Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation

Electro-mechanical Systems

Electro-mechanical Systems

Electromechanical systems are intricate configurations that effectively combine electrical and mechanical elements to achieve a desired outcome. Central to many of these systems is the DC motor, a device that converts electrical energy into mechanical motion, enabling various applications ranging from simple fans to complex robotic mechanisms.
A key component of the DC motor is the armature, a rotating circuit positioned within a magnetic field. As an electric current passes through the...

Indirect Motor Pathways

Indirect Motor Pathways

The indirect motor or extrapyramidal pathways originate in the brainstem, the lower portion of the brain that connects it to the spinal cord. They consist of several distinct tracts, each with specialized functions. The four main tracts of the indirect motor pathways are the vestibulospinal tract, the reticulospinal tract, the tectospinal tract, and the rubrospinal tract.
The vestibulospinal tract originates in the vestibular nuclei of the brainstem. The vestibular system detects changes in...

Thermal and Photochemical Electrocyclic Reactions: Overview

Thermal and Photochemical Electrocyclic Reactions: Overview

Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.

Motor Units

Motor Units

A motor unit consists of two main components: a single efferent motor neuron (i.e., a neuron that carries impulses away from the central nervous system) and all of the muscle fibers it innervates. The motor neuron may innervate multiple muscle fibers, which are single cells, but only one motor neuron innervates a single muscle fiber.

Motor Units

Motor Units

The motor unit is a fundamental component of the neuromuscular system and plays a crucial role in coordinating muscle contractions. It consists of a somatic motor neuron, which connects and controls multiple skeletal muscle fibers, forming a single functional segment. The axon of the motor neuron branches out and establishes synaptic connections known as neuromuscular junctions with individual muscle fibers within the motor unit.
Motor units come in different sizes, with smaller units...

You might also read

Related Articles

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

Sort by

Same author

GFP chromophore photophysics: ultrafast dynamics and hot ground state cooling in the neutral form.

Chemical science·2026

Same author

Utilizing Light to Control Glycopolymer-DC-SIGN Interactions via Molecular Motors.

Journal of the American Chemical Society·2026

Same author

Light-Driven Dual Rotary Molecular Motors and Beyond.

Accounts of chemical research·2026

Same author

Benzene at 200: from a simple ring to a universe of fused aromatic carbon.

Chemical science·2026

Same author

Temperature- and Light-Regulated Liquid Crystal Smart Window for Dynamic Control of Daylight and Solar Heat in All-Weather Conditions.

Angewandte Chemie (International ed. in English)·2026

Same author

Engineering Highly Photoefficient and Function-Tunable Molecular Rotary Motors toward Sunlight Responsiveness.

Journal of the American Chemical Society·2026

Search research articles

Related Experiment Video

Updated: Nov 11, 2025

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

Published on: March 13, 2019

Excited State Structure Correlates with Efficient Photoconversion in Unidirectional Motors.

Palas Roy¹, Andy S Sardjan², Arjen Cnossen²

¹School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.

The Journal of Physical Chemistry Letters

|March 30, 2021

Summary

Understanding ultrafast photochemical isomerization is key for designing molecular motors. This study links molecular structure, dark state lifetime, and vibrational spectra to photoisomerization efficiency, guiding the development of improved motor designs.

More Related Videos

Biophysical Characterization of Flagellar Motor Functions

Biophysical Characterization of Flagellar Motor Functions

Published on: January 18, 2017

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Published on: May 29, 2018

Related Experiment Videos

Last Updated: Nov 11, 2025

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

Published on: March 13, 2019

Biophysical Characterization of Flagellar Motor Functions

Biophysical Characterization of Flagellar Motor Functions

Published on: January 18, 2017

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

Published on: May 29, 2018

Area of Science:

Photochemistry
Molecular machines
Ultrafast spectroscopy

Background:

Unidirectional photomolecular motors rely on ultrafast photochemical isomerization.
An intermediate dark excited state mediates this reaction through a conical intersection (CI) with the ground state.
The relationship between molecular structure and photoisomerization efficiency remains unclear.

Purpose of the Study:

To investigate the correlation between molecular structure and photoisomerization efficiency in molecular motors.
To capture vibrational spectra of the dark state using femtosecond stimulated Raman spectroscopy.
To establish guidelines for designing more efficient molecular motor derivatives.

Main Methods:

Femtosecond stimulated Raman spectroscopy (FSRS) was employed.
Vibrational spectra of the dark state were recorded for molecular motors with varying substituents.
Photoisomerization quantum yield and dark state lifetime were measured.

Main Results:

A direct correlation was found between isomerization quantum yield, dark state lifetime, and excited state vibrational spectrum.
Electron-withdrawing substituents induced activity in lower frequency modes, linked to pyramidalization distortion at the ethylenic axle within 100 fs.
Electron-donating substituents did not promote this distortion, maintaining double bond character at the axle.

Conclusions:

The dark state structure significantly influences photoconversion performance.
Substituent effects on molecular structure, particularly ethylenic axle distortion, are critical for motor efficiency.
These findings provide a basis for rational design of enhanced photomolecular motors.