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-NH 2 (but not 2-NO 2 ), 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-NO 2 ) 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.
Heterometallic carboxylate complexes are of paramount interest in pure and applied coordination chemistry. Despite that plurality of such type compounds have been published to date, synthetic aspects ...of their chemistry often remain in the shadow of intriguing physical properties manifesting by these species. Present review summarizes reliable data on direct synthesis of low nuclearity molecular compounds as well as coordination polymers on their base with carboxylate-bridged {M
Mg} (M = Co
, Ni
, Cd
), {M
Li
} (M = Co
, Ni
, Zn
, VO
), {M
Ln
} and {M
Ln} (M = Cu
, Zn
, Co
) metal cores. Structural features and stabilization factors are considered and principal outcomes are confirmed by quantum-chemical calculations. Particular attention is paid to consideration of ligand-exchange reactions that allow controllable modification of heterometallic metal core under mild conditions giving diverse molecular complexes with modified ligand environment or Metal-Organic Frameworks with permanent porosity.
Display omitted
•A novel silver SERS substrate was fabricated by EBPVD method and characterized.•The substrate contains nanoscale pore-like structures and cavities, separated by rough surface.•The ...novel SERS substrate was proposed for detection of viruses and tested, SERS spectra of four viruses were obtained and processed.•Data analysis showed complete differentiation between viral species based on their spectral data.
Virus detection is often performed using antibody-based and polymerase chain reaction-based techniques. Such methods have major deficiencies, caused by time-consuming and labor-intensive incubation and purification steps. In this contribution, a novel SERS substrate for qualitative virus detection was developed and described. The substrate is composed of a thin silver film with folded surface structure containing pore-like nanoscale cavities and indentations, deposited on mica substrate by electron beam physical vapor deposition method. Pore-like structures are semi-regularly arrayed, with a rough surface in between, allowing for SERS activity, and their size and periodicity can be manipulated in the manufacturing process. It was speculated that viral particles could be trapped in these structures and would generate easily detectable enhanced Raman signals. The SERS substrate was tested against detection of four virus species – rabbit myxomatosis virus, canine distemper virus, tobacco mosaic virus and potato virus X. Specific spectra were obtained and analyzed for each virus. Data analysis demonstrated successful differentiation between tested species. The reported results demonstrate that novel SERS substrate is suitable for detection and identification of viral particles.
New Cosup.II substituted malonate field-induced molecular magnets {Rbsub.6Cosub.3(cpdc)sub.6(Hsub.2O)sub.12∙6Hsub.2O}n (1) and Cssub.2Co(cpdc)sub.2(Hsub.2O)sub.6n (2) (where cpdcsup.2− stands for ...cyclopropane-1,1-dicarboxylic acid dianions) were synthesized. Both compounds contain mononuclear bischelate fragments {Cosup.II(cpdc)sub.2(Hsub.2O)sub.2}sup.2 sup.− where the quasi-octahedral cobalt environment (CoOsub.6) is complemented by water molecules in apical positions. The alkali metal atoms play the role of connectors between the bischelate fragments to form 3D and 2D polymeric structures for 1 and 2, respectively. Analysis of dc magnetic data using the parametric Griffith Hamiltonian for high-spin Cosup.II supported by ab initio calculations revealed that both compounds have an easy axis of magnetic anisotropy. Compounds 1 and 2 exhibit slow magnetic relaxation under an external magnetic field (HDC = 1000 and 1500 Oe, respectively).
1,2-Bis(4-pyridyl)ethylene undergoes a photoinitiated 2+2 cross-cycloaddition reaction with allyl groups of allylmalonate in pores of a 3D metal-organic framework (MOF) Zn2(H2O)2(Amal)2(bpe) to ...produce a 3D MOF with a new topology.
The reactions of chromium(
iii
) nitrate with M
2
(cpdc) (cpdc
2−
- dianion of cyclopropane-1,1-dicarboxylic acid, M = K, Na) and rare-earth metal nitrates taken in a molar ratio of 1 : 3 : 1 yielded ...heterometallic coordination polymers {Ln
2
Cr
2
(cpdc)
6
(H
2
O)
9
·8.5H
2
O}
n
(
1
Ln
, Ln = Eu, Gd, Tb), crystallizing in tetragonal space group
P
4
3
2
1
2 (
P
4
1
2
1
2). A single crystal X-ray diffraction (XRD) study showed that the crystal structures of these compounds are formed by tris-chelate fragments {Cr(cpdc)
3
} linked into {Ln-Cr} layers and further into a 3D framework structure due to the bridging coordination of carboxylate groups to Ln atoms. When passing to Ln = Dy, Ho, Y, Er, Yb, the crystals of compounds
2
Ln
form, where the structure of {Ln-Cr} layers is retained, but the disorder of the interlayer Ln atoms, a decrease in the size of a crystal cell, and a change in the space group to
I
4
are observed. The use of K
2
(cpdc) in the syntheses of
1
Ln
and
2
Ln
is found to lead to the isolation of a side product, namely, mononuclear complex Cr(cpdc)(Hcpdc)(H
2
O)
2
·2H
2
O (
3
), with the reactions with Na
2
(cpdc) enabling obtaining only the crystals of heterometallic Ln
III
-Cr
III
compounds. Alternating current magnetic susceptibility measurements for the series
1
Ln
and
2
Ln
revealed the presence of slow relaxation of magnetization only for
1
Eu
and
2
Y
, which is due to the magnetic anisotropy of chromium ions in the presence of magnetic field and their magnetic isolation in a crystal lattice. For
1
Eu
,
1
Gd
,
1
Tb
,
2
Dy
, and
2
Ho
, thermal decomposition in an Ar atmosphere was studied. The end product of solid-state thermolysis of
2
Dy
in air at 1000 °C is shown to be submicron DyCrO
3
particles (300-400 nm).
In a new series of Ln
III
-Cr
III
cyclopropane-1,1-dicarboxylates, a decrease in the Ln
3+
ionic radius leads to a change in a space group and the transition of a 3D framework structure (Ln = Eu, Gd, Tb) into a 2D layered one (Ln = Dy, Ho, Y, Er, Yb).
Knowledge-based approach to the design of coordination polymers with a given architecture in general requires knowledge of regularities between the local coordination of metal atoms (or polynuclear ...metal-containing units), coordination modes of all ligands in a complex, and the entire framework topology. The effect of the local coordination on the dimensionality and topology of the underlying nets was demonstrated on the example of 4,4′-bipyridine (bipy), 1,2-bis(4-pyridyl)ethylene (bpe) and 1,2-bis(4-pyridyl)ethane (bpa) containing copper(
ii
) malonates. The most abundant networks were evaluated for these compounds and compared with those for previously analyzed and synthesized zinc(
ii
)-containing analogs. Eight novel complexes, namely Cu(bpe)(mal)·2CH
3
CN, Cu
4
(bipy)
4
(Me
2
mal)
4
(H
2
O)
5
·3H
2
O, Cu(bpe)(HMe
2
mal)
2
·H
2
O, Cu(bpe)(Me
2
mal)·H
2
O, Cu
4
(bpe)
3
(Et
2
mal)
4
·5H
2
O, Cu
4
(bpa)
3
(Et
2
mal)
4
·5.5H
2
O, Cu(bpe)(Amal)·0.25H
2
O, and Cu(bpa)(Amal)·0.25H
2
O (H
2
mal = malonic acid, H
2
Me
2
mal = dimethylmalonic acid, H
2
Et
2
mal = diethylmalonic acid, H
2
Amal = allylmalonic acid), were synthesized and characterized. Four of them realized the square lattice topology (
sql
) of their underlying nets, which is highly abundant for copper(
ii
) malonates with N,N′-containing linkers but rarely occurs in similar complexes based on other transition metals. The UV-sensitivity of the bpe-containing complexes as well as of the previously reported complex Cu
4
(bpe)
3
(mal)
4
·6H
2
O was studied; and Cu
4
(bpe)
3
(mal)
4
·6H
2
O was found to undergo a single-crystal-to-single-crystal photoinitiated 2 + 2 cycloaddition reaction to Cu
4
(bpe)(tpcb)(mal)
4
·6H
2
O (tpcb =
rctt
-1,2,3,4-tetrakis(pyridin-4-yl)cyclobutane). The dc-magnetic measurements of the complexes Cu(bpe)(Me
2
mal)·H
2
O, Cu(bpe)(Amal)·0.25H
2
O and Cu(bpa)(Amal)·0.25H
2
O indicated the presence of very weak antiferromagnetic intermolecular interactions. Using EPR spectroscopy, it was shown that the distortion of the polyhedron of the copper(
ii
) atom corresponded to a change in the anisotropy of the
g
-tensor.
Effect of the metal coordination on the periodicity and topology of coordination polymers is discussed on the example of copper(
ii
) malonates with N,N′-containing linkers as compared with zinc(
ii
) analogs.
Mononuclear {Cu(Me2mal)2}2– dianion has been used as a building block for the synthesis of six new coordination polymers: {Li2(H2O)2(µ‐H2O)Cu(µ4‐Me2mal)(µ‐Me2mal)}n (1), {Na2(µ‐EtOH)2Cu(µ5‐Me2mal)2}n ...(2), {K8(µ‐H2O)6Cu(µ‐H2O)(µ3‐Me2mal)(µ6‐Me2mal)2Cu2(µ5‐Me2mal)4}n (3), {K2M(H2O)5(µ‐H2O)3Cu(µ‐Me2mal)(µ3‐Me2mal)Cu(µ‐H2O)(µ‐Me2mal)(µ3‐Me2mal)}n (M = MgII (4) or NiII (5); isostructural compounds), and {K4Co3(H2O)8(µ‐H2O)4(µ3‐OH)2Cu(H2O)(µ‐Me2mal)(µ3‐Me2mal)2Cu(µ‐H2O)(µ3‐Me2mal)22}n (6). It was shown that the structures of the compounds depend on the nature and ionic radius of the heterometal. In particular, the dimensionality of the complexes increases from 1D to 2D and 3D with increasing radius of the s‐metal in compounds 1, 2, and 3, respectively. Partial replacement of K+ in 3 by Mg2+, Ni2+, or Co2+ leads to the formation of heterometallic coordination polymers 4 and 5, with 2D structure, and 3D complex 6. The compounds were characterized by single‐crystal X‐ray diffraction and EPR spectroscopy, and the magnetic properties of compounds 1, 2, and 4–6 were also studied. Further, the topological analysis of the structures and another 794 known mal‐derivatives complexes from Cambridge Structural Database (CSD, version 5.36) was performed. The main regularities determining the coordination modes of ligands and metal cations in relation to structure topology have been established and are discussed.
Mononuclear {Cu(Me2mal)2}2– dianion has been used as a building block for the synthesis of new heterometallic Cu‐Li, Cu‐Na, and Cu‐K coordination polymers that show increasing dimensionality from 1D to 2D and 3D with increasing radius of the s‐metal. Partial replacement of K+ in the Cu‐K complex by Mg2+, Ni2+, or Co2+ (MII) leads to the formation of Cu‐K‐MII coordination polymers.
A series of Ba–M II complexes with allylmalonic acid anions (Amal) BaM II (Amal) 2 (H 2 O) 3 n (M II = Mn (1), Co (2), Cu (3), and Zn (4)) were synthesized by the reaction of the corresponding ...transition metal sulfates and barium allylmalonate. The complexes were characterized by IR and EPR spectroscopy, elemental analysis, magnetochemical and solid phase thermal decomposition studies as well as powder and single-crystal X-ray crystallography. The main structural block {M II (Amal) 2 (H 2 O) x } ( x = 1 for M = Cu, x = 2 for M = Mn, Co, and Zn) in 1–4 is formed by two chelate allylmalonate anions and water molecule(s), which are surrounded by Ba 2+ ions. The magnetic measurements of paramagnetic compounds revealed weak ferromagnetic interactions between copper( ii ) ions in 3, and slow magnetic relaxation in non-zero field ( H DC = 1500 Oe) for 2. According to the TGA data of 1–4, they are decomposed via different pathways in the case of Mn II , Co II , Cu II , and Zn II since the metal ions catalyze different types of processes. However, all the complexes undergo polymerization of the allyl fragment.
A new binuclear "paddle-wheel" complex, Co2(bhbz)4(EtOH)2·4EtOH (1, Hbhbz-3,5-di(tert-butyl)-4-hydroxybenzoic acid); an isostructural zinc complex (2); a and magnetically diluted sample of ...Zn1.93Co0.07(bhbz)4(EtOH)2·4EtOH (3) were obtained. Molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction. DFT calculations for 1 indicate strong Co-Co antiferromagnetic exchange interactions in the binuclear fragment. It was shown that when one paramagnetic ion in the binuclear molecule is replaced by a diamagnetic zinc(II) ion, the remaining cobalt(II) ion can be considered as an isolated center with magnetic anisotropy, the parameters of which are determined by ab initio calculations. Magnetic properties for samples 1 and 3 were investigated and analyzed in detail.
