Related Experiment Video
Updated: Jun 4, 2026
09:22
Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Mirror helices and helicity switch at surfaces based on chiral triangular-shape oligo(phenylene ethynylenes).
Fátima Aparicio1, Fátima García, Gustavo Fernández
1Departamento de Química Orgánica, Facultad de Ciencias Químicas, Ciudad Universitaria s/n, Madrid, Spain.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|January 29, 2011
Summary
Chiral oligo(phenylene ethynylenes) (OPEs) self-assemble into helical nanostructures, with chirality influenced by peripheral chain substituents. The distance of chiral centers from the OPE core impacts aggregate stability and self-assembly mechanisms.
Area of Science:
- Supramolecular chemistry
- Materials science
- Organic chemistry
Background:
- Oligo(phenylene ethynylenes) (OPEs) are conjugated molecules known for their self-assembly properties.
- Peripheral substituents significantly influence the self-assembly behavior and resulting nanostructures.
- Chirality in molecular building blocks can lead to chiral supramolecular architectures.
Purpose of the Study:
- To investigate the self-assembly of triangular-shaped OPEs with chiral and linear paraffinic chains.
- To understand how peripheral chain structure and chirality affect supramolecular organization and properties.
- To explore the relationship between molecular structure, self-assembly mechanism, and resulting nanostructure handedness.
Main Methods:
- X-ray diffraction (XRD) for structural analysis of bulk materials.
- UV/Vis spectroscopy in solution to study self-assembly mechanisms and aggregate stability.
- Investigation of self-assembly in bulk, on surfaces, and in solution.
Main Results:
- OPEs with linear chains formed columnar packing in 2D oblique cells.
- Chiral OPEs self-assembled into helical nanostructures with opposite handedness.
- A 'helicity switch' was observed in one chiral OPE system, altering helical direction.
- Aggregate stability increased with greater distance between the stereogenic carbon and the aromatic core.
- Self-assembly mechanisms varied from cooperative to isodesmic, depending on peripheral substituents.
Conclusions:
- Peripheral chiral chains dictate the handedness of helical OPE nanostructures.
- The distance of chiral substituents from the OPE core influences supramolecular stability.
- The nature of peripheral substituents controls the self-assembly mechanism and cooperativity.
- Interactions between chiral side chains are critical for determining helical pitch, stability, and assembly pathways.
Related Concept Videos
02:25Chirality
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
02:05Prochirality
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
02:30Chirality in Nature
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid. The...
02:25Molecules with Multiple Chiral Centers
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
02:30Chirality at Nitrogen, Phosphorus, and Sulfur
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...