Hydrogen Bond-Directed Cruciform and Stacked Packing of a Pyrrole-Based Azaphenacene

Solid state packing plays a critical role in molecular materials to be applied within the area of organic electronics since the arrangement of molecules conditions the quality of the charge transport. Due to the difficulty in accurately predicting the crystal packing simply from the molecular structure, the design of molecules which can self-organize using strategically located functional groups becomes a useful approach to induce certain order directed by noncovalent interactions. The orientation of these interactions can be intentionally controlled from the early stage of molecular design and contribute to restrict the randomness of molecular arrangement in the solid state. Herein, we describe the synthesis and solid state characterization of a novel fused polyheteroaromatic system incorporating hydrogen bond donor and acceptor sites directly into a pentacyclic structure without disrupting its conjugation. A comparative study with an analogous system without hydrogen bond acceptor sites shows the remarkable effect of the hydrogen bond-directed assembly on the crystal packing and the benefits on the π–π intermolecular overlap, crucial for charge transport processes in organic semiconductors

New Advances in the One-Dimensional Coordination Polymer Copper(II) Alkanoates Series: Monotropic Polymorphism and Mesomorphism

The polymorphism in the copper­(II) alkanoates, recently discovered for one member, has been thoroughly studied for the whole series, from 3 to 16 C atoms. Three polymorphic phases have been found, all of them sharing the same molecular unit, the <i>paddle-wheel</i>, which grows forming a 1D coordination polymer or <i>catena</i>. The three polymorphs are defined by a different packing of these catenae and a specific arrangement of the alkyl chains. Ten new crystal structures of those compounds have been solved by high resolution powder diffraction and presented in this paper. The polymorphism in this series has been found to be monotropic and is responsible for the complex thermal behavior observed. The most characteristic feature, the endothermic–exothermic effect, has been explained for the first time in these compounds by a combination of data from differential scanning calorimetry (in normal and modulated modes), powder X-ray diffraction and Fourier transform infrared spectroscopy. These techniques, together with small-angle X-ray scattering and optical microscopy, were used to analyze the hexagonal columnar discotic liquid crystal phase of copper­(II) alkanoates. Thus, new information has been found in the packing and stacking of the discs formed by the paddle-wheel units, also maintained in the mesophase

Influence of Solid-State Microstructure on the Electronic Performance of 5,11-Bis(triethylsilylethynyl) Anthradithiophene

The rich phase behavior of 5,11-bis­(triethylsilylethynyl) anthradithiophene (TES ADT) – one of the most promising, solution-processable small-molecular organic semiconductors – is analyzed, revealing the highest performing polymorph among four solid-state phases, opening pathways toward the reliable fabrication of high-performance bottom-gate/bottom-contact transistors