jp9b05688_si_001.pdf (7.07 MB)
Excited-State Triplet Equilibria in a Series of Re(I)-Naphthalimide Bichromophores
journal contribution
posted on 2019-08-23, 14:35 authored by James
E. Yarnell, Kaylee A. Wells, Jonathan R. Palmer, Josué M. Breaux, Felix N. CastellanoWe
present the synthesis, structural characterization, electronic
structure calculations, and the ultrafast and supra-nanosecond photophysical
properties of a series of five bichromophores of the general structural
formula [Re(5-R-phen)(CO)3(dmap)](PF6), where
R is a naphthalimide (NI), phen = 1,10-phenanthroline, and dmap is
4-dimethylaminopyridine. The NI chromophores were systematically
modified at their 4-positions with -H (NI), -Br (BrNI), phenoxy (PONI), thiobenzene (PSNI), and piperidine (PNI), rendering a series of metal–organic
bichromophores (Re1–Re5, respectively)
featuring variability in the singlet and triplet energies in the pendant
NI subunit. Five closely related organic chromophores as well as [Re(phen)(CO)3(dmap)](PF6) (Re6) were investigated
in parallel to appropriately model the photophysical properties exhibited
in the bichromophores. The excited state processes of all molecules
in this study were elucidated using a combination of transient absorption
spectroscopy and time-resolved photoluminescence (PL) spectroscopy,
revealing the kinetics of the energy transfer processes occurring
between the appended chromophores. The spectroscopic analysis was
further supported by electronic structure calculations which identified
the origin of many of the experimentally observed electronic transitions.