Related Experiment Video
Updated: Aug 5, 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)
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Benzo[c][1,2,5]Thiadiazole Linkers Enhance the Effectiveness of Cavity-Containing Supramolecular Photocatalysts
Leonardo Amicosante1, Dominic Taylor1, Cameron L Campbell1
1Institute of Chemical Sciences, Heriot-Watt University, Riccarton, Edinburgh, UK.
Abstract:
A family of seven novel supramolecular photosensitizers comprising benzo[c][1,2,5]thiadiazole (BTZ) tethered calix[4]arene (C[4]) scaffolds has been synthesized using cross-coupling strategies with selectively halogenated C[4]s, affording target compounds in high yield using facile purification. Their respective abilities to produce singlet oxygen has been evaluated through the photo-oxidation of α-terpinene, and structure-activity relationships established, probing factors such as cavity:photosensitizer ratio, distance of cavity to photosensitizer linker, and steric hindrance around the upper-rim of the cavity. The presence of two C[4] cavities proximal to the photosensitizing BTZ unit provided vastly increased effectiveness in enhancing effective concentration through host:guest interactions, resulting in an eightfold increase in efficiency for the best-performing member of the compound library benchmarked against a small-molecule analogue, and reaching reaction completion in 1 h at 2.5 mol% loading. In contrast, systematically increasing the cavity:photosensitizing linker distance led to a reduction in improvement to 1.1-fold relative to the small molecule analogue, confirming that these factors are pivotal in designing a suitable system based on the guest substrate.
Related Concept Videos
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene

