title: Control over photoinduced energy and electron transfer in supramolecular polyads of covalently linked azaBODIPY-bisporphyrin 'molecular clip' hosting fullerene.
abstract: A 'molecular clip' featuring a near-IR emitting fluorophore, BF(2)-chelated tetraarylazadipyrromethane (aza-BODIPY) covalently linked to two porphyrins (MP, M = 2H or Zn) has been newly synthesized to host a three-dimensional electron acceptor fullerene via a 'two-point' metal-ligand axial coordination. Efficient singlet-singlet excitation transfer from (1)ZnP* to aza-BODIPY was witnessed in the dyad and triad in nonpolar and less polar solvents, such as toluene and o-dichlorobenzene, however, in polar solvents, additional electron transfer occurred along with energy transfer. A supramolecular tetrad was formed by assembling bis-pyridine functionalized fullerene via a 'two-point' metal-ligand axial coordination, and the resulted complex was characterized by optical absorption and emission, computational, and electrochemical methods. Electron transfer from photoexcited zinc porphyrin to C(60) is witnessed in the supramolecular tetrad from the femtosecond transient absorption spectral studies. Further, the supramolecular polyads (triad or tetrad) were utilized to build photoelectrochemical cells to check their ability to convert light into electricity by fabricating FTO/SnO(2)/polyad electrodes. The presence of azaBODIPY and fullerene entities of the tetrad improved the overall light energy conversion efficiency. An incident photon-to-current conversion efficiency of up to 17% has been achieved for the tetrad modified electrode.
authors: Department of Chemistry, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5017, USA. Francis.DSouza@UNT.edu
authors: Francis
authors: F
authors: D'Souza
authors: Anu N
authors: AN
authors: Amin
authors: Mohamed E
authors: ME
authors: El-Khouly
authors: Navaneetha K
authors: NK
authors: Subbaiyan
authors: Melvin E
authors: ME
authors: Zandler
authors: Shunichi
authors: S
authors: Fukuzumi
mesh_terms: D001372:Aza Compounds / Q000737:chemistry*; D001896:Boron Compounds / Q000737:chemistry*; D004563:Electrochemistry; D004579:Electron Transport; D004735:Energy Transfer; D037741:Fullerenes / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D055668:Photochemical Processes; D011166:Porphyrins / Q000737:chemistry*
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001372:Aza Compounds; D001896:Boron Compounds; D037741:Fullerenes; D011166:Porphyrins