Search results for "supramolecular"
showing 10 items of 830 documents
Equipping metallo-supramolecular macrocycles with functional groups: Assemblies of pyridine-substituted urea ligands
2012
A series of di-(m-pyridyl)-urea ligands were prepared and characterized with respect to their conformations by NOESY experiments and crystallography. Methyl substitution in different positions of the pyridine rings provides control over the position of the pyridine N atoms relative to the urea carbonyl group. The ligands were used to self-assemble metallo-supramolecular M(2)L(2) and M(3)L(3) macrocycles which are generated in a finely balanced equilibrium in DMSO and DMF according to DOSY NMR experiments and ESI FTICR mass spectrometry. Again, crystallography was used to characterize the assemblies. Methyl substitution in positions next to the pyridine nitrogen prevents coordination, while …
Cooperative H-bonds, π⋯π and anion⋯π interactions as driving forces in the construction of novel Cu(II) bis(imidazol-2-yl) supramolecular 3D framewor…
2019
Abstract Two new Cu(II) complexes with bis(2-imidazolyl) based ligands, with the formula [Cu(BIM)2(SCN)2]·2H2O (BIM = bis(2-imidazol-2-yl)methane) and [Cu(HBIMAM)2(OH2)2](BF4)4·2H2O (BIMAM = bis(2-imidazol-2-yl)methylaminomethane) have been synthesized and characterized. Both compounds contain mononuclear entities as molecular building blocks (MBBs); neutral [Cu(BIM)2(SCN)2] in compound 1 and cationic [Cu(HBIMAM)2(OH2)2]4+ in compound 2. The coordination around the metal atoms shows a tetragonally-elongated octahedral geometry (CuN4S2 and CuN4O2 chromophores). The Q-band EPR spectra of both compounds are indicative of an essentially d x 2 - y 2 ground state for copper(II) ions. The analysis…
Synthesis, Structural and Spectroscopic Characterization of Cr III , Fe III , Co III , Ni II and Cu II Complexes with an Asymmetric 1,3,4‐Thiadiazole…
2016
The reaction of the new asymmetric 1,3,4-thiadiazole-based ligand 2-[(5-ethylthio-1,3,4-thiadiazol-2-yl)hydrazonomethyl]phenol (H1ETHP) with various third-row transition metal salts resulted in the formation of six new mononuclear complexes [Cr(ETHP)2]ClO4 (1), [Fe(ETHP)2][FeCl4] (2), [Co(ETHP)(ETHP–H)] (3), [Ni(ETHP)(H1ETHP)]Cl (4), [Ni(ETHP)(H1ETHP)](ClO4) (5), [Ni(ETHP)(H1ETHP)]Br (6), and one tetranuclear complex [Cu2Cl3(ETHP)(H1ETHP)]2 (7). H1ETHP and all complexes have been analyzed by single crystal X-ray diffraction. Structural analysis of 1–6 reveals complexes of the [ML2]n+-type (n = 0,1), in which the mono anionic ligand ETHP coordinates in a tridentate NNO fashion via its imine,…
Energetic study of bifurcated hydrogen bonds in secondary structures of salts composed with dicarboxylic acids and ethylamine
2020
Abstract The nature of bifurcated hydrogen bonds prompted us to analyze the energy of supramolecular motifs on the example of new structures of carboxylic acids salts with amines, which guarantee a multitude of such interactions. Experimental and theoretical studies of four dicarboxylic salts with primary amine: ethylammonium succinate hydrate (1), tartrate hydrate (2) phthalate hydrate (3) and terephthalate (4) has been investigated along with study of the strength of interactions between the anions and cations. The complete topological analysis of the charge density for all new structures allowed designation of the estimated Cumulative Dissociation Energy (eCDE).
Solution Conformation and Self‐Assembly of Ferrocenyl(thio)ureas
2016
Conformations and (dis)assembly processes of ureas and thioureas are of fundamental importance in supramolecular chemistry, anion binding, or crystal engineering, both in solution and in the solid state. For sensing and switching processes a redox-active unit, such as the ferrocene/ferrocenium couple, is especially suitable. Here, self-assembly processes of redox-active ferrocenyl(thio)ureas FcNHC(X)NHR [X = O, R = Fc (1), Ph (2), 1-naphthyl (3), Me (4), Et (5); X = S, R = Fc (6), 1-anthracenyl (7)] through hydrogen bonds – both in the solid state and in THF and CH2Cl2 solution – are reported. Special emphasis is placed on the impact of nonclassical intramolecular NH···Fe hydrogen bonds in …
Ion-Pair Complexation with Dibenzo[21]Crown-7 and Dibenzo[24]Crown-8 bis-Urea Receptors
2016
Synthesis and ion-pair complexation properties of novel ditopic bis-urea receptors based on dibenzo[21]crown-7 (R(1) ) and dibenzo[24]crown-8 (R(2) ) scaffolds have been studied in the solid state, solution, and gas phase. In a 4:1 CDCl3 /[D6 ]DMSO solution, both receptors clearly show positive heterotropic cooperativity toward halide anions when complexed with Rb(+) or Cs(+) , with the halide affinity increasing in order I(-) <Br(-) <Cl(-) . In solution, the rubidium complexes of both receptors have higher halide affinities compared to the caesium complexes. However, Rb(+) and Cs(+) complexes of R(2) show stronger affinities toward all the studied anions compared to the corresponding catio…
Design of bimetallic magnetic chains based on oxalate complexes: towards single chain magnets
2009
We describe the synthesis, structure and magnetic characterization of several oxalate-based bimetallic 1D systems. We will exemplify how by suitable choice of the molecular building blocks and strict control of their arrangement in the solid state, the magnetic properties of these low-dimensional materials can be tuned to finally obtain bimetallic oxalate chains behaving as single-chain magnets (SCM). First, we will focus on compounds [K(18-crown-6)][MII(bpy)Cr(ox)3] (1, 2; MII = Mn, Co; bpy = C10N2H8). The MnCr derivative behaves as a 1D ferromagnet down to 2 K, the lowest investigated temperature. The lack of magnetic ordering in this chain prompted us to prepare the more anisotropic MnCo…
Solvent effects on the dimensionality of oxamato-bridged manganese(II) compounds
2018
Two new oxamate-containing manganese(II) complexes, [{Mn(H2edpba)(H2O)2}2]n (1) and [Mn(H2edpba)(dmso)2]∙dmso∙CH3COCH3∙H2O (2) (H4edpba = N,N′-ethylenediphenylenebis(oxamic acid) and dmso = dimethylsulfoxide), have been synthesized and the structures of 1 and 2 were characterized by single crystal X-ray diffraction. The structure of 1 consists of neutral honeycomb networks in which each manganese(II) is six-coordinate by one H2edpba2− ligand and two carboxylate–oxygens from two other H2edpba2− ligands building the equatorial plane. Each manganese is connected to its nearest neighbor through two carboxylate(monoprotonated oxamate) bridges in an anti-syn conformation. A dmso solution of singl…
Self‐Assembly and Characterisation of Grid‐Type Iron( II ), Cobalt( II ) and Zinc( II ) Complexes
2003
The reaction of the ligands 5 and 6, containing two tridentate binding units, with iron(II), cobalt(II) and zinc(II) leads to the self-assembly of supramolecular architectures of [2 × 2] grid type containing four ions in octahedral coordination sites. The grid-type structures have been assigned on the basis of the spectroscopic data in solution, and confirmed in the solid state in the case of complexes 6b and 6c by X-ray crystallography. The latter study revealed that each metal ion is situated in a distorted octahedral coordination environment comprising two N,N,O ligand donor sets. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Solid-State Molecular Nanomagnet Inclusion into a Magnetic Metal-Organic Framework: Interplay of the Magnetic Properties.
2015
Single-ion magnets (SIMs) are the smallest possible magnetic devices and are a controllable, bottom-up approach to nanoscale magnetism with potential applications in quantum computing and high-density information storage. In this work, we take advantage of the promising, but yet insufficiently explored, solid-state chemistry of metal-organic frameworks (MOFs) to report the single-crystal to single-crystal inclusion of such molecular nanomagnets within the pores of a magnetic MOF. The resulting host-guest supramolecular aggregate is used as a playground in the first in-depth study on the interplay between the internal magnetic field created by the long-range magnetic ordering of the structur…