# In which direction does imidazole affect the pH?

I'm reading something about nickel affinity chromatography and it talks about using imidazole to affect pH. In which direction does it change the pH?

It's acidity is given with $\mathrm{p}K_a=14.5$ for the proton as $\ce{N~1}$. The basic site is the lone pair at $\ce{N~3}$. Its basicity is given through the following equilibrium: $$\ce{Im + H+ <=> IMH+}$$ with a $\mathrm{p}K_a=7.05$.