SMILES system

The presence of a branch in the structure raises the question of where to start coding. With the SMILES system it does not matter where one starts. A SMILES interpreter will produce the same structure from any valid SMILES coding for a compound. In some circumstances, such as the system s use in databases, it is necessary to have a unique SMILES string for a molecule. Using a set of rules it is possible to uniquify a SMILES string. 

These simple rules allow very rapid encoding of most chemical structures and need only a few simple additions to cope with other atoms, charges, isomers, etc. Specification of atoms not in the organic subset, for example, is coded by use of an atomic symbol within square brackets. An extensive description of the SMILES system is given by Weininger and Weininger (1990). 

In 1986, David Weininger created the SMILES Simplified Molecular Input Line Entry System) notation at the US Environmental Research Laboratory, USEPA, Duluth, MN, for chemical data processing. The chemical structure information is highly compressed and simplified in this notation. The flexible, easy to learn language describes chemical structures as a line notation [20, 21]. The SMILES language has found widespread distribution as a universal chemical nomenclature... 

The TcIcSpcc system offens two ways of reading in a query structure. The structure can be input cither directly as a SMILES string (cf. Section 2,3.3) or via a molecule editor which converts the graphical input into the SMILES string. Figure 10.2-10 gives the input form of TeleSpec. 

As computing capabiUty has improved, the need for automated methods of determining connectivity indexes, as well as group compositions and other stmctural parameters, for existing databases of chemical species has increased in importance. New naming techniques, such as SMILES, have been proposed which can be easily translated to these indexes and parameters by computer algorithms. Discussions of the more recent work in this area are available (281,282). SMILES has been used to input Contaminant stmctures into an expert system for aquatic toxicity prediction by generating LSER parameter values (243,258). 

In reducing media, a synthetically useful variation of the Smiles rearrangement, which leads to the formation of fused ring systems, has been observed (equation 77)251. In this reaction, rearrangement is followed by displacement of the sulfinate anion by a nucleophilic o -substituent. 

Weiniger D. SMILES, a chemical language and information system. 1. Introduction to methodology and encoding rules. / Chem Inf Comput Sci 1988 28 31-6. 

Directed lithiation of aromatic compounds is a reaction of broad scope and considerable synthetic utility. The metalation of arenesulfonyl systems was first observed by Gilman and Webb and by Truce and Amos who reported that diphenyl sulfone is easily metalated at an orf/io-position by butyllithium. Subsequently, in 1958, Truce and coworkers discovered that metalation of mesityl phenyl sulfone (110) occurred entirely at an orf/io-methyl group and not at a ring carbon, as expected. Furthermore, refluxing an ether solution of the lithiated species resulted in a novel and unusual variation of the Smiles rearrangement and formation of 2-benzyl-4,6-dimethyl-benzenesulfinic acid (111) in almost quatitative yield (equation 78). Several other o-methyl diaryl sulfones have also been shown to rearrange to o-benzylbenzenesulfinic acids when heated in ether solution with... 

SMILES Simplified Molecular Input Line Entry System... 

Nowhere, perhaps, is this phenomenon better illustrated than in the phenothiazine class. The earlier volume devoted a full chapter to the discussion of this important structural class, which was represented by both major tranquilizers and antihistamines. The lone phenothiazine below, flutiazin (130), in fact fails to show the activities characteristic of its class. Instead, the ring system is used as the aromatic nucleus for a nonsteroidal antiinflammatory agent. Preparation of 130 starts with formylation of the rather complex aniline 123. Reaction with alcoholic sodium hydroxide results in net overall transformation to the phenothiazine by the Smiles rearrangement. The sequence begins with formation of the anion on the amide nitrogen addition to the carbon bearing sulfur affords the corresponding transient spiro intermediate 126. Rearomatization... 

For each selected PFC, a profile was edited including the name of the compound, its CAS (Chemical Abstracts Service) number and the SMILES (Simplified Molecular Input Line Entry System) formula. 

Daylight Chemical Information Systems Inc. SMILES home page. http //www.daylight.com/dayhtml/ smiles/index.html. 

Chemical identity may appear to present a trivial problem, but most chemicals have several names, and subtle differences between isomers (e.g., cis and trans) may be ignored. The most commonly accepted identifiers are the IUPAC name and the Chemical Abstracts System (CAS) number. More recently, methods have been sought of expressing the structure in line notation form so that computer entry of a series of symbols can be used to define a three-dimensional structure. For environmental purposes the SMILES (Simplified Molecular Identification and Line Entry System, Anderson et al. 1987) is favored, but the Wismesser Line Notation is also quite widely used. 

SMILES (Simplified Molecular Input Line Systems), 6 3-6 Smith, Adam, 24 364 Smith—Ewart kinetics, 14 715 Smith-Ewart recursion formula, 14 715 Smith-Ewart theory, 25 571, 572 VDC polymerization and, 25 697... 

It is to be noted that the QSPR/QSAR analysis of nanosubstances based on elucidation of molecular structure by the molecular graph is ambiguous due to a large number of atoms involved in these molecular systems. Under such circumstances the chiral vector can be used as elucidation of structure of the carbon nanotubes (Toropov et al., 2007c). The SMILES-like representation information for nanomaterials is also able to provide reasonable good predictive models (Toropov and Leszczynski, 2006a). 

Local SMILES attributes were defined according to hierarchy first, system is attempting to detect attributes of four symbols, i.e., [N+] or [O-] second, system is attempting to detect attributes of two symbols, i.e., Cl or Br third, all others are attributes of one symbol. 

Toropov AA, Toropova AP, Mukhamedzhanova D, Gutman I (2005a) Simplified molecular input line entry system (SMILES) as an alternative for constructing quantitative structure-property relationships (QSPR). Indian J. Chem. Sect A. 44 1545-1552. 

Weininger, D.J. SMILES a chemical language and information system. 

The text/plain example above demonstrates that HTTP networks can support distributed information systems when given appropriate languages, that is, languages that describe abstractions appropriate to that information system. Many other standard MIME types are useful. Most are very specific, for example, image/gif is a specific format for bitmapped images, application/PDF is a page description format and application/tar is a 4.3 BSD archive. Some describe more general abstractions, for example, application/xml . Private (unauthorized) MIME types are also available, for example, chemical/x-pdb and chemical/x-smiles . 

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