Polymorph Screening of Core-Chlorinated Naphthalene Diimides with Different Fluoroalkyl Side-Chain Lengths.

In this work, naphthalenediimide (NDI) derivatives are widely studied for their semiconducting properties and the influence of the side-chain length on the crystal packing is reported, along with the thermal properties of three core-chlorinated NDIs with different fluoroalkyl side-chain lengths (CF-NDI, CF-NDI and CF-NDI). The introduction of fluorinated substituents at the imide nitrogen and addition of strong electron-withdrawing groups at the NDI core are used to improve the NDI derivatives air stability. The new compound, CF-NDI, was deeply analyzed and compared to the well-known CF-NDI and CF-NDI, leading to the discovery and solution of two different crystal phases, form α and solvate form, and a solid solution of CF-NDI and CF-NDI-OH, formed by the decomposition in DMSO.

On the crystal forms of NDI-C6: annealing and deposition procedures to access elusive polymorphs.

NDI-C6 has been extensively studied for its semiconducting properties and its processability. It is known to have several polymorphs and a high thermal expansion. Here we report the full thermal characterization of NDI-C6 by combining differential scanning calorimetry, variable temperature X-ray powder diffraction, and hot stage microscopy, which revealed two different thermal behaviours depending on the annealing process.