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Chemical Design (chemical + design)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Interface Engineering for Organic Electronics

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2010
Hong Ma
Abstract The field of organic electronics has been developed vastly in the past two decades due to its promise for low cost, lightweight, mechanical flexibility, versatility of chemical design and synthesis, and ease of processing. The performance and lifetime of these devices, such as organic light-emitting diodes (OLEDs), photovoltaics (OPVs), and field-effect transistors (OFETs), are critically dependent on the properties of both active materials and their interfaces. Interfacial properties can be controlled ranging from simple wettability or adhesion between different materials to direct modifications of the electronic structure of the materials. In this Feature Article, the strategies of utilizing surfactant-modified cathodes, hole-transporting buffer layers, and self-assembled monolayer (SAM)-modified anodes are highlighted. In addition to enabling the production of high-efficiency OLEDs, control of interfaces in both conventional and inverted polymer solar cells is shown to enhance their efficiency and stability; and the tailoring of source,drain electrode,semiconductor interfaces, dielectric,semiconductor interfaces, and ultrathin dielectrics is shown to allow for high-performance OFETs. [source]

Supramolecular Crystal Engineering at the Solid,Liquid Interface from First Principles: Toward Unraveling the Thermodynamics of 2D Self-Assembly

ADVANCED MATERIALS, Issue 13 2009
Carlos-Andres Palma
Abstract The formation of highly ordered 2D supramolecular architectures self-assembled at the solid,solution interfaces is subject to complex interactions between the analytes, the solvent, and the substrate. These forces have to be mastered in order to regard self-assembly as an effective bottom-up approach for functional-device engineering. At such interfaces, prediction of the thermodynamics governing the formation of spatially ordered 2D arrangements is far from being fully understood, even for the physisorption of a single molecular component on the basal plane of a flat surface. Two recent contributions on controlled polymorphism and nanopattern formation render it possible to gain semi-quantitative insight into the thermodynamics of physisorption at interfaces, paving the way towards 2D supramolecular crystal engineering. Although in these two works different systems have been chosen to tackle such a complex task, authors showed that the chemical design of molecular building blocks is not the only requirement to fulfill when trying to preprogram self-assembled patterns at the solid,liquid interface. [source]

Metabolites in safety testing: metabolite identification strategies in discovery and development

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2009
Angus N. R. Nedderman
Abstract The publication of the FDA MIST guidelines in 2008, together with the acknowledged importance of metabolism data for the progression of novel compounds through drug discovery and drug development, has resulted in a renewed focus on the metabolite identification strategies utilised throughout the pharmaceutical industry. With the plethora of existing and emerging technologies available to the metabolite identification scientist, it is argued that increased diligence should be applied to metabolism studies in the early stages of both drug discovery and drug development, in order to more routinely impact chemical design and to comply with the concepts of the MIST guidance without re-positioning the definitive radiolabelled studies from there typical place in late development. Furthermore, these strategic elements should be augmented by a broad and thorough understanding of the impact of the derived metabolism data, most notably considerations of absolute abundance, structure and pharmacological activity, such that they can be put into proper context as part of a holistic safety strategy. The combination of these approaches should ensure a metabolite identification strategy that successfully applies the principles of the MIST guidance throughout the discovery/development continuum and thereby provides appropriate confidence in support of human safety. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Breaking symmetry in protein dimers: Designs and functions

PROTEIN SCIENCE, Issue 1 2006
Jerry H. Brown
Abstract Symmetry, and in particular point group symmetry, is generally the rule for the global arrangement between subunits in homodimeric and other oligomeric proteins. The structures of fragments of tropomyosin and bovine fibrinogen are recently published examples, however, of asymmetric interactions between chemically identical chains. Their departures from strict twofold symmetry are based on simple and generalizable chemical designs, but were not anticipated prior to their structure determinations. The current review aims to improve our understanding of the structural principles and functional consequences of asymmetric interactions in proteins. Here, a survey of >100 diverse homodimers has focused on the structures immediately adjacent to the twofold axis. Five regular frameworks in ,-helical coiled coils and antiparallel ,-sheets accommodate many of the twofold symmetric axes. On the basis of these frameworks, certain sequence motifs can break symmetry in geometrically defined manners. In antiparallel ,-sheets, these asymmetries include register slips between strands of repeating residues and the adoption of different side-chain rotamers to avoid steric clashes of bulky residues. In parallel coiled coils, an axial stagger between the ,-helices is produced by clusters of core alanines. Such simple designs lead to a basic understanding of the functions of diverse proteins. These functions include regulation of muscle contraction by tropomyosin, blood clot formation by fibrin, half-of-site reactivity of caspase-9, and adaptive protein recognition in the matrix metalloproteinase MMP9. Moreover, asymmetry between chemically identical subunits, by producing multiple equally stable conformations, leads to unique dynamic and self-assembly properties. [source]