Naslov
Elektronski prijelaz i spektar cirkularnog dikroizma kiralnih cikličkih sulfida i sulfoksida, jednostruko i dvostruko mosno povezani bifenili sa CH2SCH2 i CH2SOCH2 mostovima
(Electronic Transition and Circular Dicroism Spectr of Chiral Cyclic Sulfides and Sulfoxides. Singly and Doubly Bridged Biphenyls with CH2SCH2 and CH2SOCH2 Bridges)

Autori
Lončar, Linda ; Mintas, Mladen ; Hergold-Brundić, Antonija ; Nagl, Ante ; Sandrström, Jan ; Šarac- Arneri, Ruža

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

Izvornik
The ninth Dubrovnik International Course and Conference on the Interfaces among Mathematics, Chemistry and Compute Sciences / - , 1994, 1-1

Skup
The ninth Dubrovnik International Course and Conference on the Interfaces among Mathematics, Chemistry and Compute Sciences

Mjesto i datum
Dubrovnik, Hrvatska, 26.06.1994. - 01.07.1994

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
kiralni ciklički sulfidi i sulfoksidi
(sulfide and sulfoxide chromophores ; C2S and C2SO chromophores)

Sažetak
The nature of the electronic transitions in the sulfide and sulfoxide chromophores has been a subject of debate for a long time. Recently, the widespread use of chiral sulfoxides as intermediates in stereospecific synthesisl and the need to know their absolute configurations has given added interest to the chiroptical properties of the C2S and C2SO chromophores. In a forthcoming work, CNDO/S-CI calculations will be reported, which give transition eneries and polarization directions for these two chromophores. The correctness of the predicted polarization directions is verfied by comparing experimental and theoretical CD spectra of cyclic sulfides and sulfoxides with rigid structures and containing a second well characterized chromophore. The intensites and signs of the CD bands depend on the mutual orientations of the transitions in the two chromophores. In this work, we have combined the biphenyl chromophore with C2S, C2SO and C2SO2 groups in compounds 1-3. These compounds have been resolved into enantiomers by chromatography on triacetylcellulose, and their CD spectra have been recorded. Since the sulfone group lacks transitions in the accessible wavelenght region the CD spectrum of 3 is very similar to those of simple bridged biphenyls, whereas the CD spectra of 1 and 2 show more complexity, in particular in the region 200 – 230 nm. For the theoretical calculations, the geometries of the compounds are required. The structures of compounds 2 and 3 have been determined by X-ray crystallography, and the geometry of 1 by empirical force-field calculations. Theoretical calculations by the semiempirical method of Schellman and coworkers have given a good qualitative reproduction of the experimental CD spectrum of 2, and similar calculations are now being performed for 1.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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