Roztocki K, Szufla M, Bon V, Senkovska I, Kaskel S, Matoga D. Interlinker Hydrogen Bonds Govern CO
2 Adsorption in a Series of Flexible 2D Diacylhydrazone/Isophthalate-Based MOFs: Influence of Metal Center, Linker Substituent, and Activation Temperature.
Inorg Chem 2020;
59:10717-10726. [PMID:
32663400 PMCID:
PMC7467668 DOI:
10.1021/acs.inorgchem.0c01182]
[Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
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Four new layered flexible metal–organic
frameworks (MOFs)
containing a diacylhydrazone moiety, namely, guest-filled [Zn2(iso)2(tdih)2]n (1), [Zn2(NH2iso)2(tdih)2]n (2),
[Cd2(iso)2(tdih)2]n (3) and [Cd2(NH2iso)2(tdih)2]n (4) were synthesized using terephthalaldehyde di-isonicotinoylhydrazone
(tdih) as a linear ditopic linker as well as isophtalate
(iso) or 5-aminoisophthalate (NH2iso) as angular colinkers.
The MOFs with hexacoordinated cadmium centers feature two-dimensional
pore systems as compared to the MOFs with pentacoordinated zinc centers
showing either zero-dimensional or mixed zero-/one-dimensional voids,
as evidenced by single-crystal X-ray diffraction. In contrast to the
frameworks based on isophtalates which do not show any significant
gas uptakes, introduction of amino-substituted linker enables CO2 adsorption. Gently activated aminoisophthalate-based frameworks,
that is, guest-exchanged in methanol and heated to 100 °C, show
reversible gated CO2 adsorptions at 195 K, whereas the
increase of activation temperature to 150 °C or more leads to
one-step isotherms and lower adsorption capacities. X-ray diffraction
and IR spectroscopy reveal significant structural differences in interlayer
hydrogen bonding upon activation of materials at higher temperatures.
The work emphasizes the role of hydrogen bonds in crystal engineering
of layered materials and the importance of activation conditions in
such systems.
Interplay between a metal center and
functionalization of
isophthalate linker leads to remarkable diversity of structures and
properties in the series of layered flexible metal−organic
frameworks. Intriguing adsorption properties include stepwise gated
CO2 adsorptions and strong dependence on activation conditions.
The role of hydrogen bonds in crystal engineering of layered materials
is underscored by activation−structure−adsorption correlations.
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