Structural analysis of elastically bent organic crystals using in situ indentation and micro-Raman spectroscopy

Abstract

The structural dynamics of two elastically bendable, halogenated N-benzylideneaniline organic crystals were studied using an in situ three-point bending test and Raman spectroscopy. This study reveals the inhomogeneous molecular distribution in the elastic crystal lattice during the bent stage and further validates the known qualitative mechanistic model of elastic bendable crystals.

RETRACTED ARTICLE: Mechanically interlocked architecture aids an ultra-stiff and ultra-hard elastically bendable cocrystal

“…The elastic bending nature of the cocrystal solvate of caffeine (CAF), 4-chloro-3-nitrobenzoic acid (CNB) and methanol (1:1:1) was reported by us earlier 35,36 , but quantification of its mechanical properties and bending mechanism remained intriguing, when compared to other elastically bendable molecular crystals known today 2,10,21–23,37–40 , because this is the only system with weak hydrogen bonded, mechanically interlocked network. Hence, we reinvestigated its elastic bending using spatially resolved analysis up to atomic resolution by employing state-of-the art single crystal micro ( μ ) X-ray diffraction ( μ -SCXRD), μ -Raman and μ -Infrared ( μ -IR) spectroscopy, on both as grown (or ambient) and bent crystals.…”

“…Recent studies on mechanism of elastic bending of molecular crystals using in situ three point bending and Raman spectroscopy showed an evidence of heterogeneous molecular changes in the structure 23 . Worthy et al, using micro X-ray diffraction, demonstrated in a coordination compound, Cu(acac) 2 , that mutual rotation of molecules facilitate expansion at the outer arc and compression at the inner arc within its 1% elastic limit while extending the argument to plastic nature at higher strains 21 .…”

An Organic Crystal with High Elasticity at an Ultra‐Low Temperature (77 K) and Shapeability at High Temperatures

“…[13,14] Recently,o rganic crystals with elasticity,w hich break the traditional thinking that organic crystals are hard and brittle, have been known, and more and more elastic organic single crystals (EOSCs) have been reported. [15][16][17][18][19][20][21][22] Besides the interesting elastic phenomenon itself,p otential applications of EOSCs in flexible devices and sensors were the driving force for related studies. [23][24][25][26][27][28][29] Regarding the application of an elastic material, the influence of temperature on elasticity is not negligible.T aking rubbers (natural and synthetic) as an example,they only show elasticity and are applicable at the temperatures between the brittle (T b )a nd the viscous flow (T f )t emperatures,a nd such applicable temperatures are typically within À60 to 300 8 8Cfor the most commonly used rubbers.…”

Facile investigation of reversible nanostructure changes in flexible crystals

“…[1][2][3][4][5] Unlike entropic elasticity, in which an ordered molecular assembly returns to an unordered state according to the second law of thermodynamics, enthalpic elasticity involves a restoring force derived from a change of molecular array spacing induced by an external force and energy. 6,7 Elastically deformable organic crystals (elastic organic crystals) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] have enthalpic elasticity, which alters intermolecular packing through mechanical deformation of the crystals. [8][9][10][11][12][13][14] There is a need to investigate changes of the nanoscopic structural molecular arrangement space (or lattice) in a crystal under deformation stress.…”

“…16 Raman spectroscopy is also effective for tracking changes in intermolecular interactions. 17,18 However, synchrotron X-ray analysis is necessary to characterize nanoscopic structural changes associated with crystal bending deformation in detail, 15 which limits the accessibility of such measurements. In addition, there are currently no simple readily accessible methods to quantitatively determine the degree of a nanoscopic change with respect to the amount of deformation (strain, %).…”