Browse
Submit Data
Databases
API
Help

Dataset Information

28 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Expanded Mercaptocalixarenes: A New Kind of Macrocyclic Ligands for Stabilization of Polynuclear Thiolate Clusters.

ABSTRACT: The syntheses and properties of expanded 4-tert-butyl-mercaptocalix[4]arenes, in which the methylene linkers are replaced by -CH₂ NRCH₂ - or -CH₂ NRCH₂ - and -CH₂ NRCH₂ CH₂ CH₂ NRCH₂ - units, are described. The new macrocycles were obtained in a step-wise manner, utilizing fully protected, i. e. S-alkylated, derivatives of the oxidation-sensitive thiophenols in the cyclisation steps. Reductive cleavage of the macrobicyclic or macrotricyclic intermediates (6, 7, 11) afforded the free thiophenols (H₄ 8, H₄ 9, and H₄ 12) in preparative yields as their hydrochloride salts. The protected proligands can exist in two conformations, resembling the "cone" and "1,3-alternate" conformations found for the parent calix[4]arenes. The free macrocycles do not show conformational isomerism, but are readily oxidized forming intramolecular disulfide linkages. Preliminary complexation experiments show that these expanded mercaptocalixarenes can serve as supporting ligands for tetranuclear thiolato clusters.

SUBMITTER: Schleife F

PROVIDER: S-EPMC9313869 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

In Situ Assembled Polynuclear Zinc Oxo Clusters Using Modified Schiff Bases as Ligands.

Project description:A series of different cores and nuclearity zinc metal clusters 1-5 have been synthesized using Zn(ClO4)2·6H2O, Schiff-base primary ligands, and dibenzoyl methane (DBM) or monoethanolamine (MEA) as co-ligand in a room-temperature reaction. The structure of the complexes is characterized using single-crystal X-ray diffraction. Among them, (1) [Zn(L1)(DBM)] is mononuclear; (2) [Zn4(L2)2(DBM)4], (3) [Zn4(L2)4(H2O)2(ClO4)2]·2CH2Cl2, and (4) [Zn4(L3)2(DBM)4] have a cubane core; and (5) [Zn4(L4)4(MEA)2(ClO4)2] has a ladderlike core structure. Compounds 1-5 have also been characterized using UV-vis absorption and emission spectroscopies. For an in-depth understanding of the absorption spectra of 1 and 3, density functional theory (DFT) calculations have been performed, which suggest that the transitions correspond to the π → π* intraligand charge transfer (ILCT) transitions.

| S-EPMC8756576 | biostudies-literature

?-Octabromo- and ?-Octakis(trifluoromethyl)isocorroles: New Sterically Constrained Macrocyclic Ligands.

Project description:Presented herein is a study of the acid-induced demetalation of two sterically hindered copper corroles, Cu ?-octabromo-meso-triphenylcorrole (Cu[Br8TPC]) and ?-octakis(trifluoromethyl)-meso-tris(p-methoxyphenyl)corrole (Cu[(CF3)8TpOMePC]). Unlike reductive demetalation, which affords the free-base ?-octabromocorrole, demetalation of Cu[Br8TPC] under non- reductive conditions (CHCl3/H2SO4) resulted in moderate yields of free-base 5- and 10-hydroxy isocorroles. The isomeric free bases could be complexed to CoII and NiII, affording stable complexes. Only reductive demetalation was found to work for Cu[(CF3)8TpOMePC], affording a highly saddled, hydrated corrole, H3[5-OH,10-H-(CF3)8TpOMePC], where the elements of water had added across C5 and C10. Interaction of this novel free base with CoII resulted in Co[iso-10-H-[CF3)8TpOMePC], a CoII 10-hydro isocorrole. The new metal complexes were all characterized by single-crystal X-ray diffraction analysis and, despite their sterically hindered nature, were found to exhibit almost perfectly planar isocorrole cores.

| S-EPMC5474668 | biostudies-literature

Organolithium aggregation as a blueprint to construct polynuclear lithium nickelate clusters.

Project description:By exploiting the high aggregation of aliphatic lithium acetylides, here we report the synthesis and structural analysis of polynuclear lithium nickelate clusters in which up to 10 equivalents of organolithium can co-complex per Ni(0) centre. Exposure of the Ni(0)-ate clusters to dry air provides an alternative route to homoleptic Ni(II)-ates.

| S-EPMC10243118 | biostudies-literature

Stabilization of Near Identical Hydrogen Bonded Octameric Water Clusters in Crystal Structures of Three Distinct Non-Charged Polyamide Macrocyclic Host Molecules.

Project description:In this paper, we present a comparative analysis of the solid state structures of three well-resolved hydrates of macrocyclic host molecules 1a, 1b, and 2 containing an intrannular amide-aryl substituent (lariat arm) connected to a fixed 26-membered ring in a normal (-NHCOAr, hosts 1a and 1b) or reverse manner (-CONHAr, host 2). Despite different chemical structures, these hosts crystallize as isostructural tetrahydrates in the same P-1 space group. Moreover, their crystals exhibit identical hydrogen bond motifs resulting in a stabilization of an almost identical unusual octameric water cluster built from the cyclic tetramer core and four water molecules, attached sequentially in an "up-and-down" manner. Further analysis reveals that, among the series, the structure of host 2 provides the most suitable environment for the accommodation of this type of water cluster.

| S-EPMC8125911 | biostudies-literature

Visualizing Biological Copper Storage: The Importance of Thiolate-Coordinated Tetranuclear Clusters.

Project description:Bacteria possess cytosolic proteins (Csp3s) capable of binding large quantities of copper and preventing toxicity. Crystal structures of a Csp3 plus increasing amounts of CuI provide atomic-level information about how a storage protein loads with metal ions. Many more sites are occupied than CuI equiv added, with binding by twelve central sites dominating. These can form [Cu4 (S-Cys)4 ] intermediates leading to [Cu4 (S-Cys)5 ]- , [Cu4 (S-Cys)6 ]2- , and [Cu4 (S-Cys)5 (O-Asn)]- clusters. Construction of the five CuI sites at the opening of the bundle lags behind the main core, and the two least accessible sites at the opposite end of the bundle are occupied last. Facile CuI cluster formation, reminiscent of that for inorganic complexes with organothiolate ligands, is largely avoided in biology but is used by proteins that store copper in the cytosol of prokaryotes and eukaryotes, where this reactivity is also key to toxicity.

| S-EPMC5519932 | biostudies-literature

Non-coordinative metal selectivity bias in human metallothioneins metal-thiolate clusters.

Project description:Mammalian metallothioneins (MT-1 through MT-4) are a class of metal binding proteins containing two metal-thiolate clusters formed through the preferential coordination of d10 metals, Cu(i) and Zn(ii), by 20 conserved cysteine residues located in two protein domains. MT metalation (homometallic or heterometallic Zn(ii)/Cu(i) species) appears to be isoform specific and controlling zinc and copper concentrations to perform specific and distinct biological functions. Structural and functional relationships, and in vivo metalation studies, identified evolutionary features defining the metal-selectivity nature for MTs. Metallothionein-3 (MT-3) has been shown to possess the most pronounced Cu-thionein character forming Cu(i)-containing species more favorably than metallothionein-2 (MT-2), which possesses the strongest Zn-thionein character. In this work, we identify isoform-specific determinants which control metal binding selectivity bias in different MTs isoforms. By studying the reactivity of Zn7MT-2, Zn7MT-3 and Zn7MT-3 mutants towards Cu(ii) to form Cu(i)4Zn4MTs, we have identified isoform-specific key non-coordinating residues governing folding/outer sphere control of metal selectivity bias in MTs metal clusters. By mutating selected residues and motifs in MT-3 to the corresponding MT-2 amino acids, we dissected key roles in modulating cluster dynamic and metal exchange rates, in increasing the Cu(i)-affinity in MT-3 N-terminal β-domain and/or modulating the higher stability of the Zn(ii)-thiolate cluster in MT-2 β-domain. We thus engineered MT-3 variants in which the copper-thionein character is converted into a zinc-thionein. These results provide new insights into the molecular determinants governing metal selectivity in metal-thiolate clusters.

| S-EPMC6450656 | biostudies-literature

Macrocyclic bis(ureas) as ligands for anion complexation.

Project description:Two macrocyclic bis(ureas) 1 and 2, both based on diphenylurea, have been synthesized. Compound 1 represents the smaller ring with two ethynylene groups as linkers and 2 the larger ring with two butadiynylene groups. On thermal treatment to 130 °C molecule 1 splits up into two dihydroindoloquinolinone (3) molecules. Both compounds 1 and 2 form adducts with polar molecules such as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and act as complexing agents towards a series of anions (Cl(-), Br(-), I(-), NO3 (-), HSO4 (-)). The crystal structures of 3, 2·2DMSO, 2·2DMF, and of the complex NEt4[Br·2] have been determined. Quantitative investigations of the complexation equilibria were performed via (1)H NMR titrations. While 1 is a rather weak complexing agent, the large ring of 2 binds anions with association constants up to log K = 7.93 for chloride ions.

| S-EPMC4142877 | biostudies-literature

Supramolecular polynuclear clusters sustained cubic hydrogen bonded frameworks with octahedral cages for reversible photochromism.

Project description:Developing supramolecular porous crystalline frameworks with tailor-made architectures from advanced secondary building units (SBUs) remains a pivotal challenge in reticular chemistry. Particularly for hydrogen-bonded organic frameworks (HOFs), construction of geometrical cavities through secondary units has been rarely achieved. Herein, a body-centered cubic HOF (TCA_NH4) with octahedral cages was constructed by a C3-symmetric building block and NH4+ node-assembled cluster (NH4)4(COOH)8(H2O)2 that served as supramolecular secondary building units (SSBUs), akin to the polynuclear SBUs in reticular chemistry. Specifically, the octahedral cages could encapsulate four homogenous haloforms including CHCl3, CHBr3, and CHI3 with truncated octahedron configuration. Crystallographic evidence revealed the cages served as spatially-confined nanoreactors, enabling fast, broadband photochromic effect associated with the reversible photo/thermal transformation between encapsulated CHI3 and I2. Overall, this work provides a strategy by shaping SSBUs to expand the framework topology of HOFs and a prototype of hydrogen-bonded nanoreactors to accommodate reversible photochromic reactions.

| S-EPMC10981757 | biostudies-literature

Dinuclear Nickel Complexes of Thiolate-Functionalized Carbene Ligands and Their Electrochemical Properties.

Project description:Four dimeric nickel(II) complexes [Ni2Cl2(BnC2S)2] [1], [Ni2Cl2(BnC3S)2] [2], [Ni2(PyC2S)2]Br2 [3]Br2, and [Ni2(PyC3S)2]Br2 [4]Br2 of four different thiolate-functionalized N-heterocyclic carbene (NHC) ligands were synthesized, and their structures have been determined by single-crystal X-ray crystallography. The four ligands differ by the alkyl chain length between the thiolate group and the benzimidazole nitrogen (two -C2- or three -C3- carbon atoms) and the second functionality at the NHC being a benzyl (Bn) or a pyridylmethyl (Py) group. The nickel(II) ions are coordinated to the NHC carbon atom and the pendent thiolate group, which bridges to the second nickel(II) ion creating the dinuclear structure. Additionally, in compounds [1] and [2], the fourth coordination position of the square-planar Ni(II) centers is occupied by the halide ions, whereas in [3]2+ and [4]2+, the additional pendant pyridylmethyl groups complete the coordination spheres of the nickel ions. The electrochemical properties of the four complexes were studied using cyclic voltammetry and controlled-potential coulometry methods. The thiolate-functionalized carbene complexes [1] and [2] appear to be poor electrocatalysts for the hydrogen evolution reaction; the complexes [3]Br2 and [4]Br2, bearing an extra pyridylmethyl group, show higher catalytic activity in proton reduction, indicating that the pyridine group plays an important role in the catalytic cycle.

| S-EPMC5850092 | biostudies-literature

Multinuclear Cu(I) Clusters Featuring a New Triply Bridging Coordination Mode of Phosphaamidinate Ligands.

Project description:Phosphabenzamidine [mes-NH-C(Ph)═P-mes) (1) and phosphaformamidine (mes-NH-CH═P-mes) (4) ligands have been synthesized and characterized. The conjugate bases of 1 and 4 coordinate by each bridging three Cu(I) ions, forming hexa- and tetranuclear clusters Cu6[mes-N═C(Ph)-P-mes]3Cl4Li(THF)2 (3) and Cu4[mes-N═CH-P-mes]4 (5), respectively. Both clusters have been fully characterized using 1H NMR, 31P NMR, and X-ray crystallography. Complexes 3 and 5 exhibit a previously unknown coordination mode of phosphaamidinates, which are far less studied than their well-known amidinate counterparts.

| S-EPMC6443373 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data