A web portal for the processing of molecular structures by blind students
last update: 26.07.2017
The MOLinsight web portal is a gateway to open-source software as well as software freely accessible to students that can be integrated in strategies for blind users to process chemical structures. Here you can find documentation for available programs and a guide for specific tasks.
How to do common tasks?
We hope you enjoy the new software. Your feedback will be very welcome.
For more information please contact jas_at_fct.unl.pt
The NavMol development team: , , , , , , , .
For examples of molecular structures of organic compounds in the MDL .mol file please download the zipped file formulae.
You need to start with an existing .mol file to build a molecule. You can always start with a file with at least a bond between two atoms, for example a simple organic compound such as methane (CH4), methane.mol.
The NavMol software was highlighted in the Portuguese science TV show "Com Ciência" (RTP 2) in 02.05.2012. In the interview Dr. Florbela Pereira explains the main features of NavMol and demonstrates the software with a visually impaired student.
BrailChem was developed as a part of the ICT
Project and is
a software for visually impaired users. The
program supports a
range of file types, namely: IUPAC name, SMILES,
CDXML, CDX, CML, InChI, MOL and PDB.
server is available in the web and it
can navigate a molecular structure, read molecular
properties, identify functional groups, and read chemical
reactions. It can also convert a name into a structure if it
is available in a very large
dictionary based on the PubChem database.
Furthermore it can navigate the periodic table of the
know how the BrailChem works please go to the
client is available as a Firefox
extension. You can download and install it directly from
Firefox by clicking on
this link pointing to the extension module. Continue according
to the instructions of the browser. After the installation and
final restart of Mozilla
BrailChem can be opened from the tools
software from ChemAxon,
both in commercial and academic versions. This program
supports a wide
range of file
formats, namely: MOL, MOL2, SDF, RXN, RDF (V2000/V3000), SMILES, SMARTS/SMIRKS
(recursive), MRV, InChI, CML, PDB, and IUPAC name.
To download Marvin
Beans please go to the ChemAxon's free academic package, visit the download page, select Marvin software and
register. If you have any questions about how to apply
for, maintain or access software provided under the
Academic Package conditions please visit the ChemAxon academic package support forum or
MolConverter is a command-line program in Marvin Beans that converts between the following file formats: smiles, name, or mol for SMILES, IUPAC name, and MDL Molfile. To know how the MolConverter works please read the MolConverter notes.
OpenBabel is a free software with a chemical expert system mainly used for converting chemical file formats, which also provides the calculation of molecular properties. It supports a huge variety of common chemical file formats, including SDF/MOL, Sybyl mol2, PDB, SMILES, XYZ, and CML.
For specific installation instructions of OpenBabel-2.2.3 for Mac please go to the OpenBabel install webpage. The OpenBabel package includes a variety of programs, including the babel conversion tools Obprop and Obchiral.
Babel is a command-line program in OpenBabel that converts between file formats. To know how the babel conversion tool works please go to the OpenBabel command-line program webpage or read the Babel conversion tool notes.
The Obprop program can
print a set of standard molecular properties (e.g. molecular
weight, exact mass, number of atoms, estimated logP) for all
molecules in a file. Obprop works with a single command: obprop
The Obchiral program can print chirality information for all molecules in a file.
To know how the obchiral tool works please go to the OpenBabel command-line program webpage or read the Obchiral tool notes. You can find examples of stereochemical structures of organic compounds in MDL .mol file in the directory formulae enantiomers.
With the Obchiral tool and the NavMol program you can interpret the configuration of chiral molecules. To know more about stereochemistry please read the stereochemistry notes.
A molecular editor is a computer program for creating and modifying representations of chemical structures. There are several types of molecular editors. Molecular drawing programs are used to generate two-dimensional (flat) representations of molecules and chemical reactions. In the following you can find a brief description of three available standalone programs:
1. Marvin Sketch of Marvin Beans (described above )
This program supports a wide range of file types for import, namely: MOL, SMILES (stereochemistry is not supported) and InChI (stereochemistry is not supported).
This program supports a wide range of file types for exports, namely: SVG, OpenOffice Draw, PDF, EPS (Encapsulated Postcript), MOL, PNG, SMILES (stereochemistry is not supported) and InChI (stereochemistry is not supported).
Executable for Windows NT – bkchem-0.13.0
Linux and other Unix systems – the source code distribution has to be used, the program uses the standard distutils package for deployment and the details are in the INSTALL zipped file in the main BKchem directory. For specific information related to the MAC OS please go to the page How do I install BKChem on Mac OS X?.
To know how the BKchem works please go to the BKchem webpage.
Control+X and Control+N for a new file
Control+X and Control+S to save a file
Control+Shift+A to select all
Control+O and Control+I for chemical information (name, id, molecular formula, weight and atomic composition)
Control+X and Control+C to close the BKchem window
Using an open source software (JDXview and CSV to MIDI converter) infrared spectra can be converted into sounds of varying tones. In the sonified infrared spectra (SIRS) the visual information is converted into non-speech sounds to convey information that is used in the interpretation of scientific results (see the example for Aspirin® in the figure).
Sonified infrared spectra and their Interpretation by blind and visually impaired students, F. Pereira, J.C. Ponte-e-Sousa, R.P.S. Fartaria, V.D.B. Bonifacio, P. Mata, J. Aires-de-Sousa, A.M. Lobo, J. Chem. Educ. 2013, 90, 1028-1031.
In the press:
The sound of spectra, Chemical and Engineering News, 2013, 91, 30.
In the Web:
Sounds science: research results for the visually challenged, Pasco Phronesis Science Blog.
HOW TO DO COMMON TASKS?
Your approach to interpret a molecular structure depends on how it is represented, and your knowledge of different notations, nomenclature systems, and expertise with software.
If you know the fundamentals of the IUPAC nomenclature you should be able to interpret a molecular structure from its IUPAC name, at least for simple structures.
If you learn and get trained with the SMILES linear notation you should be able to interpret a molecule represented by a SMILES string (see the SMILES notes on the MOLinsight portal). Some structures may be easier to interpret from SMILES than from their IUPAC names, others not.
You may navigate a molecular structure represented in the MDL Molfile format with the program NavMol. It enables the user to jump from atom to atom getting information about the neighbors and bonds of each atom. With NavMol you can get explicit information about the atoms of the molecule and how they are bonded. You can get the program from the MOLinsight portal, as well as its documentation.
For more complex structures it may help to get structures represented simultaneously in the three formats (SMILES, IUPAC name, and MDL Molfile). The different formats are complementary for the quick recognition of specific aspects of the structure.
There are several software tools enabling the interconversion of molecular formats. Recommended examples of available software are babel (OpenBabel) and molconvert (Marvin Beans).
Examples are provided to convert molecules between SMILES, IUPAC name, and MDL Molfile with these programs:
To convert a molecular file into another format, use the command:
molconvert outformat inputfile
where outformat is the desired output format (smiles, name, or mol for SMILES, IUPAC name, and MDL Molfile respectively), and inputfile is the file to be converted. More details on the use of Molconverter are available.
To convert a molecular file into another use the command:
babel –i informat inputfile –o outformat outputfile
where informat is the input format, inputfile is the file to be converted, outformat is the desired output format (e.g. smiles, mol, cdx for SMILES, MDL Molfile and Chemdraw respectively), and outputfile is the new file to be saved. ChemDraw is a popular commercial molecular editor developed by CambridgeSoft. More details on the use of Babel are available.
Similarly to the interpretation of a molecular structure you may follow several approaches to build a structure depending on your expertise with different methods and tools.
Learning the SMILES notation will empower you with a very easy way of building molecules. A SMILES representation of a molecule is a very intuitive sequence of ASCII characters. This string can be directly read by most molecular editors and can be converted to virtually any molecular format (e.g. with molconvert or babel as described in section 1)
The IUPAC name can also be converted to another format with molconvert. You can also build a molecule with NavMol. See the NavMol documentation to learn it.
An InChI (IUPAC International Chemical Identifier) is a string of characters capable of uniquely representing a chemical compound. It was designed to provide a standard and human-readable way to encode molecular information and to facilitate the search for such information in databases and on the web.
A good way of checking if two molecules are the same is to convert both into the InChI format, and compare the two strings. You can generate InChI files with molconvert or babel.
With molconvert you can generate the InChI for a molecule in file Y.mol with the command: molconvert inchi Y.mol
(then take the line starting with “InChI=”)
Because the InChI representation of a molecule is unique and non-ambiguous, the two structures are the same if and only if their InChI representations match. You can compare the two strings for example with a spreadsheet, by pasting each string into a different cell and implementing a formula to compare the two cells.
You can follow the same approach to find if a molecule is included in a list of molecules.
The obprop program from the OpenBabel package can provide the main general properties of a molecule (in file filename) with a single command: obprop filename
If you want to save the result into a file result.txt you can enter the command: obprop filename > result.txt
One way to obtain the stereochemical features of a chemical structure is to generate the IUPAC name with the molconvert tool. If the molecule is stored in a chemical format with stereochemical information properly specified, then you can usually get the R/S label. If you know the fundamentals of the IUPAC nomenclature, and the CIP rules (Cahn-Ingold-Prelog rules, see the stereochemistry notes), you should be able to interpret the IUPAC name in terms of the geometrical configuration of the molecule, at least for simple structures.
Molconvert command: molconvert name name.mol
If you want to save the IUPAC name into a file name.name you can enter the command: molconvert name name.mol –o name.name
Another approach to the stereochemical information of a chemical structure is via the SMILES string obtained e.g. with molconvert or babel.
The SMILES chirality label of a chiral tetrahedral carbon atom is based on the order in which neighbor atoms of the chiral center occur in the SMILES string. Looking at the chiral center from the first atom occurring in the SMILES (or the second atom if the first is the chiral atom), the symbol "@" indicates that the following neighbors are listed anticlockwise and "@@" indicates that the neighbors are listed clockwise.
If you learn and get trained with the SMILES linear notation, and the CIP rules, you may be able to obtain the CIP R/S label from the SMILES stereochemical specification and vice-versa, and to perceive the geometrical arrangement of the ligands.
To know more about stereochemistry specification in SMILES, see the Daylight website.
A different approach to obtain stereochemical information of a chemical structure is with the obchiral tool (OpenBabel) together with NavMol. The obchiral program identifies chiral atoms and displays the ordered list of the neighbors (sorted by the atoms’ id) as well as the parity value (see the stereochemistry notes on the MOLinsight portal).
With the NavMol program you can know what the four ligands of the chiral center are, and you can assign priorities according to the CIP rules. The idea is that the geometrical arrangement of the ligands can be perceived from the parity value, and this information combined with the assignment of the CIP priorities is enough to derive the R/S label.
To assign the parity value, the four ligands are sorted by ascending atom id and the chiral center is observed with the fourth ligand pointing away from the observer. If the first three ligands in the sorted list are arranged clockwise, then the parity is 1. Otherwise it is 0. If one ligand is a hydrogen atom it is always the last ligand. If the list of ligands sorted according to the CIP rules coincides with the parity list, then the parity value 1 corresponds to R and the parity value 0 corresponds to S. The same is valid if even numbers of permutations are required to transform one list into the other. If odd numbers of permutations are required then the parity value 0 corresponds to R and the parity value 1 corresponds to S.
Obchiral command: obchiral name.mol
If you want to save the obchiral results into a file results.txt you can enter the command: obchiral name.mol > result.txt