Unusually Large Young’s Moduli of Amino Acid Molecular Crystals

Azuri, Ido; Meirzadeh, Elena; Ehre, David; Cohen, Sidney R.; Rappe, Andrew M.; Lahav, Meir; Lubomirsky, Igor; Kronik, Leeor

doi:10.1002/anie.201505813

Cited by 87 publications

(71 citation statements)

References 52 publications

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“…Such a large E of amino acid crystals had been previously obtained in high-pressure diffraction measurements (106,107). The determined E values of amino acids are remarkably high for molecular solids and suggest the hydrogen-bond network design as a pattern for rational design of ultra-stiff molecular solids (105).…”

Section: Mechanical Properties Of Molecular Crystalsmentioning

confidence: 56%

“…Values as high as 44 GPa were measured with instrumented nanoindentation (Table III). It was shown that E was strongly facet dependent and correlated with the underlying hydrogen-bonding network (105). Such a large E of amino acid crystals had been previously obtained in high-pressure diffraction measurements (106,107).…”

Section: Mechanical Properties Of Molecular Crystalsmentioning

confidence: 57%

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Application of instrumented nanoindentation in preformulation studies of pharmaceutical active ingredients and excipients

2016

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Application of instrumented nanoindentation in preformulation studies of pharmaceutical active ingredients and excipients # Nanoindentation allows quantitative determination of a material's response to stress such as elastic and plastic deformation or fracture tendency. Key instruments that have enabled great advances in nanomechanical studies are the instrumented nanoindenter and atomic force microscopy. The versatility of these instruments lies in their capability to measure local mechanical response, in very small volumes and depths, while monitoring time, displacement and force with high accuracy and precision. This review highlights the application of nanoindentation for mechanical characterization of pharmaceutical materials in the preformulation phase (primary investigation of crystalline active ingredients and excipients). With nanoindentation, mechanical response can be assessed with respect to crystal structure. The technique is valuable for mechanical screening of a material at an early development phase in order to predict and better control the processes in which a material is exposed to stress such as milling and compression.

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Section: Mechanical Properties Of Molecular Crystalsmentioning

confidence: 56%

Section: Mechanical Properties Of Molecular Crystalsmentioning

confidence: 57%

Application of instrumented nanoindentation in preformulation studies of pharmaceutical active ingredients and excipients

2016

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“…Before actuating properties of TS crystals can be explored as a platform for conversion of thermal energy to mechanical work, the range of their basic performance capabilities must be established based on commonly accepted performance indices. With exception of several special cases of organic materials with unusually high Young's moduli, organic crystals are generally known to be soft in nature, particularly when compared to metals and alloys. A large contribution to the mechanical properties of organic crystals is governed by intermolecular interactions, which are considerably weaker than the intramolecular (covalent) or metallic bonds.…”

Section: Discussionmentioning

confidence: 99%

Global Performance Indices for Dynamic Crystals as Organic Thermal Actuators

Karothu

Halabi

et al. 2020

Advanced Materials

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same basic thermodynamic principles of energy transduction and are collectively referred to as actuators. [1][2][3][4][5][6][7][8][9][10] While complex natural biomechanical systems have evolved to aid functions such as dispersal and survival, the artificially manufactured actuators are specifically designed for integration in mechatronic or adaptronic systems that range from miniature devices such as navigation and positioning systems in flying machines, to complex systems that can perform tasks in specific environments, such as humanoid robots and spacecraft. The current applications of actuators are many and diverse; they include sensors, [11,12] artificial muscles, [13] soft robotics, [14] and energy-harvesting materials. [15] Simple or complex actuating motions can be induced by heat, light, electricity, pressure, and moisture, among other stimuli, and can be realized with shape-memory polymers, [16] conductive fibers, [17] liquid crystal elastomers, [18] piezoelectric, [19] magnetostrictive, [20] and electromagnetic materials. [21] The energy supplied to the artificial actuators can vary from fluid pressure or flow in the pneumatics, to current, charge or voltage in the electromagnetic, piezoelectric and magnetostrictive actuators, to heat in shape memory and thermal expansion actuators.The active media in actuators include fluids, hard solids such as metals, and even complex soft matter such as tissuesensembles of cells with similar structure that act together to perform a specific function. While molecular crystals do not immediately appeal as working actuating medium, their dynamic properties have recently transpired as an alternative to other materials and they are thought to hold an untapped potential for miniature, soft actuating devices, quickly shaping up into a new research field, crystal adaptronics. [22,23] Smallscale demonstrations of the usefulness of molecular crystals as microscale devices, including cantilevers, [24,25] ratchets, [26] optical waveguides, [27][28][29][30][31][32][33][34][35][36] and other "crystal gears" [37] that can move or reshape are occasionally reported for dynamic crystals. Although being very illustrative, these demonstrations have thus far remained limited to a laboratory scale and have not been implemented in actual, functional devices. Some of the obstacles toward wider applications are difficulties with reproducible growth of crystals of predictable size without the use Crystal adaptronics is an emergent materials science discipline at the intersection of solid-state chemistry and mechanical engineering that explores the dynamic nature of mechanically reconfigurable, motile, and explosive crystals. Adaptive molecular crystals bring to materials science a qualitatively new set of properties that associate long-range structural order with softness and mechanical compliance. However, the full potential of this class of materials remains underexplored and they have not been considered as materials of choice in an engineer's toolbox. A set of general performance metric...

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“…[15] NT-NF,derived from MC 1 with 1equiv of CF 3 CO 2 H, demonstrated ahigher Youngsmodulus (1.33 AE 0.35 GPa) than touch-spun fibers of PEO (0.18 AE 0.05 GPa), polycaprolactone (PCL) (0.02 AE 0.00 GPa), and ap oly(ester urea) (PEU) [21] (0.68 AE 0.04 GPa) ( Figure 4G,T ables S11-S13). [24][25][26][27][28] This work establishes that imine-linked macrocycles, which are readily designed and prepared, assemble into high-aspect ratio nanotubes under mild conditions when they contain easily protonatable groups.T he enhanced basicity of the pyridine moiety compared to the imine linkages in the first inverse chromonic liquid crystal macrocycles enables assembly to proceed through the formation of pyridinium ions,i nstead of hydrolytically unstable iminium ions.T he assembly of MC 1 under sub-stoichiometric acid loadings is highly cooperative,a sd emonstrated by GPC measurements of macrocycle disappearance as well as fluorescence spec-troscopy.T he assembled nanotubes were processed into NT-NF via touch-spinning.T he resulting fibers demonstrated aY oungsm odulus of 1.33 GPa, exceeding that of several covalently linked polymers and biological filaments.M acrocycles that relied on protonating the imines with excess CF 3 CO 2 Hd id not form nanofibers suitable for mechanical testing.These findings demonstrate ageneral design principle for the synthesis of macrocycle assembles under mild conditions,a swell as the ability to touch-spin nanofibers of robust supramolecular assemblies. [23] Theh igh modulus of the NT-NF is presumably due to the interplay of multiple intermolecular forces,s uch as the electrostatic interactions that govern the initial assembly event, the hydrophobic interactions of the decyloxy side chains that are forced into close proximity,aswell as the p-p interactions present from macrocycle self-assembly.…”

Section: Angewandte Chemiementioning

confidence: 59%

Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes

Strauss¹,

Asheghali²,

Evans³

et al. 2019

Preprint

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Nanotubes assembled from macrocyclic precursors offer au nique combination of low dimensionality,s tructural rigidity,a nd distinct interior and exterior microenvironments. Usually the weak stackinge nergies of macrocycles limit the length and mechanical strength of the resultant nanotubes. Imine-linked macrocycles were recently found to assemble into high-aspect ratio (> 10 3 ), lyotropic nanotubes in the presence of excess acid. Yetthese harsh conditions are incompatible with many functional groups and processing methods,a nd lower acid loadings instead catalyze macrocycle degradation. Here we report pyridine-2,6-diimine-linked macrocycles that assemble into high-aspect ratio nanotubes in the presence of less than 1equiv of CF 3 CO 2 Hp er macrocycle.A nalysis by gel permeation chromatography and fluorescence spectroscopyrevealed acooperative self-assembly mechanism. The low acid concentrations needed to induce assembly enabled nanofibers to be obtained by touch-spinning, which exhibit higher Youngs moduli (1.33 GPa) than many synthetic polymers and biological filaments.T hese findings represent ab reakthrough in the design of inverse chromonic liquid crystals,asassembly under such mild conditions will enable the design of structurally diverse and mechanically robust nanotubes from synthetically accessible macrocycles.

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Unusually Large Young’s Moduli of Amino Acid Molecular Crystals

Cited by 87 publications

References 52 publications

Application of instrumented nanoindentation in preformulation studies of pharmaceutical active ingredients and excipients

Application of instrumented nanoindentation in preformulation studies of pharmaceutical active ingredients and excipients

Global Performance Indices for Dynamic Crystals as Organic Thermal Actuators

Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes

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