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The combination of photoswitchability and bioactivity in one compound provides interesting opportunities for photopharmacology. Here, we report a hybrid compound that in addition allows for its visual localization. It is the first demonstration of its kind and it even shows high photoswitchability. The multifunctional nanomaterial hybrid, which we present, is composed of luminescent LaVO4:Eu3+ nanoparticles and vinyl phosphonate, the latter of which inhibits butyrylcholinesterase (BChE). This inhibition increases 7 times when irradiated with a 266 nm laser. We found that it is increased even further when vinyl phosphonate molecules are conjugated with LaVO4:Eu3+ nanoparticles, leading in total to a 20-fold increase in BChE inhibition upon laser irradiation. The specific luminescence spectrum of LaVO4:Eu3+ allows its spatial localization in various biological samples (chicken breast, Daphnia and Paramecium). Furthermore, laser irradiation of the LaVO4:Eu3+@vinyl phosphonate hybrid leads to a drop in luminescence intensity and in lifetime of the Eu3+ ion that can implicitly indicate photoswitching of vinyl phosphonate in the bioactive state. Thus, combining enhanced photoswitchability, bioactivity and luminescence induced localizability in a unique way, hybrid LaVO4:Eu3+@vinyl phosphonate can be considered as a promising tool for photopharmacology.
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Ghost imaging can be used to detect objects in a nonstationary environment or in the presence of variable ambient light, making it attractive when conventional imaging methods are ineffective. However, the conventional ghost imaging algorithm is susceptible to temporal fluctuations in the detected signal. In this work, we propose a polarization-multiplexed auxiliary laser channel propagating along the same optical path with the main one. The signal in the auxiliary channel is used as a reference and allows the elimination of signal disturbance. A quantitative analysis and comparison of the proposed method's performance to the high-pass filtering method are demonstrated. For an illumination pattern refresh rate of 10 Hz, effective suppression of bucket signal fluctuations has been experimentally demonstrated. For a disturbance frequency from 1 Hz to 10 Hz, the auxiliary channel method demonstrated a ghost image Pearson correlation coefficient (PCC) of not less than 0.70, while the high-pass filtering method showed a PCC sharp drop from 0.65 to 0.02.
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In this study, ZnTe crystal was applied to provide precise thermal sensing for cryogenic temperatures. Multiple techniques, namely Raman and photoluminescence spectroscopies, were used to broaden the operating temperature range and improve the reliability of the proposed thermometers. Raman-based temperature sensing could be applied in the range of 20-100 K, while luminescence-based thermometry could be utilized in a narrower range of 20-70 K. However, the latter strategy provides better relative thermal sensitivity and temperature resolution. The best thermal performances based on a single temperature-dependent parameter attain Sr = 3.82% K-1 and ΔT = 0.12 K at T = 50 K. The synergy between multiple linear regression and multiparametric thermal sensing demonstrated for Raman-based thermometry results in a ten-fold improvement of Sr and a two-fold enhancement of ΔT. All studies performed testify that the ZnTe crystal is a promising multimode contactless optical sensor for cryogenic thermometry.
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Invited for the cover of this issue are the groups of Sergeyâ P. Tunik and his colleagues from St Petersburg University. The image depicts the strong bathochromic shift of the emission wavelength of phosphorescent platinum(II) complexes upon their aggregation in the presence of water. Read the full text of the article at 10.1002/chem.202202207.
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Five square-planar [Pt(C^N*N'^C')] complexes (Pt1-Pt5) with novel nonsymmetric tetradentate ligands (L1-L5) were synthesized and characterized. Varying the structure of the metalating aromatic systems result in substantial changes in photophysical properties and intermolecular interaction mode of the complexes in solution and in solid state. The complexes are strongly emissive in tetrahydrofuran solution, with the band maxima ranging from 560 to 690â nm. Three of these complexes (Pt1, Pt2, Pt4) afford nanospecies upon injection of their solution into water, which show aggregation-induced emission (AIE) with a strong red shift of emission bands. In the solid state, crystalline samples of these complexes demonstrate mechanochromism upon grinding with a bathochromic shift of the emission. DFT and TD-DFT computational analysis of monomeric Pt1-Pt5 in solution and model dimeric emitters formed through intermolecular interaction of Pt1, Pt2, Pt4 molecules allowed assignment of observed AIE to the 3 MMLCT excited states of Pt-Pt bonded aggregates of these complexes.
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A synthetic method for a primary 2-(thiophen-2'-yl)ethylphosphine was developed. The reaction of thiophenylethylphosphine with paraformaldehyde and primary arylamines leads to the formation of cyclic bisphosphines, namely, 1,5-di(aryl)-3,7-bis(thiophenylethyl)-1,5-diaza-3,7-diphosphacyclooctane (aryl = phenyl, p-tolyl). The obtained bisphosphines form cationic bis-P,P-chelate complexes with copper(I) tetrafluoroborate, which were structurally characterized by NMR spectroscopy, mass spectrometry, and elemental and XRD analyses. Surprisingly, the copper(I) complexes display a multiband emission in the solid state with maxima at 355-360, 425-430, and 480-490 nm and nanosecond lifetimes (1.2-1.4 ns) upon a 335 nm excitation. The excitation of the complexes at 360 nm at room temperature results in a deep-blue emission at 425-430 nm and a tail at 460-490 nm. A temperature decrease leads to an increased intensity of the emission band at 480 nm, while the luminescence lifetimes insignificantly increased up to 14 ns. Quantum chemical calculations explain the observed unusual luminescent behavior by the existence of "undistorted" and "flattened" singlet excited states of copper(I) complexes at room temperature and at 77 K, respectively.
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Accurate contactless thermometry is required in many rapidly developing modern applications such as biomedicine, micro- and nanoelectronics, and integrated optics. Ratiometric luminescence thermal sensing attracts a lot of attention due to its robustness toward systematic errors. Herein, a phonon-assisted upconversion in LuVO4:Nd3+/Yb3+ nanophosphors was successfully applied for temperature measurements within the 323-873 K range via the luminescence intensity ratio technique. Dual-activating samples were obtained by codoping and mixing single-doped nanopowders. The effect of the type of dispersion system and the Yb3+ doping concentration was studied in terms of thermometric performances. The relative thermal sensitivity reached a value of 2.6% K-1, while the best temperature resolution was 0.2 K. The presented findings show the way to enhance the thermometric characteristics of contactless optical sensors.
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Surfaces functionalized with metal nanoparticles (NPs) are of great interest due to their wide potential applications in sensing, biomedicine, nanophotonics, etc. However, the precisely controllable decoration with plasmonic nanoparticles requires sophisticated techniques that are often multistep and complex. Here, we present a laser-induced deposition (LID) approach allowing for single-step surface decoration with NPs of controllable composition, morphology, and spatial distribution. The formation of Ag, Pt, and mixed Ag-Pt nanoparticles on a substrate surface was successfully demonstrated as a result of the LID process from commercially available precursors. The deposited nanoparticles were characterized with SEM, TEM, EDX, X-ray diffraction, and UV-VIS absorption spectroscopy, which confirmed the formation of crystalline nanoparticles of Pt (3-5 nm) and Ag (ca. 100 nm) with plasmonic properties. The advantageous features of the LID process allow us to demonstrate the spatially selective deposition of plasmonic NPs in a laser interference pattern, and thereby, the formation of periodic arrays of Ag NPs forming diffraction grating.
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A family of helical dinuclear copper(i) pyridylphospholane complexes [Cu2L3X]X (X = BF4-, Cl- and Br-) was prepared. The family includes the first examples of this type of complex based on copper(i) chloride and copper(i) bromide. The two isomers typical of this class of compounds, namely head-to-head and head-to-tail complexes, were studied in solution by spectroscopic and optical methods, and in the solid state by X-ray diffraction. Furthermore, the solid-state luminescence of the complexes at different temperatures was studied, and the results were interpreted using quantum-chemical calculations. It was shown that the luminescence of the complexes is attributed to the 3(M + X)LCT transitions.
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The development of new contactless thermal nanosensors based on a ratiometric approach is of significant interest. To overcome the intrinsic limitations of thermally coupled levels, a dual activation strategy was applied. Dual activation was performed using co-doped single nanoparticles and a binary mixture of single-doped nanoparticles. Co-doped and mixed YVO4:Nd3+/Eu3+ nanoparticles were successfully demonstrated as luminescent nanothermometers and their thermometric performance, in terms of thermal sensitivity, temperature resolution and repeatability, was studied and compared.