Self-assembled Transition Metal Coordination Frameworks of ...

Ligands
The ‘H NMR spectrum of HZL3 in CDCI3 recorded at 500 MHZ (Fig. 2.10)
shows two peaks at 16.84 and 15.76 ppm, found to loss its intensity on D20 exchange.
These downfielded peaks assigned to hydrogen bonded NH protons. The multiplet
signals from 7.26 to 8.41 ppm are attributed to twelve protons of the two quinoline
rings. These results suggest the presence of thione tautomer in solution phase. The '3 C
NMR spectrum of HZL3 and ‘H NMR spectrum of H2L° taken was of very poor quality
for an assignment due to the poor solubility of these compounds.
| ' 1"!
___.;_;.__. __
ivwvvv-v-1-I-1? F _|, :71 -1 .
1sn1o1s14131211109
I l3 2
a 7 6 5 4 3"'§'“1 5 -1 ppm
Fig. 2.10. 'H NMR spectrum of HZL3.
The H and C NMR spectra of HZL in CDC]; recorded at 400 MHz (Figs.
2.11 & 2.12) are very difficult to interpret because of the crowding of peaks. The ‘H
NMR spectrum of H2L2 in CDCI3 has already been reported [4,l1]. However the
spectrum was reinvestigated, as there were contradictions like absence of thiol form
[11] and presence of tautomers [4]. The downfield peaks at 5=l5.18, 14.03, 13.67 and
I
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