To gain better understanding of the complexation behavior
of 1 with Ag+, 1H NMR titration studies were performed in
(CD3)2SO, and resulting spectral differences are depicted in
Figure S11 (Supporting Information). Complexation of 1 with
Ag+ is expected to reduce electron density about the
coordination site and induce a downfield shift for nearby
protons. As expected, in the presence of Ag+ pyridyl protons 6
and 7 exhibited distinct downfield shifts (Δ δ, 0.251, 6; 0.534
ppm 7) along with broadening of the signals.