isomerized

(adjective)

converted from one isomer to another

Related Terms

Examples of isomerized in the following topics:

  • Isomers in Coordination Compounds

    • Structural isomerism occurs when the bonds are different.
    • Optical isomerism occurs when a molecule is not superimposable with its mirror image.
    • This type of isomerism occurs when the center ion of the complex is also a potential ligand.
    • Linkage isomerism occurs with ambidentate ligands that can bind in more than one place.
    • Explain the effect of isomerization on the properties of a coordination complex.

  • Alkene Isomerization

    • The cis-trans photochemical isomerization of stilbene is a reaction of the first kind, as shown in the first diagram below.
    • This simple configurational isomerization about a single double bond is referred to as a One-Bond-Flip (OBF) event.
    • The quantum yield of trans to cis isomerization decreases in viscous solvents, accompanied by an increase in fluorescent decay.
    • Freezing the solutions to a rigid glass halts the isomerization and results in maximum fluorescence efficiency.
    • The remaining 30% undergo an electrocyclic rearrangement to an isomeric 4a,4b-dihydrophenanthrene (DHP) S1 state, as illustrated in the second diagram above.

  • Organic Isomers

    • Isomers are molecules with the same chemical formula but have different structures, which creates different properties in the molecules.

  • Boiling Point and Water Solubility

    • The second table illustrates differences associated with isomeric 1º, 2º & 3º-amines, as well as the influence of chain branching.
    • Since 1º-amines have two hydrogens available for hydrogen bonding, we expect them to have higher boiling points than isomeric 2º-amines, which in turn should boil higher than isomeric 3º-amines (no hydrogen bonding).
    • Differences associated with isomeric 1º, 2º & 3º-amines and the influence of chain branching

  • Conjugated π-Orbital Functions

    • The light induced isomerization about the central double bond of the trienes (e.g.
    • Thus, the facile isomerization and weak fluorescence, typical for trans-stilbene in fluid solutions, change to low isomerization and strong fluorescence in rigid media at low temperatures.
    • A more complex, higher energy motion that achieves double bond isomerization in restrictive environments has been described and named the Hula-Twist.
    • The difference between OBF and HT isomerization of a Z to E-triene is shown above in the second diagram.
    • Difference between OBF and HT Isomerization of a Z to E-Triene

  • Stereoisomers

    • Isomers that differ only in the spatial orientation of their component atoms are called stereoisomers.

  • Achiral Diastereomers (Meso-Compounds)

    • Investigations of isomeric tartaric acid salts, carried out by Louis Pasteur in the mid 19th century, were instrumental in elucidating some of the subtleties of stereochemistry.

  • Cyclohexadienone Reactions

    • A photo-isomerization of this kind was used by H.
    • The ketene is removed by light induced isomerization and cyclization.
    • The formation of lumisantonin parallels the isomerization observed for the simpler dienone.
    • A blue-colored non-triplet intermediate has been observed in this isomerization.
    • The thermal isomerization of lumisantonin in acetic acid is drawn at the bottom of the diagram.

  • Carbon NMR Spectroscopy

    • The isomeric pairs previously cited as giving very similar proton nmr spectra are now seen to be distinguished by carbon nmr.
    • However, in its carbon nmr spectrum cyclohexane displays a single signal at δ 27.1 ppm, generated by the equivalent ring carbon atoms (colored blue); whereas the isomeric alkene shows two signals, one at δ 20.4 ppm from the methyl carbons (colored brown), and the other at 123.5 ppm (typical of the green colored sp2 hybrid carbon atoms).
    • Finally, the last isomeric pair, quinones A & B in the green box, are easily distinguished by carbon nmr.
    • Isomer A displays only four carbon nmr signals (δ 15.4, 133.4, 145.8 & 187.9 ppm); whereas, isomer B displays five signals (δ 15.9, 133.3, 145.8, 187.5 & 188.1 ppm), the additional signal coming from the non-identity of the two carbonyl carbon atoms (one colored orange and the other magenta).

  • General Summary of Isomerism and Molecular DescriptorsInclude Relationship of Constitutional and Stereoisomers and Relationships of Stereoisomers