Related Concept Videos
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.0K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.0K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
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
Selection Rules: Photochemical Activation
1.8K
01:28Stability of Conjugated Dienes
3.3K
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
3.3K
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
10.0K
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
10.0K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.3K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.3K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
10.1K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
10.1K
You might also read
Related Articles
Articles linked to this work by shared authors, journal, and citation graph.
Sort by
Same author
Cooperative Dinuclear Activation of a Formate Intermediate in the Hydrogenation of CO<sub>2</sub> to Methanol.
Molecules (Basel, Switzerland)·2026
Related Experiment Video
Updated: Jun 15, 2025
12:07
Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes
Published on: April 1, 2013
17.1K
Limiting Molecular Twisting: Upgrading a Donor-Acceptor Dye to Drive H2 Evolution.
Kaijian Zhu1, Ainoa Paradelo Rodríguez1, Maria B Brands2
1PhotoCatalytic Synthesis Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|August 27, 2024
Summary
Co-adsorbing myristic acid with a donor-acceptor dye on NiO photocathodes suppresses photoinduced twisting. This leads to enhanced photocurrent and, remarkably, direct hydrogen evolution without a catalyst.
More Related Videos
Area of Science:
- Materials Science
- Photochemistry
- Electrochemistry
Background:
- Donor-acceptor (D-A) dyes like P1 are used to functionalize NiO photocathodes for proton reduction.
- Photoinduced intramolecular twisting of D-A dyes can affect their energy levels and performance.
- Controlling dye conformation is crucial for optimizing photoelectrochemical devices.
Purpose of the Study:
- To investigate the effect of co-adsorbed myristic acid (MA) on the photoinduced twisting of P1 dye on NiO.
- To understand how MA influences charge separation, recombination, and electrochemical potential.
- To explore the potential for MA-induced hydrogen evolution without a dedicated catalyst.
Main Methods:
- Co-adsorption of P1 dye and myristic acid (MA) on NiO photocathodes.
- Density Functional Theory (DFT) calculations.
- Time-resolved photoluminescence spectroscopy.
Main Results:
- MA suppresses photoinduced twisting of the P1 dye on NiO.
- Suppressed twisting retards charge recombination and increases photocurrent.
- MA co-adsorption enables direct H2 evolution, attributed to Ni nanoparticle formation and catalysis.
Conclusions:
- Controlling intramolecular twisting of D-A dyes is vital for efficient solar fuel devices.
- Designing twisting-limited D-A dyes offers a promising strategy for enhanced photoelectrochemical performance.
- MA's role in tuning dye behavior and enabling catalyst-free H2 evolution is demonstrated.