Intrastrand electron and energy transfer between polypyridyl complexes on a soluble polymer

• Published in: Journal of the American Chemical Society Vol. 115; no. 16; pp. 7363 - 7373
• Main Authors: Jones, Wayne E, Baxter, Steven M, Strouse, Geoffrey F, Meyer, Thomas J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.08.1993
• Subjects: 661300 > Other Aspects of Physical Science > (1992-); Applied sciences; CHEMICAL REACTION KINETICS; CHEMICAL REACTIONS; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPLEXES; COPOLYMERS; DECOMPOSITION; DERIVATIZATION; ELECTROMAGNETIC RADIATION; ELECTRON TRANSFER; ENERGY TRANSFER; ENERGY-LEVEL TRANSITIONS; Exact sciences and technology; EXCITATION; Inorganic and organomineral polymers; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KINETICS; LASER RADIATION; MATERIALS; ORGANIC COMPOUNDS; ORGANIC POLYMERS; OSMIUM COMPLEXES; OXIDATION; PETROCHEMICALS; PETROLEUM PRODUCTS; PHOTOCHEMICAL REACTIONS; PHOTOLYSIS; Physicochemistry of polymers; PLASTICS; POLYMERS; POLYOLEFINS; POLYSTYRENE; POLYVINYLS; Properties and characterization; RADIATIONS; REACTION KINETICS; RUTHENIUM COMPLEXES; SYNTHETIC MATERIALS; TRANSITION ELEMENT COMPLEXES 400201 > Chemical & Physicochemical Properties; Cationic complex; Deactivation; Organic ligand; Photoinduced effect; Styrene(chloromethyl) copolymer; Transition metal Complexes; Heteronuclear complex; Polynuclear complex; Platinoid Complexes; Charge transfer compound; Kinetic parameter; Rate constant; Osmium II Complexes; Energy transfer; Ruthenium II Complexes; Styrene copolymer
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00069a039

Intrastrand electron and energy transfer between pendant sites in a derivatized 1:1 copolymer of styrene and p-(chloromethyl)styrene have been studied by laser flash photolysis. The polymer [p-PS-Ru[sub 22][sup II]Os[sub 5][sup II]](PF[sub 6])[sub 54], in which 22 of the approximately 27 repeat units of an average strand were Ru[sup II] and 5 Os[sup II], was prepared by nucleophilic displacement of chloride by [M(bpy)[sub 2](bpyCH[sub 2]OH)][sup 2+] (M is Ru or Os: bpy is 2,2[prime]-bipyridine; bpyCH[sub 2]OH is 4-Me-4[prime]-CH[sub 2]OH-2,2[prime]-bipyridine) under basic conditions. Following Ru[sup II] [yields] bpy laser flash excitation there was evidence for a rapid ([tau] < 5 ns) Ru[sup II*] [yields] Os[sup II] energy transfer component with the remaining Ru[sup II*] emission relatively unperturbed compared to [p-PS-Ru[sub 27][sup II]](PF[sub 6])[sub 54]. On the basis of these observations it was inferred that Ru[sup II*] [yields] Os[sup II] energy transfer (which is spontaneous by 0.36 eV) does occur with k(295 [+-] 2K, CH[sub 3]CN) > 2 x 10[sup 8] s[sup [minus]1], but only to Os[sup II] sites that are adjacent to Ru[sup II*]. Energy transfer self-exchange from Ru[sup II*] to Ru[sup II] ([Delta]G[degrees] = 0.0 eV) is slow with k < 1 x 10[sup 6] s[sup [minus]1]. In the presence of 35 mM of the irreversible, oxidative quencher [p-CH[sub 3]OC[sub 6]H[sub 4]N[sub 2]](BF[sub 4]) in CH[sub 3]CN [approximately]94% of the emission from [p-PS-Ru[sup II][sub 22]Os[sup II][sub 5]](PF[sub 6])[sub 54] is quenched. Transient absorption measurements under these conditions show an instantaneous loss of Os[sup II] [yields] bpy, Ru[sup II] [yields] bpy absorption (bleaching) in the visible, consistent with excitation and oxidative quenching during the laser pulse. 43 refs., 9 figs., 1 tab.