it would be best to use VCD in the 1500 - 1100 cm-1 region which will have many bending modes from C-C, C-H and many other groups.

The main problem is obtaining a good VCD spectrum in non-polar solvent and doing calculations that accurately model all conformations and solvent effects.

If it has 6 stereocenters, it would be nice if you could determine the relative configuration from NMR

Thank you very much for the reply,

I do have an idea about the relative configuration from key NOE signals, i wonder if that would help make the calculations shorter? by calculating the structures based on the relative configurations by NMR. I also had the idea of determining one sterocenter in the compounds by Mosher's method since that center is bearing a hydroxyl group.

I have read multiple papers that reported the addition of excitons to some molecules to help establish their AC. However, i failed to understand the purpose of adding such excitons (mainly carbonyl groups). I appreciate any clarification you may have. Thank you again and Cheers

The Exciton chirality method in VCD seems to work, but there can be problems if you have more than 2 carbonyls because the coupling between them is not obvious. See my paper (Article Determination of the Absolute Configurations Using Exciton C...

And also (Article Absolute Configuration of (−)-Centratherin, a Sesquiterpenoi...

Which would give the wrong AC by the EC method

Of course the addition of carbonyl exciton pairs does not necessarily hurt. Usually you get more carbonyls when you convert alcohol groups into esters which makes it more soluble in nonpolar solvents. but the EC chirality method for VCD is not an advisable route to interpret that data. Though I will say that it does seem to work. DFT VCD calculations would be much better. Either way you still need to know all the conformations.

The purpose of adding excitons specifically for VCD may be to increase VCD signal or to give another VCD peak wich may improve the confidence in the assignment of an AC by VCD

Thank you very much Dr Covington, your help is greatly appreciated.

I think my compounds wont need the adition of an extra carbonyl since they already posses two. I will try using VCD/DTF calculations alone.