Related Experiment Video
Updated: Jun 22, 2026
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
07:12
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Capped subporphyrins.
Yasuhide Inokuma1, Atsuhiro Osuka
1Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 6068502, Japan.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 9, 2009
Summary
New capped subporphyrins were synthesized and characterized. Subporphyrin 13 shows slow spiral interconversion due to charge-transfer and CH-pi interactions, impacting its optical properties.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Photochemistry
Background:
- Subporphyrins are macrocyclic compounds with unique electronic and structural properties.
- Capping strategies can modulate the properties of macrocyclic systems.
- Understanding structure-property relationships is crucial for designing new functional molecules.
Purpose of the Study:
- To synthesize novel C(3)-symmetric capped subporphyrins.
- To investigate the structural, conformational, and photophysical properties of these capped systems.
- To elucidate the role of cap structure and electronic nature in subporphyrin behavior.
Main Methods:
- Lindsey's macrocyclization for synthesis.
- X-ray diffraction for structural analysis.
- Variable-temperature (1)H NMR spectroscopy for conformational studies.
- UV-Vis spectroscopy for photophysical characterization.
Main Results:
- Successful synthesis of capped subporphyrins 12-16.
- X-ray analysis revealed selective capping with a benzene moiety.
- Solvent incorporation observed in larger cavity subporphyrins (15, 16).
- Tight structures with close interplanar separations in subporphyrins 12 and 13.
- Variable-temperature (1)H NMR showed spiral interconversions (P/M forms) in subporphyrins 12, 13, and 16.
- Subporphyrin 13 exhibited slow interconversion (ΔH‡ = 76.4 kJ mol⁻¹) with optical shifts (Soret-like and Q(0,0) bands).
Conclusions:
- Capped subporphyrins can be synthesized with controlled structures.
- Arm length and cap electronics influence cavity size and conformational dynamics.
- Subporphyrin 13's properties are attributed to through-space charge-transfer and CH-pi interactions.
- These findings offer insights into designing functional supramolecular systems.
![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
Related Concept Videos
02:36Crown Ethers
Crown ethers are cyclic polyethers that contain multiple oxygen atoms, usually arranged in a regular pattern. The first crown ether was synthesized by Charles Pederson while working at DuPont in 1967. For this work, Pedersen was co-awarded the 1987 Nobel Prize in Chemistry. Crown ethers are named using the formula x-crown-y, where x is the total number of atoms in the ring and y is the number of ether oxygen atoms. The term 'crown' refers to the crown-like shape that these ether molecules take.
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
01:17Oxidation of Phenols to Quinones
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
01:41The Supercomplexes in the Crista Membrane
The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
01:14Drug Metabolism: Phase II Reactions
Phase II reactions are essential for the detoxification and elimination of drugs from the body. These reactions involve the conjugation of parent drugs or their phase I metabolites with endogenous molecules, resulting in more hydrophilic drug conjugates. The primary conjugation reactions in this phase are sulfation and glucuronidation. Both sulfation and glucuronidation typically produce biologically inactive metabolites. However, in some cases involving prodrugs, active metabolites may be...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.