Polymorphism-driven Distinct Nanomechanical, Optical, Photophysical, and Conducting Properties in a Benzothiophene-quinoline.

Polymorphic forms of organic conjugated small molecules, with their unique molecular shapes, packing arrangements, and interaction patterns, provide an excellent opportunity to uncover how their microstructures influence their observable properties. Ethyl-2-(1-benzothiophene-2-yl)quinoline-4-carboxylate (BZQ) exists as dimorphs with distinct crystal habits - blocks (BZB) and needles (BZN). The crystal forms differ in their molecular arrangements - BZB has a slip-stacked column-like structure in contrast to a zig-zag crystal packing with limited π-overlap in BZN.

Molecular Basis for the Mechanical Response of Sulfa Drug Crystals.

Comprehension of the nanomechanical response of crystalline materials requires the understanding of the elastic and plastic deformation mechanisms in terms of the underlying crystal structures. Nanoindentation data were combined with structural and computational inputs to derive a molecular-level understanding of the nanomechanical response in eight prototypical sulfa drug molecular crystals. The magnitude of the modulus, E, was strongly connected to the non-covalent bond features, that is, the bond strength, the relative orientation with the measured crystal facet and their disposition in the crystal lattice.