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Welcome to ChiralDB


What is ChiralDB

ChiralDB is an open-source database for chiral nanomaterials, including both molecules and clusters. It is especially dedicated to the collection of spectroscopic data and the automated computation of properties such as the g-factor and the polarizability, both chiral and achiral.


Compared to other broader projects, such as NOMAD, it is more restricted in scope. However, it provides an out-of-the-box, user-friendly platform for uploading and sharing optical data concerning chiral nanomaterials. It enables users to explore the properties of such objects effectively.

About ChiralForce

ChiralForce (see more about the project here on the official page) is an European project aiming for a new way of separating eneatiomers using chiral oprical forces rather than chemical methods. Below a short animation represent the idea:

What can you do with ChiralDB

At its core, ChiralDB is a chiral nanomaterials database with a user-friendly web interface. However, as hinted previously, it also provides users with a simple automated computation of properties starting from the provided spectral data, either computed with ab-initio or classical methods or obtained, more traditionally, through experiments. As it stands, ChiralDB provides the following functionalities:

This is the first step in the use of ChiralDB. Users can upload a molecule for which they obtained spectral data. The upload process itself is straightforward: registered users access a form with fields for the different properties of the molecule, e.g., the name, the chemical composition, etc., and a file upload field for a CSV file containing the spectral properties. After submission, the molecule is inserted into the database, and the relevant additional properties are computed automatically in the backend.

The g-factor is a measure of the chiroptical activity of the molecule. In itself, it is just the ratio between the ECD and the absorption spectrum of the molecule. ChiralDB automatically computes it for every value of the wavelength for which spectral data were computed/measured. It also identifies its maximum absolute value and the corresponding wavelength.

Thanks to a Python function provided by S. Golat at KCL, ChiralDB is able to compute the full complex chiral and achiral polarizabilities of the uploaded molecule. While the polarizabilities are defined as tensorial quantities depending on the orientation of the molecules, here we take an isotropy assumption, considering that the measurements are done experimentally on samples where the molecules are randomly oriented.

Computationally, the spectral data is obtained by computing the trace over different orientations, thus obtaining scalar polarizabilities, which, in relation to the fully tensorial quantities, can be seen as the trace. Spectral data only allow us to compute the imaginary part of the complex polarizabilities. In the code, we exploit the analytical properties of such quantities to compute the real part using the Kramers-Kronig relations.

One of the things we are interested in is the comparison of the properties between different molecules. ChiralDB allows users to compare two molecules to study their differences. This can be performed on two different molecules, say a Hexahelicene and a Br-Hexahelicene, on the same molecule obtained under different experimental/computational conditions (different solvent, concentration, etc.) or between experimental and computational results.
The comparison presents graphs with the spectral and computed properties represented in the same plot so that users can have a quick qualitative look at the differences between the results.

Users may be interested in conducting more thorough inspections on the data, both computed and uploaded by other users. This is possible by using the download CSV functionality present in every molecule data card. Users may select one or more of the fields which will then be inserted into a CSV file downloaded to the user's computer. Publications indicated in the upload procedure can also be downloaded as a BibTeX file so that data used in a publication can then be properly referenced.
Note that, while viewing molecules is allowed to all users, downlaoding raw data is restricted to logged in users.

How To Use ChiralDB

To use the functionalities offered by ChiralDB, first of all you have to register a new user, note that you can still view the molecules even as an unregistered guest, however you are limited in that you can not add a new molecule nor download data relative to the molecules. Once you registered a new user you proceed to login with your credentials.
To add a new molecule click on the nav bar link Molecules, a drop down menu will open up, select Add molecule, a form will open up with fields for different properties concerning the molecule you wnt to add to the database.