Three sulfur-containing alkaloids aplospojaveedins A-C (1-3) with a hitherto undescribed carbon skeleton comprising octahy-dronaphthalene, , -unsaturated lactam and glycine-cysteine moieties were isolated from . Their structures were elucidated by 1D and 2D NMR spectroscopy, HR-MS, X-ray diffraction analysis, DFT-NMR and TDDFT-ECD calculations. A plausible biosynthetic pathway and putative targets are described.
View Article and Find Full Text PDFReaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸN,O]Ni/Cu(II), [Ni(L1)] (1) and [Cu(L1)] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸN,O]Ni/Cu(II), [Ni(L2)] (3) and [Cu(L2)] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N,O-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples.
View Article and Find Full Text PDFSeven new coordination networks, [Fe(tbbt)](BF) (), [Co(tbbt)](BF) (), [Fe(tbbt)](ClO) (), [Co(tbbt)](ClO) (), [Fe(NCS)(tbbt)] (), [Co(NCS)(tbbt)] (), and [Fe(HO)(tbbt)]Br·2HO (), were synthesized with the linker 1,1'-(-2-butene-1,4-diyl)bis-1,2,4-triazole (tbbt) and structurally investigated. The structure of complexes - is composed of three interpenetrating, symmetry-related 3D networks. Each individual 3D network forms a primitive, nearly cubic lattice () with BF or ClO anions present in the interstitial spaces.
View Article and Find Full Text PDFThe flavin derivatives 10-methyl-isoalloxazine (MIA) and 6-fluoro-10-methyl-isoalloxazine (6F-MIA) were incorporated in two alternative metal-organic frameworks, (MOFs) MIL-53(Al) and MOF-5. We used a post-synthetic, diffusion-based incorporation into microcrystalline MIL-53 powders with one-dimensional (1D) pores and an in-situ approach during the synthesis of MOF-5 with its 3D channel network. The maximum amount of flavin dye incorporation is 3.
View Article and Find Full Text PDFCondensation of 2-hydroxybenzaldehyde (salicylaldehyde) or 2-hydroxy-1-naphthaldehyde with 2-ethylaniline yields the Schiff base compound of ()-2-(((2-ethylphenyl)imino)methyl)phenol (HL) or ()-1-(((2-ethylphenyl)imino)methyl)naphthalen-2-ol (HL), which in turn react with the dinuclear complex of [Rh(η-cod)(µ-OCCH)] (cod = cycloocta-1,5-diene) to afford the mononuclear (η-cod){()-2-(((2-ethylphenyl)imino)methyl)phenolato-κN,O}rhodium(I), [Rh(η-cod)(L)] () or (η-cod){()-1-(((2-ethylphenyl)imino)methyl)naphthalen-2-olato-κN,O}rhodium(I), [Rh(η-cod)(L)] () (L or L = deprotonated Schiff base ligand). The X-ray structure determination revealed that the HL exists in the solid state not as the usual (imine)N···H-O(phenol) form (enolamine form) but as the zwitterionic (imine)N-H···O(phenol) form (ketoamine form). H NMR spectra for HL in different solvents demonstrated the existence of keto-enol tautomerism (i.
View Article and Find Full Text PDFA second-generation hydrogen bond donor (HBD) anion receptor with an inner amide cavity and an outer urea cavity can selectively and efficiently extract arsenate (AsO) from water in the presence of competitive oxoanions and halides. The X-ray structure showed encapsulation of AsO in a π-stacked dimeric capsular assembly of the receptor, the first crystallography-based example of pentavalent AsO trianion recognition by a HBD receptor.
View Article and Find Full Text PDFAroyl-S,N-ketene acetals are a novel highly diverse class of aggregation-induced emission fluorogens (AIEgens) with a plethora of interesting properties. An expanded compound library of more than 110 dyes set the stage for the first qualitative control and tuneability of all aspects of their photophysical properties. The interplay of substituents not only allows tuning and prediction of the emission color, but also of the intensity, and quantum yields both in solids and in the aggregated state; these can be rationalized by scrutinizing intermolecular interactions in the crystalline solid state.
View Article and Find Full Text PDFThe metal-organic framework (MOF) [Zn(Isa-az-tmpz)]·~1-1.5 DMF with the novel T-shaped bifunctional linker 5-(2-(1,3,5-trimethyl-1H-pyrazol-4-yl)azo)isophthalate (Isa-az-tmpz) was obtained as a conglomerate of crystals with varying degrees of enantiomeric excess in the chiral tetragonal space groups P422 or P422. A topological analysis of the compound resulted in the rare -topology, deviating from the expected -topology, which has been found before in pyrazolate-isophthalate-functionalized MOFs using the supramolecular building layer (SBL) approach.
View Article and Find Full Text PDFThe 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) NiCo-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.
View Article and Find Full Text PDFReactions of enantiopure ( or )--1-(phenyl)ethyl-2,4-X,X-salicylaldimine (-H or -H; X, X = dihalogen) with Zn(II)-nitrate give bis[( or )--1-(phenyl)ethyl-2,4-X,X-salicylaldiminato-κN,O]-zinc(II), (Δ-Zn or Λ-Zn) with Δ/Λ-chirality induction at-metal in the -symmetric molecules. EI-mass spectra show parent ion peaks. X-ray structures indicate that two phenolate-oxygen and two imine-nitrogen atoms from two molecules of the Schiff bases coordinate to the Zn(II) ion in a pseudotetrahedral geometry.
View Article and Find Full Text PDFInorg Chem
September 2021
The enantiopure Schiff bases ( or )--1-(X-CH)ethyl-2-hydroxy-1-naphthaldimine {X = H [( or )-HL1], -CHO [( or )-HL2], and -Br [(- or )-HL3]} react with cobalt(II) acetate to give bis[( or )--1-(X-CH)ethyl-2-oxo-1-naphthaldiminato-κ,]-Λ/Δ-cobalt(II) {X = H [Λ/Δ-Co-( or )-L1], -CHO [Λ/Δ-Co-( or )-L2], and -Br [Λ/Δ-Co-( or )-L3]} (-), respectively. Induced Λ and Δ chirality originates at the metal center of the -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 and but irreversible phase transformation for .
View Article and Find Full Text PDFCondensation 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 with copper(ii) acetate under reflux to give green microcrystals of bis[(R or S)-2-((E)-1-(1-(Ar)ethylimino)ethyl)phenolato-κ2N,O]-Λ/Δ-copper(ii), {Ar = C6H5 (Λ/Δ-Cu-R- or S-L1), p-CH3OC6H4 (Λ/Δ-Cu-R- or S-L2)} with induction of Λ/Δ-chirality at-metal. The presence of Schiff base ligands in the paramagnetic green microcrystals is confirmed by decomplexation reaction with NaCN via reduction of Cu(ii) to Cu(i) in DMSO-d6 solution.
View Article and Find Full Text PDFACS Appl Mater Interfaces
October 2017
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).
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