Slope <i>s</i> and y-axis intersections <i>l₀</i> for calibration curves established for typical measurement sessions.

<p>Slope <i>s</i> and y-axis intersections <i>l₀</i> for calibration curves established for typical measurement sessions.</p

Photograph of the special made Dewar WG-821-TMR-SPECIAL (labelled “B”) containing a 100 µL tablet in a 8 mm precision bore Suprasil tube 513A-1PP-7SUP (labelled “A”).

<p>A Bruker 3122SHQE resonator is also shown in the figure indicating the position of the special made Dewar with the 100 µL tablet inside the resonator. Both the Suprasil tube and Dewar are from Wilmad-LabGlas (Vineland, New Jersey, USA).</p

Table shows the initial results of quantification of ROS in rat myocardial tissue samples (first column) and the results of a repeated series of measurements after storage in −80°C during six month (second column).

<p>Third column show the difference between the two measurement sessions. (Estimated uncertainty ±10 µM (k = 1)).</p

EPR peak-to-peak value as a function of [CP•] in calibration samples of CP• solved in KHB (circles).

<p>Calibration curve calculated using least-squares-method for the shown example was deduced to <i>s</i> = 0.03436 µM⁻¹ (slope of calibration curve) and <i>l₀</i> = 0.24179 (the y-axis intersection of the calibration curve (dimensionless)).</p

EPR spectra for CP• (grey line) and CM• (black line) obtained at 150 K using the parameters for quantitative EPR.

<p>For clarity only the central part of the spectra is shown and EPR spectra was normalised for equal signal intensity.</p

Photophysical and DFT Characterization of Novel Pt(II)-Coupled 2,5-Diaryloxazoles for Nonlinear Optical Absorption

Several new bis-phosphine platinum­(II) complexes with 2,5-diaryl-substituted oxazole-containing alkyne ligands have been synthesized and optically characterized in solution. Measurements of nonlinear absorption showed strong attenuation of laser light at 532 and 600 nm. The light absorption of the Pt complexes was shifted from the near-UV region for the ground state to the red region for the excited triplet state, and was associated with large extinction coefficients. The optical limiting effect can be explained by triplet–triplet excited state absorption in conjunction with fast excited singlet–to-triplet intersystem crossing and slow triplet–to-ground-state decay, in comparison with the pulse length of the laser. DFT calculations show good predictability of the S₀–S₁ and S₀–T₁ energy gaps and offer insight into the interaction strength between Pt and the alkyne ligands. The use of this type of ligand, with weak absorption for the Pt­(II) complexes in the visual wavelength range as a key feature, enables the possibility to further improve these molecular systems for nonlinear absorption applications

Toward a Molecular Understanding of the Detection of Amyloid Proteins with Flexible Conjugated Oligothiophenes

Molecular and electronic structures and optical absorption properties of oligothiophenes used for spectral assignment of amyloid deposits have been investigated for a family of probes known as luminescent conjugated oligothiophenes (LCOs). Theoretical absorption spectra have been determined using conformational averaging, combining classical molecular dynamics (MD) simulations with quantum mechanical/molecular mechanics (QM/MM) time-dependent density functional theory (TD-DFT) spectrum calculations. Theoretical absorption spectra are in excellent agreement with experiments, showing average errors below 5 nm for absorption maxima. To couple observed properties to molecular structures, a measure of planarity is defined, revealing a strong correlation between the transition wavelength of the first and dominating electronically excited state and dihedral rotations. It is shown that from this correlation, predictions can be made of the absorption properties of probes based only on information from MD trajectories. We show experimentally that red shifts observed in the excitation maxima of LCOs when bound to amyloid protein aggregates are also evident in absorption spectra. We predict that these red shifts are due to conformational restriction of the LCO in a protein binding pocket, causing a planarization of the conjugated backbone. On the basis of our studies of planarity, it is shown that such shifts are both possible and realistic

Silica Hybrid Sol–Gel Materials with Unusually High Concentration of Pt–Organic Molecular Guests: Studies of Luminescence and Nonlinear Absorption of Light

The development of new photonic materials is a key step toward improvement of existing optical devices and for the preparation of a new generation of systems. Therefore synthesis of photonic hybrid materials with a thorough understanding and control of the microstructure-to-properties relationships is crucial. In this perspective, a new preparation method based on fast gelation reactions using simple dispersion of dyes without strong covalent bonding between dye and matrix has been developed. This new sol–gel method is demonstrated through synthesis of monolithic siloxane-based hybrid materials highly doped by various platinum­(II) acetylide derivatives. Concentrations of the chromophores as high as 400 mM were obtained and resulted in unprecedented optical power limiting (OPL) performance at 532 nm of the surface-polished solids. Static and time-resolved photoluminescence of the prepared hybrid materials were consistent with both OPL data and previous studies of similar Pt­(II) compounds in solution. The impacts of the microstructure and the chemical composition of the matrix on the spectroscopic properties, are discussed

Evidence for Age-Dependent <i>in Vivo</i> Conformational Rearrangement within Aβ Amyloid Deposits

Deposition of aggregated Aβ peptide in the brain is one of the major hallmarks of Alzheimer’s disease. Using a combination of two structurally different, but related, hypersensitive fluorescent amyloid markers, LCOs, reporting on separate ultrastructural elements, we show that conformational rearrangement occurs within Aβ plaques of transgenic mouse models as the animals age. This important mechanistic insight should aid the design and evaluation of experiments currently using plaque load as readout

Evidence for Age-Dependent <i>in Vivo</i> Conformational Rearrangement within Aβ Amyloid Deposits

Deposition of aggregated Aβ peptide in the brain is one of the major hallmarks of Alzheimer’s disease. Using a combination of two structurally different, but related, hypersensitive fluorescent amyloid markers, LCOs, reporting on separate ultrastructural elements, we show that conformational rearrangement occurs within Aβ plaques of transgenic mouse models as the animals age. This important mechanistic insight should aid the design and evaluation of experiments currently using plaque load as readout