TY - JOUR

T1 - Rational Synthesis and Investigation of Porous Metal-Organic Framework Materials from a Preorganized Heterometallic Carboxylate Building Block

AU - Sapianik, Aleksandr A.

AU - Zorina-Tikhonova, Ekaterina N.

AU - Kiskin, Mikhail A.

AU - Samsonenko, Denis G.

AU - Kovalenko, Konstantin A.

AU - Sidorov, Alexey A.

AU - Eremenko, Igor L.

AU - Dybtsev, Danil N.

AU - Blake, Alexander J.

AU - Argent, Stephen P.

AU - Schröder, Martin

AU - Fedin, Vladimir P.

PY - 2017/2/6

Y1 - 2017/2/6

N2 - 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-bdc2-; 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.

AB - 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-bdc2-; 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.

KW - COORDINATION POLYMERS

KW - STRUCTURAL-CHARACTERIZATION

KW - CO2 CAPTURE

KW - TRINUCLEAR COMPLEXES

KW - ADSORPTION

KW - 4,4-BIPYRIDINE

KW - DIVERSITY

KW - LIGANDS

KW - UNITS

KW - MOF-5

UR - http://www.scopus.com/inward/record.url?scp=85011899098&partnerID=8YFLogxK

U2 - 10.1021/acs.inorgchem.6b02713

DO - 10.1021/acs.inorgchem.6b02713

M3 - Article

C2 - 28072527

AN - SCOPUS:85011899098

VL - 56

SP - 1599

EP - 1608

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 3

ER -