Supramolecular D⋯A-layered structures based on germanium complexes with 2,3-dihydroxynaphthalene and N,N′-bidentate ligands

Abstract

The concept of using redox-active ligands is often considered from ‘their effect on the metal center properties’ point of view. We present the reverse side of this approach – change of redox properties of ligands under the influence of metal.

Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

“…Density functional theory (DFT) calculations were performed using the Gaussian 09 program package [75] at the B3LYP/ Def2TZVP level. The applied approximation was recently shown [76,77] to accurately reproduce the geometry, electronic, and energy characteristics of metal complexes with redox-active ligands. The stationary points on the potential energy surfaces were located by full geometry optimization with the calculation of the force constant matrix and checking for the stabilities of the DFT wave function.…”

Derivatives of penta-, hexa-, and hepta-coordinated tin with Schiff bases and 1,10-phenanthroline: structure, redox and optoelectronic properties

“…Previously, we have observed such an effect for the complex of phenanthroline with germanium catecholate. 5 In this case, the potential of the reduction peak of 2 is also noticeably lower than that of 1 (Table 1): −1.94 vs. −2.16 V, which corresponds to a thermodynamically more favourable process by 5.09 kcal mol −1 . Compared to phenanthroline ( E p red = −2.36 V), this difference is even more significant and corresponds to 9.75 kcal mol −1 .…”

“…For instance, it is possible to increase their availability, and thus, increase the reactivity of the compound, in particular, impart the desired redox properties, to reduce the band gap, thereby changing the semiconductor and optoelectronic properties, to fine-tune the catalytic behavior. The examples include the dramatic decrease in the reduction potential and the increase in the availability of LUMO of germanium derivatives in the presence of N-donors, 2–4 the preparation of D⋯A-layered structures based on germanium complexes with 2,3-dihydroxynaphthalene and N , N ′-bidentate ligands with a narrow HOMO/LUMO gap (∼2 eV), 5 the fine tuning of the germylene HOMO level in the presence of N, S, P, and O-donor ligands, which determines the ability of germylenes to participate in oxidative addition reactions. 6,7 The key methods in the listed studies of germanium coordination compounds are voltammetry and UV-vis spectroscopy, which, when used in combination, make it possible to experimentally quantify the position of the frontier orbitals of the substrate.…”

Remote Stereoelectronic Effects in Pyrrolidone- and Caprolactam-Substituted Phenols: Discrepancies in Antioxidant Properties Evaluated by Electrochemical Oxidation and H-Atom Transfer Reactivity

“…It also reacts with DPPH by almost an order of magnitude faster than QC and more than 3 orders of magnitude faster than BHT and TMP. This difference is likely to originate from the synergy of two effectsthe high reactivity of 1,2,3-substituted trihydroxyaromatic compounds − and the presence of the lactam/OH hydrogen bond discussed above.…”

“…Top: Calculated BDEs and Ionization Potential for Each Compound and Bottom: Intramolecular H-Bonding Facilitates Oxidation but Hinders HAT Scheme 6. Origin of Increased Antioxidant Activity in Ortho-Dihydroxyaromatic Compounds: the Formation of Semiquinones (Potentials from 64,65 ) and the Formation of an Intramolecular Hydrogen Bond 68 The Journal of Organic Chemistry a sigma acceptor and cannot stabilize the oxidized intermediates (radical or radical cation) by resonance. 9 The situation changes in an interesting way when going from 3 to 4 and from 7 to 8.…”