Search results for " bonding"
showing 10 items of 934 documents
Distortions of [Sb2Cl10]4– Bioctahedra and Phase Transitions in the Chloroantimonate(III) (C3H5NH3)2[SbCl5]·(C3H5NH3)Cl
2007
Bis(allylammonium)pentachloroantimonate(III) - allylammonium chloride, (C3H5NH3)2[SbCl5] · (C3H5NH3)Cl, belongs to the chloroantimonate(III) organic-inorganic salts family. The DSC studies of this compound showed two anomalies at 181 K and at 223 K. Both are associated with phase transitions, which mainly occur due to ordering-disordering processes of the organic cations. Between 181 and 223 K the structure is incommensurate. The crystal structure was determined at 298 and 86 K. At both temperatures the crystal structure consists of (C3H5NH3)+ cations, anionic distorted [Sb2Cl10]4− units and isolated Cl− ions. In the room-temperature phase two out of three, and in the low-temperature phase …
ChemInform Abstract: Chemistry and Properties of Solids with the (NZP) Skeleton
2010
Abstract Solids with an [NZP] skeleton in their structure from a very broad family presenting very different properties with varying chemical composition. These properties range from radioactive nuclide immobilization and insulation to ionic and/or electronic conduction, extending to the field of very low thermal expansion among others. The open [NZP] skeleton provides the stability and flexibility necessary to form continuous ranges of solid solution, allowing the tailoring of the best composition-property-structure material. Chemical activity may become particularly high at the surface and absorption reactions and catalytic properties have the highest interest at present. In this paper, c…
Chemistry and properties of solids with the [NZP] skeleton
1993
Abstract Solids with an [NZP] skeleton in their structure from a very broad family presenting very different properties with varying chemical composition. These properties range from radioactive nuclide immobilization and insulation to ionic and/or electronic conduction, extending to the field of very low thermal expansion among others. The open [NZP] skeleton provides the stability and flexibility necessary to form continuous ranges of solid solution, allowing the tailoring of the best composition-property-structure material. Chemical activity may become particularly high at the surface and absorption reactions and catalytic properties have the highest interest at present. In this paper, c…
Sugar-induced stabilization of the monoolein Pn3m bicontinuous cubic phase during dehydration
2001
To explore the molecular mechanism of the protective function of sugars on cubic lipidic systems, the mesomorphic properties of the monoolein-water system, dehydrated in the presence of a series of sugars, have been studied by osmotic stress experiments. Two bicontinuous inverse cubic structures $(Pn3m$ and $\mathrm{Ia}3d)$ and a lamellar ${L}_{\ensuremath{\alpha}}$ phase form under dehydration in pure water. In sugar solutions, the $\mathrm{Pn}3m$ phase shows an extraordinary stability: as a function of sugar concentration, the lattice parameter decreases to very low values, but no phase transitions occur. Instead, the $\mathrm{Pn}3m$ to $\mathrm{Ia}3d$ phase transition is obtained by equi…
Efficient light-induced phase transitions in halogen-bonded liquid crystals
2016
Here, we present a new family of light-responsive, fluorinated supramolecular liquid crystals (LCs) showing efficient and reversible light-induced LC-to-isotropic phase transitions. Our materials design is based on fluorinated azobenzenes, where the fluorination serves to strengthen the noncovalent interaction with bond-accepting stilbazole molecules, and increase the lifetime of the cis-form of the azobenzene units. The halogen-bonded LCs were characterized by means of X-ray diffraction, hot-stage polarized optical microscopy, and differential scanning calorimetry. Simultaneous analysis of light-induced changes in birefringence, absorption, and optical scattering allowed us to estimate tha…
Thermoelectric Transport in Cu7PSe6 with High Copper Ionic Mobility
2014
Building on the good thermoelectric performances of binary superionic compounds like Cu2Se, Ag2Se and Cu2S, a better and more detailed understanding of phonon-liquid electron-crystal (PLEC) thermoelectric materials is desirable. In this work we present the thermoelectric transport properties of the compound Cu7PSe6 as the first representative of the class of argyrodite-type ion conducting thermoelectrics. With a huge variety of possible compositions and high ionic conductivity even at room temperature, the argyrodites represent a very good model system to study structure-property relationships for PLEC thermoelectric materials. We particularly highlight the extraordinary low thermal conduct…
Semiempirical Correlation between Optical Band Gap Values of Oxides and the Difference of Electronegativity of the Elements. Its Importance for a Qua…
1997
A semiempirical correlation between the optical band gap of binary oxides and the difference of electronegativity between the oxygen and metallic elements (Pauling's extraionic energy) is proposed. In the frame of the proposed correlation an estimate of the repulsive term in the total lattice energy of ionic oxides is obtained in very good agreement with the existing data. An extension of the correlation to the ternary oxides and hydroxides is proposed by using the concept of average cationic or anionic group electronegativity. The usefulness of the proposed correlation for the in situ characterization of passive films on metals and alloys by photocurrent spectroscopy is illustrated by repo…
Highly Photoluminescent Blue Ionic Platinum-Based Emitters
2019
New cycloplatinated N-heterocyclic carbene (NHC) compounds with chelate diphosphines (P^P) as ancillary ligands: [Pt(R-C^C*)(P^P)]PF6 (R = H, P^P = dppm (1A), dppe (2A), dppbz (3A); R = CN, P^P = dppm (1B), dppe (2B), dppbz (3B)) have been prepared from the corresponding starting material [{Pt(R-C^C*)(μ-Cl)}2] (R = H, A, R = CN, B) and fully characterized. The new compound A has been prepared by a stepwise protocol. The photophysical properties of 1A–3A and 1B–3B have been widely studied and supported by the time-dependent-density functional theory. These compounds show an efficient blue (dppe, dppbz) or cyan (dppm) emission in PMMA films (5 wt %), with photoluminescence quantum yield (PLQY…
Efficient Green Light-Emitting Electrochemical Cells Based on Ionic Iridium Complexes with Sulfone-Containing Cyclometalating Ligands
2013
A new approach to obtain green-emitting iridiumA complexes is described. The synthetic approach consists of introducing a methylsulfone electron-withdrawing substituent into a 4-phenylpyrazole cyclometalating ligand in order to stabilize the highest- occupied molecular orbital (HOMO). Six new complexes have been synthe- sized incorporating the conjugate base of 1-(4-(methylsulfonyl)phenyl)-1 H- pyrazole as the cyclometalating ligand. The complexes show green emission and very high photoluminescence quantum yields in both diluted and concentrated films. When used as the main active component in light-emit- ting electrochemical cells (LECs), green electroluminance is observed. High efficienci…
Self-absorption in a light-emitting electrochemical cell based on an ionic transition metal complex
2015
We report on the quantitative and qualitative effects of self-absorption in light-emitting electrochemical cells (LECs) based on ionic transition metal complexes (iTMCs), as measured in-situ during electric driving. A yellow-emitting iTMC-LEC comprising an active material thickness of 95 nm suffers a 4% loss of the emission intensity to self-absorption, whereas the same type of device but with a larger active-material thickness of 1 mu m will lose a significant 40% of the light intensity. We also find that the LEC-specific effect of doping-induced self-absorption can result in a drift of the emission spectrum with time for iTMC-LECs, but note that the overall magnitude of doping-induced sel…