Planning a Supramolecular Titration

As in most avenues in Sciences, and indeed life, success in performing a Supramolecular titration experiment depends largely on good preparation and planning. In this series of articles we will explore how we can plan our supramolecular titration experiments.

Let’s start with what do we qualify as success? The answer will of course depend to some degree on the system investigated and the hypothesis we are testing. That said, most of us would probably like to see the experiments yield quality data that would allow us to determine the binding strength and perhaps also the binding stoichiometry with high degree of confidence and accuracy.

In upcoming articles on this site we will explain better how you can evaluate the quality of the data you might obtain. For the time being lets look at the main steps that you need to consider. We make the asssumption here that you have a host and guest and you are planning to do a binding study involving this host-guest pair. So what should you do? I break this down to eight key steps:

1. Start with gathering data on any related systems. This may give you valuable hints towards the expected type of association strength and stoichiometry you might get.
2. Based on this, your own experience and any other information you have, make some prediction on what sort of binding constants you expect, in terms of their magnitude.
3. Think also about what sort of stoichiometry you might expect. You will often need to confirm this through your experiments but it helps having an initial hypothesis.
4. You then need to check the purity and quantity of the host and guest that’s you available to you. In some cases, these factors will impose certain limitation on how you can proceed with your work, e.g. when the host is only available on the scale of a few milligrams.
5. Equally importantly, you need to consider the solvent or solvents you want to work with. There are several conflicting factors here which include potential (future) practical application of your systems, how solvents affect various types of non-covalent interactions but most importantly, the solubility of your host and guest in the solvents you are considering.
6. You also need to consider the method you want to use. Here, your choice should NOT be guided simply by convenience, familiarity or costs but rather the most appropriate technique when considering both the concentration range you need to target and which method is likely to give you the most information rich data upon the host forming a complex with the guest.
7. You then need to plan how many titration points you wish to perform. Here you need to balance practical / cost and time management issues with the desire to collect as many data points as possible.
8. Finally you need to plan exactly how you are going to prepare your host and guest solutions and how you will add your guest to your host. Here you need to consider various factors again including available quantities of the host and guest, cost of solvents as well as potential “matrix” and dilution effects.

This list is probably not complete but it should cover most of the key issues you need to consider. In upcoming articles we will explore the above in more details. In the meantime, don’t hesitate to contact us or comment on the article below if you wish to add anything or any of the above point are unclear to you.

Until next – cheers – Palli @ supramolecular.org