Naslov
π-stacking of semiquinone radicals determines magnetic and electrical properties of crystals

Autori
Molčanov, Krešimir ; Šantić, Ana ; Stilinović, Vladimir ; Kojić-Prodić, Biserka ; Stalke, Dietmar ; Landeros-Rivera, Bruno ; Hernandez- Trujillo, Jesus ; Kertesz, Miklos ; Mou, Zhongyu

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
East-West Chemistry Conference : Book of Abstracts / Culha, Mustafa ; Zdravkovski, Zoran - Istanbul : Turkish Chemical Society, Society of Chemists and Technologists of Macedonia, 2017, 48-48

Skup
East-West Chemistry Congress - EWCC2017

Mjesto i datum
Skopje, Sjeverna Makedonija, 12.10.2017. - 14.10.2017

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
semiquinones, pi-stacking, semiconductivity, magnetic properties

Sažetak
Semiquinones are a class of stable organic radicals with a great potential for design of novel organic electronics and multifunctional materials. Since the radicals are planar, they typically form π-stacks, which stabilise crystal packing and determine magnetic and electrical properties of the crystals. Two types of stacks π-have been described: 1) Peierls-distorted with alternating short (< 3.1 Å) and long (> 3.35 Å) interplanar distances (i.e. comprising dimers of radicals with paired spins), which are diamagnetic and isolators and 2) stacks of equidistant radicals which are 1D antiferromagnetic and semiconductors. Despite its importance, π-stacking of planar organic radicals has been little studied from the fundamental point of view. Here we present a detailed study of a series of salts with different semiquinones: tetrachloro- (Cl4Q), tetrabromo (Br4Q) and 5, 6-dichloro-2, 3- dicyanosemiquinone (DDQ). We have correlated geometry of the π-interaction with electrical conductivity and magnetic properties, and used crystal engineering to optimise them. Electronegativity (i.e. electron-withdrawing) of the substituents plays a double role: i) it stabilises the radical by enhancing delocalisation of π electrons and ii) lowers the energy of the HOMO orbital, thus increasing band gap related to electronic transport. We have described a novel type of stacking with charge transfer between semiquinone radicals and neutral quinone molecules. Studies of X-ray charge density revealed fine details of electronic structure of the radical and the π- interactions of semiquinones.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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