics and kinetics of crystal nucleation and growth. It is often challenging to exact simultaneous control over multiple physicochemical properties, such as crystal size, habit, chirality, polymorph, and composition. Engineered materials often rely upon postsynthesis (top-down) processes to introduce properties that would otherwise be challenging to attain through direct (bottom-up) approaches. We discuss the application of crystal engineering to heterogeneous catalysts with a focus on four general themes: ( a) tailored nanocrystal size, ( b) controlled environments surrounding active sites, ( c) tuned morphology with well-defined facets, and ( d) hierarchical materials with disparate pore size and active site distributions. We focus on nonporous materials, including metals and metal oxides, and two classes of porous materials: zeolites and metal organic frameworks. We review novel synthesis methods involving synergistic experimental and computational design approaches, the challenges facing catalyst development, and opportunities for future advancement in crystal engineering.

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Anarchy in the solid state: structural dependence on glass-forming ability in triazine-based molecular glasses

Tetrahedron ◽

10.1016/j.tet.2009.07.026 ◽

2009 ◽

Vol 65 (36) ◽

pp. 7393-7402 ◽

Cited By ~ 32

Author(s):

James D. Wuest ◽

Olivier Lebel

Keyword(s):

Solid State ◽

Glass Forming Ability ◽

Molecular Glasses ◽

Structural Dependence ◽

Glass Forming

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Structure–mechanical property correlations in mechanochromic luminescent crystals of boron difluoride dibenzoylmethane derivatives

IUCrJ ◽

10.1107/s2052252515015134 ◽

2015 ◽

Vol 2 (6) ◽

pp. 611-619 ◽

Cited By ~ 30

Author(s):

Gamidi Rama Krishna ◽

Ramesh Devarapalli ◽

Rajesh Prusty ◽

Tiandong Liu ◽

Cassandra L. Fraser ◽

...

Keyword(s):

Solid State ◽

Mechanical Behaviour ◽

Crystal Engineering ◽

Mechanical Analysis ◽

Slip Systems ◽

Crystalline Materials ◽

Organic Solid ◽

Boron Difluoride ◽

Deformation Tests ◽

Mechanochromic Luminescence

The structure and mechanical properties of crystalline materials of three boron difluoride dibenzoylmethane (BF2dbm) derivatives were investigated to examine the correlation, if any, among mechanochromic luminescence (ML) behaviour, solid-state structure, and the mechanical behaviour of single crystals. Qualitative mechanical deformation tests show that the crystals of BF2dbm(tBu)2can be bent permanently, whereas those of BF2dbm(OMe)2exhibit an inhomogeneous shearing mode of deformation, and finally BF2dbmOMe crystals are brittle. Quantitative mechanical analysis by nanoindentation on the major facets of the crystals shows that BF2dbm(tBu)2is soft and compliant with low values of elastic modulus,E, and hardness,H, confirming its superior suceptibility for plastic deformation, which is attributed to the presence of a multitude of slip systems in the crystal structure. In contrast, both BF2dbm(OMe)2and BF2dbmOMe are considerably stiffer and harder with comparableEandH, which are rationalized through analysis of the structural attributes such as the intermolecular interactions, slip systems and their relative orientation with respect to the indentation direction. As expected from the qualitative mechanical behaviour, prominent ML was observed in BF2dbm(tBu)2, whereas BF2dbm(OMe)2exhibits only a moderate ML and BF2dbmOMe shows no detectable ML, all examined under identical conditions. These results confirm that the extent of ML in crystalline organic solid-state fluorophore materials can be correlated positively with the extent of plasticity (low recovery). In turn, they offer opportunities to design new and improved efficient ML materials using crystal engineering principles.

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Organometallic chemistry meets crystal engineering to give responsive crystalline materials

Chemical Communications ◽

10.1039/c5cc09427e ◽

2016 ◽

Vol 52 (7) ◽

pp. 1327-1337 ◽

Cited By ~ 11

Author(s):

A. Bacchi ◽

P. Pelagatti

Keyword(s):

Organometallic Chemistry ◽

Crystal Engineering ◽

Crystalline Materials

Like the meeting between the heroes Garibaldi and the King of Sardinia Vittorio Emanuele II led to United Italy, the meeting between organometallic chemistry and crystal engineering led to responsive crystalline materials.

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Plasticity in zwitterionic drugs: the bending properties of Pregabalin and Gabapentin and their hydrates

IUCrJ ◽

10.1107/s2052252519004755 ◽

2019 ◽

Vol 6 (4) ◽

pp. 630-634 ◽

Cited By ~ 5

Author(s):

U. B. Rao Khandavilli ◽

Matteo Lusi ◽

Patrick J. Frawley

Keyword(s):

Mechanical Properties ◽

Crystal Engineering ◽

Weak Interactions ◽

Molecular Crystals ◽

Structural Features ◽

Microscopic Structure ◽

Bending Properties ◽

Crystalline Materials ◽

Area Of Interest ◽

Macroscopic Plasticity

The investigation of mechanical properties in molecular crystals is emerging as a novel area of interest in crystal engineering. Indeed, good mechanical properties are required to manufacture pharmaceutical and technologically relevant substances into usable products. In such endeavour, bendable single crystals help to correlate microscopic structure to macroscopic properties for potential design. The hydrate forms of two anticonvulsant zwitterionic drugs, Pregabalin and Gabapentin, are two examples of crystalline materials that show macroscopic plasticity. The direct comparison of these structures with those of their anhydrous counterparts, which are brittle, suggests that the presence of water is critical for plasticity. In contrast, structural features such as molecular packing and anisotropic distribution of strong and weak interactions seem less important.

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Atomic Diffusion in Bulk Metallic Glasses

MRS Proceedings ◽

10.1557/proc-554-275 ◽

1998 ◽

Vol 554 ◽

Cited By ~ 3

Author(s):

Ulrich Geyer ◽

Achim Rehmet ◽

Susanne Schneider

Keyword(s):

Metallic Glasses ◽

Bulk Metallic Glasses ◽

Atomic Diffusion ◽

Undercooled Liquid ◽

Glass Forming ◽

Atomic Transport ◽

Theoretical Predictions ◽

Experimental Findings ◽

Liquid States ◽

Undercooled Melts

AbstractDiffusion experiments in bulk metallic glasses are reviewed. Measurements carried out so far are focused on Zirconium based alloys and cover the amorphous and deeply undercooled liquid states as well as the equilibrium and slightly undercooled melts. Experimental findings are compared with theoretical predictions for atomic transport in glass forming systems.

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