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Carolina Garau

Publications and source records attributed to Carolina Garau.

5 recordsLinked to original sources
PubMed2003

Dual binding mode of s-triazine to anions and cations.

Ab initio calculations were performed on complexes between cations and s-triazine, which has a small and positive quadrupole moment. Minimum energy pi-complexes were found between s-triazine and cations. Minimum pi-complexes with anions were previously reported. This ability of s-triazine to form stable complexes with either anions or cations is studied using several theoretical methods. A likely explanation of this duality is the stabilization obtained from the ion-induced polarization. [structure: see text]

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PubMed2003

Weak C-H/pi interaction participates in the diastereoselectivity of a host-guest complex in the presence of six strong hydrogen bonds.

[structure: see text] We report a study of the interaction between methylmethanetriacetic acid (MMTA) and a tripodal amidopyridine receptor 1, where the geometry of the binding is in part governed by a weak C-H/pi interaction in the presence of six strong N(O)-H.O(N) hydrogen bonds. There are two possible binding geometries for the 1:1 complex 1.MMTA; combining computational and experimental evidence we demonstrate that the endo binding mode is more favorable as the result of a C-H/pi interaction.

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PubMed2002

Predicting experimental complexation-induced changes in (1)H NMR chemical shift for complexes between zinc-porphyrins and amines using the ab initio/GIAO-HF methodology.

Ab initio calculations were carried out on zinc-porphyrins complexed to several amines: N-(3,5-dimethyl-pyridin-4-yl)-formamide, 1,4-diazabiciclo[2.2.2]octane (DABCO), and 1-azabiciclo[2.2.2]octane (quinuclidine). The proton chemical shifts of these complexes were calculated ab initio at the GIAO-HF/6-311G//HF/3-21G level of theory, and the obtained values agree satisfactorily with experimental results. The complexation-induced changes in (1)H NMR chemical shifts correlate well with differences in association constants of several host-guest complexes.

Journal Article↗
PubMed2002

Quantification of aromaticity in oxocarbons: the problem of the fictitious "nonaromatic" reference system.

Despite the extensive research reported in the literature, the concept of aromaticity has eluded rigorous quantification. The main reason for this undesirable reality is the fact that aromaticity is a differential property. While bond orders, atomic charges and electronegativity differences are properties of the molecule under analysis, the aromaticity concept often refers to the difference between some property of the molecule and that of an artificial "nonaromatic" reference system. A rigorous definition of such a reference system is non-existing and therefore constituting the main barrier to obtain a satisfactory quantification of the aromatic concept. Oxocarbon acids and their anions are examples where the criteria of aromaticity that use reference systems are unsuccessful, only NICS criterion gives satisfactory results. Wiberg bond indexes and 17O NMR chemical shifts are also useful to study such compounds.

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