Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, USA.
J Phys Chem A. 2010 Jul 8;114(26):7003-13. doi: 10.1021/jp1005567.
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.
已经合成了一系列含铂的有机金属二聚体配合物，并在单光子和双光子（2PA）吸收条件下研究了它们的光物理性质。这些配合物具有通式[DPAF-C≡C-Pt(PBu(3))(2)-C≡C-Ar-C≡C-Pt(PBu(3))(2)-C≡C-DPAF]，其中 Ar 是一个 π 共轭单元，Bu=n-丁基，DPAF=二苯基氨基-2,7-芴基。核心 Ar 单元包括 1,4-亚苯基、2,5-噻吩基、5,5'-(2,2'-联噻吩基)、2,5-(3,4-亚乙基二氧噻吩基)、2,1,3-苯并噻二唑和 4,7-二噻吩-2-基-2,1,3-苯并噻二唑。吸收和光致发光光谱表明，这些配合物具有基于核心[-Pt(PBu(3))(2)-C≡C-Ar-C≡C-Pt(PBu(3))(2)-]发色团以及 DPAF 单元的低激发态。配合物的光激发产生单重态激发态，该激发态迅速经历系间窜跃，提供具有微秒时间域寿命的三重态。在大多数情况下，最低能量的三重态定域在核心发色团上。测量了飞秒 2PA 光谱以及配合物溶液的三重态-三重态吸收光谱和纳秒强度相关透射率。每个配合物在近红外区域（lambda approximately 700-750nm）都具有 2PA 吸收带，其截面为 50-200 GM，归因于 DPAF 发色团。这些配合物在可见光和近红外区域（lambda approximately 500-800nm，(TT) approximately 5-10 x 10(4) M(-1) cm(-1))也具有宽的三重态-三重态吸收。每个配合物在近红外区域（600-800nm）都表现出纳秒脉冲的有效非线性吸收，我们证明，这种效应在 2PA 截面最大值与激发三重态吸收光谱匹配的发色团中最为有效。
