3 research outputs found
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 ĻāĻ 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 copperĀ(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 endothermicāexothermic 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 copperĀ(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-bisĀ(triethylsilylethynyl)
anthradithiophene
(TES ADT) ā one of the most promising, solution-processable
small-molecular organic semiconductors ā 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