Search results for "Conjugate"
showing 10 items of 644 documents
ChemInform Abstract: Microwave-Assisted Tandem Organocatalytic Peptide-Coupling Intramolecular aza-Michael Reaction: α,β-Unsaturated N-Acyl Pyrazoles…
2015
Conjugated N-acyl pyrazoles are successfully employed in the organocatalytic enantioselective intramolecular aza-Michael reaction as ester surrogates.
Theoretical characterization of the electronic structure of polymeric systems combining disilanylene and /spl pi/-conjugated units
1994
Summary form only given. Polymeric organosilicon systems are in the forefront of research, due to their intriguing properties (semiconducting behavior, photoconduction, non-linear optical properties, and thermo- and piezochromism). The fundamental skeletons of most of these polymers consist of a /spl sigma/-electron network formed by silicon-silicon bonds. Recently, polymeric organosilicon systems containing a regular alternation of a disilanylene unit and carbon /spl pi/-conjugated moiety as phenylene, ethynylene, or ethenylene have been synthesized. The purpose of this contribution is to perform a detailed study of the electronic structure of polymers containing alternated disilanylene an…
Observation of Very Narrow Linewidths in the Fluorescence Excitation Spectra of Single Conjugated Polymer Chains at 1.2 K
2007
Fluorescence emission and excitation spectra of single poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] polymer molecules embedded in poly(methylmethacrylate) have been recorded at 1.2 K. The ubiquitous spectral diffusion causes large variations in the spectral shape and apparent linewidth in the emission spectra. Nevertheless, we find very narrow (approximately 0.1 cm(-1)) purely electronic zero-phonon lines in the excitation spectra, which are 2 orders of magnitude smaller than previous estimates of the homogeneous linewidth. These results complement the molecular description of the low energy transitions in conjugated polymers.
New amphiphilic conjugates of mono- and bis(carboxy)-PEG(2,000) polymers with lipoamino acids as surface modifiers of colloidal drug carriers
2010
Effects of tannin-containing diets on small ruminant meat quality
2010
Tannins are phenolic compounds present in several forages, tree leaves and by-products used for small ruminant feeding in the Mediterranean area. Although the effects of dietary tannins on small ruminant growth performances have been largely studied, only in the last ten years researchers have started to study the effects of tannins on meat quality. Meat from small ruminants given tanniniferous diets is lighter in colour compared to meat from animals given the same diets but in which the effects of tannins have been eliminated by the supplementation of polyethylene glycol. This result has been obtained with tannins from different feeds (carob pulp, acacia leaves or sulla fresh herbage). Rec…
Studies on the diurnal courses of the contents of abscisic acid, 1-aminocyclopropane carboxylic acid and its malonyl conjugate in needles of damaged …
1993
Summary The diurnal courses of the contents of 1-aminocyclopropane carboxylic acid (ACC), its malonyl conjugate (MACC) and abscisic acid (ABA) in the two-year-old needles of damaged and undamaged spruce trees (Picea abies L.) were investigated. The contents of ACC and MACC were significantly higher in the needles of the damaged trees as compared with the undamaged ones. In the needles of the damaged spruce trees, the ACC and MACC contents, and ABA contents as well, fluctuated to a greater extent than those in the undamaged spruce trees during the day. The relationships between ACC-ABA and MACC-ACC contents as well are also discussed.
Non-linear optical spectra of excitons in polydiacetylene
1992
Abstract Adding long-range Coulomb interactions to the Su-Schrieffer-Heeger model makes it possible to investigate excitonic states in conjugated polymers. Various characteristic features due to these states as well as due to the electron-hole continuum can be found in the calculated non-linear optical susceptibilities. In particular the electroabsorption spectrum and the third harmonic generation intensity and its dependence on the system size are examined. Using only moderate interaction strength, various experiments in polydiacetylene can be interpreted in a consistent way.
ChemInform Abstract: Glycoconjugates as Tumor-Associated Antigens and Ligands in Regulatory Processes
2010
ChemInform Abstract: Mixed Dialkylaluminum Chlorides and Mixed Trimethylorganoaluminates in Chemoselective 1,4-Addition Reactions to Alkylidene Malon…
2010
Mixed alkyl-methyl- and aryl-methylorganoaluminum chlorides 6 were formed by reaction of methylaluminum dichloride with organolithium or Grignard compounds and used for chemoselective 1,4 addition of higher alkyl, aryl, alkenyl and alkinyl groups to alkylidine malonic esters 1 and 2. As an alternative, mixed trimethylorganoaluminates 7 can also be applied for these Michael addition reactions. For conjugate addition of alkenyl groups to alkylidene malonates 1 and 2, alkenyl diisopropylalanes 10 obtained from alkynes and diisopropylaluminum hydride proved the most efficient reagents. Using these novel mixed organoaluminum compounds, β-branched malonic (carboxylic) acid derivatives 3c, 8, 9 an…
Novel Porphyrin-Cholic Acid Conjugates as Receptors for Biologically Important Anions
2005
A series of novel receptors showing high binding affinity in aqueous media for biologically important anions are reported. These naturally chromophoric porphyrin-based receptors contain cholic acids connected via quaternary alkyl ammonium amido linkages.