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Material profiling for photocrystallography

OAI: oai:purehost.bath.ac.uk:openaire_cris_publications/be9ce4e3-841c-4547-8f2f-e5df7f04aa9f DOI: https://doi.org/10.1021/cg301386s
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Abstract

The photophysical properties of seven luminescent
iridium complexes are characterized in their single-crystal
form, and the photoactivity is related to their molecular
structures. Specifically, solid-state optical emission spectra and
associated lifetimes are determined from single crystals of
iridium complexes containing three bidentate ligands: two
variously substituted 2-phenylbenzothiazoles and either a 2,4-
pentadione (acetylacetone) or 2-pyridinecarboxylic (picolinic)
acid. All complexes studied exhibit emissive behavior in the
solid-state which originates from 3π−π* and metal-to-ligandcharge-
transfer (MLCT) electronic transitions; this is supported by density functional theory. Phosphorescence is observed in all
cases with microsecond lifetimes, ranging from 0.30 to 2.4 μs at 298 K and 1.4−4.0 μs at 100 K. Structure−property relationships
are established which are relevant to the potential solid-state application of this series of luminescent complexes as organic light
emitting diodes (OLED) material components. In addition, these materials are assessed for their suitability to time-resolved
pump−probe photocrystallography experiments, which will reveal their photoexcited state structure. Accordingly, the design
process by which materials are selected and technical parameters are defined for a photocrystallography experiment is illustrated.
This family of complexes presents a case study for this photocrystallography material profiling. Results show that the timeresolved
photoexcited state structure, featuring the MLCT transition is, in principle at least, viable for two of these complexes.