Luminescent complexes of Re(I) and Ru(II) with appended macrocycle groups derived from 5,6-dihydroxyphenanthroline: cation and anion binding
Φόρτωση...
Ημερομηνία
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Royal Society of Chemistry
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Dalton Transactions
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
A range of ligands in which a macrocyclic unit is fused to a 1, 10- phenanthroline unit has been prepared starting from 5,6- dihydroxyphenanthroline. The ligands are L(1) in which the pendant ligand is 18- crown- 6; L(2), in which the pendant ligand is benzo- 24- crown- 8; and L(3), in which the macrocycle contains two carboxamide units. Ligands L(1) and L(2) can bind Group 1 and 2 metal cations in their crown- ether cavities; L(3) contains two H- bond ( amide) donors and is suitable for anion- binding. Luminescent complexes of the form [ Ru( bipy) (2)L] (2+), [ ReL( CO)(3)Cl] and [ RuL( CN) (4)] (2-) were prepared and some were structurally characterised; their interactions with various guest species were investigated by luminescence and NMR spectroscopy. For complexes with the crown ethers ( L(1) and L(2)), binding of K(+) was rather weak, but the electrostatic effect due to the charge on the host complex was clear with [ RuL(1) ( CN)(4)] (2-) binding K(+) more strongly than [ Ru( bipy)(2)L(1)] (2+). Binding to the pendant crown ethers was much stronger with Ba(2+), and both [ ReL(1) ( CO) (3)Cl] and [ ReL(2) ( CO)(3)Cl] showed substantial luminescence quenching in MeCNon addition of Ba(2+) ions, with binding constants of 4. 5 x 10(4) M(-1) for [ ReL(1) ( CO)(3)Cl] /Ba(2+) and 1. 3 x 10(5) M(-1) for [ ReL(2) ( CO)(3)Cl] / Ba(2+). Complexes [ Ru( bipy)(2)L(3)] (2+) and [ ReL(3) ( CO)(3)Cl], due to their H- bond donor sites, showed binding of dihydrogenphosphate to the macrocycle. Whereas [ ReL(3) ( CO)(3)Cl] showed 1 : 1 binding with ( H(2)PO(4))(-) in dmso with a binding constant of 65 M(-1), [ Ru( bipy)(2)L(3)] (2+) showed 1 : 2 binding, with microscopic association constants of ca. 1 x 10(6) and 1. 6 x 10(6) M(-1) in MeCN. The fact that K(2) > K(1) suggests a cooperative interaction whereby binding of the first anion makes binding of the second one easier to an extent which overcomes electrostatic effects, and a model for this is proposed which also accounts for the substantial increase in luminescence from [ Ru( bipy)(2)L(3)] (2+) ( 5- fold enhancement) when the second ( H(2)PO(4))(-) anion binds. Both [ Ru( bipy)(2)L(3)] (2+) and [ ReL(3) ( CO) (3)Cl] undergo complete luminescence quenching and a change in colour to near- black in the presence of ( anhydrous) fluoride in MeCN, probably due to deprotonation of the carboxamide group. These changes are however irreversible on a long timescale and lead to slow decomposition.
Περιγραφή
Λέξεις-κλειδιά
active receptor molecules, crown-ether receptors, electrochemical recognition, polypyridine complexes, selective recognition, cooperative binding, metal-cations, ligands, ruthenium(ii), ion
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000226553000017
http://pubs.rsc.org/en/content/articlepdf/2005/dt/b416293e
http://pubs.rsc.org/en/content/articlepdf/2005/dt/b416293e
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας