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Macrocyclic Receptors for Biologically Relevant Metal Ions
Published in Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney, Macrocyclic Receptors for Environmental and Biosensing Applications, 2022
Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney
Metals and their complexes are ubiquitous in life processes. They are essential for human health as they serve both structural and functional roles including the maintenance of cellular functions involved in a wide range of biological activities. Alkali and alkaline earth metals are involved in many biological processes such as maintenance of membrane charge balance and electrical conductivity (Da Silva and Williams 2001). First-row transition elements such as iron, copper, zinc, manganese, cobalt, chromium, molybdenum, vanadium and nickel are required in trace amounts. These are essential inorganic nutrients as their deficiency results in the impairment of a physiological function (Underwood and Mertz 1987). Numerous proteins incorporate metal ions in their structure. These metal centers can act as strong Lewis acids that can activate coordinated ligands for reactivity, for example, a water molecule coordinated to a Zn(II) center becomes a potent nucleophile for amide bond hydrolysis of a protein substrate (Bertini et al. 2007). In a large number of biological molecules, transition metals showing variable valency are present as enzyme co-factors and involved in different redox reactions. Electron transfer units such as cytochromes, iron-sulfur clusters and blue copper proteins shuttle electrons to other proteins that require redox chemistry for their function, while many other redox proteins catalyze multi-electron oxidation/reduction reactions directly on a substrate.
Alternate Feedstocks
Published in James G. Speight, Refinery Feedstocks, 2020
Briefly, the alkali metals consist of the chemical elements lithium (li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). Together with hydrogen, they make up Group I of the Periodic Table (Figure 9.1). On the other hand, the alkaline earth metals are the six chemical elements in Group 2 of the Periodic Table and are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These elements have very similar properties – they are shiny, silvery-white, and are somewhat reactive at standard temperature and pressure. Finally, the heavy metals are less easy to define but are generally recognized as metals with relatively high density, atomic weight, or atomic number. The common transition metals such as copper (Cu), lead (Pb), and zinc (Zn) are often classed as heavy metals but the criteria used for the definition and whether metalloids (types of chemical elements which have properties in between, or that are a mixture of, those of metals and nonmetals) are included, vary depending on the context. These metals are often found in functional molecules such as the porphyrin molecules, which include chlorophyll and contain magnesium.
Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Acyl groups - Groups formed by removing the hydroxy groups from oxoacids that have the general structure RC(=O)(OH) and replacement analogues of such acyl groups. [5] Adiabatic process - A thermodynamic process in which no heat enters or leaves the system. Admittance (Y) - Reciprocal of impedance. Y = G + iB, where G is conductance and B is susceptance. [1] Adsorption - A process in which molecules of gas, of dissolved substances in liquids, or of liquids adhere in an extremely thin layer to surfaces of solid bodies with which they are in contact. [10] Albedo* - The ratio of the light reflected or scattered from a surface to the intensity of incident light. The term is often used in reference to specific types of terrain or to entire planets. Alcohols - Compounds in which a hydroxy group, -OH, is attached to a saturated carbon atom. [5] Aldehydes - Compounds RC(=O)H, in which a carbonyl group is bonded to one hydrogen atom and to one R group. [5] Aldoses - Aldehydic parent sugars (polyhydroxyaldehydes H[CH(OH)]nC(=O)H, n>1) and their intramolecular hemiacetals. [5] Aldoximes - Oximes of aldehydes: RCH=NOH. [5] Alfvén number (Al) - A dimensionless quantity used in plasma physics, defined by Al = v(µ)1/2/B, where is density, v is velocity, µ is permeability, and B is magnetic flux density. [2] Alfvén waves - Very low frequency waves which can exist in a plasma in the presence of a uniform magnetic field. Also called magnetohydrodynamic waves. Alicyclic compounds - Aliphatic compounds having a carbocyclic ring structure which may be saturated or unsaturated, but may not be a benzenoid or other aromatic system. [5] Aliphatic compounds - Acyclic or cyclic, saturated or unsaturated carbon compounds, excluding aromatic compounds. [5] Alkali metals - The elements lithium, sodium, potassium, rubidium, cesium, and francium. Alkaline earth metals - The elements calcium, strontium, barium, and radium. [7] Alkaloids - Basic nitrogen compounds (mostly heterocyclic) occurring mostly in the plant kingdom (but not excluding those of animal origin). Amino acids, peptides, proteins, nucleotides, nucleic acids, and amino sugars are not normally regarded as alkaloids. [5] Alkanes - Acyclic branched or unbranched hydrocarbons having the general formula CnH2n+2, and therefore consisting entirely of hydrogen atoms and saturated carbon atoms. [5] Alkenes - Acyclic branched or unbranched hydrocarbons having one carbon-carbon double bond and the general formula CnH2n. Acyclic branched or unbranched hydrocarbons having more than one double bond are alkadienes, alkatrienes, etc. [5] Alkoxides - Compounds, ROM, derivatives of alcohols, ROH, in which R is saturated at the site of its attachment to oxygen and M is a metal or other cationic species. [5] Alkyl groups - Univalent groups derived from alkanes by removal of a hydrogen atom from any carbon atom: CnH2n+1-. The groups derived by removal of a hydrogen atom from a terminal carbon atom of unbranched alkanes form a subclass of normal alkyl (n-alkyl) groups. The groups RCH2-, R2CH-, and R3C- (R not equal to H) are primary, secondary, and tertiary alkyl groups, respectively. [5]
Effects of strontium on the morphological and photosynthetic physiological characteristics of Vicia faba seedlings
Published in International Journal of Phytoremediation, 2023
Xi Chen, Ningying Zhong, Yayun Luo, Yinfeng Ni, Ziyi Liu, Guo Wu, Ting Zheng, Yuxi Dang, Huiling Chen, Wei Li
The alkaline earth metal strontium (Sr) has an abundance of 340 mg·kg−1 in the earth's crust (Coudert 2015). Sr exists in nature as four stable isotopes of 84Sr, 86Sr, 87Sr and 88Sr, mainly distributed in minerals such as celestite and strontianite, among which 88Sr accounts for 82.58% of the total (Burger et al. 2019a; Liao et al. 2017). In recent years, the concentration of 88Sr in soil has increased rapidly due to human activities such as mining, reaching 247–7,600 mg·kg−1 (Barcanet al. 1998; WHO 2010; Burger et al. 2019a). The radionuclide 90Sr (T1/2 = 28.7 years) is a fission product of uranium-235 (235U) and plutonium-239 (239Pu) that is released into the environment with nuclear tests and nuclear leakage accident (Wang et al. 2017). The radionuclides in the air can enter the soil by atmospheric precipitation or precipitation, and the radionuclides in water can enter the soil by irrigation (Sahoo et al. 2016).
Complexation between nickel(II), cobalt(III) and hydrazones derived from pyridoxal 5′-phosphate and hydrazides of 2-,3-,4-pyridinecarboxylic acids in aqueous solution
Published in Journal of Coordination Chemistry, 2018
G. A. Gamov, M. N. Zavalishin, A. Y. Khokhlova, A. V. Gashnikova, V. V. Aleksandriiskii, V. A. Sharnin
A study of stability of metal complexes of hydrazones derived from pyridoxal or pyridoxal 5′-phosphate is important since the stability constant characterizes the binding ability of Schiff base towards ion. However, there are only a few papers devoted to determination of stability constants of PL-derived coordination compounds. For instance, Fe(II) and Fe(III) ions mixed with pyridoxal isonicotinoyl hydrazone (PIH), pyridoxal benzoyl hydrazone (PBH), 3-hydroxyisonicotinaldehyde isonicotinoyl hydrazone and salicylic aldehyde isonicotinoyl hydrazone (SIH) have been found to form the complexes of FeLx=1–2Hy=1–4 composition [5]. The quantity of ligand ions and protons in these complexes depended on pH of the medium. The stability constants of complexes of different compositions were determined. Recently, the study of iron(III) complexation with PIH and SIH has been repeated [6]; these hydrazones have been confirmed to be efficient iron scavengers. The composition and stability of complexes formed by PIH, PBH, pyridoxal p-methoxybenzoyl hydrazone, pyridoxal meta-fluorobenzoyl hydrazone and Ca(II), Mg(II), Zn(II) ions were studied similarly [7]. The constant of alkaline earth metal ion complexation was determined to be low. Besides, a recent report describes the complex formation between gallium(III) and 2-oxo-2-[N-(2,4,6-trihydroxy-benzilyden)-hydrazino]-acetamide [8].
Catalytic CO2-MEA absorptions with the aid of CaCO3, MgCO3, and BaCO3 in the batch and semi-batch processes
Published in Chemical Engineering Communications, 2020
Huancong Shi, Min Huang, Yuandong Huang, Mingqi Cui, Raphael Idem
Furthermore, the Zwitterion mechanism has been re-investigated in detail with molecular simulation methods (Xie et al., 2010). Xie et al. (2010) conducted simulated molecular structure, Energy Diagrams, Transition States and Activation Energy (Ea) of CO2-MEA reactions via Zwitterion mechanism. The simulation works indicate the role of base in the facilitation of carbamate formation, where base can be OH–, amine, or H2O (Xie et al., 2010). Therefore, we extended to Lewis base such as alkaline earth metal carbonate MCO3, and “M” could be Ca, Mg, and Ba in IIA group of the Periodic Table.