Christine O. Paul-Roth

Platinum and palladium complexes of fluorenyl porphyrins as red phosphors for light-emitting devices

Platinum(II) and palladium(II) complexes of a porphyrin with fluorenyl groups linked directly at the meso-positions (TFP) have been synthesized and characterized. Their luminescence properties in solution have been studied under ambient conditions and at 77 K. Compared to the corresponding complexes of tetraphenylporphyrin TPP, the emission is red-shifted in both cases. Radiative rate constants are found to be enhanced by the fluorenyl substituents, although non-radiative decay rates are also increased in solution. Short-wavelength UV excitation leads to no detectable fluorenyl-based fluorescence, indicating that a very efficient transfer of energy to the porphyrin occurs. An OLED in which PtTFP is used as a red phosphor has been prepared and its electroluminescence performance assessed. High current “roll-off” is significantly delayed to higher currents compared to previously described OLEDs that make use of standard platinum porphyrins as emitters, an effect which can be attributed to the shorter radiative lifetime of PtTFP.

Ruthenium–porphyrin-catalyzed carbenoid addition to allylic compounds: application to [2,3]-sigmatropic rearrangements of ylides

Abstract The catalytic effectiveness of ruthenium porphyrins for ylide generation in reactions of ethyl diazoacetate and diisopropyl diazomethylphosphonate with allylic amines, sulfides and iodides is described for the first time. These reactions result mainly in products of the [2,3]-sigmatropic rearrangement of intermediate allylic ylides.

Cyclopropanation of alkenes with diisopropyl diazomethylphosphonate catalysed by ruthenium porphyrin complexes

Stereoselectivities, regioselectivities and yields for cyclopropanation reactions of diisopropyl diazomethylphosphonate (DAMP) with styrene derivatives, catalysed by ruthenium porphyrins, are reported and compared with those observed for cyclopropanation reactions catalysed by other metalloporphyrins. Linear correlations are observed when the rates for competitive cyclopropanation and ratio of the stereoisomers obtained are plotted against Hammet constants of various ring-substituted groups on styrene. Isomeric distribution for the cyclopropanation of 1,3-pentadiene with diisopropyl diazomethylphosphonate is reported. Competition studies between cyclopropanation and diazo insertion into heteroatom-hydrogen bonds and also between cyclopropanation and sigmatropic reaction are reported. A first example of asymmetric cyclopropanation with a chiral catalyst is also described.

Enhanced two-photon absorption cross-sections of zinc(II) tetraphenylporphyrins peripherally substituted with d 6 -metal alkynyl complexes

The syntheses of new Zn(II) tetraphenylporphyrin (ZnTPP) derivatives functionalized with electron-rich d6-transition metal alkynyl complexes at their periphery are reported. Z-scan measurements reveal remarkably large effective two-photon absorption (TPA) cross-sections in the visible range for these compounds.

Cyclopropyl phosphonate ester synthesis catalyzed by ruthenium porphyrins: first characterization of a phosphonate carbene complex

Abstract Catalytic systems derived from Ru(CO)porphyrins are extremely efficient at converting styrene and diisopropyl diazomethyl phosphonate to cyclopropyl phosphonate esters in high yields and with high stereoselectivity; a monocarbene complex Ru(TPP)(CH{P(O)(O i Pr) 2 }) has been isolated as a possible catalytically active species.

Dendritic molecular assemblies for singlet oxygen generation: meso-tetraphenylporphyrin-based biphotonic sensitizers with remarkable luminescence

Four new TPP-based chromophores (1–4) peripherally functionalized with dendrons containing 2-fluorenyl groups were studied for their potential to serve in photodynamic therapy. Their linear and nonlinear optical properties were investigated. With significant TPA cross-sections at 790 nm, good singlet oxygen generation capabilities and relatively large intrinsic fluorescence, sensitizers such as 1 might become particularly appealing for theranostics.

Synthesis and Characterization of New Conjugated Fluorenyl-Porphyrin Dendrimers for Optics

A new family of conjugated meso-tetraphenylporphyrin-based dendrimers with four (TPP1, TPP2), eight (TPP3, TPP4, TPP5) and up to sixteen (TPP6) fluorenyl groups has been synthesized and fully characterized. These tetraphenylporphyrin-cored dendrimers present peripheral alkynyl π-conjugated dendrons with fluorenyl termini. The meso-aryl rings of these porphyrins are functionalized either in para- (TPP1, TPP2, and TPP3) or meta-positions (TPP4, TPP5, and TPP6). Their detailed luminescence properties are discussed in reference to two porphyrins lacking fluorenyl dendrons (TPP-H1,2,3 and TPP-H4,5,6). A strong dependence of their luminescence quantum yield and lifetime on their structures is stated, their nonlinear optical properties were also discussed.

New Conjugated meso-Tetrafluorenylporphyrin-Cored Derivatives as Fluorescent Two-Photon Photosensitizers for Singlet Oxygen Generation

A series of three conjugated meso-porphyrin dendrimers containing conjugated dendrons featuring 2,7-fluorenyl groups, incorporating overall 8, 12, or 28 fluorenyl units have been synthesized and characterized. The photophysical properties of these new compounds were studied in the context of photodynamic therapy. The relevant linear and nonlinear optical properties were measured in organic media and useful structure-properties relationships were derived.

New porphyrin-based dendrimers with alkene linked fluorenyl antennae for optics

The design of porphyrin-based dendrimers featuring conjugated dendrons via alkene spacers herein demonstrates their important role in determining linear optical properties, as well as two-photon absorption (PA) and singlet oxygen photosensitising properties. Improvement in these properties compared to those observed for their analogous alkyne spacers makes these molecules appealing for combined 2-photon-based photodynamic therapy (PDT) and imaging.