Naslov
Anion binding study of urea-, thiourea- and amide- based receptors by NMR spectroscopy

Autori
Bregović, Nikola ; Cindro, Nikola ; Frkanec, Leo ; Užarević, Krunoslav ; Tomišić, Vladislav

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

Izvornik
Pharma NMR Conference: Application of NMR Spectroscopy in Pharmaceutical Industry : Programme & Book of Abstracts / Novak, Predrag ; Tomišić, Vladislav ; Bregović, Nikola - Zagreb : International Association of Physical Chemists (IAPC), 2015, 33-33

Skup
Pharma NMR Conference: Application of NMR Spectroscopy in Pharmaceutical Industry

Mjesto i datum
Rovinj, Hrvatska, 23.09.2015. - 25.09.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
anion binding ; dehydroacetic acid ; (thio)urea ; amide ; stability constant ; NMR spectroscopy

Sažetak
In the field of anion binding peak selectivity and high binding affinity are rarely reported, especially in competitive media. In order to accomplish these goals it is necessary to expand the understanding of the anion binding reaction by indentifying all interactions that contribute to the stabilization of the complexes and gathering information regarding the structure of the compexes. In this work, the complexation of several anions by receptors based on dehydroacetic acid bearing urea (1), thiourea (2a and 2b), and amide (3a–c) moieties (scheme 1) was investigated in acetonitrile (MeCN) and dimethyl sulfoxide (DMSO). 1H NMR was proven to be a very efective technique for the study of anion complexation of the investigated compounds, due to pronounced changes in chemical shift of the (thio)urea and amide NH- proton signals upon complexation. Further on, the subtle changes regarding the signal of the amine proton during the titrations with H2PO4– strongly indicated that the carbonyl oxygen acted as a proton acceptor allowing the formation of additional hydrogen bond which stabilizes the complex. Recent microcalorimetric measurements regarding H2PO4– dimerisation were expanded using 31P NMR spectroscopy.1 Gathered data was used in order to obtain reliable stability constants of dihydrogenphosphate complexes. Acetate and dihydrogen phosphate complexes with thiourea derivatives were found to be the most stable ones. This could be attributed to the shape and size complementarity of these anions and the thiourea moiety, as well as to the highest proton donating properties of thioureas. It was also found that the arrangement of the amide groups in the structure of receptors 3a and 3b plays an important role in the stabilisation of the anion complexes. References 1. N. Bregović, N. Cindro, L. Frkanec, K. Užarević, V. Tomišić, Chem. Eur. J. 20 (2014) 15863–15871. Acknowledgements: The work was funded by Croatian science foundation (SupraCAR: IP-2014-09-7309) and European Regional Development Fund and Ministry of Science Education and Sports (RC.2.2.08-0024).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA