Fullerene bridged metallocyclodextrin donor–acceptor complexes: optical spectroscopy and photophysics

Abstract

Two pyridine substituted beta-cyclodextrins have been synthesized and coordinated to the photoactive metal centres, [Ru(II)(bpy)2] and [Re(I)(CO)3bpy], where bpy is 2,2'-bipyridyl. The photophysical and electrochemical properties of these model complexes have been examined and compared with dinuclear complexes formed when C60 was included between two cyclodextrin cavities of the metallocyclodextrin units. On inclusion of C60, significant quenching of the emission of the luminophores is observed. Concentration and laser power dependence confirm that this quenching is intramolecular. The quenching process is interpreted in terms of a photoinduced electron transfer between the photosensitizer and C60 centre on the basis of spectroscopic and electrochemical evidence. Rate constants of 1.3 +/- 0.1 x 10(8) and 7.0 +/- 0.4 x 10(7) s(-1) have been determined for the Ru and Re based complexes, respectively. Significantly, these large rate constants indicate that that there is substantial electronic communication across the cyclodextrin at least for excited state processes.

Interfacial supramolecular cyclodextrin-fullerene assemblies: host reorientation and guest stabilization

“…Mono-6-deoxy-6-(4-pyridylmethyl)amino-b-cyclodextrin, b-CD-py, and di-6 A ,6 B -deoxy-6-(4-pyridylmethyl)amino-gcyclodextrin, g-CD-(py) 2 (Scheme 1) were prepared as previously reported. 28,29 Substrate preparation. Gold electrodes were polished on polishing pads with aluminium oxide slurry in H 2 O (particle size 0.3 mm followed by 0.05 mm).…”

“…Previously, we successfully formed bicapped C 60 inclusion complexes with functionalised CDs. 28 These inclusion complexes can also be formed by stirring C 60 and CD in methanol for 1 h. 49 It was anticipated that treatment of the backfilled CD monolayer in this way would result in formation of a 'capped' layer as shown in Scheme 3.…”

“…The propensity for thin layers or solid deposits of fullerene to photopolymerise under visible irradiation is well known. 27,28,57 This process can be monitored using Raman and prolonged exposure to laser radiation (458 nm) causes solid C 60 to photopolymerize reflected in shifts of the A g pentagonal pinch mode from 1469 cm À1 to 1456 cm À1 (Fig. 4(c)).…”

Electrochemically Induced Release of a Luminescent Probe from a Rhenium‐Containing Metallopolymer

“…fac ‐[Re(2,2′‐bpy)(CO) 3 (PVP) 10 ]PF 6 and fac ‐[Re(2,2′‐bpy)(CO) 3 (py)]PF 6 were prepared by modifying a literature procedure 19. Scheme illustrates the general approach.…”

Harnessing the Synergistic and Complementary Properties of Fullerene and Transition-Metal Compounds for Nanomaterial Applications

“…These systems also exhibit evidence of electronic interactions between the fullerene cage and the metal-containing moiety in the excited state, which results in significant quenching of the emission of the metal-containing luminophore by the fullerene cage. 268…”