Designing Multifunctional 5‑Cyanoisophthalate-Based Coordination Polymers as Single-Molecule Magnets, Adsorbents, and Luminescent Materials
dataset
posted on 2016-10-07, 15:51 authored by Jose M. Seco, Itziar Oyarzabal, Sonia Pérez-Yáñez, Javier Cepeda, Antonio Rodríguez-DiéguezDetailed
structural, magnetic, and photoluminescence characterization
of a family of new compounds based on 5-cyanoisophthalate (CNip) ligand
and several transition metal or lanthanide ions, namely, [Cu3(μ3-CNip)2(μ-H2O)2(μ3-OH)2]n (1), {[Co3(μ4-CNip)3(DMF)4]·∼2DMF}n (2), [Cd(μ4-CNip) (DMF)]n (3), {[Ln2(μ4-CNip)(μ3-CNip)2(DMF)4]·∼DMF·H2O}n (4-Ln) (with LnIII = Tb, Dy, and Er), {[Gd6(μ3-CNip)5(μ4-CNip)3(μ-form)2(H2O) (DMF)10]·∼3DMF·3H2O}n (5), {[Zn32(μ4-CNip)12(μ-CNip)12(μ4-O)8(H2O)24]·∼12DMF}n (6) (where DMF = dimethylformamide, form = formate),
is reported. The large structural diversity found in the system may
be explained mainly in terms of the coordination characteristics that
are inherent to the employed metal ions, the coordination versatility
of the dicarboxylic ligand and the synthetic conditions. Interestingly,
some crystal structures (three-dimensional (3D) frameworks of 4-Ln and 5 and 3D network of 6)
exhibit open architectures containing large solvent-occupied void
systems, among which 5 reveals permanent porosity as
confirmed by N2 adsorption measurements at 77 K. Magnetic
direct current (dc) susceptibility data on compounds 1, 2, and 5 were measured. Moreover, compounds 2, 4-Dy, 4-Er, and 5 show slow magnetic relaxation, from which it is worth highlighting
the effective energy barrier of 44 K at zero dc field for the dysprosium
counterpart. Compound 5 also deserves to be mentioned
given the few 3D Gd-organic frameworks reported examples. Photophysical
properties were also accomplished at different temperatures, confirming
both the fluorescent emission of 5-cyanoisophthalate ligands when
coordinated to cadmium ions in 3 and their capacity to
sensitize the long-lived fluorescence of the selected lanthanide ions
in 4-Ln. Broken symmetry and time-dependent density functional
theory computational calculations support the experimental luminescence
and magnetic properties.
