Effect on charge transfer and charge recombination by insertion of a naphthalene-based bridge in molecular dyads based on borondipyrromethene (bodipy).
The photophysical properties of two related dyads based on a N,N-dimethylaniline donor coupled to a fully-alkylated boron dipyrromethene (Bodipy) acceptor are described. In one dyad, BD1, the donor unit is attached directly to the Bodipy group, whereas in the second dyad, BD2, a naphthalene spacer separates the two units. Cyclic voltammograms recorded for the two dyads in deoxygenated MeCN containing a background electrolyte are consistent with the reversible one-electron oxidation of the N,N-dimethylaniline group and the reversible one-electron reduction of the Bodipy nucleus. There is a reasonable driving force (ΔG(CT)) for photoinduced charge transfer from the N,N-dimethylaniline to the Bodipy segment in MeCN. The charge-transfer state is formed for BD1 extremely fast (1.5 ps), but decays over 140 ps to partially restore the ground state. On the other hand, the charge-transfer state for BD2 is formed more slowly, but it decays extremely rapidly. Charge recombination for both dyads leads to a partial triplet formation on the Bodipy group. The naphthalene spacer group is extremely efficient at promoting back electron transfer.
Molecular Photonics Laboratory, School of Chemistry, Newcastle University, Newcastle upon Tyne, UK. a.c.benniston@ncl.ac.uk
Andrew C
AC
Benniston
Sophie
S
Clift
Jerry
J
Hagon
Helge
H
Lemmetyinen
Nikolai V
NV
Tkachenko
William
W
Clegg
Ross W
RW
Harrington