Premium
Novel Phthalocyaninatobis(alkylcarboxylato)silicon( IV ) Compounds: NMR Data and X‐ray Structures To Study the Spacing Provided by Long Hydrocarbon Tails That Enhance Their Solubility
Author(s) -
SosaSánchez Jose L.,
SosaSánchez Arturo,
Farfán Norberto,
ZamudioRivera Luis S.,
LópezMendoza Gerson,
Pérez Flores Javier,
Beltrán Hiram I.
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500003
Subject(s) - triclinic crystal system , chemistry , crystallography , chemical shift , molecule , ligand (biochemistry) , hydrocarbon , octahedron , carboxylate , nmr spectra database , proton nmr , nuclear magnetic resonance spectroscopy , solubility , supramolecular chemistry , stereochemistry , x ray , crystal structure , spectral line , organic chemistry , biochemistry , receptor , physics , astronomy , quantum mechanics
The reaction between trans ‐PcSiCl 2 ( 1 ) and the potassium salts of six fatty acids ( 2 a–2 f ) led to the trans ‐PcSi[OOC(CH 2 ) n CH 3 ] 2 compounds ( 3 a–3 f ), which were characterised by elemental analysis, IR, UV/Vis and 1 H, 13 C, and 29 Si NMR spectroscopy. From a detailed study of the NMR spectra, the strong anisotropic currents of the Pc macrocycle were found to have an effect on up to the sixth methylenic group. As expected, the length of the hydrocarbon tail does not affect the chemical shift of the 29 Si nucleus of any of the compounds, appearing at around −222.6. The structures of PcSi[OOC(CH 2 ) n CH 3 ] 2 , where n =7, 10, 12, 13 and 20, were determined by X‐ray crystallography. All the compounds were found to be triclinic with a P $\bar 1$ space group. In all cases the observed crystallographic pseudosymmetry is C i and the asymmetric unit consists of half a molecule. The silicon atom is at the centre of a distorted octahedron and hence its coordination number is six. The carboxylate fragments are in a trans configuration with respect to the Pc macrocycle. The supramolecular structures are discussed in detail herein. The correlation between the 1 H NMR chemical shifts and the position of the corresponding carbon atoms in the hydrocarbon tail reveals that the dicarboxylate substituents exhibit a spacer‐like behaviour that enhances the solubility. A detailed study of the tail variable allowed us to evaluate the loss of radial shielding along the Pc 2− ligand.