ISSN:
0947-6539
Keywords:
hydrogen bonds
;
metalloreceptor
;
molecular recognition
;
nucleobases
;
pi interactions
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Thiacyclophane ligands 1 and 2, containing a meta-xylyldithiaether unit, an aromatic spacing unit and a polyether chain, were prepared in good yield in a three-step synthesis. The macrocyclic organopalladium complexes [Pd(L)-(MeCN)][BF4] (3: L = 1; 4: L = 2) were prepared through palladation of the respective thiacyclophane ligand by reaction with [Pd(MeCN)4][BF4]2. These complexes act as metalloreceptors to aromatic amines such as p-aminopyridine (pap), m-aminopyridine (map) and the DNA nucleobases adenine and guanine. Binding occurs through simultaneous first- and second-sphere coordination. This involves three separate interactions: first-sphere σ donation from an aromatic N atom to the Pd centre, second-sphere hydrogen bonds between the NH2 group and polyether O atoms, and π stacking between the electron-poor aromatic rings of the substrate and the electron-rich aromatic spacing units of the receptor. 1H NMR spectra exhibit chemical shift changes indicative of the H-bonding and π-stacking interactions in solution. X-ray structures for thiacyclophane 1, metalloreceptor [Pd(1)(MeCN)][BF4] (3), metalloreceptor/model substrate complexes [Pd(1)(pap)][BF4 (5) and [Pd(2)-(pap)][BF4] (7), and metalloreceptor/nucleobase complexes [Pd(1)(adenine)][BF4] (13), [Pd(2)(adenine)][BF4] (14) and [Pd(1)(guanine-BF3)][BF4] (15b) show details of these interactions in the solid state.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19970030807
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