23 December, 2012

SMILING VS SMILES


Assalamulaikum.
Hello, how are you my friends?
Today, we want share with you about SMILES. Do you know what SMILES is about?
Maybe you think smiles is like this.
                                                      
It is true.

But actually we want to tell you about Simplified Molecular Input Line Entry Specification (SMILES).
Simplified Molecular Input Line Entry Specification (SMILE) is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. Its strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules. For example in figure 1.

                                
         Visualization of 3-cyanoanisole as COc(c1)cccc1C#N.
Figure 1

It is simple, using atomic symbol and follows unique rules. It is used widely around the world computationally.

 To write the molecules in SMILES you should follow symbol in the table bellow.

Symbol for SMILES

Single bond
-
Double bond
=
Triple bond
#

Aromatic
*can be omitted
:

Branches
Atom enclosure in parentheses,( )
Atom in aromatic
Lower cases, example: c1ccccc1
[Fe++]

Iron(II) cation

Isomeric
/ or \. Example: trans-1,2-dibromoethene: Br/C=C/Br
                            cis-1,2-dibromoethene: Br/C=C\Br
 
Chirality
@
Metal
[Al]  

But there a certain rules we need to follow:
1.      A branch cannot begin a SMILES notation
2.      A branch cannot immediately follow a double- or triple-bond symbol
3.      Numbers indicate start and stop of ring. Same number indicates start and end of the ring, entered immediately following the start/end atoms.

Do you want to try? You can click here






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