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Topic review
Updated time: 27 Oct 2020
Submitted by: Syed Adil
Definition: Catalytic oxidation of alcohol to their analogous carbonyls is one of the key organic reactions in both scientific and industrial applications, with universal production of 10,000 million tons/year of carbonyls in the 20th century. Such as, aldehyde and ketone derivatives are extensively employed as precursors in insecticide, flame-retardant, cosmetic, confectionery, flavoring, pharmaceutical, and beverage industries.
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Topic review
Updated time: 25 Aug 2021
Submitted by: Massimiliano Gaeta
Definition: Over the years, chiral discrimination of chiral molecules such as amino acids, alcohols, amines, hydroxy-carboxylic acids, etc. has aroused the interest of the scientific community. Thus, numerous studies have reported the possibility to discriminate several organic guests by using both symmetric and asymmetric porphyrin derivatives. Nevertheless, this entry exclusively focuses on chiral porphyrinoids as probes for asymmetric recognition and sensing, illustrating the main aspects concerning the chiral recognition phenomena of a multitude of chiral organic guests through several chiral mono- and bis-porphyrins via different spectroscopic techniques.
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Topic review
Updated time: 19 Apr 2021
Submitted by: Evgeny Kopnin
Definition: High pressure applications is strongly required for the synthesis of these materials because it is only way to stabilize gold oxides which are thermally very unstable at ambient pressures.
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Topic review
Updated time: 08 Oct 2021
Submitted by: Junnian Wei
Definition: Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure-function relationship of organocopper compounds could advance the rational design and development of new Cu-based reactions and organocopper reagents. Compared to the mono-carbonic ligand, the C,N- and C,C-bidentate ligands better stabilize unstable organocopper compounds. Bidentate ligands can chelate to the same copper atom via η2-mode, forming a mono-cupra-cyclic compounds with at least one acute C-Cu-C angle. When the bidentate ligands bind to two copper atoms via η1-mode at each coordinating site, the bimetallic macrocyclic compounds will form nearly linear C-Cu-C angles. The anionic coordinating sites of the bidentate ligand can also bridge two metals via μ2-mode, forming organocopper aggregates with Cu-Cu interactions and organocuprates with contact ion pair structures. The reaction chemistry of some selected organocopper compounds is highlighted, showing their unique structure–reactivity relationships.
Entry Collection : Chemical Bond
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Topic review
Updated time: 07 May 2021
Submitted by: Svetlana Baca
Definition: Cluster-based coordination polymers (CCPs) are constructed from metal coordination clusters that are bridged by polytopic organic ligands forming multidimensional systems such as one-dimensional (1D) chains, two-dimensional (2D) layers, and three-dimensional (3D) metal-organic frameworks. Structurally well-defined polynuclear Mn(II,III)/Fe(III)-oxo pivalate and isobutyrate clusters recommend them-selves as extremely versatille building blocks where their ancillary coordination ligands are sufficiently flexible to allow the formation of a wide variety of 1D, 2D and 3D CCPs.
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Topic review
Updated time: 15 Jan 2021
Submitted by: Luca Gonsalvi
Definition: The use of CO2 as C1 building block for chemical synthesis is receiving growing attention, due to the potential of this simple molecule as abundant and cheap renewable feedstock. Among the possible reductants used in the literature to bring about CO2 reduction to C1 derivatives, hydroboranes have found various applications, in the presence of suitable homogenous catalysts. The main results obtained since 2016 in the synthetic design of main group, first and second row transition metals for use as catalysts for CO2 hydroboration are summarized.
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Topic review
Updated time: 28 Dec 2020
Submitted by: Rodica Olar
Definition: Very few biological active Cu(II) complexes entered in clinical trials as result of poor water solubility and lipophilicity, low stability as well as in vivo inactivation. Their pharmacological and/or oral administration profile can be improved either by physically encapsulation or by conjugation to an organic matrix via a moiety able to coordinate Cu(II). As result, a large variety of species were developed as delivery carriers such as liposomes, synthetic or natural polymers or dendrimers.
Entry Collection : MedlinePlus
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Others
Updated time: 30 Oct 2020
Submitted by: Dayane Reis
Abstract: A dinuclear copper(II) complex of (1) (where bipy = 2,2′‑bipyridine, bzt = benzoate and ox = oxalate) was synthesised and characterised by diffractometric (powder and single-crystal XRD) and thermogravimetric (TG/DTG) analyses, spectroscopic techniques (IR, Raman, electron paramagnetic resonance spectroscopy (EPR) and electronic spectroscopy), magnetic measurements and density functional theory (DFT) calculations. The analysis of the crystal structure revealed that the oxalate ligand is in bis(bidentate) coordination mode between two copper(II) centres. The other four positions of the coordination environment of the copper(II) ion are occupied by one water molecule, a bidentate bipy and a monodentate bzt ligand. An inversion centre located on the ox ligand generates the other half of the dinuclear complex. Intermolecular hydrogen bonds and pi-pi for the organisation of the molecules in the solid state. Molar magnetic susceptibility and field dependence magnetisation studies evidenced a weak intramolecular–ferromagnetic interaction (J = +2.9 cm‑1) between the metal ions. The sign and magnitude of the calculated J value by density functional theory (DFT) are in agreement with the experimental data.
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Topic review
Updated time: 19 Jan 2021
Submitted by: Alexander Medvedev
Definition: Peroxosolvates - adductsofhydrogen peroxide and molecules or salts formed by hydrogen bonding.
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Topic review
Updated time: 24 May 2021
Submitted by: Valentin Grachev
Definition: Electron Paramagnetic Resonance, EPR is resonance absorption of microwave quanta by electron spins placed in a swept external magnetic field B at a definite value of magnetic field. Other used names are Electron Magnetic Resonance, EMR and Electron Spin Resonance, ESR.
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