Synthesis, Light-Emitting, and Two-Photon Absorption Properties of Platinum-Containing Poly(arylene-ethynylene)s Linked by 1,3,4-Oxadiazole Units

Abstract

A series of soluble and thermally stable group 10 platinum(II) polyyne polymers of the type [-CtC-Pt(PBu 3 ) 2 -CtC-Ar-Ox-Ar-] n (where Ox = 1,3,4-oxadiazole; Ar = p-C 6 H 4 or 2,7-dihexyl-9,9fluorene) and [-CtC-Pt(PBu 3 ) 2 -CtC-Ar-Ox-Ar-Ox-Ar-] n (where Ar = 2,7-dihexyl-9,9-fluorene) along with their corresponding dinuclear model compounds [Ph-Pt(PEt 3 ) 2 -CtC-Ar-] 2 -Ox-(where Ar = p-C 6 H 4 or 2,7-dihexyl-9,9-fluorene) and [Ph-Pt(PEt 3 ) 2 -CtC-Ar-Ox-] 2 -Ar-(where Ar = 2,7dihexyl-9,9-fluorene) were prepared and characterized. The regiochemical structure of the polymers has been ascertained by single-crystal X-ray analysis on the model compoundThe photophysical properties (absorption, excitation, emission, and nanosecond transient absorption spectra) of these metalated compounds in 2MeTHF at 298 and 77 K are reported. These findings are correlated by density functional theory (DFT) calculations. Geometry optimizations predict totally planar molecules for these metalated complexes and polymers, allowing better π-conjugation across the main chain. The ligands are strongly fluorescent but become also phosphorescent when the Pt atom is introduced in the backbone of the conjugated organometallic complexes and polymers. These emissions are assigned to ππ* transitions in all cases involving the Pt d xy orbitals. These Pt compounds exhibit two-photon absorption (2PA), and their 2PA cross sections (σ 2 ) have been determined. The potential of exploiting such metallopolymers for the design of electrophosphorescent polymer light-emitting devices (PLEDs) and their use as single-dopant for white PLEDs have also been discussed.

Coordination Programming of Photofunctional Molecules

“…These types of molecules feature intense one-photon absorptions in the visible and NIR regions, which are due to intramolecular charge-transfer (ICT) transitions, high fluorescent quantum yields, and large two-photon absorption cross sections. These features make D-A-D and A-D-A quadrupolar molecules promising materials for applications such as bioimaging [ 103 , 104 ], photodynamic therapy (PDT) [ 105 ], optical power limiting [ 106 , 107 ], organic light emitting diodes (OLEDs) [ 108 , 109 , 110 ], organic photovoltaic devices (OPVs) [ 111 , 112 ], and organic field effect transistors (OFETs) [ 113 , 114 ]. The electron acceptor abilities of Pechmann dye and its structural isomers make them excellent components for the D-A-D type of quadrupolar molecules; despite this, such systems have not yet been investigated.…”

Two-photon luminescent metal complexes for bioimaging and cancer phototherapy

“…However, the excitation signal of the UV-vis region (λ ex = 350-500 nm) limits their therapeutic applications.The benefits of the depth discrimination properties of metal complexes with TPA provide a practical solution. Although various metal complexes have been developed with large TPA cross-sections[65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80], reports on two-photon metal complexes as PDT agents have been rare. For example, Ru(II) complexes have demonstrated their efficiency for TPA as early as the1990s[61,62], but the first Ru-photosensitizer for two-photon PDT was not reported until 2009 by Lemercier[68].…”

Strong nonlinear optical phosphorescence from water-soluble polymer dots: Towards the application of two-photon bioimaging

“…According to the value of the triplet quantum yield (1.36%) of Ir(III) complex in Pdots, the maximal TPA action cross section of the Pdots in water was then calculated to be 15 GM. To the best of our knowledge, this value was among the largest TPA action cross-sections of phosphorescent materials in water, indicating that it was highly promising in the application of two-photon bioimaging [17,18].…”