Related Experiment Video
Updated: Nov 18, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Comparative Study of the Gas-phase Cyclodimer Formations of Uracil and 6-azauracil in Excited State and through
Abstract:
The photocyclodimerization mechanisms of two oxo tautomers of uracil and 6-azauracil were studied at the CC2 level of theory and cc-pVDZ basis functions. Uracil was explored in three orientations of the monomers - cis-anti, trans-syn and trans-anti, while 6-azauracil - in all four orientations. Conical intersections S0/S1 were found at the CASSCF(2,2)/6-31G* theoretical level. The study propose a photophysical mechanisms of photoformation and photodestruction of cyclodimers (CDs), which occur through the 1∆∆* electron excited states (spectroscopically bright states). The photophysical relaxations (internal conversions) to the ground states are mediated by conical intersections S0/S1, which we found and discussed in the current paper.
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Thermal and Photochemical Electrocyclic Reactions: Overview
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...
Stereoisomerism of Cyclic Compounds
Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...

