Premium
Interaction of Sulfonated Ruthenium(II) Polypyridine Complexes with Surfactants Probed by Luminescence Spectroscopy
Author(s) -
GarcíaFresnadillo David,
Orellana Guillermo
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20010919)84:9<2708::aid-hlca2708>3.0.co;2-m
Subject(s) - chemistry , micelle , ammonium bromide , luminescence , ruthenium , quenching (fluorescence) , bromide , pulmonary surfactant , amphiphile , aqueous solution , solvent , inorganic chemistry , photochemistry , nuclear chemistry , organic chemistry , fluorescence , physics , optoelectronics , quantum mechanics , catalysis , biochemistry , polymer , copolymer
Abstract Novel anionic [RuL 2 L′] 2− complexes, where L stands for (1,10‐phenanthroline‐4,7‐diyl)bis(benzenesulfonate) (pbbs; 3a ) or (2,2′‐bipyridine)‐4,4′‐disulfonate (bpds; 3b ), and L′ is N ‐(1,10‐phenanthrolin‐5‐yl)tetradecanamide (pta; 2a ) or N ‐(1,10‐phenanthrolin‐5‐yl)acetamide (paa; 2b ), were synthesized, and their interaction with the prototypical surfactants sodium dodecylsulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and Triton X‐100 (TX‐100) was investigated by electronic absorption, luminescence spectroscopy, emission‐lifetime determinations, and O 2 ‐quenching measurements. [Ru(pbbs) 2 (pta)] 2− ( 5a ) displayed cooperative self‐aggregation in aqueous medium at concentrations above 1.3 μ M ; the observed association was enhanced in the presence of either β ‐cyclodextrin or NaCl. This amphiphilic Ru II compound showed the strongest interaction with all the detergents tested: nucleation of surfactant molecules around the luminescent probe was observed below their respective critical micellar concentrations. As much as a 12‐fold increase of the emission intensity and a 3‐fold rise in the lifetime were measured for 5a bound to TX‐100 micelles; the other complexes showed smaller variations. The O 2 ‐quenching rate constants decreased up to 1/8 of their original value in H 2 O ( e.g. , for [Ru(bpds) 2 (pta)] 2− ( 6a ) bound to CTAB micelles). Luminescence‐lifetime experiments in H 2 O/D 2 O allowed the determination of the metal‐complex fraction exposed to solvent after binding to surfactant micelles. For instance, such exposure was as low as 25% for pta complexes⋅CTAB aggregates. The different behaviors observed were rationalized in terms of the Ru II complex structure, the electrostatic/hydrophobic interactions, and the probe environment.