Chemical structure formats

As many different file formats have been developed since the early 1970s, the need for a standard chemical structure format has been increasingly felt. Various attempts have been made by different groups of the chemical commimity to define and push such a format, but none has achieved unanimous acceptance. 

Chem3D can read a wide variety of popular chemical structure files, including Gaussian, MacroModel, MDL, MOPAC, PDB, and SYBYL. Two-dimensional structures imported from ChemDraw or ISIS/Draw are automatically converted to three-dimensional structures. The Chem3D native file format contains both the molecular structure and results of computations. Data can be exported in a variety of chemical-structure formats and graphics files. 

Chapter 7 introduces ways in which RDBMS can be used to handle chemical structural information using SMILES and SMARTS representations. It shows how extensions to relational databases allow chemical structural information to be stored and searched efficiently. In this way, chemical structures themselves can be stored in data columns. Once chemical structures become proper data types, many search and computational options become available. Conversion between different chemical structure formats is also discussed, along with input and output of chemical structures. 

Chemical Structure Formation and Morphology in Ultrathin Polyurethane Films on Metals... 

Therefore, selected spectroscopic and microscopic techniques are applied to the characterization of chemical structure formation and morphology in thin polyurethane (PU) layers on Au, Al, and Cu Infrared spectroscopy offers convenient access to the integral chemical properties of thin-fihn and bulk-like polymer samples, while optical (OM) and scanning force microscopy (SFM) allow detailed insights into homogeneity and topology. 

It can be concluded after all that the results reveal very specific features caused by metal-polymer interactions in the interphase of cured PU on different metal surfaces, though further experimental efforts are needed to gain a more complete understanding of the underlying chemical reactions and adhesion mechanisms. Furthermore, remarkable quantitative differences can be seen in the chemical structure formation of thin PU films with regard to reaction rate and degree of isocyanate consumption. 

C. Wehlack, W. Possart, Chemical structure formation and morphology in ultrathin polyurethane films on metals, Proc. oral pres., 7th European Adhesion Conference EURADH 2004, Freiburg im Breisgau, September 5-9, 2004. 

In the chemical sense, one can immediately appreciate the potential and transversal applicability of these concepts, which have been reviewed authoritatively. There are numerous and varied chemical objects that are either slow to form or whose formation competes with that of other structures. Templates direct chemical structure formation, favoring the synthesis of a given product, and improving selectivity over other possible products. They can make feasible the preparation of chemical objects that would otherwise be impractical, such as catenanes and knots (see Self-Assembled Links Catenanes and Templated Synthesis of Knots and Ravels, Self-Processes). These considerations made Busch derive what has become a widely accepted definition a chemical template organizes an assembly of atoms, with respect to one or more geometric loci, in order to achieve a particular linking of atoms. ... 

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