Related Experiment Video
Updated: Aug 9, 2026
09:22
Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Chiroptical inversion induced by sandwiching units in chiral polythiourethane
Atsushi Nagai1, Bungo Ochiai, Takeshi Endo
1Department of Polymer Science and Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan.
Chemical Communications (Cambridge, England)
|April 1, 2006
Summary
The chiroptical behavior of chiral polythiourethane copolymers can be inverted by incorporating bulky segments. This finding offers new possibilities for designing advanced chiral materials with tunable optical properties.
Area of Science:
- Polymer Chemistry
- Chiral Materials Science
- Organic Synthesis
Background:
- Chiral polythiourethanes exhibit unique chiroptical properties influenced by their structure.
- Hydrogen bonding plays a crucial role in regulating the chiroptical behavior of these polymers.
- Controlling chiroptical properties in chiral polymers is essential for advanced optical applications.
Purpose of the Study:
- To investigate the effect of incorporating sterically demanding segments on the chiroptical behavior of chiral polythiourethanes.
- To explore the synthesis of novel copolymers using cationic ring-opening copolymerization.
- To understand the interplay between polymer architecture and chiroptical response.
Main Methods:
- Synthesis of chiral cyclic thiourethanes from L-serine.
- Cationic ring-opening copolymerization to create polythiourethane copolymers.
- Spectroscopic analysis to characterize chiroptical properties and polymer structure.
Main Results:
- The chiroptical behavior of the hydrogen-bond-regulated chiral polythiourethane segment was successfully inverted.
- Incorporation of sterically demanding segments led to the observed inversion.
- Copolymerization allowed for precise control over the polymer architecture and resulting optical properties.
Conclusions:
- Steric hindrance in copolymer segments can effectively reverse the inherent chiroptical properties of chiral polythiourethanes.
- This strategy provides a versatile method for tuning the optical characteristics of chiral polymers.
- The findings open avenues for developing novel chiral materials for optical devices and sensors.
More Related Videos
Related Concept Videos
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...
02:23SN2 Reaction: Stereochemistry
In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
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...
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...
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
02:33Stereoisomerism of Cyclic Compounds
In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...