81998-05-2Relevant articles and documents
Sequence and Structure of Peptoid Oligomers Can Tune the Photoluminescence of an Embedded Ruthenium Dye
Zborovsky, Lieby,Tigger-Zaborov, Hagar,Maayan, Galia
, p. 9098 - 9107 (2019)
The understanding of structure–function relationships within synthetic biomimetic systems is a fundamental challenge in chemistry. Herein we report the direct correlation between the structure of short peptoid ligands—N-substituted glycine oligomers incorporating 2,2′-bipyridine groups—varied in their monomer sequence, and the photoluminescence of RuII centers coordinated by these ligands. Based on circular dichroism and fluorescence spectroscopy we demonstrate that while helical peptoids do not affect the fluorescence of the embedded RuII chromophore, unstructured peptoids lead to its significant decay. Transmittance electron microscopy (TEM) revealed significant differences in the arrangements of metal-bound helical versus unstructured peptoids, suggesting that only the latter can have through-space interactions with the ruthenium dye leading to its quenching. High-resolution TEM enabled the remarkable direct imaging of singular ruthenium-bound peptoids and bundles, supporting our explanation for structure-depended quenching. Moreover, this correlation allowed us to fine-tune the luminescence properties of the complexes simply by modifying the sequence of their peptoid ligands. Finally, we also describe the chiral properties of these Ru–peptoids and demonstrate that remote chiral induction from the peptoids backbone to the ruthenium center is only possible when the peptoids are both chiral and helical.
New Ru(II)/Os(II)-polypyridyl complexes for coupling to TiO2 surfaces through acetylacetone functionality and studies on interfacial electron-transfer dynamics
Banerjee, Tanmay,Biswas, Abul Kalam,Sahu, Tuhin Subhra,Ganguly, Bishwajit,Das, Amitava,Ghosh, Hirendra Nath
, p. 13601 - 13611 (2014)
New Ru(II)- and Os(II)-polypyridyl complexes have been synthesized with pendant acetylacetone (acac) functionality for anchoring on nanoparticulate TiO2 surfaces with a goal of developing an alternate sensitizer that could be utilized for designing an efficient dye-sensitized solar cell (DSSC). Time-resolved transient absorption spectroscopic studies in the femtosecond time domain have been carried out. The charge recombination rates are observed to be very slow, compared with those for strongly coupled dye molecules having catechol as the anchoring functionality. The results of such studies reveal that electron-injection rates from the metal complex-based LUMO to the conduction band of TiO2 are faster than one would expect for an analogous complex in which the chromophoric core and the anchoring moiety are separated with multiple saturated C-C linkages. Such an observation is rationalized based on computational studies, and a relatively smaller spatial distance between the dye LUMO and the TiO2 surface accounted for this. Results of this study are compared with those for analogous complexes having a gem-dicarboxy group as the anchoring functionality for covalent binding to the TiO2 surface to compare the role of binding functionalities on electron-transfer dynamics. the Partner Organisations 2014.
Supramolecular Control of Charge-Transfer Dynamics on Dye-sensitized Nanocrystalline TiO2 Films
Hirata, Narukuni,Lagref, Jean-Jacques,Palomares, Emilio J.,Durrant, James R.,Nazeeruddin, M. Khaja,Gratzel, Michael,Di Censo, Davide
, p. 595 - 602 (2004)
A [Ru(dcbpy)2(NCS)2 dye has been chemically modified by the addition of a secondary electron donor moiety, N,N-(di-p-anisylamino)phenoxymethyl. Optical excitation of the modified dye adsorbed to nanocrystalline TiO2 films
Using intramolecular energy transfer to transform non-photoactive, visible-light-absorbing chromophores into sensitizers for photoredox reactions
Gu, Jing,Chen, Jin,Schmehl, Russell H.
, p. 7338 - 7346 (2010)
This work discusses the synthesis, photophysical behavior, and photoinduced electron-transfer reactivity of multichromophoric molecules having a visible-light-absorbing MLCT component coupled to a ligand with a localized excited state of the same spin multiplicity that serves to lengthen the excited-state lifetime of the complex significantly. The appropriate ligands were prepared by Wittig coupling of a bipyridine derivative with pyrenecarboxaldehyde. The modified ligand, a pyrene-vinyl-bipyridyl ensemble (pyrv-bpy), was then reacted with RuCl3 to yield [(pyrv-bpy) 2RuCl2]. The complex has MLCT absorption out to 800 nm, and excitation results in the formation of a ligand-localized excited state with a lifetime long enough to undergo bimolecular electron-transfer reactions. The pyrenylvinyl "localized" excited state of the complex reacts via photoinduced electron transfer with a variety of viologen and diquat electron acceptors. The remarkable aspect of the electron-transfer process is that whereas the excited state can be considered to be ligand-localized the photoredox reaction almost certainly involves the direct formation of the one-electron-oxidized metal center.
Mechanochemical Release of Non-Covalently Bound Guests from a Polymer-Decorated Supramolecular Cage
G?stl, Robert,Küng, Robin,Pausch, Tobias,Rasch, Dustin,Schmidt, Bernd M.
supporting information, p. 13626 - 13630 (2021/05/10)
Supramolecular coordination cages show a wide range of useful properties including, but not limited to, complex molecular machine-like operations, confined space catalysis, and rich host–guest chemistries. Here we report the uptake and release of non-covalently encapsulated, pharmaceutically-active cargo from an octahedral Pd cage bearing polymer chains on each vertex. Six poly(ethylene glycol)-decorated bipyridine ligands are used to assemble an octahedral PdII6(TPT)4 cage. The supramolecular container encapsulates progesterone and ibuprofen within its hydrophobic nanocavity and is activated by shear force produced by ultrasonication in aqueous solution entailing complete cargo release upon rupture, as shown by NMR and GPC analyses.
Light-Activated Electron Transfer and Turnover in Ru-Modified Aldehyde Deformylating Oxygenases
Bains, Rajneesh K.,Miller, Jessica J.,Van Der Roest, Hannah K.,Qu, Sheng,Lute, Brad,Warren, Jeffrey J.
supporting information, p. 8211 - 8217 (2018/07/25)
Conversion of biological molecules into fuels or other useful chemicals is an ongoing chemical challenge. One class of enzymes that has received attention for such applications is aldehyde deformylating oxygenase (ADO) enzymes. These enzymes convert aliphatic aldehydes to the alkanes and formate. In this work, we prepared and investigated ADO enzymes modified with RuII(tris-diimine) photosensitizers as a starting point for probing intramolecular electron transfer events. Three variants were prepared, with RuII-modification at the wild type (WT) residue C70, at the R62C site in one mutant ADO, and at both C62 and C70 in a second mutant ADO protein. The single-site modification of WT ADO at C70 using a cysteine-reactive label is an important observation and opens a way forward for new studies of electron flow, mechanism, and redox catalysis in ADO. These Ru-ADO constructs can perform the ADO catalytic cycle in the presence of light and a sacrificial reductant. In this work, the Ru photosensitizer serves as a tethered, artificial reductase that promotes turnover of aldehyde substrates with different carbon chain lengths. Peroxide side products were detected for shorter chain aldehydes, concomitant with less productive turnover. Analysis using semiclassical electron transfer theory supports proposals for hopping pathway for electron flow in WT ADO and in our new Ru-ADO proteins.
Optically Reconfigurable Monolayer of Azobenzene Donor Molecules on Oxide Surfaces
McElhinny, Kyle M.,Huang, Peishen,Joo, Yongho,Kanimozhi, Catherine,Lakkham, Arunee,Sakurai, Kenji,Evans, Paul G.,Gopalan, Padma
, p. 2157 - 2168 (2017/03/16)
The structural configuration of molecules assembled at organic-inorganic interfaces within electronic materials strongly influences the functional electronic and vibrational properties relevant to applications ranging from energy storage to photovoltaics.
Ion Pair-Directed Regiocontrol in Transition-Metal Catalysis: A Meta-Selective C-H Borylation of Aromatic Quaternary Ammonium Salts
Davis, Holly J.,Mihai, Madalina T.,Phipps, Robert J.
supporting information, p. 12759 - 12762 (2016/10/13)
The use of noncovalent interactions to direct transition-metal catalysis is a potentially powerful yet relatively underexplored strategy, with most investigations thus far focusing on using hydrogen bonds as the controlling element. We have developed an ion pair-directed approach to controlling regioselectivity in the iridium-catalyzed borylation of two classes of aromatic quaternary ammonium salts, leading to versatile meta-borylated products. By examining a range of substituted substrates, this provides complex, functionalized aromatic scaffolds amenable to rapid diversification and more broadly demonstrates the viability of ion-pairing for control of regiochemistry in transition-metal catalysis.
Artificial photosynthesis dendrimers integrating light-harvesting, electron delivery and hydrogen production
Xun, Zhiqing,Yu, Tianjun,Zeng, Yi,Chen, Jinping,Zhang, Xiaohui,Yang, Guoqiang,Li, Yi
supporting information, p. 12965 - 12971 (2015/06/25)
A series of artificial photosynthesis complexes, Gn-Ir-Hy (n = 1-4), were constructed by attaching iridium complexes and [Fe-Fe]-hydrogenase mimic to the periphery and core, respectively, of poly(aryl ether) dendrimers of different generations. The iridium complexes act as the light-harvesting antennae and the hydrogenase mimic core is the catalytic center. Light-harvesting, photoinduced electron-transfer, and hydrogen photochemical production were hierarchically realized within the dendritic photosynthesis mimics using triethylamine as the sacrificial electron donor. The catalytic activity is enhanced as the generation of dendritic catalysts increases, and the turnover number for generation 4 is nearly 4 times more than that of generation 1. The peripheral antennae not only harvest photons but also act as electronic energy reservoirs for the photochemical production, which facilitates the catalytic process together with the increased light-harvesting and protection effects of dendritic frameworks. Therefore, efficient artificial photosynthesis systems with complete light-harvesting and catalytic functions can be advanced with such rational design.
Squaraine-sensitized composite of a reduced graphene oxide/Tio2 photocatalyst π Stacking as a new method of dye anchoring
Joseph, K. L. Vincent,Lim, Jonghun,Anthonysamy,Kim, Hyoung-Il,Choi, Wonyong,Kim, Jin Kon
, p. 232 - 239 (2015/02/18)
We synthesized a near infra-red (NIR)-absorbing squaraine dye (VJ-S) showing strong absorption and emission maxima at 684 and 704 nm, respectively, with a high molar extinction coefficient (ε) of 1.277 × 105 M-1 cm-1 and a band gap of 1.77 eV. Its oxidation and reduction potentials were found to be 0.889 and -0.795 V, respectively, with HOMO and LUMO levels of -5.21 and -3.53 eV, respectively. We also prepared the self-assembled core/shell nanocomposite r-NGOT, where TiO2 is the core and reduced nano-sized graphene oxide (r-NGO) is the shell. When VJ-S was anchored on r-NGOT, it showed π-π stacking with r-NGO, which is confirmed by Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and electron energy loss spectroscopy. The optical absorption spectrum of the VJ-S/r-NGOT nanocomposite measured with diffuse reflectance UV/visible absorption spectroscopy covers the whole range of visible light wavelengths up to 800 nm. The photocatalytic activity of VJ-S/r-NGOT at visible light wavelengths (λ > 420 nm) is much higher than that of r-NGOT alone. This journal is
