Near-infrared (NIR) luminescence and photoacoustic (PA) imaging have attracted increasing attention for the real-time monitoring of biological samples due to high sensitivity, resolution, and pronounced signal detection depth, respectively. For improved contrast, both techniques require imaging agents possessing high absorption in the red-NIR range. Herein, we took advantage of a ternary complex formed with the anionic ytterbium(III) tetrakis(2-thenoyltrifluoroacetonate) ([Yb(tta)(4)](-)) and the cationic NIR-absorbing chromophore, 1,1 '-diethyl-2,2 '-dicarbocyanine (Cy+), to evaluate its potential to act as a dual-mode NIR luminescence and PA imaging agent. We demonstrated that, upon excitation with red-NIR light, Cy[Yb(tta)(4)] encapsulated into polystyrene nanoparticles is able to generate both NIR Yb3+ emission and a PA signal in an imaging experiment performed in a tissue-mimicking phantom.

New ytterbium complexes K(Solv)x[Yb(Ln)2] (Solv = ethanol and/or water) with 2-tosylaminobenzylidene-aryloylhydrazones (H2L1, aryloyl = benzoyl; H2L2, aryloyl = 2-naphthoyl) demonstrated high solubility and hole mobility (ca. 2.6 × 10-6 cm2 V-1 s-1), while their electron mobility and PLQY were different. The substitution of a benzoyl substituent with naphthoyl resulted in a significant increase of the electron mobility (6.9 × 10-7vs. 1.7 × 10-6 cm2 V-1 s-1) and a decrease of the quantum yield (1.2% vs. 0.6%). As a result, the optimized OLEDs based on the K[Yb(Ln)2] layer demonstrated efficiencies up to 385 μW W-1 and 441 μW W-1, indicating the superior importance of charge mobility over the quantum yield. These are the highest efficiencies of the Yb electroluminescence.

Solution behaviour in DMSO using 1D and 2D NMR spectroscopy was performed for lanthanide complexes Ln(L)(HL) and Ln(HL)2Cl, containing non-macrocyclic 2-(tosylamino)-benzylidene-N-benzoylhydrazone (H2L), and the structure of [Yb(L)]+ cation in solution was determined. Based on the NMR data, the possibility to obtain novel complexes containing [Ln(L)2]- was predicted, which was successfully synthesized, and the crystal structure of K(C2H5OH)3[Yb(L)2] was determined. Thanks to its high quantum yield of NIR luminescence (1.3 ± 0.2%), high absorption, low toxicity, and the stability of its anion against dissociation in DMSO, K(H2O)3[Yb(L)2] was successfully used for bioimaging.

Exchange-coupled hard/soft ferrite nanoparticles are prospective to squeeze out a part of expensive magnets based on rare-earth elements. However, the known exchange-coupled composite ferrite nanoparticles often suffer from the lack of a powerful enough hard magnetic core, high defectivity of magnetic phases, and a poor interface between them. Herein, we demonstrate the first efficient synthesis of sandwiched nanomagnets, which exhibit a pronounced exchange-coupling effect. This work is featured by the use of individual highly coercive strontium hexaferrite nanoplates prepared by a borate glass crystallization method as cores for the composite particles. The high crystal quality of the hexaferrite cores as the substrate promotes the epitaxial growth of CoFe2O4 layers on the 001 facets from an organic high-boiling solvent and results in the enhancement of the remanent magnetization and maximum energy product of the composite material. The results of this work open new prospects for the fabrication of multilayer oxide heterostructures with synergetic performance, which expands the applications of exchange-coupled composites.

We report here a near-infrared (NIR) emitting lanthanide-based metal-organic framework (MOF) in which Yb 3+ cations are sensitized by fluorescein (FL) as a low energy absorbing chromophore (FL@CD-MOF-161). The unique design of CD-MOF-161 allows for the entrapment of FL molecules in its pores during the synthesis and crystal growth, ensuring the efficient loading and spreading of chromophores within the crystal volume. The emission in the near-infrared (NIR) spectral range offers breakthrough perspectives in fields of applications such as material science and biology. As examples, NIR-emitting probes and materials have a strong potential for the creation of secret tags and night-vision devices 1 while the in vivo fluorescent optical imaging will benefit from an improved light penetration due to a reduced tissue absorption, a lower scattering and the minimization of the detrimental contribution of tissues autofluorescence. 1-3 NIR signals can be advantageously used for diagnostic imaging in which the ability to accurately detect small foci is a key advantage to act early in order to treat a pathology. 4 The applications for intra-operative optical imaging and guided surgery can also be considered with NIR wavelengths as they allow to perform surgical acts in ambient light. 5, 6 Despite the large amount of attractive theoretical evidences related to the use of NIR signals for in vivo imaging and promising experimental demonstrations 3, 7 , the number of NIR-emitting probes that can potentially be used in vivo remains scarce. The chemistry and the spectroscopy of lanthanide(III) cations (Ln 3+ ) is an active field of research as several of

We report here a near-infrared (NIR) emitting lanthanide-based metal-organic framework (MOF) in which Yb3+ are sensitized by fluorescein (FL) as a low energy absorbing chromophore (FL@CD-MOF-161). The unique design of CD-MOF-161 allows for the entrapment of FL molecules in its pores during the synthesis and crystal growth, ensuring the efficient loading and spreading of chromophores within the crystal volume.

Lanthanide complexes Ln(L-1)(HL1) (Ln = Lu, Yb, Er, Gd, Eu, Sm) and Ln(L-2)(HL2) (Ln = Lu, Yb, Gd, Eu) with 2-(tosylamino)-benzylidene-N-(aryloyl)hydrazones (H2L1, aryloyl = 2-hydroxybenzoyl; H2L2, aryloyl = isonicotinoyl) were obtained with the aim to explore them as new luminescent materials. They were found to form monomeric species independently on the aryloyl group, and their crystal structures were determined from single-crystal X-ray data (Yb(L-2)(HL2)center dot 0.5(C2H5OH)), as well as from powder X-ray data by Rietveld refinement (Eu(L-1)(HL1)). Ytterbium complexes exhibited intense luminescence, which allowed using them in host-free organic light-emitting diodes, which demonstrated remarkable efficiency of near infrared electroluminescence (50 mu W/W) at low voltage (5 V). The special mechanism of europium luminescence quenching allowed using europium complexes as luminescent thermometers, which demonstrated very high sensitivity up to 12%/K. The theory of luminescence thermometry based on a three-level system was proposed, which allowed predicting sensitivity with high accuracy (error within 20%).

Depending on the local excess of lanthanide ions (Ln = Lu, Yb, Er, Dy, Tb, Gd, Eu, Nd) or 2-(tosylamino)-benzylidene-N-benzoylhydrazone (H2L), lanthanide complexes, containing either a mono-deprotonated ligand (Ln(HL)2X, X = Cl, NO3) or both mono- and dideprotonated ligands (Ln(L)(HL)), were preparatively obtained. The crystal structures of Lu(HL)2Cl, Yb(L)(HL)(H2O)2, Yb(L)(HL)(EtOH)2(H2O) and Er(L)(HL), determined by single crystal diffraction data or from powder diffraction data using Rietveld refinement, have shown the surprising resemblance. The study of luminescence temperature dependence of Eu(HL)2Cl and Eu(L)(HL) showed that europium luminescence is quenched by thermally-activated 5D0 → T1 energy transfer. Luminescent thermometers based on these complexes demonstrated the sensitivity of up to 7.7% at 85 K which is the highest value above liquid-nitrogen temperatures obtained to date.

Synthesis, morphology investigation and the study of luminescent properties temperature dependence of surface modified bimetallic europium-terbium fluorides (L@TbxEu1-xF3, L= benzoate or terephthalate anion), as well as their use in bioimaging is described. It was shown that the synthetic route and the solvent affects the TbxEu1-xF3 nanoparticle morphology. Moreover, the oriented attachment of Tb0.999Eu0.001F3 crystallites was observed for the first time. Luminescence intensity of nanoparticle surface modified with aromatic carboxylate anions significantly increased, depending on the ligand used, while the temperature sensitivity of TbxEu1-xF3 was only slightly affected by the organic ligand. The examination of L@Tb0.999Eu0.001F3 temperature dependence revealed excellent linearity both in low temperature range (77-293 K) and in physiological range (305-330 K) with temperature sensitivity of 0.4% K-1 at 40 degrees C. According to in cellulo tests, tph@Tb0.999Eu0.001F3 demonstrated uniform distribution in cell cytoplasm and exhibited intense ionic luminescence of both terbium and europium.

Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. Accepted Manuscript Dalton Transactions

New NIR emitting materials were found among the lanthanide complexes with 2-(tosylamino)benzylidene-N-benzoylhydrazone. Complexes of Nd(3+), Er(3+) and Yb(3+), as well as Eu(3+), Gd(3+) and Lu(3+), were synthesized for the first time. Owing to the absence of vibration quenching the ytterbium complex was found to exhibit a photoluminescence quantum yield of 1.4%. Since the sensitization efficiency was calculated to be 55%, the losses in the quantum yield are probably due to Yb-Yb resonant energy transfer.

Natalia Kulikova, Vladimir Kholodov, Galina Lebedeva, Olga Philippova, Anton Kovalenko, Irina Perminova Department of Soil Science, M.V. Lomonosov Moscow State University, Leninskie Gory, 119992 Moscow, Russia, knat@darvodgeo.ru Dokuchaev Soil Science Institute of RAAS, Pyzhevskii pereulok 7, 109017 Moscow, Russia Department of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory, 119992 Moscow, Russia

Humic substances (HS) have been the subject of numerous scientific studies due to their mitigating effects on contaminants toxicity to biota. The detoxifying properties of HS are generally attributed to their capability for binding ecotoxicants of different classes including heavy metals. The binding of heavy metals to HS causes formation of less bioavailable complexes followed by lowering their toxicity and bioaccumulation. Therefore, development of approaches which are aimed to intensify binding ability of HS in relation to ecotoxicants are of ultimate importance. Oxygen containing functional groups of HS are supposed to be responsible for HS binding properties in relation to heavy metals. Thus, enrichment of HS with above mentioned moieties might provide increase in chelating properties of humics followed by increase in detoxifying ability of HS. The goal of this study was to estimate detoxifying ability of coal derived HA and their hydroquinone enriched derivatives in relation to copper. 2. MATERIAL AND METHODS For this study humic acids isolated from leonardite was used (CHP). To synthesize hydroquinone enriched derivatives, polycondensation of CHP with hydroquinone has been carried out using HS : hydroquinone ratio as 1 g : 250 mg. Two initials concentration of CHP such as 5 and 12% were used and two corresponding derivatives assigned as CHP- HBQ250-5% and CHP-HBQ250-12% were obtained. The total and carboxylic acidity of the preparations was determined using standard barita and calcium acetate techniques, respectively. The obtained results demonstrated higher contents of both carboxylic and phenol acidic groups in the synthesized derivatives as compared to the initial humic material. That finding indicated successfulness of the performed modification.

Conception, synthèse et caractérisation de composés de lanthanide fonctionnant comme agents bimodaux d'imagerie photoacoustique et d'émission proche infrarouge Différents types de nouvelles techniques d'imagerie biologique ont attiré une attention croissante au cours des dernières années, y compris la luminescence proche infrarouge et l'imagerie photoacoustique. Ces deux techniques fonctionnent avec de la lumière rouge – proche infrarouge dans la plage de la fenêtre de transparence biologique, ce qui permet de diminuer l'atténuation du signal dans les applications in vivo. Chaque technique possède des avantages spécifiques : l'imagerie par luminescence proche infrarouge présente une résolution et une sensibilité élevées, tandis que l'imagerie photoacoustique permet d'atteindre une profondeur de détection de signal plus élevée. La combinaison de ces deux modalités d'imagerie doit permettre de surmonter la limitation de chaque technique et d'obtenir des informations complémentaires. Cependant, le nombre d'agents d'imagerie bimodal combinant photoacoustique et luminescence proche infrarouge est encore faible alors que leur développement est en forte demande. Les ions lanthanide(III) ont des propriétés optiques uniques : ils présentent des bandes d'émission sous forme de lignes étroites dont les longueurs d’onde sont fixes dans le visible et dans le proche infrarouge, une grande différence d'énergie entre les longueurs d'onde d'excitation et d'émission et de longues durées de vie de luminescence. Il existe une restriction importante : les intensités d'émission des ions lanthanide(III) sont limitées par leurs faibles coefficients d'absorption en raison de la nature interdite de la plupart des transitions f-f. Pour surmonter cette limitation, des chromophores organiques fortement absorbants peuvent être utilisés comme sensibilisateurs en captant l'énergie de la lumière d'excitation et en la transférant aux niveaux d'acceptation du ion lanthanide(III). Dans ce travail, nous proposons d'utiliser la combinaison d'un ion lanthanide(III) émettant dans la région proche infrarouge et de chromophores organiques comme agents bimodaux pour l'imagerie photoacoustique et la luminescence proche infrarouge. Pour valider cette hypothèse, trois systèmes différents ont été choisis : i) des tétrakis β-dicétonates des lanthanide(III) formés avec des chromophores de cyanine, ii) des métallacrowns des lanthanide(III) modifiées avec des chromophores absorbant dans la région du proche infrarouge, iii) des nanoparticules de fluorure de lanthanide(III) modifiées en surface. Pour chaque système, la synthèse, la caractérisation et l'étude de la structure du composé correspondant de lanthanide(III) ont été réalisées. Les propriétés de luminescence proche infrarouge et photoacoustique des agents obtenus ont été intensivement étudiées, suggérant la possibilité de leurs applications in vivo.