Wiswesser line notation example

An alternative way to represent molecules is to use a linear notation. A linear notation uses alphanumeric characters to code the molecular structure. These have the advantage of being much more compact than the connection table and so can be particularly useful for transmif-ting information about large numbers of molecules. The most famous of the early line notations is the Wiswesser line notation [Wiswesser 1954] the-SMILES notation is a more recent example that is increasingly popular [Weininger 1988]. To construct the Wiswesser... 

The above is based on the calculation of a collective r for the whole molecule. This value changes the HOMO of either the diene or dienophile, as is necessary. This equation is accurate to about 0.5 eV on either side of the known values [15]. The value of ttotal is inserted into the HOMO-LUMO calculation as the parameter r Y), Note that in its pure form, this equation only yields values for the HOMO orbitals. Corrections are used for the calculation of the LUMO values. Table 1 contains examples of the Wiswesser Line Notation and the raw r values used in the computation of orbital energies. 

There are several linear canonical notations for the input of chemical structures into the computer notable among these are the Wiswesser line notation [226] and the IUPAC notation [227], which are used in industrial information systems. In order to achieve a canonical notation, a large number of rules are necessary, more than three hundred in the Wiswesser line notation [226]. Furthermore, the resulting notation is quite arbitrary and very far from the usual practice of a chemist for example, acetone is 1V1 in the Wiswesser notation. In conclusion, both coding a formula and reading a coded formula in the Wiswesser notation require highly trained chemists. 

Two-dimensional representations alternative to the molecular graph are the linear notation systems, like, for example, Wiswesser Line Notation system (WLN) [Smith and Baker, 1975] and SMILES notation [Weininger, 1988 Weininger etal., 1989 Wei-ninger, 1990 Convard et al, 1994 Hinze and Welz, 1996]. 

Two-dimensional representations alternative to the molecular graph are the linear notation systems, for example, Wiswesser Line Notation system (WLN) [Smith and Baker, 1975], SMILES [Weininger, 1988, 1990, 2003 Weininger, Weininger et al., 1989 Convard, Dubost et al., 1994 Hinze and Welz, 1996], and SMARTS (SMART - Daylight Chemical Information Systems, 2004). CAST (CAnonical representation of STereochemistry) is a method that gives a linear notation that canonically represents stereochemistry around a specific site in a molecule [Satoh, Koshino et al, 2000, 2001, 2002],... 

Briefly, notation systems attempt to record full, multidimensional structural descriptions in a linear form, by the use of more comprehensive symbols than atoms and bonds (e.g. symbols for particular chains, rings, functional groups). Thus, more information is recorded implicitly, in Uie rides of the notation, and less is recorded explicitly in the notations for individual compounds. The rules can therefore be quite complicated, in order to ensure the notations are unique and unambiguous. For the Wiswesser Line Notation, the rules are given in Smith, E. G. The Wis-wesser Line-Formula Chemical Notation. New York McGraw-Hill 1968. In this notation, for example, saturated carbon chains are simply indicated by an arable numeral equal to the number of carbons in the chain, branch-... 

The Wiswesser line notation was already invented in 1938, i.e., before the advent of computers that could effectively use it [10-14], In 1960, the Institute for Scientific Information (ISI) developed the Index Chemicus, based on the Wiswesser line notation. The Wiswesser line notation is based on sequences of letters, numbers, and other characters as shown in Table 14.5. Numbers refer to the number of carbon atoms. For example, QV refers to acetic acid, and Q2 refers to ethyl alcohol. 

Wiswesser Line Notation is likely to be used at ICI Pharmaceuticals Division for many years to come, not least because of its use in commercial databases bought by ICI, for example the Index Chemicus Registry System tapes (8). 

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