Three-branched dendritic dipolar nonlinear optical chromophores, more than three times a single-strand chromophore?
2008 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, no 47, 14751-14761 p.Article in journal (Refereed) Published
To elucidate the dependence of the nonlinear optical (NLO) response on the conformation of triply branched derivatives, a new series of D-pi-A dendrimers has been synthesized. A combined approach of experiments (UV-vis and EOA measurements) and computational predictions (semiempirical and ab initio) was applied both on the dendrimers and on the corresponding single-strand chromophores. It has been shown that depending on the surrounding media the NLO activity of a flexible dendrimer can be very different. Two limiting cases are proposed: (i) the dendrimer resembles a solution of the corresponding single-strand chromophores with about 3-fold concentration, where the hyperpolarizability is the sum of the effect of three noninteracting single-strand subunits ("independent chromophores" limit); (ii) the dendrimers show nearly parallel or helical alignments of the single-strand subunits. Because of this change of conformation the NLO activity can be enhanced up to nine times the value of the "independent chromophores" limit and, thus, are more than a single strand chromophore. Conformers of dendrimers with interacting single-strand chromophores have been identified experimentally in nonpolar solutions by the EOA spectroscopy and possible structures have been revealed by numerical calculations, which could moreover show the tendency of the effects on the hyperpolarizability due to structural changes of the flexible dendritic architecture. Implications for future research developments are given to implement the "more than three times" concept.
Place, publisher, year, edition, pages
2008. Vol. 112, no 47, 14751-14761 p.
Dendrimers; Numerical analysis; Ab initio; Computational predictions; Dendritic architectures; Future researches; Hyperpolarizability; Limiting cases; New series; Nlo activities; Nonlinear optical chromophores; Nonlinear optical responses; Nonpolar solutions; Numerical calculations; Semiempirical; Structural changes; Chromophores
IdentifiersURN: urn:nbn:se:kth:diva-6972DOI: 10.1021/jp802369cISI: 000261056400010ScopusID: 2-s2.0-57449109538OAI: oai:DiVA.org:kth-6972DiVA: diva2:11837
QC 20100820. Tidigare titel: Three-branched dendritic NLOphores, more than three times a single-strand chromophore? Titel ändrad och uppdaterad från Submitted till Published 20100820.2007-04-162007-04-162012-03-21Bibliographically approved