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Journal ArticleDOI: 10.1021/ACS.CGD.0C01743

Elastic Molecular Crystals: From Serendipity to Design to Applications

04 Mar 2021-Crystal Growth & Design (American Chemical Society (ACS))-Vol. 21, Iss: 4, pp 2566-2580
Abstract: The mechanical adaptiveness of long-range ordered molecular crystals has long been ignored due to their brittle nature, unlike polymers and flexible biomaterials. However, the recent emergence of e...

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12 results found

Journal ArticleDOI: 10.1039/D1CE00388G
28 Apr 2021-CrystEngComm
Abstract: Recent interest in functional flexible molecular crystals has the potential to provide unique optoelectronic applications and stimuli-responsive chemistry. In crystal engineering, the designing of crystal structures from molecular structures has resulted in various functional molecular crystals for controlling photons, phonons, electrons, and magnons. The flexible behavior of molecular crystals, such as stress-induced response shape deformation, is another new feature recently realized by molecular and crystal structure design strategies. Such flexible molecular crystals with crystal features, such as intrinsic and mechano-responsive properties, have potential powerful applications, such as in wearable devices. Herein, the concept of functional flexible molecular crystals is highlighted, demonstrating the intrinsic properties of mechanical deformability and mechano-responsiveness induced by changes in crystal shape. Some outstanding examples of the light emission and electrical conduction properties of functional flexible molecular crystals are discussed. Key insight into similar future developments that offer intrinsic and mechanical stimuli-responsive behavior toward flexible molecular crystal devices is also provided.

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Topics: Light emission (52%), Crystal (50%)

6 Citations

Open accessJournal ArticleDOI: 10.1039/D1CE00642H
01 Sep 2021-CrystEngComm
Abstract: The ability to selectively tune the optical and the mechanical properties of organic molecular crystals offers a promising approach towards developing flexible optical devices. These functional properties are sensitive to crystallographic packing features and are hence expected to vary with polymorphic modification. Using as a model system the photoluminescent material 4-bromo-6-[(6-chloropyridin-2-ylimino)methyl]phenol (CPMBP), we herein demonstrate the simultaneous tuning of mechanical flexibility and photoluminescence properties via polymorphism. Two new polymorphic forms of CPMBP were obtained from a solution and fully characterised using a combination of experiments and density functional theory simulations. These polymorphic forms exhibit remarkably distinct mechanical properties and an order of magnitude difference in photoluminescence quantum yield. The mechanically plastic form has a higher quantum yield than the brittle polymorphic form. However, their photoluminescence emission profile is largely unaffected by the observed polymorphism, thereby demonstrating that the optical properties and bulk mechanical properties can in principle be tuned independently. By distinguishing between active (involving absorption and emission) and passive (involving no absorption) light propagation, the waveguiding properties of the plastic form of CPMBP (form II) were explored using the straight and bent crystals to highlight the potential applications of CPMBP in designing flexible optical devices. Our results demonstrated that polymorph engineering would be a promising avenue to achieve concurrent modulation of the optical and mechanical properties of photoluminescent molecular crystals for next-generation flexible optical device applications.

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Topics: Photoluminescence (53%)

3 Citations

Journal ArticleDOI: 10.1039/D1CE00401H
Amy J. Thompson1, Anna Worthy2, Arnaud Grosjean1, Jason R. Price3  +2 moreInstitutions (3)
01 Sep 2021-CrystEngComm
Abstract: While the first report of molecular crystals that could bend without breaking was well over a decade ago, the development of suitable characterisation tools remains a priority. Due to the broad reaching applications of these materials in advanced technologies, it is important to develop both mechanical and mechanistic understanding. Micro-focused mapping experiments were designed with the intent of bridging the gap between the measurement of mechanical properties and molecular-scale structural understanding. Herein, we describe a methodology for determining the mechanisms of deformation in flexible crystals with atomic precision and provide examples where it has been implemented. Although micro-focused mapping experiments have potential for application in the determination of mechanisms of flexibility, great care must be taken during both experimental design and data analysis.

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3 Citations

Journal ArticleDOI: 10.1039/D1CE00467K
Sumair A. Rather1, Binoy K. Saha1Institutions (1)
01 Sep 2021-CrystEngComm
Abstract: The crystal structures of Cu(acac)2 and 9,10-anthraquinone are very similar and both of them exhibit elastic bending. The mechanism of thermal expansion has been correlated with the mechanism of bending for Cu(acac)2. Then this idea has been used to postulate the bending mechanism in a 9,10-anthraquinone crystal from a thermal expansion study.

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Topics: Bending (55%), Crystal (53%), Thermal expansion (51%)

2 Citations

Journal ArticleDOI: 10.1039/D1CE00724F
Sotaro Kusumoto1, Akira Sugimoto2, Daisuke Kosumi2, Yang Kim2  +3 moreInstitutions (2)
23 Aug 2021-CrystEngComm
Abstract: In this communication, an organic crystal of the polar space group Pc that is capable of plastic bending in response to external mechanical stress is reported, and its high dielectric constant and strong second-order harmonic generation (SHG) effect have been demonstrated.

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1 Citations


98 results found

Journal ArticleDOI: 10.1021/JA403264C
Gautain R Desiraju1Institutions (1)
Abstract: How do molecules aggregate in solution, and how do these aggregates consolidate themselves in crystals? What is the relationship between the structure of a molecule and the structure of the crystal it forms? Why do some molecules adopt more than one crystal structure? Why do some crystal structures contain solvent? How does one design a crystal structure with a specified topology of molecules, or a specified coordination of molecules and/or ions, or with a specified property? What are the relationships between crystal structures and properties for molecular crystals? These are some of the questions that are being addressed today by the crystal engineering community, a group that draws from the larger communities of organic, inorganic, and physical chemists, crystallographers, and solid state scientists. This Perspective provides a brief historical introduction to crystal engineering itself and an assessment of the importance and utility of the supramolecular synthon, which is one of the most important concepts in the practical use and implementation of crystal design. It also provides a look to the future from the viewpoint of the author, and indicates some directions in which this field might be moving.

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Topics: Crystal chemistry (57%), Crystal engineering (57%), Crystal (53%)

947 Citations

Journal ArticleDOI: 10.1038/NMAT2704
01 Apr 2010-Nature Materials
Abstract: Silk features exceptional mechanical properties such as high tensile strength and great extensibility, making it one of the toughest materials known. The exceptional strength of silkworm and spider silks, exceeding that of steel, arises from beta-sheet nanocrystals that universally consist of highly conserved poly-(Gly-Ala) and poly-Ala domains. This is counterintuitive because the key molecular interactions in beta-sheet nanocrystals are hydrogen bonds, one of the weakest chemical bonds known. Here we report a series of large-scale molecular dynamics simulations, revealing that beta-sheet nanocrystals confined to a few nanometres achieve higher stiffness, strength and mechanical toughness than larger nanocrystals. We illustrate that through nanoconfinement, a combination of uniform shear deformation that makes most efficient use of hydrogen bonds and the emergence of dissipative molecular stick-slip deformation leads to significantly enhanced mechanical properties. Our findings explain how size effects can be exploited to create bioinspired materials with superior mechanical properties in spite of relying on mechanically inferior, weak hydrogen bonds.

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925 Citations

Open accessJournal ArticleDOI: 10.1016/S1369-7021(04)00124-5
01 Mar 2004-Materials Today
Abstract: The last ten years have seen the discovery of amorphous metal alloys that are glass forming at cooling rates as slow as 1°C s −1 to 100°C s −1 in the bulk via conventional metal processing such as casting, but with the ease of molding of polymers. They are twice as strong as steel, have greater wear and corrosion resistance, are tougher than ceramics, and yet have greater elasticity. Increased plasticity in amorphous/crystalline composites now promises new structural applications.

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Topics: Amorphous metal (61%), Amorphous solid (58%), Ceramic (53%) ... show more

549 Citations

Journal ArticleDOI: 10.1039/C0CS00163E
Jin-Chong Tan1, Anthony K. Cheetham1Institutions (1)
Abstract: The mechanical properties of hybrid framework materials, including both nanoporous metal–organic frameworks (MOFs) and dense inorganic–organic frameworks, are discussed in this critical review. Although there are relatively few studies of this kind in the literature, major recent advances in this area are beginning to shed light on the fundamental structure–mechanical property relationships. Indeed research into the mechanical behavior of this important new class of solid-state materials is central to the design and optimal performance of a multitude of technological applications envisaged. In this review, we examine the elasticity of hybrid frameworks by considering their Young's modulus, Poisson's ratio, bulk modulus and shear modulus. This is followed by discussions of their hardness, plasticity, yield strength and fracture behavior. Our focus is on both experimental and computational approaches. Experimental work on single crystals and amorphized monoliths involved primarily the application of nanoindentation and atomic force microscopy to determine the elastic moduli and hardness properties. The compressibility and bulk moduli of single crystals and polycrystalline powders were studied by high-pressure X-ray crystallography in the diamond anvil cell, while in one instance spectroscopic ellipsometry has also been used to estimate the elastic moduli of MOF nanoparticles and deposited films. Theoretical studies, on the other hand, encompassed the application of first principles density-functional calculations and finite-temperature molecular dynamics simulations. Finally, by virtue of the diverse mechanical properties achievable in hybrid framework materials, we propose that a new domain be established in the materials selection map to define this emerging class of materials (137 references).

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Topics: Elastic modulus (53%), Bulk modulus (53%), Nanoindentation (53%) ... show more

510 Citations

Journal ArticleDOI: 10.1038/NATURE08603
Peter Fratzl1, Friedrich G. Barth2Institutions (2)
25 Nov 2009-Nature
Abstract: Living organisms use composite materials for various functions, such as mechanical support, protection, motility and the sensing of signals. Although the individual components of these materials may have poor mechanical qualities, they form composites of polymers and minerals with a remarkable variety of functional properties. Researchers are now using these natural systems as models for artificial mechanosensors and actuators, through studying both natural structures and their interactions with the environment. In addition to inspiring the design of new materials, analysis of natural structures on this basis can provide insight into evolutionary constraints on structure-function relationships in living organisms and the variety of structural solutions that emerged from these constraints.

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470 Citations

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