title: Fixed distance photoinduced electron transfer between Fe and Zn porphyrins encapsulated within the Zn HKUST-1 metal organic framework.
abstract: An attractive strategy for the development of photocatalytic metal organic framework (MOF) materials is to co-encapsulate a photoactive electron donor with a catalytic electron acceptor within the MOF. Here we report the co-encapsulation of both Zn(ii) tetrakis(tetra 4-sulphonatophenyl)porphyrin (Zn4SP) and Fe(iii) tetrakis(tetra 4-sulphonatophenyl)porphyrin (Fe4SP) into an HKUST-1 (Zn) MOF and demonstrate photoinduced electron transfer (ET) between the co-encapsulated guest. Photo-excitation of the Zn4SP results in fixed-distance inter-molecular ET between the encapsulated (3)Zn4SP and the Fe(iii)4SP as evident by the reduction in the encapsulated (3)Zn4SP lifetime from 890 μs (kobs = 1.1 × 10(3) s(-1)) to 83 μs (kobs = 1.2 × 10(4) s(-1)) in the presence of Fe4SP giving a kET ∼ 1.1 × 10(4) s(-1). The data are consistent with ET taking place between encapsulated porphyrins that are two cages apart in distance with a reorganizational energy of ∼1.65 eV, β = 1.25 and ΔG° = -0.97 eV (within a semi-classical Marcus theory framework).
authors.affiliation: Department of Chemistry, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620, USA. rwlarsen@usf.edu.
authors.forename: Randy W
authors.initials: RW
authors.lastname: Larsen
authors.forename: Lukasz
authors.initials: L
authors.lastname: Wojtas
mesh_terms: D004579:Electron Transport / Q000502:physiology; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D000073396:Metal-Organic Frameworks; D009942:Organometallic Compounds / Q000737:chemistry* / Q000378:metabolism; D010775:Photic Stimulation / Q000379:methods; D011166:Porphyrins / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000073396:Metal-Organic Frameworks; D009942:Organometallic Compounds; D011166:Porphyrins; C539834:bis(1,3,5-benzenetricarboxylate)tricopper(II); D007501:Iron; D015032:Zinc