Directly Coupled Versus Spectator Linkers on Diimine Pt acetylidesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 6 февраля 2018 г.
Аннотация:Modification of light-harvesting units with anchor-
ing groups for surface attachment often comprom ises light-
harnessing properties. Herein, a series of [donor–acceptor–
anchor] platinum(II) diimine (bis-)acetylides was developed
in order to systematically compare the effect of conjugated
versus electronically decoupled modes of attachment of pro-
tected anchoring groups on the photophysical properties of
light-harvesting units. The first examples of “decoupled”
phosphonate diimine Pt
II
complexes are reported, and their
properties are compared and contrasted to those of carbox-
ylate analogues studied by a diversity of methods. Ultrafast
time-resolved IR and transient absorption spectroscopy re-
vealed that all complexes have a charge-transfer (CT) lowest
excited state with lifetimes between 2 and 14 ns. Vibrational
signatures and dynamics of CT states were identified; the as-
signment of electronic states and their vibrational origin was
aided by TDDFT calculations. Ultrafast energy redistribution
accompanied by structural changes was directly captured in
the CT states. A significant difference between the structures
of the electr onic ground and CT excited states, as well as dif-
ferences in the structural reorganisation in the complexes
bearing directly attached or electronically decoupled anchor-
ing groups, was discovered. This work demonstrates that de-
coupling of the anchoring group from the light-harvesting
core by a saturat ed spacer is an easy approach to combine
surface attachment with high reduction potential and ten
times longer lifetime of the CT excited state of the light-ab-
sorbing unit, and retain electron-transfer photoreactivity es-
sential for light-harvesting applications.