Blue amorphous materials

Bis(dimesitylboryl)-2,2 -bithiophene (BMB-2T, 242) forms a stable amorphous glass and emits pure blue color with a high fluorescence QE of 86% in THF solution [270]. However, an OLED with ITO/m-MTDATA/TPD/BMB-2T/Mg Ag emits with a broad emission due to an exciplex with TPD. The exciplex can be prevented by insertion of a thin layer of 1,3,5-tris(biphenyl-4-yl)benzene (TBB) between TPD and BMB-2T, leading to a pure blue emission. It seems that the boron complex or boron-containing compounds easily form an exciplex with common HTMs. Other similar blue emitter materials also demonstrate such behavior. 

The X-ray diffraction patterns of the AlPO and CoAPO samples indicate pure phases, except for some samples of CoAPO —34, which might contain amorphous material. However, in view of the product compositions (Table 1) it must be concluded that many samples are not pure since the (Al+Co)/P ratio is considerably greater than 1. In these cases, part of the aluminium and/or cobalt must be present in extra-framework species. In particular, samples prepared with high cobalt concentrations in the gel and samples of CoAPO -34 exhibit unfavourable element ratios. These samples are also often less homogeneous in that they can contain white particles, whereas the major phase exhibits a blue colour. 

Figure 5 Section of human postburn hypertrophic scar tissue, stained with Cuprolinic blue and uranyl acetate, showing thin collagen fibrils embedded in an abundant interfibrUlar matrix. Clumps of densely stained amorphous materials are probably biglycan and/or versi-can. Note the paucity of periodically attached decorin DS chains on the collagen fibrils (contrast with Fig. 4). The scale bar represents 100 nm.

Figure 13 shows the structure factors S(Q) of AIST and GST obtained using X-ray diffraction. The crystalline forms of both materials have sharp Bragg peaks (red lines), and the amorphous forms (blue lines) have typical halo patterns. However, oscillations up to the maximum Q value in a-AIST indicate a structure with well defined short-range order. The total correlation fimctions T(r) for AIST and GST are shown in Fig. 14. The T(r) for crystalline (c-) AIST and c-GST, which are very similar beyond 4 A. Small differences between the two crystalline forms are found at shorter distances, for example the double peak in c-AIST (2.93 A and 3.30 A) and a single peak in c-GST (2.97 A). The T(r) for the amorphous materials, however, are significantly different the first peak in amorphous (a-)...

By freeze-fracture analysis, this amorphous material was found to be associated with the openings of plasma membrane vesicles. The amorphous material did not stain with PAS or Alcian blue or fluorescent lectins and was thereby thought unlikely to be mucin or other glycoprotein (Williams and Elias, 1981). 

Under the microscope perineurium and endoneurium are thickened. Typically (Dereux 1963) but not always (Veltema and Verjaal 1961) the appearance resembles that of hypertrophic polyneuritis, type Dejerine-Sottas (Edstrom et al. 1959). Microscopic lesions vary in intensity in different sections, and are most marked where the tissue appears edematous on gross examination. Here, the axis cylinders are diminished in number and are separated by an amorphous material which stains metachromatic with cresyl violet, toluidin blue and PAS (Cammermeyer 1956). The accumulation of serous fluid which apparently is responsible for the swelling (Gordon and Hudson 1959, Alexander 1966) may be limited to peripheral bundles, and the metachromatic material may become less or may... 

Fig. 6.7 Annealing of cascade-induced amorphous pockets by molecular dynamics, a State immediately after the cascade, b After Ins annealing at 1300K the amorphous material has recrystallized and selfinterstitials and vacancy clusters are left behind. The vacancies and their clusters induce tensile stress in the neighboring atoms and these are shown as blue spheres. The self-interstitials are shown as red and gray spheres [48]...

Color/Transparency. Almost all amorphous engineering thermoplastics, except PC and some polyester carbonates, are inherently colored. Even polycarbonates have yellowness indexes (YI) (36) of 0.1 to 5.0. Colorless material is produced from these resins by compounding with complementary blue dyes which reduce transmission. Ha2e in amorphous resins is an indication of particulates. Ha2e reduces optical clarity and transmission. 

T. Noda, H. Ogawa, and Y. Shirota, A blue-emitting organic electroluminescent device using a novel emitting amorphous molecular material, 5,5 -/)/.v(dimcsityIboryl)-2,2 -bithiophene, Adv. Mater., 11 283-285 (1999). 

M. Kinoshita, H. Kita, and Y. Shirota, A novel family of boron-containing hole-blocking amorphous molecular materials for blue- and blue-violet-emitting organic electroluminescent devices, Adv. Func. Mater., 12 780-786 (2002). 

A growing number of reports are appearxng concerning %<3) of materials as determined by THG experiments. Among organics a variety of poly(diacetylenes), e. g., 4-BCMU (4-butoxycarbonylmethylurethane polydiacetylene) (15,109) have been studied as pure materials and as LB films, 110) Crystalline films of poly(4-BCMU) in the red form, were found to have higher %<3) than amorphous films, attributed to the orientational effect of crystallization.(109) The blue form also has been studied. 111) Maximum values of %<3) reported to date are 1 x 10 10 esu at 1.3 l. Poly (phenylacetylene) THG at 1.06 lhas recently been measured. 111) The 2- and 3-photon resonance enhanced value of %<3) determined is 7 x 10 12 esu. 

Taushanoff S, Le KV, Williams J, Twieg RJ, Sadashiva BK, Takezoe H, Jakli A (2010) Stable amorphous blue phase of bent-core nematic liquid crystals doped with a chiral material. J Mater Chem 20 5893-5898... 

Despite some indisputable progress in the understanding of the nature and composition of platinum blues derived from m-(NH3)2P(" which has been achieved within the last twenty years, in particular thanks to X-ray crystallography, there is still no comprehensive picture available on the -blues . This is true in particular for the platinum pyrimidine blues , on which this review had focused. The amorphous nature of these materials has restricted the methods of investigation to questions such as metal-metal separations [97] or delocalization of spins due to the presence of Ptm centers in a Pt chain [29] [51]. These methods have, however, not provided insight... 

Solid-state cellulose can also be noncrystalline, sometimes called amorphous. Intermediate situations are also likely to be important but not well characterized. One example, nematic ordered cellulose has been described [230]. In most treatments that produce amorphous cellulose, the whole fiber is severely degraded. For example, decrystallization can be effected by ball milling, which leaves the cellulose as a fine dust. In this case, some crystalline structure can be recreated by placing the sample in a humid environment. Another approach uses phosphoric acid, which can dissolve the cellulose. Precipitation by dilution with water results in a material with very little crystallinity. There is some chance that the chain may adopt a different shape (a collapsed, sixfold helix) after phosphoric acid treatment. This was concluded because the cellulose stains blue with iodine (see Figure 5.12), similar to the sixfold amylose helix in the starch-iodine complex. 

Copolymers with longer polyene segments were found to be insoluble in the reaction solvent (toluene). In these materials, the polyacetylene fraction was crystalline (97). Copolymers with a low acetylene content were composed of a variety of isolated crystalline structures within an amorphous matrix, whereas those containing 50% or more polyacetylene had a morphology that resembled fibrillar polyacetylene. Dried copolymer solutions and suspensions gave blue films with the mechanical properties characteristic of the carrier polymer. No increase in environmental stability was observed. 

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