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Polyradical PROXYL/TEMPO Conjugates Connected by Ester/Amide Bridges: Synthesis, Physicochemical Studies, and DFT Calculations
Author(s) -
Gurská Mária,
Brezová Vlasta,
Šalitroš Ivan,
Švorc Ľubomír,
Špánik Ivan,
Moncoľ Ján,
Pavlik Ján,
Szolcsányi Peter
Publication year - 2021
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202000803
Subject(s) - radical , chemistry , electron paramagnetic resonance , supramolecular chemistry , cyclic voltammetry , antiferromagnetism , amide , electrochemistry , magnetism , molecule , transition metal , computational chemistry , crystallography , photochemistry , organic chemistry , nuclear magnetic resonance , catalysis , physics , quantum mechanics , condensed matter physics , electrode
Abstract Abstract : A series of di‐/trinitroxide esters and amides featuring PROXYL and/or TEMPO radicals connected with alicyclic bridges were prepared in 61–92 % yields and their properties were analysed by using multiple experimental techniques. The examination of EPR spectra of radicals in organic solvents augmented with DFT calculations brought valuable information on the conformational dynamics and spin exchange mechanisms. Cyclic voltammetry investigations revealed (quasi)reversible electrochemical behaviour of studied nitroxides with their half‐wave potentials ranging from −51 to −17 mV. SQUID measurements of selected radicals revealed that the magnetism of di‐ and trinitroxides is significantly different, since antiferromagnetic coupling in biradicals is notably larger than in triradicals. The single‐crystal X‐ray analysis of selected biradicals revealed the existence of 3D supramolecular networks of molecules linked through hydrogen‐bonding interactions. These polynitroxide radicals can serve as promising bridging or chelating ligands in the synthesis of transition‐metal‐based molecular magnets.