3D NMR studies of DAB-16 dendrimer

The HMQC-TOCSY 3D NMR technique has been used to study the DAB-16 [poly (propyleneimine)] dendrimer (the third generation) on a 750 MHz spectrometer. In the HMQC-TOCSY 3D NMR spectrum, it is possible to disperse H-1 signals based on the well-resolved C-13 chemical shifts and to obtain both one-bond H-1-C-13 connectivities and multibond H-1-C-13 connectivities by tracing the correlations within the same proton spin system from the HMQC-TOCSY slices. The overlapping H-1 resonances for core, interior, and exterior methylenes can be clearly resolved and assigned from the 3D NMR.