Related Experiment Video
Updated: Apr 2, 2026

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
Relaxation Photoprocesses in a Crowned Styryl Dye and its Metal Complex
Michael V Rusalov1, Boris M Uzhinov2, Sergey I Druzhinin3
1Department of Chemistry, MV Lomonosov Moscow State University, Leninskie Gory 1, 119991, Moscow, Russian Federation. mvrusalov@yandex.ru.
Abstract:
The effects of solvent and crown-ether moiety on spectral properties of pyridinium styryl dye were studied by steady-state absorption and fluorescent spectroscopy. Analysis of viscosity and polarity effects on fluorescence quantum yield and Stokes shift permitted us to suggest that there is a two stage process of excited state relaxation. The macrocyclic moiety has a little influence on the first stage of relaxation, which manifests itself in a magnitude of Stokes shift, but suppresses considerably the second stage, which manifests itself in a magnitude of fluorescence quantum yield. The metal complex shows an additional stage of excited state relaxation, namely, photorecoordination of metal cation within the macrocyclic cavity.
Related Concept Videos
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Complexation Equilibria: Factors Influencing Stability of Complexes
Colors and Magnetism
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...
Deactivation Processes: Jablonski Diagram
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.

