Related Experiment Video
Updated: Mar 14, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Photocontrol of Polar Aromatic Interactions by a Bis-Hemithioindigo Based Helical Receptor
Manuel Guentner1, Edgar Uhl1, Peter Mayer1
1Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, Munich, Germany.
Abstract:
The first example of a bis-hemithioindigo (bis-HTI)-based molecular receptor was realized. Its folding and selective binding affinity for aromatic guest molecules can be precisely controlled by visible light and heat. The thermodynamically stable state of the bis-HTI is the s-shaped planar Z,Z-configuration. After irradiation with 420 nm light only the E,Z-configuration is formed in a highly selective photoisomerization. The E,Z-isomer adopts a helical conformation because of the implementation of repulsive steric interactions. The E,Z-configured helix is able to recognize electron-poor aromatic guests exclusively through polar aromatic interactions and also distinguishes between regioisomers. After heating, the Z,Z-configuration is completely restored and the aromatic guest molecule is efficiently released.
Related Concept Videos
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Thermal and Photochemical Electrocyclic Reactions: Overview
Cycloaddition Reactions: MO Requirements for Photochemical Activation

![[DPEPhosbcpCu]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)