Naslov
π-Interactions of quinoid rings in the solid state

Autori
Molčanov, Krešimir ; Kojić-Prodić, Biserka

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

Izvornik
YoungChem 2011 Book of Abstracts / Brzozka, Zbigniew - Varšava : Warsaw University of Technology, 2011, 57-57

ISBN
978-83-61037-28-6

Skup
9th Internationa Congress of Young Chemists

Mjesto i datum
Kraków, Poljska, 12.10.2011. - 16.10.2011

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
π-interactions; quinoid rings; crystal structure; chloranilic acid; dihydroxiquinone

Sažetak
π-Interactions of aromatic molecules are well-known and were extensively studied. The aromatic rings stack either as parallel and offset or T-shaped ; in such arrangements σ-π attractions outperform π-π repulsions. However, parallel, face-to-face arrangement is energetically unfavourable due to strong repulsion of π electrons. π-Interactions of quinoid molecules were little studied. Recently, we discovered that some substituted 2, 5-dihydroxyquinones stack face-to-face in crystals ; distances between centroids of contiguous rings are 3.2 - 3.4 Å, which is significantly shorter than the sum of van der Waals radii (for carbon it is 3.5 Å), and also much shorter than distances in aromatic stacks (typically 3.65 - 4.3 Å). Quantum-chemical calculations indicate unusually strong dispersion interactions with energies of about 20 kcal mol-1 being comparable to strong hydrogen bonds. The electronic structure of quinoid rings is in favour of face-to-face stacking ; π electrons are not delocalised (as in aromatics), but distinguishable single and double bonds exist. Therefore, π-π repulsion is minimised and σ-π attraction maximised in parallel, face-to-face arrangement. Such interactions have a great potential in crystal engineering and design of functional materials.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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