NMR Spin-Spin Coupling Constants in Polymethine Dyes as Polarity Indicators
2012 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 37, 11677-11684 p.Article in journal (Refereed) Published
Herein, we explore the use of spinspin coupling constants (SSCCs) in merocyanine (MCYNE) dyes as indicators of polarity. For this purpose, we use CarParrinello hybrid quantum mechanics/molecular mechanics (QM/MM) to determine the structures of MCYNE in solvents of different polarity, followed by computations of the SSCCs by using QM/MM linear-response theory. The molecular geometry of MCYNE switches between neutral, cyanine-like, and zwitterionic depending on the polarity of the solvent. This structural variation is clearly reflected in the proton SSCCs in the polymethine backbone, which are highly sensitive to the dielectric nature of the environment; this mechanism can be used as a polarity indicator for different microenvironments. This result is highlighted by computing the SSCCs of the MCYNE probe in the cavity of the beta-lactoglobulin protein. The computed SSCCs clearly indicate a non-polar hydrophobic dielectric nature of this cavity.
Place, publisher, year, edition, pages
2012. Vol. 18, no 37, 11677-11684 p.
dyes, merocyanines, NMR spectroscopy, polarity, structure elucidation
IdentifiersURN: urn:nbn:se:kth:diva-102901DOI: 10.1002/chem.201200270ISI: 000308313100025ScopusID: 2-s2.0-84865746711OAI: oai:DiVA.org:kth-102901DiVA: diva2:558605
FunderSwedish e‐Science Research Center
QC 201210042012-10-042012-09-282013-03-14Bibliographically approved