Related Experiment Video
Updated: Oct 6, 2025
05:47
Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts
Published on: August 7, 2018
7.9K
Understanding Ir(III) Photocatalyst Structure-Activity Relationships: A Highly Parallelized Study of Light-Driven
Stephen DiLuzio1, Timothy U Connell1, Velabo Mdluli1
1Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Journal of the American Chemical Society
|January 13, 2022
Summary
This study screened 1440 iridium complexes for photoreduction of tin and zinc. Optimized catalysts require high light absorption, excited state quenching, and cage escape efficiencies for efficient metal deposition.
Area of Science:
- Photochemistry
- Materials Science
- Catalysis
Background:
- Heteroleptic iridium complexes ([Ir(C^N)2(N^N)]+) are investigated for photochemical applications.
- Photoreduction of metal cations is crucial for materials synthesis and energy storage.
Purpose of the Study:
- To evaluate the photochemical activity of 1440 distinct iridium complexes for Sn(II) and Zn(II) photoreduction.
- To establish structure-activity relationships and elucidate the mechanism of photoreduction.
Main Methods:
- High-throughput synthesis and screening of 1440 heteroleptic iridium complexes.
- Kinetic data collection using home-built photoreactors and automated fitting for initial rates.
- Development of a formal photochemical rate law.
Main Results:
- Measured initial rates for Sn(0) and Zn(0) deposition ranged from 0-120 μM/s and 0-90 μM/s, respectively.
- No clear correlations were found between photochemical reactivity and photophysical properties (excited state lifetime, emission spectra).
- Initial rates correlated with incident photon flux and three elementary efficiencies: light absorption, excited state quenching, and cage escape.
Conclusions:
- The most active photocatalysts exhibit high efficiencies in light absorption, excited state quenching, and cage escape.
- Catalyst engineering strategies should focus on maximizing these three elementary efficiencies.
- The developed kinetic treatment provides mechanistic insights into structure-function trends for photocatalyst design.
Related Concept Videos
01:34The Z-Scheme of Electron Transport in Photosynthesis
10.8K
The light reactions of photosynthesis assume a linear flow of electrons from water to NADP+. During this process, light energy drives the splitting of water molecules to produce oxygen. However, oxidation of water molecules is a thermodynamically unfavorable reaction and requires a strong oxidizing agent. This is accomplished by the first product of light reactions: oxidized P680 (or P680+), the most powerful oxidizing agent known in biology. The oxidized P680 that acquires an electron from the...
10.8K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.5K
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...
3.5K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
8.2K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
8.2K
02:13Reduction of Alkenes: Catalytic Hydrogenation
12.7K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
12.7K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.9K
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
1.9K
01:18Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
2.3K
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...
2.3K