Materials Literature
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The temperature dependence of the ac susceptibility under pressure has been used to track the N\'eel temperature ${T}_{\mathrm{N}}$ of the Mott insulators ${\mathrm{L}\mathrm{a}\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$, ${\mathrm{C}\mathrm{a}\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$, and ${\mathrm{Y}\mathrm{C}\mathrm{r}\mathrm{…
Box clever: A very stable box-shaped cyclic tetramer (see picture) was formed from meso-pyridyl substituted meso–meso-linked zinc(II) diporphyrin, in which the porphyrin subunits are held in a rigorous perpendicular orientation.
Transgenic goats to spin webs! The silk of spider nets (see picture) possesses unique mechanical properties. By using suitable microbiological methods, a structurally similar fiber protein has recently been prepared that, after spinning, exhibits comparable strength and elasticity to natural spider silk. The American…
The ground state and the light-induced metastable states of ${\mathrm{Na}}_{2}[\mathrm{Fe}(\mathrm{CN}{)}_{5}\mathrm{NO}]\ensuremath{\cdot}2{\mathrm{H}}_{2}\mathrm{O}$ were investigated by polarized optical absorption spectroscopy on single crystals. An orbital level scheme is proposed for the ground state and the two…
A [3×3] Ag+9 metallogrid self-assembles by a highly complex mechanism involving several intermediates, which may be generated at different metal/ligand stoichiometries. Extensive NMR spectroscopic studies have allowed the unraveling of the structure of these species and have revealed that the final grid entity present…
Polyaspartic acid (PASP) is an environmentally benign agent for the dissolution of calcium salt deposits. In this study, the chelating power of PASP with calcium is investigated by performing the potentiometric titration against PASP solutions. It was found that PASP is fully deprotonated at pH 7. The titration curves…
Porphyrin (P), porphycene (Pc), corrphycene (Cn), and hemiporphycene (Hpc) represent a series of well defined "4-N in" constitutional porphyrin isomers. These isomers, in the form of their octaethyl derivatives, represent a congruent set of porphyrinoids whose properties can be compared. In this study we report how va…
An analysis on the conductance of multiwall carbon nanotubes (MWNT's) is presented. Recent experiment indicated that MWNT's are good quantum conductors. Our theory shows that tunneling current between states on different walls of a defect-free, infinitely long MWNT is vanishingly small in general, which leads to the q…
The tripodal ligand tris[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-buten]amine (LH(3)) is capable of coordinating to two different lanthanide ions to give complexes formulated as [LLnLn'(NO(3))(3)].x H(2)O. The stepwise synthetic procedure consists of introducing first a Ln(III) ion in the inner N(4)O(3) coordination site…
We report the two-photon-induced photoisomerization of 3-[1-(1,2-dimethyl-1H-indol-3-yl)-ethylidene]-4-isopropylidene-dihydrofuran-2,5-dione ( 1 ), a photochromic compound with λ max = 385 nm, using 775-nm femtosecond pulsed laser irradiation. The resulting photoisomer had λ max = 582 nm. The kinetic rate constant for…
Upon treating elemental sulfur with [AgSbF(6)], [AgAl(hfip)(4)], [AgAl(pftb)(4)] (hfip=OCH(CF(3))(2), pftb =OC(CF(3))(3)) the compounds [Ag(S(8))(2)][SbF(6)] (1), [AgS(8)][Al(hfip)(4)] (2), and [Ag(S(8))(2)](+)[[Al(pftb)(4)](-) (3) formed in SO(2) (1), CS(2) (2), or CH(2)Cl(2) (3). Compounds 1-3 were characterized by…
Chains change: Novel valence-ordering structures of the ground states of MMX chain compounds, [Pt2(RCS2)4I]∞ (1: R=nBu, 2: R=Et), are determined by low-temperature crystal-structure analyses to be -Pt2+-Pt3+-I−-Pt3+-Pt2+-I−-. Magnetic susceptibility measurements of 1 (see graph) revealed an abrupt drop in magnitude fr…
Molecular sieving to take your breath away: The breathing ionic crystal 1 is synthesized by the complexation of Keggin-type [α-SiW12O40]4− (red) polyoxometalate with a macro cation [Cr3O(OOCH)6(H2O)3]+ (green and white). The water of crystallization is easily removed from 1 by evacuation to form a guest-free phase 2.…
The distinctive features of well-defined, three-dimensional macromolecules with topologies designed to enhance solubility and amplify end-group functionality facilitated nanophase morphologies in mixtures with organosilicates and ultimately nanoporous organosilicate networks. Novel macromolecular architectures includi…
Big rings and nanocleavage: Whereas a variety of molybdenum oxide based nanoobjects can be obtained by self-assembly concomitant with a variety of modifications of a parent cluster system under alterable boundary conditions, drastic changes—comparable to a molecular-scissors-type activity—can even cause splitting of t…
The oxidation behavior of Ti3AlC2 powders has been investigated in air by means of simultaneous TGA-DSC, XRD, Raman spectra, SEM, EDS and BET specific surface measurement to understand the intrinsic oxidation behavior of this newly developed ternary compound. The starting and complete oxidation temperatures determined…
Interdependencies between experimental spectra, representing line or plane projections of electronic densities, are derived from their consistency and symmetry conditions. Some additional relations for plane projections are obtained by treating them as line projections of line projections. The knowledge of these depen…
The competition between the long range Coulomb attractive and the short range repulsive interaction in ionic nanocrystals creates an effective negative pressure, which causes the lattice parameter a to increase with decreasing nanoparticle size d. A simple ``Madelung model'' is used to predict the dependence of the la…
We calculate the inelastic light scattering from X-rays, which allows the photon to transfer both energy and momentum to the strongly correlated charge excitations. We find that the charge transfer peak and the low energy peak both broaden and disperse through the Brillouin zone similar to what is seen in experiments…
Photoemission from a single self-organized GaAs/AlGaAs quantum dot (QD) is temporally resolved with picosecond time resolution. The emission spectra consisting of the multiexciton structures are observed to depend on the delay time and the excitation intensity. Quantitative agreement is found between the experimental…