176220-38-5Relevant articles and documents
Semiconductor-based interfacial electron-transfer reactivity: Decoupling kinetics from pH-dependent band energetics in a dye-sensitized titanium dioxide/aqueous solution system
Yan, Susan G.,Hupp, Joseph T.
, (1996)
Hexaphosphonation of Ru(bpy)32+ provides a basis for surface attachment to nanocrystalline TiO2 in film (electrode) or colloidal form and for subsequent retention of the molecule over an extraordinarily wide pH range. Visible excitation of the surface-attached complex leads to rapid injection of an electron into the semiconductor. Return electron transfer, monitored by transient absorbance spectroscopy, is biphasic with a slow component that can be reversibly eliminated by adjusting the potential of the dark electrode to a value close to the conduction-band edge (ECB). Evaluation of the fast component yields a back-electron-transfer rate constant of 5(±0.5) × 107 s-1 that is invariant between pH = 11 and H0 = -8, despite a greater than 1 eV change in ECB (i.e., the nominal free energy of the electron in the electrode). The observed insensitivity to large changes in band-edge energetics stands in marked contrast to the behavior expected from a straightforward application of conventional interfacial electron-transfer theory and calls into question the existing interpretation of these types of reactions as simple inverted region processes.
Synthesis and characterization of novel heteroleptic Ru(II) bipyridine complexes for dye-sensitized solar cell applications
Seo, Jinhyung,Jeong, Mingyeong,Na, Seo Yeong,Lee, Eugin,Kim, Yang-Rae,Park, Byoungchoo,Kim, Byeong Hyo
, p. 1445 - 1452 (2019/07/29)
Abstract: Four heteroleptic ruthenium(II) complexes, [Ru(L1)(L2)(NCS)2] (where L1 = 4,4′-bis[2-(1,1′-biphenyl)-4-ylethenyl]-2,2′-bipyridine (bpbpy) or 4,4′-bis[2-(3,4-dimethoxyphenyl)ethenyl]-2,2′-bipyridine (dmpbpy); L2 = 4,4′-dicarboxy-2,2′-bipyridine (dcbpy) or 4,4′-bis(E-carboxyvinyl)-2,2′-bipyridine (dcvbpy)), were synthesized from a one-pot reaction of [RuCl2(p-cymene)]2 and L1 followed by the addition of the anchoring ligand, L2. From these new heteroleptic ruthenium(II) complexes containing carboxylic acid-functionalized ligands, the tetrabutylammonium salt forms of the ruthenium(II) complexes, [Ru(L1)(L2)(NCS)2][TBA], were obtained in reasonable yields and applied as dyes in dye-sensitized solar cell (DSSC) devices. Among the DSSCs fabricated with the [Ru(L1)(L2)(NCS)2][TBA] dyes, a DSSC fabricated with the [Ru(bpbpy)(dcbpy)(NCS)2][TBA] dye exhibited the best power conversion efficiency (η) of 4.27%, while the cells fabricated with other dyes had η between 1.94 and 2.68%. Graphic abstract: [Figure not available: see fulltext.].
Directly Coupled Versus Spectator Linkers on Diimine PtII Acetylides—Change the Structure, Keep the Function?
Archer, Stuart A.,Keane, Theo,Delor, Milan,Bevon, Elizabeth,Auty, Alexander J.,Chekulaev, Dimitri,Sazanovich, Igor V.,Towrie, Michael,Meijer, Anthony J. H. M.,Weinstein, Julia A.
, p. 18239 - 18251 (2017/12/07)
Modification of light-harvesting units with anchoring groups for surface attachment often compromises light-harnessing properties. Herein, a series of [donor–acceptor–anchor] platinum(II) diimine (bis-)acetylides was developed in order to systematically compare the effect of conjugated versus electronically decoupled modes of attachment of protected anchoring groups on the photophysical properties of light-harvesting units. The first examples of “decoupled” phosphonate diimine PtII complexes are reported, and their properties are compared and contrasted to those of carboxylate analogues studied by a diversity of methods. Ultrafast time-resolved IR and transient absorption spectroscopy revealed that all complexes have a charge-transfer (CT) lowest excited state with lifetimes between 2 and 14 ns. Vibrational signatures and dynamics of CT states were identified; the assignment of electronic states and their vibrational origin was aided by TDDFT calculations. Ultrafast energy redistribution accompanied by structural changes was directly captured in the CT states. A significant difference between the structures of the electronic ground and CT excited states, as well as differences in the structural reorganisation in the complexes bearing directly attached or electronically decoupled anchoring groups, was discovered. This work demonstrates that decoupling of the anchoring group from the light-harvesting core by a saturated spacer is an easy approach to combine surface attachment with high reduction potential and ten times longer lifetime of the CT excited state of the light-absorbing unit, and retain electron-transfer photoreactivity essential for light-harvesting applications.
