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Updated: Jun 12, 2026
Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera
Published on: December 27, 2018
Optimizing simultaneous two-photon absorption and transient triplet-triplet absorption in platinum acetylide
Kye-Young Kim1, Abigail H Shelton, Mikhail Drobizhev
1Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, USA.
Abstract:
A series of platinum-containing organometallic dimer complexes has been synthesized and the photophysical properties have been investigated under one- and two-photon (2PA) absorption conditions. The complexes have the general structure [DPAF-C[triple bond]C-Pt(PBu(3))(2)-C[triple bond]C-Ar-C[triple bond]C-Pt(PBu(3))(2)-C[triple bond]C-DPAF], where Ar is a pi-conjugated unit, Bu = n-butyl, and DPAF = diphenylamino-2,7-fluorenylene. The core Ar units include 1,4-phenylene, 2,5-thienylene, 5,5'-(2,2'-bithienylene), 2,5-(3,4-ethylenedioxythiophene, 2,1,3-benzothiadiazole, and 4,7-dithien-2-yl-2,1,3-benzothiadiazole. Absorption and photoluminescence spectroscopy indicates that the complexes feature low-lying excited states based on both the core [-Pt(PBu(3))(2)-C[triple bond]C-Ar-C[triple bond]C-Pt(PBu(3))(2)-] chromophore as well as the DPAF units. Photoexcitation of the complexes produces a singlet state excited state, which rapidly undergoes intersystem crossing to afford a triplet state that has a lifetime in the microsecond time domain. In most cases, the lowest energy triplet state is localized on the core chromophore. Femtosecond 2PA spectra are measured along with triplet-triplet absorption spectra and nanosecond intensity-dependent transmission for solutions of the complexes. Each of the complexes features a 2PA absorption band in the near-infrared region (lambda approximately 700-750 nm) with a cross section 50-200 GM that is ascribed to the DPAF chromophore. The complexes also feature broad triplet-triplet absorption throughout the visible and near-infrared regions (lambda approximately 500-800 nm, (TT) approximately 5-10 x 10(4) M(-1) cm(-1)). Each of the complexes exhibits efficient nonlinear absorption of nanosecond pulses in the near-infrared region (600-800 nm), and we demonstrate that effect is most efficient in the chromophores where the 2PA cross section maxima coincides spectrally with the excited triplet state absorption.
