Solvothermal reactions
of HgX2 with 2,2′-(1,2-phenylene)-bis(N-pyridin-3-yl)acetamide, L, in ethanol afforded
[Hg(L)X2]
n
(X
= Cl, 1; Br, 2; I, 3), which
are isostructural one-dimensional (1D) zigzag chains, while layering
reactions of a ethanoic solution of L with a methanoic
solution and an acetonitrile solution of HgI2, respectively,
gave 1D helical chains [Hg(L)I2·MeOH]
n
, 4, and [Hg(L)I2·MeCN]
n
, 5.
In marked contrast to 1 and 2, the iodide-containing 3 is able to exhibit reversible structural transformation
with 4 and 5 by adsorption and desorption
of methanol and acetonitrile, suggesting the importance of N–H---X
and Hg---X interactions in the evaluation of structural transformation.
Moreover, complexes 4 and 5 exhibit reversible
crystal to crystal transformation triggered by solvent exchange. Complexes 3–5 represent a unique example that the
solvents show a significant effect on folding and unfolding of the
HgI2 single-stranded helical coordination polymers.