Six dynamic metal–organic
frameworks, namely, {[Cd(1,4-bib)(glut)]·(4H2O)}
n
(1), {[Zn(1,4-bib)(glut)]·(4H2O)}
n
(2), {[Co(1,4-bib)(3,5-pydc)]·(2H2O)}
n
(3), {[Mn(1,4-bib)(3,5-pydc)]·(2H2O)}
n
(4), {[Zn(1,4-bib)(3-mglut)]·(4H2O)}
n
(5), and {[Zn(1,4-bib)(2,2′-dmglut)]·(2H2O)}
n
(6) from 1-(4-(1H-imidazole-1-yl)butyl)-1H-imidazole (1,4-bib)
using four different dicarboxylic acids salt [disodium glutarate (Na2glut), pyridine-3,5-dicarboxylate (3,5-pydc), 3-methyl glutarate
(3-mglut), 2,2′-dimethyl glutarate (Na22,2′-dmglut)],
and four different divalent transition metal ions have been synthesized.
Out of these, the structure of compound 3 has been previously
reported although synthesized in different method, whereas the rest
of the compounds are new. All of these synthesized compounds are characterized
by single crystal and powder X-ray diffraction and other physicochemical
methods. All the compounds exhibit 2D structure as evident by single
crystal X-ray studies. Interestingly, all of these compounds show
crystalline to crystalline phase transformation. Variable temperature
PXRD study indicates compounds 1 and 6 show
single-step phase transformation and the rest show two-step phase
transformation upon desolvation. All of these transformations have
also been established by IR spectroscopy. Among the structural transformations
listed, 1–5 show reversible crystalline
to crystalline phase transformation on desolvation and resolvation,
whereas 6 shows an irreversible transformation. All of
these transformations are thoroughly investigated by PXRD and IR spectroscopy.
Sorption studies with CO2 and N2 were also performed
for all the metal–organic frameworks and characteristic surface
adsorptions are found in all the cases.