Introduction of a urea R-NH-CO-NH-R group as a seven-membered diazepine ring at the center of 4,4'-biphenyl-dicarboxylic acid leads to a urea-functionalized dicarboxylate linker (L1) from which four zinc metal-organic frameworks (MOFs) could be obtained, having a {Zn(μ-O)(OC-)} SBU and IRMOF-9 topology (compound [Zn(μ-O)(L1)], 1, from dimethylformamide, DMF) or a {Zn(OC-)} paddle-wheel SBU in a 2D-network (compound [Zn(L1)(DEF)·2.5DEF], 2, from diethylformamide, DEF). Pillaring of the 2D-network of 2 with 4,4'-bipyridine (bipy) or 1,2-bis(4-pyridyl)ethane (bpe) gives 3D frameworks with rhombohedrally distorted pcu-a topologies ([Zn(L1)(bipy)], 3 and [Zn(L1)(bpe)], 4, respectively). The 3D-frameworks 1, 3, and 4 are 2-fold interpenetrated with ∼50% solvent-accessible volume, albeit of apparently dynamic porous character, such that N adsorption at 77 K does not occur, while H at 77 K (up to ∼1 wt %) and CO at 293 K (∼5 wt %) are adsorbed with large hystereses in these flexible MOFs. The urea-functionalized MOF 3 exhibits an uptake of 10.9 mmol g (41 wt %) of SO at 293 K, 1 bar, which appears to be the highest value observed so far. Compounds 3 and 4 adsorb 14.3 mmol g (20 wt %) and 17.8 mmol g (23 wt %) NH, respectively, which is at the top of the reported values. These high uptake values are traced to the urea functionality and its hydrogen-bonding interactions to the adsorbents. The gas uptake capacities follow the specific porosity of the frameworks, in combination with pore aperture size and affinity constants from fits of the adsorption isotherms.
Reactions of enantiopure (S or R)-N-1-(phenyl)ethyl-2,4-X1,X2-salicylaldimine (S-H or R-H; X1, X2 = dihalogen) with Zn(II)-nitrate give bis[(S or R)-N-1-(phenyl)ethyl-2,4-X1,X2-salicylaldiminato-κ2N,O]-zinc(II), (Δ-ZnS or Λ-ZnR) with Δ/Λ-chirality induction at-metal in the C2-symmetric molecules....
The enantiopure Schiff
bases (
R
or
S
)-
N
-1-(X-C
6
H
4
)ethyl-2-hydroxy-1-naphthaldimine
{X = H [(
R
or
S
)-HL1],
p
-CH
3
O [(
R
or
S
)-HL2],
and
p
-Br [(
R
- or
S
)-HL3]} react with cobalt(II) acetate to give bis[(
R
or
S
)-
N
-1-(X-C
6
H
4
)ethyl-2-oxo-1-naphthaldiminato-κ
2
N
,
O
]-Λ/Δ-cobalt(II) {X = H
[Λ/Δ-Co-(
R
or
S
)-L1],
p
-CH
3
O [Λ/Δ-Co-(
R
or
S
)-L2], and
p
-Br [Λ/Δ-Co-(
R
or
S
)-L3]} (
1
–
3
), respectively. Induced Λ and Δ chirality originates
at the metal center of the
C
2
-symmetric
molecule in pseudotetrahedral geometry. Differential scanning calorimetry
analyses explored the thermal stability of the complexes, which undergo
reversible phase transformation from crystalline solid to isotropic
liquid phase for
1
and
3
but irreversible
phase transformation for
2
. Like other cobalt(II) complexes,
compounds
1
–
3
exhibit a continuous
ensemble of absorption and circular dichroism bands, which span from
the UV to IR region and can be collected into a superspectrum. Infrared
vibrational circular dichroism (IR-VCD) spectra witness the coupling
between Co
2+
-centered low-lying electronic states and ligand-centered
vibrations. The coupling produces enhanced and almost monosignate
VCD spectra, with both effects being mode-dependent in terms of the
A
or
B
symmetry (in the
C
2
point group) and distance from the Co
2+
core.
Condensation of 2-hydroxy-benzophenone (HL') with (R or S)-(Ar)ethylamine yields the enantiopure Schiff bases (S or R)-2-((E)-1-(1-(Ar)ethylimino)ethyl)phenol {Ar = C6H5 (S- or R-HL1), p-CH3OC6H4 (S- or R-HL2)}. These Schiff bases react...
The exploration of earth-abundant electrocatalysts with high performance for the oxygen evolution reaction (OER) is eminently desirable and remains a significant challenge. The composite of the metal-organic framework (MOF) Ni10Co-BTC (BTC = 1,3,5-benzenetricarboxylate) and the highly conductive carbon material ketjenblack (KB) could be easily obtained from the MOF synthesis in the presence of KB in a one-step solvothermal reaction. The composite and the pristine MOF perform better than commercially available Ni/NiO nanoparticles under the same conditions for the OER. Activation of the nickel-cobalt clusters from the MOF can be seen under the applied anodic potential, which steadily boosts the OER performance. Ni10Co-BTC and Ni10Co-BTC/KB are used as sacrificial agents and undergo structural changes during electrochemical measurements, the stabilized materials show good OER performances.
Aroyl‐S,N‐ketene acetals put a novel, promising class of dyes on the stage of AIEgens. Like a puppet on a string, all their photophysical properties like AIE and solid‐state emission properties, the starting point of aggregation and, as shown by Hirshfeld analysis, the solid‐state quantum yield can easily be fine‐tuned and completely controlled by the choice and interplay of substituents at the aroyl‐S,N‐ketene acetal. More information can be found in the Research Article by T. J. J. Müller and co‐workers (DOI: 10.1002/chem.202202579).
A second-generation hydrogen bond donor (HBD) anion receptor with an inner amide cavity and an outer urea cavity can selectively and efficiently extract arsenate (AsO43–) from water in the presence...
The reaction of the N,O-heteroditopic bifunctional ligand 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoic acid (H2mpba) with Cu(NO3)2·2.5H2O and Zn(NO3)2·4H2O or Zn(CH3COO)2·2H2O in N,N-dimethylformamide (DMF) results in concomitant formation of three bimetallic metal-organic frameworks (MOFs) with...
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