Related Experiment Video
Updated: Jan 2, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Isomeric Dithienophosphepines: The Impact of Ring Fusion on Electronic and Structural Properties
Kevin Padberg1, Johannes D R Ascherl2, Frank Hampel1
1Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nürnberg, Nikolaus-Fiebiger-Strasse 10, 91058, Erlangen, Germany.
Abstract:
The synthesis and extensive experimental (X-ray crystallography, UV/Vis spectroscopy, cyclic voltammetry) and theoretical (DFT calculations) characterization of two isomeric dithieno[b,f]phosphepines (DTPs) are presented herein. The relative orientation of the phosphepine and the thiophene moieties has a decisive impact on the electronic and structural properties of these compounds. Moreover, the thiophene units allow for a facile subsequent functionalization through direct Pd-catalyzed C-H coupling, which renders DTPs highly promising building blocks for organophosphorus functional materials.
Related Concept Videos
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Stereoisomerism of Cyclic Compounds
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.
Variables Affecting Phosphorescence and Fluorescence
Stability of Conjugated Dienes
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.

