Related Experiment Video
Updated: Jun 23, 2026
08:52
Chemical Dimerization-Induced Protein Condensates on Telomeres
Published on: April 12, 2021
Photodimerization of chromone
Masami Sakamoto1, Masayuki Kanehiro, Takashi Mino
1Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. sakamotom@faculty.chiba-u.jp
Chemical Communications (Cambridge, England)
|April 21, 2009
Summary
Irradiation of chromone formed two dimer types: anti-head-to-tail (HT) and trans-fused HT isomers. X-ray analysis confirmed the structures of these novel chromone dimers.
Area of Science:
- Photochemistry
- Organic Chemistry
- Crystallography
Background:
- Chromone (benzo-gamma-pyrone) is a core structure in many natural products.
- Understanding chromone photochemistry is crucial for synthetic and medicinal chemistry applications.
Purpose of the Study:
- To investigate the photochemical behavior of simple chromone.
- To identify and characterize the dimers formed upon irradiation of chromone.
Main Methods:
- Photochemical irradiation of chromone.
- X-ray structural analysis for dimer characterization.
Main Results:
- Formation of two distinct chromone dimers: anti-head-to-tail (HT) and trans-fused HT isomers.
- Definitive structural elucidation of both dimer types using X-ray crystallography.
Conclusions:
- Chromone undergoes dimerization upon irradiation, yielding specific anti-HT and trans-fused HT isomers.
- X-ray crystallography provides unambiguous structural confirmation for these photochemical products.
Related Concept Videos
01:26Photochemical 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
Selection Rules: Photochemical Activation
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
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.
01:26Thermal 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.
02:04Polytene Chromosomes
Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...
01:29The Photochemical Reaction Center
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...
01:11Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.