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Macrocyclic Receptors for Precious 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
Cyclam has been extensively used and examined as a ligand for a variety of metal ions including noble metals. Jermakowicz-Bartkowiak reported the synthesis, characterization and sorption properties of a new resin 32 based on vinylbenzyl chloride–divinylbenzene copolymer functionalized by 1,4,8,11-tetraazacyclotetradecane (cyclam). The sorption studies were conducted under static conditions with a mixture of precious and base metal ions. The resin bearing the cyclam moieties was found to be highly effective and selective for Au3+, Pt4+ and Pd2+ from HCl solutions. Maximum sorption properties were achieved in 0.1M HCl solution. During a dynamic procedure, the sorption of Au3+, Pt4+ and Pd2+ in the presence of 20-fold excess metals, i.e., Cu2+, Ni2+, Fe3+ resulted in the outcome of up to 400 mg of noble metals per gram of dry resin. Thus, the cyclam functionalized resin was found to be very suitable for the preconcentration and separation of Au, Pt and Pd in hydrometallurgical or separation procedures (Jermakowicz-Bartkowiak 2007).
Molecular design of supramolecular polymers with chelated units and their application as functional materials
Published in Journal of Coordination Chemistry, 2018
Igor E. Uflyand, Gulzhian I. Dzhardimalieva
In particular, thermo-responsive MSPs that use a thermally induced interconversion between cis- and trans-isomers on the cyclam block are of interest [269]. In the cis-isomer, the substituents are on the same side of the cyclam plane, whereas in the trans-isomeric subunits are located above and below the cyclam plane. In the MSPs formed by the bis-tpy-cyclam-ligand and Ni(II) ions, the temperature-initiated cis-trans transitions on the cyclam block lead to a macroscopic phase sol–gel transition. Initially, the kinetically preferred cis-isomers, which form coil-like aggregates, are present in the solution. During heating, the cis-form passes into the trans-form, and the coils expand to the rod-coils, which leads to aggregates consisting of rigid and flexible segments and to gelling (Figure 54).
Copper(II) catalyses the reduction of perchlorate by both formaldehyde and by dihydrogen in aqueous solutions
Published in Journal of Coordination Chemistry, 2018
Dror Shamir, Dan Meyerstein, Israel Zilbermann, Ariela Burg, Yael Albo, Alexander I. Shames, Radion Vainer, Eitan J.C. Borojovich, Guy Yardeni, Haya Kornweitz, Eric Maimon
In order to determine at which stage the perchlorate is reduced, the synthetic procedure was repeated, eliminating in each experiment one of the reagents [i.e. cyclam, pyrophosphate, formaldehyde or copper(II)] and measuring the chloride yield. The removal of cyclam or of pyrophosphate does not affect the reduction of perchlorate. However, the results of these experiments clearly point out that only copper and formaldehyde are essential for the perchlorate reduction.
Crystal structure, spectroscopic properties, and Hirshfeld surface analysis of a Ni2+-doped 3,14-diethyl-2,13-diaza-6,17-diazoniatricyclo (16.4.0.07,12)docosane dichloride dihydrate
Published in Journal of Coordination Chemistry, 2020
Dohyun Moon, Jonghyoun Jeon, Jong-Ha Choi
The strong absorption band at 1490–1450 cm−1 can be assigned to CH2 scissoring. The CH2 wagging and twisting vibrations as well as the ν(C–C) and ν(C–N) modes occur at 1400–1000 cm−1. IR spectroscopy is useful for assigning the cis and trans configurations of transition metal complexes with cyclam derivatives [5, 6]. In general, the trans isomer exhibits two groups of bands: overlapping peaks near 870 cm−1 arising from the secondary amine vibration and a single band near 800 cm−1, arising from the methylene vibration. However, the cis isomer exhibits at least three bands at 890–830 cm−1 due to N–H wagging modes, while the methylene vibration splits into two peaks at 820–790 cm−1 [5,6, 28–30]. The peaks that appear in these two ranges of the IR spectra must be carefully assigned because the Ni2+ compound contains both organic [H2(L)]Cl2·2H2O and complex [Ni(L)]Cl2·2H2O moieties. By subtracting the IR spectral peaks of free L from the IR spectra of 1, the absorption peaks of pure [Ni(L)]Cl2·2H2O moiety can be obtained. In 1, two bands around 870 cm−1 and a single absorption at 800 cm−1 are assigned to the N–H wagging and CH2 rocking vibrations, respectively. The three absorption peaks attributed to the secondary amine and methylene vibrations are consistent with the trans-configuration of the constrained cyclam ligand. Notably, the absorption band positions of the scissoring (δ), wagging (ω), twisting (γ), and rocking (ρ) modes of CH2 deformations are not significantly affected by changing the central metal ion and counter anion in transition metal complexes [5, 6, 28–32]. The IR spectral data support the square planar geometry of [Ni(L)]Cl2·2H2O.