SMILES

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smile! :)

assalamualaikum

do you know what is SMILES is? 

Today we will introduced you with SMILES or known as the simplified molecular input line entry specification. SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. The SMILES stings can be imported by most molecule editors for conversion back into two-dimensional drawing or three dimensional models of the molecules.

There are two types of SMILES bond:

• Conical SMILES

Refers to the version of the SMILES specification that includes rules for ensuring that each distinct chemical molecule has a single unique SMILES representation.

• Isomeric SMILES

Refers to the version of the SMILES specification that includes extensions to support the specification of isotopes, chirality and configuration about the double bond.

SMILES Bonds

Single*	-
Double	=
Triple	#
Aromatic	:

SMILES Charges : specify attached hydrogens and charges in square brackets, the number of attached hydrogens is the symbol H followed by optional digit. For example: 

[H+] proton

[OH-] hydroxyl anion

[OH3+] hydronium cation

[Fe++] iron(III) cation

[NH4+] ammonium cation

There are also restrictions of using SMILES, such as : 
1. a branch cannot begin a SMILES notation
2. a branch cannot immediately follow a double- or triple-bond symbol

for example:   C=(CC)C is invalid
                     C(=CC)C or C(CC)=C is valid 

If you want to view the examples of SMILES, here are a few molecules with their correct SMILES strings. CLICK HERE ;-)