Rational Synthesis and Investigation of Porous Metal-Organic Framework Materials from a Preorganized Heterometallic Carboxylate Building Block

Aleksandr A Sapianik; Ekaterina N Zorina-Tikhonova; Mikhail A Kiskin; Denis G Samsonenko; Konstantin A Kovalenko; Alexey A Sidorov; Igor L Eremenko; Danil N Dybtsev; Alexander J Blake; Stephen P Argent; Martin Schröder; Vladimir P Fedin

doi:10.1021/acs.inorgchem.6b02713

Rational Synthesis and Investigation of Porous Metal-Organic Framework Materials from a Preorganized Heterometallic Carboxylate Building Block

Inorg Chem. 2017 Feb 6;56(3):1599-1608. doi: 10.1021/acs.inorgchem.6b02713. Epub 2017 Jan 10.

Authors

Aleksandr A Sapianik¹, Ekaterina N Zorina-Tikhonova², Mikhail A Kiskin², Denis G Samsonenko^{1

3}, Konstantin A Kovalenko^{1

3}, Alexey A Sidorov², Igor L Eremenko², Danil N Dybtsev^{1

3}, Alexander J Blake⁴, Stephen P Argent⁴, Martin Schröder^{1

5}, Vladimir P Fedin^{1

3}

Affiliations

¹ Nikolaev Institute of Inorganic Chemistry, SB RAS , 3 Akad. Lavrentiev Avenue, 630090 Novosibirsk, Russia.
² N. S. Kurnakov Institute of General and Inorganic Chemistry, RAS , 31 Leninsky Avenue, 119991 Moscow, Russia.
³ Novosibirsk State University , 2 Pirogova Street, 630090 Novosibirsk, Russia.
⁴ School of Chemistry, University of Nottingham , Nottingham NG7 2RD, U.K.
⁵ School of Chemistry, University of Manchester , Manchester M13 9PL, U.K.

PMID: 28072527
DOI: 10.1021/acs.inorgchem.6b02713

Abstract

The tetranuclear heterometallic complex [Li₂Zn₂(piv)₆(py)₂] (1, where piv^- = pivalate and py = pyridine) has been successfully employed as a presynthesized node for the construction of four porous metal-organic frameworks (MOFs) [Li₂Zn₂(R-bdc)₃(bpy)]·solv (2-R, R-bdc^2-; R = H, Br, NH₂, NO₂) by reaction with 4,4'-bipyridine (bpy) and terephthalate anionic linkers. The [Li₂Zn₂] node is retained in the products, representing a rare example of the rational step-by-step design of isoreticular MOFs based on complex heterometallic building units. The permanent porosity of the activated frameworks was confirmed by gas adsorption isotherm measurements (N₂, CO₂, CH₄). Three compounds, 2-H, 2-Br, and 2-NH₂ (but not 2-NO₂), feature extensive hysteresis between the adsorption and desorption curves in the N₂ isotherms at low pressures. The substituents R decorate the inner surface and also control the aperture of the channels, the volume of the micropores, and the overall surface area, thus affecting both the gas uptake and adsorption selectivity. The highest CO₂ absorption at ambient conditions (105 cm³·g^-1 or 21 wt % at 273 K and 1 bar for 2-NO₂) is above the average values for microporous MOFs. The photoluminescent properties of the prototypic 2-H as well as the corresponding host-guest compounds with various aromatic molecules (benzene, toluene, anisole, and nitrobenzene) were systematically investigated. We discovered a rather complex pattern in the emission response of this material depending on the wavelength of excitation as well as the nature of the guest molecules. On the basis of the crystal structure of 2-H, a mechanism for these luminescent properties is proposed and discussed.