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Highlights: [•] Energy transfer from the excited 3*MLCT to aromatic hydrocarbons has been studied. [•] Strongly exergonic as well as isoenergetic processes have been investigated. [•] Solvent viscosity affects the energy transfer rates in the both studied cases. [•] The overall energy transfer rate constants have been found to be slower than diffusion. [•] Magnetic quantum number conservation rule was applied to explain the observed deviations. [Copyright &y& Elsevier]

Abstract: Decays of emission from the excited metal-to-ligand-charge-transfer triplet state (3*MLCT) have been investigated for several luminescent Ir(III) complexes in acetonitrile solutions. Experiments have been performed in the absence as well as in the presence of organic acceptor quenchers (A) having triplet state (3*A) energies close to that characteristic of the 3*MLCT state. This similarity in energies between the 3*MLCT and 3*A states allows observing reversible energy transfer (REN) processes that manifest as changes in the emission decay profiles. In the presence of an organic quencher, the 3*MLCT emission decays change from mono-exponential (characteristic of the excited 3*MLCT state of the investigated complexes) to bi-exponential. The analysis of these observed bi-exponential decays (performed using the Birks’ formalism) enables the determination of the kinetic parameters characterizing the investigated forward and backward REN processes. The applied approach is proposed as an alternative method for determining molecular triplet state energies and lifetimes that are sometimes difficult to measure in liquid media. [Copyright &y& Elsevier]

Purpose: To introduce a new approach for keratoconus detection based on corneal microstructure observed in vivo derived from a single Scheimpflug image., Methods: Scheimpflug single-image snapshots from 25 control subjects and 25 keratoconus eyes were analyzed; from each group, five subjects were randomly selected to provide out-of-sample data. Each corneal image was segmented, after which the stromal pixel intensities were statistically modeled with a Weibull distribution. Distribution estimated parameters α and β , characterizing corneal microstructure, were used in combination with a macrostructure parameter, central corneal thickness (CCT), for the detection of keratoconus. In addition, receiver operating characteristic curves were used to determine the sensitivity and specificity of each parameter for keratoconus detection., Results: The combination of CCT (sensitivity = 88%; specificity = 84%) with microscopic parameters extracted from statistical modeling of light intensity distribution, α (sensitivity = 76%; specificity = 76%) and β (sensitivity = 96%; specificity = 88%), from a single Scheimpflug image was found to be a successful tool to differentiate between keratoconus and control eyes with no misclassifications (sensitivity = 100%; specificity = 100%) with coefficients of variation up to 2.5%., Conclusions: The combination of microscopic and macroscopic corneal parameters extracted from a static Scheimpflug image is a promising, non-invasive tool to differentiate corneal diseases without the need to perform measurements based on induced deformation of the corneal structure., Translational Relevance: The proposed methodology has the potential to support clinicians in the detection of keratoconus, without compromising patient comfort., Competing Interests: Disclosure: A. Consejo, None; J. Solarski, None; K. Karnowski, None; J.J. Rozema, None; M. Wojtkowski, None; D.R. Iskander, None, (Copyright 2020 The Authors.)

In view of the ever-growing demand for efficient triplet photosensitizers and photoactive components of various optoelectronic devices, we herein report the synthesis and properties of hexaiodo-subphthalocyanines (I 6 SubPcs). The improved five-step route to 4,5-diiodophthalonitrile, which serves as precursor for the synthesis of the I 6 SubPcs, is reported. The improved synthesis merely required one chromatographic separation to afford the high-purity target product. Highly desirable photophysical and photochemical properties were induced in the I 6 SubPcs due to the presence of six heavy iodine atoms. In particular, high values of the singlet-oxygen quantum yields (Φ Δ ) ranging from 0.83 to 0.9 were measured. The I 6 SubPcs investigated proved to be phosphorescent at 77 K in 2-MeTHF with emission band maxima (λ P ) located at λ=957 and 970 nm. The excited-triplet-state energies (E T ) were estimated to be approximately 1.30 eV, whereas the triplet lifetimes (τ T ) were found to be 27.7 and 30.1 μs. The CV/DPV measurements indicated that both I 6 SubPcs exhibited one irreversible oxidation and one quasi-reversible reduction. The spectroelectrochemical measurements pointed to a relative stability and reversibility of the electrochemically formed anion radical, that is, I 6 SubPc .- , and an instability of the species formed upon one-electron oxidation, that is, I 6 SubPc .+ . Estimation of E HOMO gave a value of approximately -5.8 eV whereas E LUMO was found to be located at around -3.8 eV., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)