SMILES nomenclature

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... 

Figure 8.1 Example of (a) a structure diagram, (b) systematic nomenclature, (c) connection table in MDL format (see URL http //www.mdli.com), and (d) SMILES for a molecule.

Compound nomenclature, compound codes, fUPAC names, SMILES strings... 

One of the common character formats or chemical nomenclature of a valence model which is recognizable by a number of 2D-structure drawing programs is SMILES (Weininger, 1988). A full SMILES language tutorial can be accessed at http // www.daylight.com/dayhtml/smiles/. The general rules for biochemical compounds are as follows ... 

IUPAC-like expressions, true IUPAC nomenclature names, and InChl and SMILES representations of chemical compounds are well suited for detection by machine learning approaches. Conditional random fields (CRFs)41 and support vector machines have been used for the detection of IUPAC expressions in scientific literature 42 Other approaches are based on rules sets43 44 or combinations of machine learning with rule-based approaches 45 All these approaches have in common that they face one significant problem the name-to-structure problem. 

The Java applet that comes with NMRShiftDB includes an array of features for molecular display (such as ball-and-stick, wireframe, space-fill, etc.), translation into SMILES nomenclature, and possibility of structure editing. Searching of chemicals can be based on (amongst others) chemical name, keyword, CAS number, literature title/author, and chemical formula. 

This chapter discusses lUPAC and CAS nomenclature systems and the SMILES notation, along with examples of each. Multiple names for a single well-defined substance—ethyl acrylate—are also presented. 

The SMILES notation is a means by which certain chemical structures can be described using a series of simple letters and numbers expressed in linear fashion, even for complex cyclic structures. This approach is particularly useful as input for computer models when chemical names and CASRN are unknown. As mentioned above, SMILES is an important tool in hazard and exposure modeling used in EPA s voluntary Sustainable Futures Program [1]. It can also be used to identify substances under REACH, and examples are shown in the nomenclature Technical Guidance Document (TGD) along with molecular and structural formulas. 

SMILES is an acronym for Simplified Molecular Input Line Entry Specification. The algorithm is a universal nomenclature. It was developed in 1988 by Weininger [15]. Several computer programs use now the SMILES algorithm. We briefly show a few most important rules to represent chemical structures by SMILES. We definitely refer to a more detailed version that is given in the Internet [16]. 

---