Supramolecular
dimer of water is the simplest of the small water
clusters [(H
2
O)
n
,
n
= 2–10]. During the course of our work on supramolecular
coordination networks of three-component systems (divalent metal ion,
tridentate capping ligand, and ditopic carboxylate linker), a cyclic
water dimer is found to be entrapped in the network of [Ni
2
(6-Mebpta)
2
(adc)
2
]·2H
2
O (
1
) (6-Mebpta = 2-methyl-
N
-((6-methylpyridin-2-yl)methyl)-
N
-(pyridin-2-ylmethyl)propan-2-amine and adc = acetylenedicarboxylate).
Based on the single-crystal structure of
1
, the water
dimer plays an important role in connecting the bis(adc) bridged dinickel
synthons to form a one-dimensional (1D) supramolecular network. To
emphasize the role of 6-Mebpta in the judicious choice of components
for
1
, one simple modification to it by having another
methyl group in the second pendant pyridyl group to make 6,6′-Me
2
bpta (2-methyl-
N
,
N
-bis((6-methylpyridin-2-yl)methyl)propan-2-amine)
did not allow the formation of any water cluster in [Ni(6,6′-Me
2
bpta)(adc)(H
2
O)]·H
2
O (
2
), where a different coordination environment around Ni(II) is also
observed. Further quantification of the difference in supramolecular
interactions observed in
1
and
2
has been
assessed by Hirshfeld surface analysis. Both
1
and
2
are obtained in good yields at room temperature (methanol
as solvent) and are further characterized by elemental analysis, Fourier
transform infrared (FTIR) and Raman spectroscopy, powder X-ray diffraction,
and thermogravimetric analysis.