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121.
Dr. Zhijia Wang Mikhail Ivanov Dr. Yuting Gao Laura Bussotti Prof. Paolo Foggi Huimin Zhang Prof. Nino Russo Prof. Bernhard Dick Prof. Jianzhang Zhao Prof. Mariangela Di Donato Dr. Gloria Mazzone Prof. Liang Luo Prof. Matvey Fedin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(5):1091-1102
Spin–orbit charge-transfer intersystem crossing (SOCT-ISC) is useful for the preparation of heavy atom-free triplet photosensitisers (PSs). Herein, a series of perylene-Bodipy compact electron donor/acceptor dyads showing efficient SOCT-ISC is prepared. The photophysical properties of the dyads were studied with steady-state and time-resolved spectroscopies. Efficient triplet state formation (quantum yield ΦT=60 %) was observed, with a triplet state lifetime (τT=436 μs) much longer than that accessed with the conventional heavy atom effect (τT=62 μs). The SOCT-ISC mechanism was unambiguously confirmed by direct excitation of the charge transfer (CT) absorption band by using nanosecond transient absorption spectroscopy and time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The factors affecting the SOCT-ISC efficiency include the geometry, the potential energy surface of the torsion, the spin density for the atoms of the linker, solvent polarity, and the energy matching of the 1CT/3LE states. Remarkably, these heavy atom-free triplet PSs were demonstrated as a new type of efficient photodynamic therapy (PDT) reagents (phototoxicity, EC50=75 nm ), with a negligible dark toxicity (EC50=78.1 μm ) compared with the conventional heavy atom PSs (dark toxicity, EC50=6.0 μm, light toxicity, EC50=4.0 nm ). This study provides in-depth understanding of the SOCT-ISC, unveils the design principles of triplet PSs based on SOCT-ISC, and underlines their application as a new generation of potent PDT reagents. 相似文献
122.
Pierre Thureau Simone Sturniolo Miri Zilka Fabio Ziarelli Stéphane Viel Jonathan R. Yates Giulia Mollica 《Magnetic resonance in chemistry : MRC》2019,57(5):256-264
Structure determination of functional organic compounds remains a formidable challenge when the sample exists as a powder. Nuclear magnetic resonance crystallography approaches based on the comparison of experimental and Density Functional Theory (DFT)-computed 1H chemical shifts have already demonstrated great potential for structure determination of organic powders, but limitations still persist. In this study, we discuss the possibility of using 13C-13C dipolar couplings quantified on powdered theophylline at natural isotopic abundance with the help of dynamic nuclear polarization, to realize a DFT-free, rapid screening of a pool of structures predicted by ab initio random structure search. We show that although 13C-13C dipolar couplings can identify structures possessing long range structural motifs and unit cell parameters close to those of the true structure, it must be complemented with other data to recover information about the presence and the chemical nature of the supramolecular interactions. 相似文献
123.
Rajan Kumar Subir Kumar Ray Dr. Saikat Mukherjee Sudipta Saha Dr. Arijit Bag Prof. Dr. Pradip Kr. Ghorai Prof. Dr. Nirmalya Ghosh Prof. Dr. Raja Shunmugam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13514-13522
The development of organic photoluminescent materials, which show promising roles as catalysts, sensors, organic light-emitting diodes, logic gates, etc., is a major demand and challenge for the global scientific community. In this context, a photoclick polymerization method is adopted for the growth of a unique photoluminescent three-dimensional (3D) polymer film, E, as a model system that shows emission tunability over the range 350–650 nm against the excitation range 295–425 nm. The DFT analysis of energy calculations and π-stacking supports the spectroscopic observations for the material exhibiting a broad range of emission owing to newly formed chromophoric units within the film. Full polarization spectroscopic Mueller matrix studies were employed to extract and quantify the molecular orientational order of both the ground (excitation) and excited (emission) state anisotropies through a set of newly defined parameters, namely the fluorescence diattenuation and fluorescence polarizance. The information contained in the recorded fluorescence Mueller matrix of the organic polymer material provided a useful way to control the spectral intensity of emission by using pre- and post-selection of polarization states. The observation was based on the assumption that the longer lifetime of the excited dipolar orientation is attributed to the compactness of the film. 相似文献
124.
125.
The spin‐dependent transport properties, including spin polarization and spin‐flip for phosphorene superlattice in the presence of an extrinsic Rashba spin‐orbit interaction (RSOI) based on the transfer matrix method, are studied. The results show that the number of barriers in the superlattice structure plays a dominant role in output spin polarization, which can be used in designing optimized spintronic devices. In addition, by controlling on the Rashba strength, an incident spin‐up electron can be transmitted as a spin‐down electron. Also, it enables to convert the unpolarized incident electronic beam (with zero spin polarization) into an arbitrary output spin polarization, which plays a significant role in qubit circuits. 相似文献
126.
In the past years there has been a great interest in self-doped TiO2 nanotubes (blue TiO2 nanotubes) compared to undoped ones owing to their high carrier density and conductivity. In this study, blue TiO2 nanotubes are investigated as photoanode materials for photoelectrochemical water splitting. Blue TiO2 nanotubes were fabricated with enhanced photoresponse behavior through electrochemical cathodic polarization on undoped and annealed TiO2 nanotubes. The annealing temperature of undoped TiO2 nanotubes was tuned before cathodic polarization, revealing that annealing at 500 °C improved the photoresponse of the nanotubes significantly. Further optimization of the blue TiO2 nanotubes was achieved by adjusting the cathodic polarization parameters. Blue TiO2 nanotubes obtained at the potential of –1.4 V (vs. SCE) with a duration of 10 min exhibited twice more photocurrent response (0.39 mA cm-2) compared to the undoped TiO2 nanotube arrays (0.19 mA cm-2). Oxygen vacancies formed through the cathodic polarization decreased charge recombination and enhanced charge transfer rate; therefore, a high photoelectrochemical activity under visible light irradiation could be achieved. 相似文献
127.
Meng-Che Tu Deepa Rajwar Gopal Ammanath Palaniappan Alagappan Umit Hakan Yildiz Bo Liedberg 《Analytica chimica acta》2016
A colorimetric Al3+ sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al3+ in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al3+ led to an evident visual color change. The lowest concentration of Al3+ for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al3+ in tap water. The proposed methodology showed selective and sensitive detection for Al3+ in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring. 相似文献
128.
Colloidal lithography is an efficient and low-cost method to prepare an ordered nanostructure array with new shapes and properties. In this study, square-shaped and cone-shaped Au nanostructures were obtained by 70° angle deposition onto polystyrene bead array with the diameter of 500 nm when a space of 120 nm is created between the neighbor beads by plasma etching. The gaps between the units decrease when the Au deposition time increases, which leads to the polarized enhanced local field, in agreement with the surface-enhanced Raman scattering spectra (SERS) observations and finite-difference time-domain (FDTD) simulations. When the Au deposition time increased to 5 min, 5 nm gaps form between the neighbor units, which gave an enhancement factor of 5 × 109. The SERS chip was decorated for the detection of the liver cancer cell marker Alpha-fetoprotein (AFP) with the detection limit down to 5 pg/mL. 相似文献
129.
This Trends article highlights the recent advances published between 2012 and 2015 in solid-state 17O NMR for organic and biological molecules. New developments in the following areas are described: (1) new oxygen-containing functional groups, (2) metal organic frameworks, (3) pharmaceuticals, (4) probing molecular motion in organic solids, (5) dynamic nuclear polarization, and (6) paramagnetic coordination compounds. For each of these areas, the author offers his personal views on important problems to be solved and possible future directions. 相似文献
130.
《Journal of computational chemistry》2017,38(2):65-80
Our Fuzzy‐Border (FB) continuum solvent model has been extended and modified to produce hydration parameters for small molecules using POlarizable Simulations Second‐order Interaction Model (POSSIM) framework with an average error of 0.136 kcal/mol. It was then used to compute pK a shifts for carboxylic and basic residues of the turkey ovomucoid third domain (OMTKY3) protein. The average unsigned errors in the acid and base pK a values were 0.37 and 0.4 pH units, respectively, versus 0.58 and 0.7 pH units as calculated with a previous version of polarizable protein force field and Poisson Boltzmann continuum solvent. This POSSIM/FB result is produced with explicit refitting of the hydration parameters to the pK a values of the carboxylic and basic residues of the OMTKY3 protein; thus, the values of the acidity constants can be viewed as additional fitting target data. In addition to calculating pK a shifts for the OMTKY3 residues, we have studied aspartic acid residues of Rnase Sa. This was done without any further refitting of the parameters and agreement with the experimental pK a values is within an average unsigned error of 0.65 pH units. This result included the Asp79 residue that is buried and thus has a high experimental pK a value of 7.37 units. Thus, the presented model is capable or reproducing pK a results for residues in an environment that is significantly different from the solvated protein surface used in the fitting. Therefore, the POSSIM force field and the FB continuum solvent parameters have been demonstrated to be sufficiently robust and transferable. © 2016 Wiley Periodicals, Inc. 相似文献