Highly sensitive luminescence nanothermometry and thermal imaging facilitated by phase transition

Currently available temperature measurements or imaging at nano-micro scale are limited to fluorescent molecules and luminescent nanocrystals, whose spectral properties respond to temperature variation. The principle of operation of these conventional temperature probes is typically related to temperature induced multiphonon quenching or temperature dependent energy transfers, therefore, above 12%/K sensitivity and high thermal resolution remain a serious challenge. Here we demonstrate a novel class of highly sensitive thermographic phosphors operating in room temperature range with sub-kelvin thermal resolution, whose temperature readings are reproducible, luminescence is photostable and brightness is not compromised by thermal quenching. Corroborated with phase transition structural characterization and high spatio-temporal temperature imaging, we demonstrated that optically active europium ions are highly and smoothly susceptible to monoclinic to tetragonal phase transition in nanocrystalline (54 ± 14 nm) LiYO2 host, which is evidenced by changed number and the splitting of Stark components as well as by smooth variation of contribution between magnetic and electric dipole transitions. Further, reducing the size of phosphor from bulk to nanocrystalline matrix, shifted the phase transition temperature from 100 °C down to room temperature. These findings provide insights into the mechanism underlaying phase transition based luminescence nanothermometry and motivate future research toward new, highly sensitive, high temporal and spatial resolution nano-thermometers aiming at precise studying heat generation or diffusion in numerous biological and technology applications

Benzyl Dihydrazone versus Thiosemicarbazone Schiff Base: Effects on the Supramolecular Arrangement of Cobalt Thiocyanate Complexes and the Generation of CoN6 and CoN4S2 Coordination Spheres

In this study, we examine the coordination chemistry of benzyl dihydrazone and thiosemicarbazone Schiff bases featuring different chelation modes, steric bulk, and reactivities towards cobalt(II) thiocyanate. The tetradentate benzyl dihydrazone ligands coordinate to the Co(SCN)2 fragment to form CoN6 coordination spheres (1–3), whereas the thiosemicarbazone ligands provide CoIII complexes featuring CoN4S2 coordination spheres (4 and 5) and charge-balancing anions {SCN– and [Co(SCN)4]2– for 4 and 5, respectively}. Hirshfeld surface (HS) analysis revealed a substituent effect that results in an increasing number of H···H contacts in the order –H < –CH3 < –Ph (1–3, respectively). The H bonding in 4 and 5 as well as the associated energies were computed by the DFT approach, and these interactions appear to be crucial for the formation of the supramolecular systems. The DFT study also suggested that the H-bonded dimers in 5 are examples of the recently described “antielectrostatic” H bonds. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

5-Aryl-2-furaldehydes in the synthesis of tetrahydropyrimidinones by Biginelli reaction

5-Aryl-2-furaldehydes, obtained by furfural arylation with arenediazonium salts, react with ethyl acetoacetate or acetylacetone and (thio)- urea in the presence of FeCl3·6H2O as a catalyst. A series of ethyl 4-(5-aryl-2-furyl)-6-methyl-2-oxo(thioxo)-1,2,3,4-tetrahydropyrimidine- 5-carboxylates was obtained. © 2018 Springer Science+Business Media, LLC

5-Aryl-2-furaldehydes in the synthesis of tetrahydropyrimidinones by Biginelli reaction

5-Aryl-2-furaldehydes, obtained by furfural arylation with arenediazonium salts, react with ethyl acetoacetate or acetylacetone and (thio)- urea in the presence of FeCl3·6H2O as a catalyst. A series of ethyl 4-(5-aryl-2-furyl)-6-methyl-2-oxo(thioxo)-1,2,3,4-tetrahydropyrimidine- 5-carboxylates was obtained. © 2018 Springer Science+Business Media, LLC

(4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a, 8-hexahydro-4H-furo[2,3-f]isoindole-4-carboxylic acid

The asymmetric unit of the title compound, C17H 15NO4, contains two independent molecules with similar geometric parameters. In both molecules, the conformation of the cyclohexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the -pyrrolidinone ring as the flap. In the crystal, O - H⋯O hydrogen bonds between the carboxylic and carbonyl groups link alternate independent molecules into chains propagating in the b-axis direction. The crystal packing also features weak C - H⋯π interactions

New Dihydrogenhypodiphosphates of Alkaline‐Earth Metals: Preparation, Crystal Structure, Vibrational Spectrum and Thermal Behavior of AE[H 2

Two new alkaline-earth metal dihydrogenhypodiphosphates, AE[H2P2O6] ⋅ n H2O (AE=Ca, Sr and n=1.5, 2) have been prepared and structurally characterized by single crystal X-ray diffraction. Calciumdihydrogenhypodiphosphate sesquihydrate, Ca[H2P2O6] ⋅ 1.5 H2O (1) (lattice parameters: a=6.619(1) Å, b=10.201(1) Å, c=20.922(2) Å, β=107.95(1)°, VEZ=1343.9(2) Å3, Z=4), crystallizes in the monoclinic space group P21/c and strontiumdihydrogenhypodiphosphate dihydrate, Sr[H2P2O6] ⋅ 2 H2O (2) (lattice parameters: a=7.548(1) Å, b=11.906(1) Å, c=7.880(1) Å, VEZ=708.2(2) Å3, Z=4), in the orthorhombic space group Pbcn. The crystal structure of compound 1 consists of chains of edge- and face-sharing of [CaO6] and [CaO8] polyhedra linked by dihydrogenhypodiphosphate(IV) anions to form a three-dimensional network. The structure of 2 consists of alternating layers of chains of edge-sharing [SrO8] polyhedra and respective anionic units. The different water-content compositions result from the corresponding alkaline-earth metal coordination polyedra and by the preferred number of water molecules in their coordination sphere, respectively. The IR/Raman spectra of the title compounds have been recorded and interpreted, especially with respect to the [H2P2O6]2− group. The phase purity of 2 was verified by powder diffraction measurements

Benzyl Dihydrazone versus Thiosemicarbazone Schiff Base: Effects on the Supramolecular Arrangement of Cobalt Thiocyanate Complexes and the Generation of CoN6 and CoN4S2 Coordination Spheres

In this study, we examine the coordination chemistry of benzyl dihydrazone and thiosemicarbazone Schiff bases featuring different chelation modes, steric bulk, and reactivities towards cobalt(II) thiocyanate. The tetradentate benzyl dihydrazone ligands coordinate to the Co(SCN)2 fragment to form CoN6 coordination spheres (1–3), whereas the thiosemicarbazone ligands provide CoIII complexes featuring CoN4S2 coordination spheres (4 and 5) and charge-balancing anions {SCN– and [Co(SCN)4]2– for 4 and 5, respectively}. Hirshfeld surface (HS) analysis revealed a substituent effect that results in an increasing number of H···H contacts in the order –H < –CH3 < –Ph (1–3, respectively). The H bonding in 4 and 5 as well as the associated energies were computed by the DFT approach, and these interactions appear to be crucial for the formation of the supramolecular systems. The DFT study also suggested that the H-bonded dimers in 5 are examples of the recently described “antielectrostatic” H bonds. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

(4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a, 8-hexahydro-4H-furo[2,3-f]isoindole-4-carboxylic acid

The asymmetric unit of the title compound, C17H 15NO4, contains two independent molecules with similar geometric parameters. In both molecules, the conformation of the cyclohexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the -pyrrolidinone ring as the flap. In the crystal, O - H⋯O hydrogen bonds between the carboxylic and carbonyl groups link alternate independent molecules into chains propagating in the b-axis direction. The crystal packing also features weak C - H⋯π interactions

(4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a,8-hexahydro-4H-furo[2,3-f]isoindole-4-carboxylic acid

The asymmetric unit of the title compound, C17H15NO4, contains two independent molecules with similar geometric parameters. In both molecules, the conformation of the cyclohexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the α-pyrrolidinone ring as the flap. In the crystal, O—H...O hydrogen bonds between the carboxylic and carbonyl groups link alternate independent molecules into chains propagating in the b-axis direction. The crystal packing also features weak C—H...π interactions