Materials Literature
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The synthesis of a series of soluble poly(2,7-phenanthrylene)s and poly(3,6-phenanthrylene)s is presented. Depending on the nature of the repeat units they constitute analogues of poly( p -phenylene) (PPP) and poly( p -phenylenevinylene) (PPV) and thus should give rise to different modes of extended π -conjugation. In…
We studied the electrochemical and spectroscopic properties of a series of extended silole-based chromophores to understand the effect of structure on behavior. By changing the substituents attached to the chromophore, we observed large variations in luminescence quantum efficiency (ca. 0-0.6), lambdamax for absorbanc…
Abstract The chemical structure of a water‐soluble polysaccharide, coded as TM3b, extracted from sclerotia of Pleurotus tuber‐rigium was analyzed to be a hyperbranched β‐ D ‐glucan with β‐(1→6), β‐(1→4), and β‐(1→3)–linked residues, with degree of branching (DB) of 57.6%. The results from size‐exclusion chromatography…
Paramagnetic lanthanide(III) complexes that contain hyperfine-shifted exchangeable protons offer considerable advantages over diamagnetic molecules as chemical exchange saturation transfer (CEST) agents for MRI. As part of a program to investigate avenues to improve the sensitivity of such agents, the CEST characteris…
An apparently first-order polyamorphic transition has been observed with increasing pressure at ambient temperature in a molecular glass of composition Ge(2.5)As(51.25)S(46.25) Raman spectroscopic measurements on pressure-quenched samples and in situ x-ray diffraction measurements indicate that this transition corresp…
The difference in the morphology and crystallization aspects of hydrogen-bond-mediated self-assembling systems with single and double hydrogen-bonding motifs is studied here with carbamates as an example. These carbamates have alkyl side chains of various lengths, from C(4) to C(18). The biscarbamates with double hydr…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSensory Polymers for Electron-Rich Analytes of Biological InterestYoungmi Kim and Timothy M. SwagerView Author Information Department of Chemistry and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Ca…
The carbon contents in carburized steels were investigated by electron probe microanalysis (EPMA) for a range of carbon levels in the solid solution less than 1 wt%. This article describes the difficulties encountered with the classic analytical procedure using the k ratio of X-ray intensities and the phi(rhoz) model.…
Numerical self-consistent-field theory calculations by Tyler and Morse [Phys. Rev. Lett. 94, 208302 (2005)] predict a stable orthorhombic network phase with space group in very weakly segregated diblock copolymer melts. Here, we examine the predicted stability of this phase within a simple Landau theory of weakly orde…
Abstract Summary: The oligomeric A 2 plus monomeric B 3 synthetic methodology provided highly branched, poly(ether urethane)s based on TMP (B 3 ) and isocyanate endcapped polyethers. 13 C NMR spectroscopic assignments for the branched polyurethanes were verified using model urethane‐containing compounds based on TMP a…
Abstract Summary: The unique crystallization behavior of a poly[(butylene succinate)‐ co ‐adipate] (PBSA) nanocomposite is addressed. Nanocomposites have been prepared by melt blending PBSA and organically modified synthetic fluorine mica (OSFM) in a batch mixer. The structure of the nanocomposite is studied by using…
2,5-Dialkoxypoly( p -phenyleneethynylene) ( 3 ) functionalized with N - t -BOC- l -phenylalanine molecules was synthesized by Pd-catalyzed reaction of dioctyloxybis[(trimethylsilyl)ethynyl]benzene ( 1 ) with aromatic diiodide 2 linked to two amino acid units by six carbon atoms alkoxy chains. Optical properties were i…
A series of porphyrins substituted in one or two meso positions by diphenylphosphine oxide groups has been prepared by the palladium-catalyzed reaction of diphenylphosphine or its oxide with the corresponding bromoporphyrins. Compounds {MDPP-[P(O)Ph2]n} (M = H2, Ni, Zn; H2DPP = 5,15-diphenylporphyrin; n = 1, 2) were i…
The internal structure of PbSe nanocrystals was deduced using synchrotron X-ray photoemission spectroscopy for three different sizes of nanocrystals. The photoemission data revealed the layered structure of PbSe nanocrystals with the crystalline PbSe core surrounded by a nonstoichiometric Pb(1-x)Se shell, finally pass…
The CdS and CdS-Ag core-shell quantum dots (QDs) have been prepared. The nanostructures of the QDs were revealed by transmisson electron microscopy and absorption spectra, respectively. The third-order nonlinear optical properties of the core-shell QDs have been studied by using Z-scan technique with femtosecond pulse…
A facile and mild means of controllably preparing a series of single-crystalline alkaline-earth metal fluoride nanowires of reproducible shape and varying sizes (see figure) using a simple, room-temperature approach has been developed. This approach is based on the use of readily commercially available polycarbonate t…
Bubbles pushed through a quasi-two-dimensional channel self-organize into a variety of periodic lattices. The structures of these lattices correspond to local minima of the interfacial energy. The "flowing crystals" are long-lived metastable states, a small subset of possible local minima of confined quasi-two-dimensi…
Crystal structures, magnetic and thermodynamic properties of the spin-crossover compound tris(2-picolylamine)iron(II) dichloride (with 2-propanol solvent molecules) have been measured in the temperature range from 15 to 293 K. X-ray diffraction, SQUID, and calorimetric experiments all showed two first-order phase tran…
PbSe nanorods and branched nanorods are grown using binary Au–Fe3O4 nanoparticles as seeds. PbSe nucleates on the gold portion of the seed particle and grows anisotropically as one or more straight or branched nanorods. Seeding with binary particles has significant advantages over seeding with pure-metal particles. Th…
General, efficient and inexpensive methods for the synthesis of dendritic building blocks methyl 3',4'-dihydroxybiphenyl-4-carboxylate, 3',5'-dihydroxybiphenyl-4-carboxylate, and methyl 3',4',5'-trihydroxybiphenyl-4-carboxylate were elaborated. In all syntheses the major step involved an inexpensive Ni(II)-catalyzed S…