evergreen

I might be wrong about this, but isn't there also supposed to be some stabilization from pi-anti-bond interaction with lone pairs electrons from the methoxy? Or is that only with heterocyclic compounds?

Also, changes in pH and allosteric regulation affect the conformation of hemoglobin, which can complex to the oxygen molecules. As far as binding or not binding carbon dioxide, you can't bind CO2, but you can transport it dissolved in the blood as bicarbonate and carbonic acid. This is how your blood regulates it's pH, which consequently affects whether the heme binds/releases oxygen.

Have you already tried to dissolve the lignin in CH2Cl2? Personally, I don't see why you can't. I used CH2Cl2 often when doing IRspec work. UVspec is on a different wavelength.