Return to Answer

EDIT: It is clear now that NickT was looking for an experimental solution. My post deals with a computational solution. We can delete my response if need be until a more relevant question arises.

Determining the interaction energy between two defined monomers such as your aromatic Triazole and amide is a rather straightforward process. This process is referred to as the supramolecular approach. I'll point you to a paper that analyzes the benzene dimer. This method is strictly a computational one so a bit of knowledge in computational chemistry is necessary.

It seems that NickT was looking for an experimental solution. My post deals, however, with a computational solution.

Determining the interaction energy between two defined monomers such as your aromatic triazole and amide is a rather straightforward process. This process is referred to as the supramolecular approach. I'll point you to a paper that analyzes the benzene dimer. This method is strictly a computational one so a bit of knowledge in computational chemistry is necessary.

$E_{int} = E_{dimer} - (E_{mon1} + E_{mon2})$

Here we have some interaction energy ($E_{int}$) determined from the difference of a dimer energy ($E_{dimer}$) and the sum of the two monomers ($E_{monomer}$). If both monomers were equivalent (say, you were interested in the interaction energy of the benzene dimer where each monomer was a benzene ring), you could simplify the summation to two times the energy of one monomer ($2E_{mon}$). In your particular case, you have two different monomers.

1. Define your monomers. You will need to determine what part of your 'dimer' system is important for describing this weak interaction. I recommend keeping the aromatic ring and truncating the ring with something similar to what is being truncated. You could cap your monomer with a hydrogen or a methyl group for example. If the piece you've cut out is highly polarizable, cap with something with a similar property. If your truncated piece is neutral in charge, cap with something that is neutral. You get the idea.
2. Define your dimer. Your dimer is simply a combination of your two defined monomers.
3. Determine the method you want to implement. Post-Hartree-Fock methods are essential for this. Note that if you use the widely-implemented MP2 method, your answer may be way off (can over-estimate pi-pi interactions by as much as 200%!). The CCSD(T) method is recommended.
4. Define your basis set. For aromatic systems your best bet would be to use Dunning-Hunzaga's correlation consistent family of basis sets. I recommend using aug-cc-pVTZ for good results. Whatever you decide, be sure your basis set includes polarization and diffuse functions. The suggested basis set does this (augmented means diffuse on all atoms whereas pVTZ means 'polarized-valence triple zeta').
5. Determine the energies of your monomers and dimer. You will want to run a single-point energy calculation on your monomers and your dimer. Optimize your monomers first but freeze all atoms except those you added to cap your monomer.
6. Determine the interaction energy. Plug your energies into the equation given above and determine the interaction energy. Convert to whatever units you wish to use (I prefer kJ/mol but most people use kcal/mol so you may want to use that).

$$E_{\mathrm{int}} = E_{\mathrm{dimer}} - (E_{\mathrm{mon1}} + E_{\mathrm{mon2}})$$

Here we have some interaction energy ($E_{\mathrm{int}}$) determined from the difference of a dimer energy ($E_{\mathrm{dimer}}$) and the sum of the two monomers ($E_{\mathrm{monomer}}$). If both monomers were equivalent (say, you were interested in the interaction energy of the benzene dimer where each monomer was a benzene ring), you could simplify the summation to two times the energy of one monomer ($2\times E_{\mathrm{mon}}$). In your particular case, you have two different monomers.

1. Define your monomers. You will need to determine what part of your 'dimer' system is important for describing this weak interaction. I recommend keeping the aromatic ring and truncating the ring with something similar to what is being truncated. You could cap your monomer with a hydrogen or a methyl group for example. If the piece you've cut out is highly polarizable, cap with something with a similar property. If your truncated piece is neutral in charge, cap with something that is neutral. You get the idea.
2. Define your dimer. Your dimer is simply a combination of your two defined monomers.
3. Determine the method you want to implement. Wavefunction based or density functional theory (DFT) will work for this. The former will be prohibitively expensive.
4. Define your basis set. For aromatic systems your best bet would be to use Dunning-Hunzaga's correlation consistent family of basis sets. I recommend using aug-cc-pVTZ for good results. Whatever you decide, be sure your basis set includes polarization and diffuse functions. The suggested basis set does this (augmented means diffuse on all atoms whereas pVTZ means 'polarized-valence triple zeta').
5. Determine the energies of your monomers and dimer. You will want to run a single-point energy calculation on your monomers and your dimer. Optimize your monomers first but freeze all atoms except those you added to cap your monomer.
6. Determine the interaction energy. Plug your energies into the equation given above and determine the interaction energy. Convert to whatever units you wish to use (I prefer kJ/mol but most people use kcal/mol so you may want to use that).

EDIT: It is clear now that NickT was looking for an experimental solution. My post deals with a computational solution. We can delete my response if need be until a more relevant question arises.