Linked Life Data

21090739

Source:http://linkedlifedata.com/resource/pubmed/id/21090739

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
50
pubmed:dateCreated
2010-12-17
pubmed:abstractText
To gain a deeper understanding of how structural modifications may influence photochemical properties of 4'-phenyl-2,2':6',2''-terpyridines, the investigations presented here focus on electron delocalization in 4'-phenyl-2,2':6',2''-terpyridine derivatives and their Ru(II) and Zn(II) complexes. In those systems of neighboring aromatic rings the considerable torsion between the rings is commonly regarded to be the limiting factor for a well pronounced ?-conjugation between the rings. A common approach to improve the ?-conjugation is to lower the steric hindrance, thus achieving a more planar geometry. Here, we present a fundamentally different approach towards enhanced ?-conjugation by manipulation of the electronic properties of the pyridine-phenyl (py-ph) bond. This is accomplished by introducing various substituents at the phenylene moiety or coordinating the terpyridine moiety to transition metal ions. The electron delocalization was quantified via the DFT-calculated ellipticity in the bond-critical point (BCP) of the py-ph bond. This ellipticity can be modified due to substituents in the para position of phenylene and via the transition metals coordinated to the terpyridine moiety. Changes in electron density distribution induced by the substituents and the metal ions are further studied by means of intermolecular electron density difference plots. It was shown that a NH(2) group in the para position of the phenyl ring as well as the coordination to Ru(II) or Zn(II) ions significantly enhances the ?-character of the py-ph bond. Surprisingly, an even higher ?-character of the py-ph bond is achieved by introducing additional NH(2) groups in ortho position to the py-ph bond, despite the increased torsion between pyridine and phenylene. The introduction of other substituents (-NO(2), -Br, -CN, -vinyl, -ethynyl) studied within the presented work enables an actuation of the electron delocalization between terpyridine and phenylene. In doing so, the ellipticity is a concise quantity to characterize electron delocalization in the studied systems. Furthermore, the ellipticity in the BCP of the py-ph bond is related to the corresponding geometrical properties (e.g., bond length and dihedral angle) and to the DFT-calculated HOMO and LUMO energies.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1520-5215
pubmed:author
pubmed:issnType
Electronic
pubmed:day
23
pubmed:volume
114
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13163-74
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
A concept to tailor electron delocalization: applying QTAIM analysis to phenyl-terpyridine compounds.
pubmed:affiliation
Institute of Physical Chemistry, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743, Jena, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't