Nuclear Magnetic Resonance (NMR) spectroscopy

Instrument

Bruker Avance with 300 Mhz Cryomagnet from Spectrospin & Bruker

Analysis target

Allows investigations of protons (¹H) and carbon-13 (¹³C) aiming at molecular structural identification.

Sample prerequisites

Organic molecules including oligomers and polymers should be soluble in suitable deuterated solvents at room temperature (e.g. CDCl₃, D₂O, (CD₃)₂CO, (CD₃)₂SO, CD₃OD).

Analysis characteristics

¹H NMR provides ideally quantitative information on sample proton composition (number of protons on particular carbon and interaction with neighbor protons (spin), ¹H containing functional groups, next neighbor groups). ¹³C NMR ideally reveals all non-symmetric carbons in a molecule, provides details of the type of carbon (e.g. aliphatic, aromatic, vinylic, carboxylate etc.) and entails the substitution on a particular carbon. Two dimentional (2-D) NMR spectroscopy correlates ¹H and ¹³C resonances that greatly assist in molecule compositional and structural assignments.

In short, a total proton and carbon assignment is often possible (especially in small molecules) and thereby a total structural evaluation is possible. For polymers in particular monomer or functional group identifications are often possible, (block) copolymer composition can normally be estimated.

Sample requirements

For ¹H NMR min. 10 mg; for ¹³C NMR preferably >50 mg; for both we use 0.5-0.7 mL of deuterated solvent.