The introduction of hydroxyl groups into ligands is able to transfer high hydrophilic features to the related
metal systems. The atom-economy synthetic procedure adopted which consists in the one-step
Cyclopentene-oxide ring opening, quantitatitatively affords stereoselective formation of the multi-hydroxyl
rac-1,2,4- C5H2[CH(CH2)3CHOH]3 Cpººº ligand1. Rh complexation of Cpººº gives rise to a novel class of
water-soluble complexes (L,L)RhCpººº (LL=NBD 1, COD 2, CH2CH2 3, CO 4) (Scheme 1) characterized
by their spectroscopic features (ESI-MS, IR, 2D NMR, n.O.e.).
The X-ray diffraction studies of 1a reveal the occurrence of one couple of enantiomeric pairs in the crystal
structure, whilst the crystal packing shows an interesting self-organization in chains of dimeric units of 1a,
promoted by strong intermolecular hydroxyl H-bonding. This effect has been exploited by performing VT
NMR experiments in different solvents (CDCl3, Py, DMSO). Unpredictably, in the absence of chiral tag, 1
exhibits solvent-dependent chiroptical properties (CD, αD^
25), which are correlated to UV transitions and DFT
calculations. The intra/inter molecular H-binding is crucial in driving the equilibrium between the observed
atropisomers 1a and 1b, by varying the planar chirality on the two π-complexes.
| Identifer | oai:union.ndltd.org:unibo.it/oai:amsdottorato.cib.unibo.it:1044 |
| Date | 15 April 2008 |
| Creators | Natanti, Paolo <1979> |
| Contributors | Bordoni, Silvia |
| Publisher | Alma Mater Studiorum - Università di Bologna |
| Source Sets | Università di Bologna |
| Language | Italian |
| Detected Language | English |
| Type | Doctoral Thesis, PeerReviewed |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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