Musketeer

A software tool for fitting data from titration experiments.

Installation

Windows & MacOS:

You can install the latest .msi or .dmg installer here.

Any platform (requires Python)

Install the latest release of python from the official website. Then, in a terminal window or command prompt, type:

• Mac: python3 -m pip install musketeer
• Windows: python -m pip install musketeer

You can now run Musketeer any time by typing:

• Mac: python3 -m musketeer
• Windows: python -m musketeer

Usage Instructions

Example files

Two example files are provided:

• A UV-Vis titration with guest absorption, from https://doi.org/10.1039/D2SC04271A
• A 31-P NMR denaturation experiment, from https://doi.org/10.1039/D1SC02288A

Loading titration data

When starting Musketeer, you will see the option to either Create a new fit file or Open an existing file. Musketeer can directly open the following files:

• .fit files created using Musketeer
• .csv files obtained using Cary UV/Vis spectrometers
• .csv files exported from Mnova as "NMR 1D Peak List"

For other data sources, select Create a new fit file, and click Enter/edit spectroscopic data. This will open a spreadsheet interface where you can type or paste titration data. If you would like to request support for a new file format, please describe it by submitting a feature request!

Model specification

Once a file is loaded, the left side of the window will show a series of dropdown menus. Going from top to bottom, each of these can be adjusted to describe some part of the model:

• The Experiment section allows you to edit the signals to fit, specify the concentrations or cumulative addition volumes for each data point, and whether the system is under fast or slow exchange.
• The Equilibria section allows you to define the complexes formed in your system, and specify known values for equilibrium constants or relationships between them (such as the absence of cooperativity).
• The Spectra section allows you to define which compounds contribute to the observed signal, limit the number of variables by defining specific states that contribute to the signals (e.g. spectroscopically active groups), fix known spectra, or constrain the fitted spectra (e.g. force UV-Vis spectra to be non-negative).
• The Fitting section controls how the fit from different signals is weighted, which is currently only recommended for backwards compatibility.

If a dropdown requires you to input more data, it will show more information at the top of a popup window.

Fitting

When you have selected the appropriate option in each dropdown, press Fit to fit the data. Several tabs will appear, showing the fit to the data points, the calculated speciation, and the fitted equilibrium constants and spectra. The save button to the bottom left of each plot allows you to save it as an image file.

To compare the fit to a different model, Copy fit can create a new tab with the same options, some of which can then be modified. If you change any options, it may be necessary to re-enter the dropdowns below it as well: for example, if you add a new complex, you may need to re-enter which equilibrium constants are fixed.

Finally, the File->Save at the top of the screen allows you to save your work as a .fit file, which you can reopen at another time, or share with others.