Effect of Double Branching in α,ω-Substituted Oligothiophenes on Thermal Solid-State Properties
| Autor: | Ulrich Ziener, Markus Braumüller, Khosrow Rahimi, Ahmed Mourran, Roman Vill, Jochen Gülcher, Wim H. de Jeu |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Silicon
Stereochemistry Chemistry Atomic force microscopy Organic Chemistry Solid-state chemistry.chemical_element 02 engineering and technology Branching points 010402 general chemistry 021001 nanoscience & nanotechnology Branching (polymer chemistry) 01 natural sciences 0104 chemical sciences law.invention Crystallography Optical microscope law Thermal Physical and Theoretical Chemistry 0210 nano-technology Linker |
| Zdroj: | European Journal of Organic Chemistry. 2017:1727-1735 |
| ISSN: | 1434-193X |
| DOI: | 10.1002/ejoc.201700046 |
| Popis: | A systematic series of septi-, nona- and undecithiophenes and corresponding pre-oligomers with five different dendrimer-like branched end groups were synthesized and their thermal solid-state properties were investigated. The substituents vary in terms of length of the linkers between the silicon branching points. Comparison of the series reveals that the linker connecting the oligomeric core with the first branching point has the strongest effect on the thermal properties. Furthermore, the relatively large volume of the substituents causes surprisingly low overall transition enthalpies and entropies for the oligomers of 10 - 20 kJ mol-1 and 15 - 40 J mol-1 K-1, respectively, while the pre-oligomers with interrupted conjugation display values in the range of 15 - 40 kJ mol-1 and 40 - 100 J mol-1 K-1, respectively. Polarizing optical microscopy (POM) displays textures pointing to smectic and columnar liquid crystalline phases but x-ray and AFM data of a representative example are typical for cubic phases. |
| Databáze: | OpenAIRE |
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