Diverse Mechanical Properties of 1,3-Bis(4-nitrophenyl) thiourea–DMSO Dimorphic Solvates

Abstract

The distinct mechanical properties of concomitant dimorphs (Form α and Form β) of 1,3-bis(4-nitrophenyl) thiourea−DMSO solvate (TU-DMSO) have been investigated via experimental and computational techniques. This includes analysis of the molecular arrangement for the individual crystalline forms, considering the interaction energies responsible for stabilization of the dimers, comparing their lattice energies, and corroborating the results obtained from nanoindentation experiments. The work gives a plausible explanation for elastic bending of Form α crystals that includes synergistic contributions from electrostatic and dispersion components of intermolecular interactions. In addition to this, it suggests the role of the flexible torsions in thiourea along with expansion−compression in the outer-inner arc as a means to accommodate the strain due to bending. The relatively soft and compliant behavior of the former polymorph is highlighted by almost a 3-fold difference in hardness and elastic modulus values [Form α (115 MPa, 2.7 GPa) and Form β (334 MPa, 7.41 GPa)]. The nanoindentation experiments also support the observance of splitting of Form α crystals on excessive mechanical agitation.

Polymorphs with Remarkably Distinct Physical and/or Chemical Properties

“…Hasija et al . reported [86] the concomitant existence of dimorph of 1,3‐bis(4‐nitrophenyl) thiourea−DMSO solvate (TU‐DMSO) ( 37 , Scheme 7) as Form α (needle‐shaped crystal) and Form β (block shaped crystal) (Figure 32a–b) and investigated their stress‐induced mechanical properties. Upon application of external stress, crystals of Form α bent elastically; whereas, the crystal of Form β was found to disintegrate into smaller fragments.…”

Deformation-induced phosphorescence shift in a 2D elastically flexible organic single crystal: role of chalcogen-centered weak interactions

“…1 In recent years, there have been plenty of examples reported which show that molecular crystals can be elastically (reversibly) and plastically (permanently) deformed, exceptionally at a macroscopic level when subjected to mechanical force. 1–3 Such impressive mechanical adaptability in organic crystals opens a new window of opportunity for their potential use in smart flexible displays, optoelectronic devices, optical sensors, and so on. 4 In this regard, organic single crystals, showing luminescence as well as mechanically compliant behavior, are of particular interest.…”

Synthetic Strategies toward Higher Cocrystals of Some Resorcinols

“…Scheme 1. Resorcinol Derivatives Used in Previous Works 39,40,43,46,47,49 In any crystal structure, short-range supramolecular synthons may be considered to organize themselves into higher dimensional LSAMs following Aufbau principles. 59 These long-range synthons/modules carry subtle characteristics of structure that are responsible for the finer details of crystal packing.…”

“…Matters become more involved when the investigator embarks on a systematic study of higher cocrystals, namely, those that contain three or more distinct molecular components. − Crystals with more than two molecular components are of interest, in that there is a question as to whether an increase in the number of components leads to further modularity in crystal properties leading to polyfunctional materials. − As in binary systems, higher cocrystal formation is enabled by mutual recognition of chemical and geometrical features in the constituent molecules through critical properties of the relevant supramolecular synthons. , The first development in the direction of higher order cocrystals was executed by the Aakeröy group, where they designed a ternary cocrystal based on a graded interaction hierarchy . The best donor establishes a hydrogen bond with the best acceptor, while the second best donor prefers to bind with the second best acceptor to give hydrogen-bonded ternary cocrystals .…”