Electronic Delocalization in the Radical Cations of Porphyrin Oligomer Molecular Wires.

The radical cations of a family of π-conjugated porphyrin arrays have been investigated: linear chains of N = 1-6 porphyrins, a 6-porphyrin nanoring and a 12-porphyrin nanotube. The radical cations were generated in solution by chemical and electrochemical oxidation, and probed by vis-NIR-IR and EPR spectroscopies. The cations exhibit strong NIR bands at ∼1000 nm and 2000-5000 nm, which shift to longer wavelength with increasing oligomer length.

Photophysics of aminophenyl substituted pyrrolopyrrole cyanines.

A series of novel pyrrolopyrrole cyanines (PPCys) bearing various aminophenyl substituents at the diketopyrrolopyrrole (DPP) core are presented. Compared to their alkoxyphenyl substituted analogues, these dyes feature additional intense electronic transitions of charge-transfer character which give detailed insight into the optical properties of PPCys. The energetic mixing of the involved orbitals has pronounced effects on the absorption and fluorescence behavior.

Noninvasive photoacoustic and fluorescence sentinel lymph node identification using dye-loaded perfluorocarbon nanoparticles.

The contrast mechanisms used for photoacoustic tomography (PAT) and fluorescence imaging differ in subtle, but significant, ways. The design of contrast agents for each or both modalities requires an understanding of the spectral characteristics as well as intra- and intermolecular interactions that occur during formulation. We found that fluorescence quenching that occurs in the formulation of near-infrared (NIR) fluorescent dyes in nanoparticles results in enhanced contrast for PAT.

Asymmetric PPCys: strongly fluorescing NIR labels.

By a stepwise synthesis strategy biofunctionalized Pyrrolopyrrole Cyanines (PPCy) with an asymmetric substitution pattern were obtained. These exhibit extremely strong and narrowband NIR absorption and fluorescence. Internalization of a peptide bound PPCy is demonstrated using live cell microscopy.

Long fluorescence lifetime molecular probes based on near infrared pyrrolopyrrole cyanine fluorophores for in vivo imaging.

Fluorescence lifetime (FLT) properties of organic molecules provide a new reporting strategy for molecular imaging in the near infrared (NIR) spectral region. Unfortunately, most of the NIR fluorescent dyes have short FLT typically clustered below 1.5 ns.

Pyrrolopyrrole cyanine dyes: a new class of near-infrared dyes and fluorophores.

Pyrrolopyrrole cyanine (PPCy) dyes are presented as a novel class of near-infrared (NIR) chromophores, which are synthesized in a condensation reaction of diketopyrrolopyrrole with heteroarylacetonitrile compounds. Their optical properties are marked by strong and narrow-band NIR absorptions. Complexation products with BF(2) and BPh(2) show strong NIR fluorescence and hardly any absorption in the visible range.