Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Thermal Sigmatropic Reactions: Overview01:16

Thermal Sigmatropic Reactions: Overview

Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
Polymer Classification: Stereospecificity01:26

Polymer Classification: Stereospecificity

Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)01:22

Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)

Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
Newman Projections02:06

Newman Projections

Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
Chirality at Nitrogen, Phosphorus, and Sulfur02:30

Chirality 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...
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Hydrophobic-Hydrophilic Double-Layered Shells for Paraffin-Based Heat Storage Microcapsules.

Langmuir : the ACS journal of surfaces and colloids·2026
Same author

Switchable and Self-Learning Enantioseparation Based on Ultrafast Helix Induction and Memory of a Helical Polyacetylene.

Journal of the American Chemical Society·2026
Same author

Engineering Cylindrical Polymer Particles: Mechanisms and Fabrication under Mechanical Stress.

Langmuir : the ACS journal of surfaces and colloids·2026
Same author

Twisted Host-Guest Systems Exhibit Superamplification of Asymmetry via Coupled Strong Association and Helicity-Driven Cooperativity.

Journal of the American Chemical Society·2025
Same author

Nanoscale chemical characterization of functionalized graphene by heterodyne AFM-IR and chemical force microscopy.

Nanoscale·2025
Same author

Amplification of Asymmetry for Dynamic Helical Polymers through 1:1 Host-Guest Interactions: Theoretical Models for Majority Rule and Sergeants and Soldiers Effects.

Journal of the American Chemical Society·2025

Related Experiment Video

Updated: May 9, 2026

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
09:22

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives

Published on: February 7, 2017

Chiroptical inversion in helical Si-Si bond polymer aggregates.

Nozomu Suzuki1, Michiya Fujiki, Ruth Kimpinde-Kalunga

  • 1Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan.

Journal of the American Chemical Society
|August 8, 2013
PubMed
Summary

The chiroptical properties of helical polysilane aggregates are influenced by side chain length and solvent. A critical n-propyl side chain length enables solvent-dependent chiroptical inversion, predictable by theoretical models.

More Related Videos

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
10:35

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Published on: May 29, 2018

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
06:44

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

Related Experiment Videos

Last Updated: May 9, 2026

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
09:22

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives

Published on: February 7, 2017

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
10:35

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Published on: May 29, 2018

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
06:44

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

Area of Science:

  • Polymer Chemistry
  • Supramolecular Chemistry
  • Spectroscopy

Background:

  • Helical polymers exhibit unique chiroptical properties.
  • Understanding factors controlling chiroptical properties in polymer aggregates is crucial for materials science.
  • Previous studies have explored helical polysilanes but lacked detailed analysis of side chain effects on aggregation-induced chiroptical changes.

Purpose of the Study:

  • To investigate the influence of achiral alkyl side chain length on the chiroptical properties of helical polysilane aggregates.
  • To determine the role of cosolvent fraction in modulating chiroptical behavior.
  • To develop and validate a theoretical model for predicting chiroptical inversion in these systems.

Main Methods:

  • Synthesis of poly[alkyl-(S)-2-methylbutylsilane]s with varying achiral alkyl side chains (ethyl to n-hexyl).
  • Circular dichroism (CD) spectroscopy to analyze chiroptical properties of polymer aggregates.
  • Theoretical calculations using a combination of the cholesteric hard-core model and exciton chirality method, including TD-DFT (B3LYP, 6-31G(d)) on decamer models.

Main Results:

  • Chiroptical sign in CD spectra of polysilane aggregates is dependent on both achiral side chain length and cosolvent fraction.
  • The n-propyl side chain exhibited a critical length, leading to solvent-dependent chiroptical inversion upon aggregation.
  • Theoretical models successfully predicted the observed side chain length-dependent chiroptical inversion.

Conclusions:

  • Achiral side chain length is a key determinant of chiroptical properties in helical polysilane aggregates.
  • Solvent environment plays a significant role in controlling aggregation-induced chiroptical inversion.
  • The combined theoretical approach provides a powerful tool for understanding and predicting chiroptical phenomena in helical polymer systems.