Conjugated Helicene Oligomers Displaying an Odd-Even Conformational and Aggregation Effect
- 1Department of Chemistry
- 2Stanford University
- 3Department of Chemical Engineering
Abstract
Helicenes attract attention due to their spring-shaped structures and conjugated backbones. Synthesizing longer helicenes allows for structure-property relationship investigation as additional coil layers are achieved. Therefore, developing helicenes as building blocks for oligomers and polymers will increase understanding of property tuning upon chain extension. We report the synthesis of discrete oligomers using the helicene N[5]HDI from lengths n=1 to n=5. Selective bromination of the oligomers allows for extension to longer oligomers, as well as the potential to use them as monomer units in polymerizations. The oligomers exhibit an odd-even effect, where odd oligomers prefer a ‘coiled’ conformation, while even oligomers prefer a ‘snake’ conformation. This results in improved orbital overlap and effective conjugation in odd oligomers, and small changes in electronics but increased aggregation in even oligomers. The synthesis and structure-property tuning of N[5]HDI oligomers is an important step toward incorporating helicenes into polymers with enhanced mechanical and electronic properties.
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BibTeX
@misc{mow2026conjugated,
title = {{Conjugated Helicene Oligomers Displaying an Odd-Even Conformational and Aggregation Effect}},
author = {Rachael K. Mow and Zhenan Bao},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009541/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009541/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Conjugated Helicene Oligomers Displaying an Odd-Even Conformational and Aggregation Effect
AU - Rachael K. Mow
AU - Zhenan Bao
PY - 2026
DA - 2026/09/28
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009541/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009541/v1
AB - Helicenes attract attention due to their spring-shaped structures and conjugated backbones. Synthesizing longer helicenes allows for structure-property relationship investigation as additional coil layers are achieved. Therefore, developing helicenes as building blocks for oligomers and polymers will increase understanding of property tuning upon chain extension. We report the synthesis of discrete oligomers using the helicene N[5]HDI from lengths n=1 to n=5. Selective bromination of the oligomers allows for extension to longer oligomers, as well as the potential to use them as monomer units in polymerizations. The oligomers exhibit an odd-even effect, where odd oligomers prefer a ‘coiled’ conformation, while even oligomers prefer a ‘snake’ conformation. This results in improved orbital overlap and effective conjugation in odd oligomers, and small changes in electronics but increased aggregation in even oligomers. The synthesis and structure-property tuning of N[5]HDI oligomers is an important step toward incorporating helicenes into polymers with enhanced mechanical and electronic properties.
ER -