Metal‐like Ductility in Organic Plastic Crystals: Role of Molecular Shape and Dihydrogen Bonding Interactions in Aminoboranes. (24th April 2020)

• Record Type: Journal Article
• Authors: Mondal, Amit; Bhattacharya, Biswajit; Das, Susobhan; Bhunia, Surojit; Chowdhury, Rituparno; Dey, Somnath; Reddy, C. Malla
• Is Part Of: Angewandte Chemie. Volume 132:Number 27(2020)
• Page Start: 11064
• Page End: 11073
• Publication Date: 2020-04-24
• Subjects: aminoboranes -- dihydrogen bonds -- ductile crystals -- molecular globularity -- plastic crystals; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202001060
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Ductility is a common phenomenon in many metals but is difficult to achieve in molecular crystals. Organic crystals bend plastically on one or two face‐specific directions but fracture when stressed in any other arbitrary directions. An exceptional metal‐like ductility and malleability in the isomorphous crystals of two globular molecules, BH3 NMe3 and BF3 NMe3, is reported, with characteristic tensile stretching, compression, twisting, and thinning. The mechanically deformed samples, which transition to lower symmetry phases, retain good long‐range order amenable to structure determination by single‐crystal X‐ray diffraction. Molecules in these high‐symmetry crystals interact through electrostatic forces (B − −N + ) to form columnar structures with multiple slip planes and weak dispersive forces between columns. On the other hand, the limited number of facile slip planes and strong dihydrogen bonding in BH3 NHMe2 negates ductility. Our study has implications for the design of soft ferroelectrics, solid electrolytes, barocalorics, and soft robotics. Abstract : Slip slidin ' away : Aminoborane crystals can be deformed mechanically while retaining high crystallinity because multiple slip planes exist in their high‐symmetry structures. The presence of dihydrogen bonds in a similar semiglobular system, BH3 NHMe2, negates ductility. Mechanically castable plastic crystals are appealing for applications such as ferroelectrics and soft robotics.