The exciton dynamics of 6,13-bis(triisopropylsilyl-ethynyl) pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high concentration solutions.Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were near identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration, and we obtain a bimolecular rate constant of $4\times10^9$\,M$^{-1}$s$^{-1}$ in chloroform. The observed rate constant grows at high concentrations. This effect is modelled in terms of the hard sphere radial distribution function.NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43M$^{-1}$. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured.These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution, and that while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.

INTRODUCTION The quality and function of movements undergo deterioration due to weight gain. Aerobic training normalizes body weight, improves the health status, and in addition, it is expected to improve the dynamics of movements. The aims of this study were to prove the beneficial effects of recreational physical activities on the movements. METHODS Participants were divided into five different age categories: second childhood, adolescence, mature age I, mature age II, and aging. Squatting and vertical jumping of the participants were measured at the beginning and at the end of a 5-month training program. These movements simulated ordinary daily movements. Changes in the body were determined by InBody230. APAS 3D system was used for movement analysis. RESULTS The results showed significant improvements in body weight, fat mass, muscle mass, fat mass-body weight ratio, muscle mass-body weight ratio, body mass index, body fat percentage, and waist-hip ratio. During jumping, the lifting and sinking of the center of gravity's (CG) position and its velocity and acceleration were improved. In case of squatting, the results showed significant improvements in the velocity and acceleration of dynamical characteristics of the CG. Other correlations were observed between changes in body composition and the dynamics of movements. DISCUSSION The research proved that recreational training optimized body composition and improved the characteristics of CG's dynamics. The study suggests considerable connection between body composition and the characteristics of the movements' dynamics. From this point of view, our training program was the most effective in the working age groups.

Photon upconversion is a process that creates high-energy photons under low photon energy excitation. The effect of molecular geometry on the triplet fusion upconversion process has been investigated in this work through the design and synthesis of four new 9,10-diphenylanthracene (DPA) derivatives by employing platinum octaethylporphyrin as the triplet sensitizer. These new emitter molecules containing multiple DPA subunits linked together via a central benzene core exhibit high fluorescence quantum yields. Interestingly, large differences in the triplet fusion upconversion performance were observed between the derivatives with the meta-substituted dimer showing the closest performance to the DPA reference. The differences are discussed in terms of the statistical probability for obtaining a high-energy singlet excited state from triplet fusion, f, for both inter- and intramolecular processes and the effect of magnetic field on the upconversion efficiency. These results demonstrate the challenges to be overcome in improving triplet fusion upconversion efficiency based on multichromophoric emitter systems.

A series of dicyanopyrazine and dicyanoimidazole derived push-pull molecules have been prepared and further investigated as photoredox catalysts. The fundamental properties of the catalysts were studied by DSC, X-ray analysis, absorption/emission spectra, and electrochemistry and were completed with the DFT results. The catalytic activity has been evaluated in visible light induced alpha-functionalization of amines (cross-dehydrogenative coupling and annulation reaction of tetrahydroisoquinolines). Thorough structure-property-catalytic activity relationships were elucidated. The developed series of tailored organic photoredox catalysts allows synthetic chemists to perform desired reactions under sustainable and mild conditions employing solely visible light as a source of energy.

Six novel oxazaborines based on 7-aminocoumarin substituted by either fluoride or phenyl group on the boron atom were prepared from the corresponding enaminones. The compounds were characterized by means of 1H, 13C, 19F, and 11B NMR in solution, X-ray diffraction in crystal, UV–Vis spectroscopy, and electrochemistry. The observed optical properties were compared to the DFT calculations. Dynamic behaviour of selected oxazaborines was studied by means of 19F and 1H VT NMR and 2D EXSY. Both the enaminones and oxazaborines exhibit relatively strong fluorescence both in solid state and in frozen 2-methyltetrahydrofuran at 77 K, but none in solution. In some cases, phosphorescence was observed as well. Preliminary aggregation tests revealed aggregation induced emission (AIE) properties of the studied molecules. Concerning the electrochemical properties, the first reduction of all the oxazaborines studied proceeds as transport controlled one-electron (quasi)reversible process whereas the first oxidation of BPh2 oxazaborines proceeds as a two-electron irreversible process most probably of the ECE type. The oxidation of BF2 compounds was not possible to obtain within the given potential window. Analysis of frontier orbitals showed that change from BF2 to BPh2 leads to decrease of energy gap.

This study is focused on explanation of the remarkable photophysical behaviour of the 1-(4,6-dichloro-1,3,5-triazin-2-yl)-pyrene (PyTC2) compound which has been introduced as a fluorescent polarity probe. This compound exhibits large solvatochromic red-shift of fluorescence emission band while maintaining high fluorescence quantum yield and monoexponential decay kinetics throughout the whole solvent polarity scale. As the semi-empirical calculations reported in the original paper have not revealed any excited state possessing a high dipole moment, it has been suggested that the red-shift originates from planarization of the emitting excited state in polar solvents in contrast to unchanged twisted geometry in non-polar solvents. However, both the extent of the red-shift and the disappearance of the vibronic structure in polar solvents indicate that the emission originates from an excited state with high dipole moment and that the semi-empirical methods may not be sufficient to describe the emitting state of this molecule correctly. Thus, we have performed TD-DFT calculations including the potential energy surface scans. According to these calculations and scans, the emission takes place from a planarized intramolecular charge-transfer (ICT) state. This is in good agreement with all aspects of the observed fluorescence behaviour of PyTC2. Independent experimental evidence for the ICT has been provided by analysis of resonance Raman intensities where bands corresponding to enhanced normal modes residing on triazine and the stretching mode between pyrene and triazine moieties have been identified. The formation of the photoinduced ICT together with easy and inexpensive preparation make this compound and its derivatives candidate as push-pull building blocks for the design of advanced functional materials.

We have investigated the ultrafast carrier dynamics in a 1 μm bulk In0.265Ga0.735N thin film grown using energetic neutral atom-beam lithography/epitaxy molecular beam epitaxy. Cathodoluminescence and X-ray diffraction experiments are used to observe the existence of indium-rich domains in the sample. These domains give rise to a second carrier population and bi-exponential carrier cooling is observed with characteristic lifetimes of 1.6 and 14 ps at a carrier density of 1.3 × 1016 cm−3. A combination of band-filling, screening, and hot-phonon effects gives rise to a two-fold enhanced mono-exponential cooling rate of 28 ps at a carrier density of 8.4 × 1018 cm−3. This is the longest carrier thermalization time observed in bulk InGaN alloys to date.

The hot carrier solar cell is an advanced concept photovoltaic device that is predicted to deliver efficiencies in excess of conventional single bandgap devices. The design requires the ability to concurrently have extended carrier thermalization times within an absorber material, giving a hot carrier population, and the ability to efficiently collect the hot carriers at an energy above the bandgap of the absorber material. In order to achieve this, we require an absorber material with a long-lived hot carrier population. We investigate the carrier thermalization rates of InIn0.17Ga0.83As/GaAs0.80P0.20 multiple quantum well samples with different barrier thicknesses. For a 40 quantum well strain-balanced structure, the cooling lifetime is found to be 1.23 ± 0.07 ns, but in samples which are not strain-balanced, defect-assisted carrier cooling increases the thermalization rate. Immediately following an ultrafast excitation, the initial carrier temperature is greater in samples with wider barriers. However, any gain in carrier temperature from utilizing wide barriers is negated by an increased thermalization rate as one deviates from strain-balanced conditions. We conclude that strain balancing is required for multiple quantum well hot carrier absorbers.

Photochemical upconversion via triplet-triplet annihilation is a promising technology for improving the efficiency of photovoltaic devices. Previous studies have shown that the efficiency of upconversion depends largely on two rate constants intrinsic to the emitting species. Here, we report that one of these rate constants can be altered by deuteration, leading to enhanced upconversion efficiency. For perylene, deuteration decreases the first order decay rate constant by 16 ± 9% at 298 K, which increases the linear upconversion response by 45 ± 21% in the low excitation regime.

We report the observation of singlet fission in aqueous suspensions of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn) nanoparticles (NPs) synthesized using the reprecipitation method. By altering the synthesis conditions we are able to fabricate NPs which evolve from a system of poorly coupled to highly coupled chromophores. This morphological evolution can also be suppressed for a period of several months. Absorption spectra confirm that the particles evolve over time, displaying increased intermolecular interaction, if the initial reaction conditions seeded a polycrystalline sample. We correlate these differences in morphologies to different rates of singlet state decay, where higher intermolecular interaction drives a more rapid rate of decay. Ultrafast time-resolved photoluminescence spectroscopy confirms a short first excited singlet state lifetime (<2 ps), and transient absorption spectroscopy is used to probe the generation of triplets. We find that NPs with greater interchromophore coupling are less efficient at singlet fission. This is surprising and contrasts with previous reports of fission in TIPS-Pn. It is suggested that the slow morphological evolution used to generate highly coupled chromophores also introduces singlet exciton traps. We observe a persistent singlet signal in transient absorption measurements and a long-lived fluorescence anisotropy component, supporting this hypothesis. As such, it is clear that both long-range and short-range order play significant roles in the efficacy of singlet fission. A rapid initial fluorescence polarization dephasing is also observed (<1 ps), suggesting that excitons rapidly migrate over crystalline grain boundaries or within amorphous regions.

Photochemical upconversion in a quasi-solid gel proceeds with an identical efficiency to an otherwise identical liquid composition.

Novel bichromophoric compounds bearing 2-aminoanthracene as the donor of excitation energy and 3-aminoperylene or 3-aminobenzanthrone as the acceptor of excitation energy and s-triazinyl ring as the spacer were synthesized and characterized. The UV/Vis absorption and fluorescence spectra as well as fluorescence quantum yields in different solvents were measured. On the basis of experimental results and semi-empirical quantum chemical calculations, the relationships between the chemical structure and photo-physical properties of prepared compounds were investigated.

New N-triazinyl derivatives were synthesized by reaction of cyanuric chloride with 1- and 9-aminoanthracenes and subsequent nucleophilic substitution of chlorine atoms on triazinyl ring with methoxy and/or phenylamino groups. The compounds were characterized by 1H and 13C NMR and mass spectra. The influence of the chemical structure and solvent polarity on the UV/Vis absorption and fluorescence spectra and fluorescence quantum yields were investigated. Semi-empirical computations revealed highly polar CT states in singlet excited state manifold connected with charge-transfer from the hydrocarbon moiety to the triazinyl ring. The relationships between the CT-to-emitting state energy gap, solvent polarity and fluorescence quantum yield were discussed.

The geometry and excited state characteristics of five N-triazinyl derivatives of 1-aminopyrene were calculated using AM1, CNDO/S and ZINDO/S methods. For the optimized structures of the studied molecules, Lb, La and Bb transitions (localized on the amino pyrene moiety) were found, as well as charge-transfer states characterized by a charge transfer from the amino pyrene to the triazinyl ring. The energy of such strongly polar charge-transfer states depends on the chemical structure of the compound and on the solvent polarity. The relationships among each charge-transfer-to-emitting state energy gap, solvent polarity and fluorescence quantum yield of the studied compounds are discussed.

Absorption and fluorescence spectra and fluorescence quantum yields of 18 D-;π-A push-pull compounds were measured. The investigated chromophores consist of 4,5-dicyanoimidazole — bearing donor — substituted and systematically extended π-conjugated spacers. The influence of temperature and solvent polarity on the spectral and photophysical properties was investigated. Employing INDO/S calculations, the structure–property relationships were discussed.

N-(4,6-dichloro-1,3,5-triazin-2-yl)-2-aminoanthracene was synthesized by substitution of one chlorine atom of 2,4,6-trichloro-1,3,5-triazine with 2-aminoanthracene. A new series of N-triazinyl-2-aminoanthracenes was prepared by nucleophilic substitution of one or both chlorine atoms on N-(4,6-dichloro-1,3,5-triazin-2-yl)-2-aminoanthracene with electron-donating methoxy or phenylamino groups. The UV/Vis absorption, fluorescence and excitation spectra as well as the fluorescence quantum yields of the prepared compounds were measured in 1,4-dioxane, ethyl acetate, dibutyl ether and acetonitrile; nanosecond kinetics of the fluorescence decay was measured in different solvents. The influence of the character of the substituent on triazinyl ring and of the solvent polarity upon the absorption and fluorescence spectra and fluorescence quantum yields are discussed.

Backround: Recently a somatic point mutation in the FOXL2 gene has been characterized in ovarian adult type of granulosa cell tumor (ATGCT) (94.6%), thecomas (12.5%), but not in juvenile type of ovarian granulosa cell tumor, other ovarian sex cord tumors and ovarian surface epithelial neoplasms. Whether this mutation is present in testicular ATGCT or incompletely differentiated sex cord stromal tumor (ISCST) is not known.Design: Four ATGCTs, 4 ISCST were immunohistochemically investigated with anti-FOXL2 and 3 ovarian ATGCTs were used as positive control.Results: Weak-to-moderate immunoreactivity was found in all tested testicular and ovarian tumors. PCR and direct sequencing were used for detection of c.402C > G of the FOXL2 gene. No mutation was found in any of the testicular ATGCTs or ISCSTs whereas all ovarian tumors showed the c.402C > G point mutation of the FOXL2 gene.Conclusions: On the basis of this small series of these rare testicular neoplasms, it seems that the c. 402C> G mutation of the FOXL2 gene frequently found in adult type of ovarian GCT does not play any significant role in the development of ATGCT and ISCST.

Fluorescence anisotropy measurements were performed on a set of multichromophoric compounds, which contain a different number of aminopyrenyl moieties linked to a triazine ring, in order to reveal the nature of both the electronic excited states and relaxation pathways of the compounds. Our experimental results complement quantum chemical calculations. We propose that the lowest excited state from which fluorescence proceeds is localized on a single individual aminopyrene moiety. In contrast, excitation to a higher excited state is likely followed by a migration of energy to another nearby aminopyrene chromophore before the internal conversion to the emitting state takes place. We suggest that this migration is responsible for the experimentally measured decrease of fluorescence anisotropy of the studied compounds.

N-Acetyl and N-triazinyl 3-aminoperylenes were prepared. N-(4,6-Dichloro-1,3,5-triazin-2-yl)-3-aminoperylene was synthesized by the condensation of 3-aminoperylene with cyanuric chloride; other N-triazinyl derivatives were prepared by the successive substitution of chlorine atoms with methoxy or aniline groups. The structure and purity of the compounds were confirmed by elemental analysis, NMR spectroscopy and mass spectrometry. The UV/vis absorption, fluorescence and excitation spectra as well as the fluorescence quantum yields for the compounds were measured in dibutyl ether, 1,4-dioxane, ethyl acetate and acetonitrile; fluorescence lifetimes were measured in ethyl acetate and dimethyl sulfoxide. The influences of both the character of the N-substituent and the solvent polarity upon the spectra and quantum yields are discussed.

An alternative procedure has been described for the syntheses of several bi- and trichromophoric compounds consisting of 1-aminopyrene and 3-aminobenzanthrone chromophoric subsystems connected by an s-triazinyl ring spacer. The synthetic method used, which utilises an autoclave under autogenous pressure, is suitable for the nucleophilic substitution of both chlorine atoms within the triazinyl ring by weakly basic aromatic amines. The structures of the synthesized compounds were confirmed using elemental analysis, 1H NMR, and mass spectra. UV/vis absorption and fluorescence spectra and fluorescence quantum yields were measured. The dependence of fluorescence intensity and fluorescence quantum yields on solvent polarity was investigated.