- Graphite Conjugation Eliminates Redox Intermediates in Molecular Electrocatalysis
-
The efficient interconversion of electrical and chemical energy requires the intimate coupling of electrons and small-molecule substrates at catalyst active sites. In molecular electrocatalysis, the molecule acts as a redox mediator which typically undergoes oxidation or reduction in a separate step from substrate activation. These mediated pathways introduce a high-energy intermediate, cap the driving force for substrate activation at the reduction potential of the molecule, and impede access to high rates at low overpotentials. Here we show that electronically coupling a molecular hydrogen evolution catalyst to a graphitic electrode eliminates stepwise pathways and forces concerted electron transfer and proton binding. Electrochemical and X-ray absorption spectroscopy data establish that hydrogen evolution catalysis at the graphite-conjugated Rh molecule proceeds without first reducing the metal center. These results have broad implications for the molecular-level design of energy conversion catalysts.
- Jackson, Megan N.,Kaminsky, Corey J.,Oh, Seokjoon,Melville, Jonathan F.,Surendranath, Yogesh
-
-
Read Online
- Fe-N/C oxygen reduction catalysis prepared by covalent attachment of 1,10-phenanthroline to a carbon surface
-
Nonprecious metal catalysts (NPMC) for the oxygen reduction reaction were prepared by surface modification of a carbon black with 5,6-diamino-1,10- phenanthroline through diazonium and benzimidazole coupling chemistry. Both methodologies covalently attach 1,10-phenanthroline to the surface. Oxygen-free cyclic voltammograms (CV) obtained for these modified carbons showed a clearly defined redox peak at ca. 650 mV versus normal hydrogen electrode, which we attribute to phenanthroline-type groups on the carbon surface. Introduction of Fe and subsequent pyrolysis at 700°C under a N H3 / N2 atmosphere yielded catalysts that were highly active toward the oxygen reduction reaction. The redox peak at 650 mV was present in the oxygen-free CVs for the most active catalysts, though less intense. Nevertheless, this indicates the presence pyridinic-type active sites in the heat treated catalysts and may be a useful tool in the study of NPMC.
- Pauric, Allen D.,MacLean, Brian J.,Easton, E. Bradley
-
-
Read Online
- A rational synthesis of a novel imidazo[4,5-f][1,10]phenanthroline templated Schiff base: Characterization, photoluminescence and DFT/TD-DFT study
-
A new imidazo[4,5-f][1,10]phenanthroline (imp) derivative imidazo-N5,N6-bis((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenyl)methylene)-1,10-phenanthroline-5,6-diamine (impap) was synthesized in five steps starting from bare phenanthroline (phen) precursors. The novel compound was fully characterized by 1H-NMR, IR, elemental analysis and electrospray ionization mass spectroscopy (ESI-MS) techniques. Solid state emission spectrum of impap showed two distinct strong emission maxima with large Stokes shifts. The ground state gas phase geometry of impap was predicted by DFT calculations. Excited state properties of the molecule were examined through TD-DFT calculations conducted at the optimized geometry. Responsible transitions for the strong fluorescence of impap were assigned to single component charge transfer transitions with large oscillator strengths based on the ground state calculated molecular orbital contributions.
- Karslio?lu,Demir,Yilmaz,G?rdük
-
-
Read Online
- Synthesis of new phenanthroline-based heteroditopic ligands - Highly efficient and selective fluorescence sensors for copper(II) ions
-
The heteroditopic phenanthroline derivatives 5,6-bis(2-pyridylcarboxamido)- 1,10-phenanthroline (H2L1) and 5,6-bis[(4-methoxy-2- pyridyl)carboxamido]-1,10-phenanthroline (H2L2) have been prepared and characterized, together with their luminescent ruthenium(II) complexes [Ru(bpy)2(H2L1,2)]-(PF 6)2 and [Ru(H2L1) 3](PF6)2 and the corresponding iron(II) complex [Fe(H2L1)3](PF6)2. In these complexes, the metal ion is coordinated by the bidentate phen site of H2L. The luminescence of the ruthenium complexes (λ ex = 450 nm, λemca. 620 nm) is completely quenched by Cu2+ ions in the micromolar concentration range and, to a lesser extent, by other metal ions. At pH 5, the response of the luminescent sensors is highly Cu2+-selective. Heterodinuclear complexes [Ru(bpy) 2(LM)](PF6)2, [Ru(LM)3](PF 6)2, and [Fe(LM)3](PF6)2 have been isolated for M = Cu2+, Ni2+, Co2+, and Pd2+. It is suggested that M is coordinated to the tetradentate N4 site of L by two deprotonated amide N atoms and two pyridyl groups. This coordination type is confirmed by the EPR spectrum of the compound [Ru II(bpy)2(L1CuII)](PF 6)2. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Comba, Peter,Kraemer, Roland,Mokhir, Andriy,Naing, Kyaw,Schatz, Erik
-
-
Read Online
- Synthesis of free and ruthenium coordinated 5,6-diamino-1,10- phenanthroline
-
A new preparative route to 5,6-diamino-1,10-phenanthroline is described which triples the isolated yields found in existing syntheses (67% vs. 22% from 1,10-phenanthroline) and utilizes mild reaction conditions. The method is general and can even be used on chiral metal complexes containing the appropriate starting material/ligand, 1,10-phenanthroline-5,6-dione, with retention of stereochemistry.
- Bodige, Swamy,MacDonnell, Frederick M.
-
-
Read Online
- Electron Storage Capability and Singlet Oxygen Productivity of a RuII Photosensitizer Containing a Fused Naphthaloylenebenzene Moiety at the 1,10-Phenanthroline Ligand
-
As a novel rylene type dye a diimine ligand with a fully rigid and extended π-system in its backbone was prepared by directly fusing a 1,10-phenanthroline building block with 1,8-naphthalimide. The corresponding heteroleptic ruthenium photosensitizer bearing one biipo and two tbbpy ligands was synthesized and extensively analyzed by a combination of NMR, single crystal X-ray diffraction, steady-state absorption and emission, time-resolved spectroscopy and different electrochemical measurements supported by time-dependent density functional theory calculations. The cyclic and differential pulse voltammograms revealed, that the naphthaloylenebenzene moiety enables an additional second reduction of the ligand. Moreover, this ligand possesses a very broad absorption in the visible region. In the RuII complex this causes an overlap of ligand-centered and metal-to-ligand charge transfer transitions. The emission of the complex is clearly redshifted compared to the ligand emission with very long-lived excited states lifetimes of 1.7 and 24.7 μs in oxygen-free acetonitrile solution. This behavior is accompanied by a surprisingly high oxygen sensitivity. Finally, this photosensitizer was successfully applied for the effective evolution of singlet oxygen challenging some of the common RuII prototype complexes.
- Yang, Yingya,Brückmann, Jannik,Frey, Wolfgang,Rau, Sven,Karnahl, Michael,Tschierlei, Stefanie
-
-
Read Online
- Broadly versus Barely Variable Complex Chromophores of Planar Nickel(II) from κ3- N, N′, C and κ3- N, N′, O Donor Platforms
-
This work reports on complex chromophores of planar nickel(II) of the general formula [(κ3-N,N′,C/O)Ni-ER], which combines a κ2-N,N′-coordinate aromatic N-heterocycle with a pendant phenyl/phenol donor and the variable coligands ER (= carboxylato, phenolato, amido, and arylthiolato). The absorption properties of the planar complex chromophores vary broadly depending on the interplay of the three constituting components. Increasing the manifold of π?-orbitals at the N-heterocyclic moiety through π-extension along 1,10-phenanthroline, tetrahydrodipyridophenazine, and dipyridophenazine has only a small impact on the energies of charge transfer type transitions across the visible (vis) to near-infrared (NIR) spectral region and is due to an inversion among spatially distinct but energetically close unoccupied molecular orbitals. Substantial absorptivity across the visible spectral region rather associates with the increasing capability among carboxylato, phenolato, amido, and arylthiolato coligands to engage in Ni-O/N/S π-bonding. This adds a mechanism for electronic coupling of coligand RE- and π?-orbitals at the N-heterocycle fragment through occupied d orbitals at nickel, enabling light-induced charge transfer. Aryl-S- performs best in this regard, but {Ni-O/N/S}-to-(N-heterocycle-π?) charge transfer efficacy depends on donor-acceptor orbital alignment and appears to be kinetically hindered except for amido coligands owing to polar effects. Irrespective of the nature of coligand RE-, the choice of the pendant phenyl/phenol side arm rules overall absorptivity by setting the energy of occupied frontier molecular orbitals.
- Alrefai, Riyadh,H?rner, Gerald,Schubert, Hartmut,Berkefeld, Andreas
-
-
Read Online
- [1,2,5]Thiadiazolo[3,4-f][1,10]phenanthroline as a building block for organic materials
-
[1,2,5]Thiadiazolo[3,4-f][1,10]phenanthroline was prepared using a straightforward and efficient methodology, in four steps, starting from phenanthroline. This compound was fully characterized by mass spectrometry, IR, UV, 1H and 13C NMR spectroscopy, and its structure was determined by X-ray crystallography. Georg Thieme Verlag Stuttgart.
- Conte, Gilmar,Bortoluzzi, Adailton J.,Gallardo, Hugo
-
-
Read Online
- Combining a Phenanthroline Moiety with Two Peralkylated Guanidine Residues: Janus Head Pro-Ligands
-
A novel family of Janus head pro-ligands is described that combine a phenanthroline moiety with two peralkylated guanidine residues. The bis-bidentate molecules provide coordination sites with metal-differentiating properties and thus are especially well suited to form heterobinuclear complexes. Synthesized members of this family differ in their substitution patterns and comprise variants with tetramethyl-, tetraethyl-, dipentylene-, dimethylethylene-, and dimethylpropylene-guanidino functionalities. They were characterized by low-temperature X-ray crystallography and studied by means of temperature-dependent 1H NMR spectroscopy, which provided information on the dynamics of their guanidine moieties. Furthermore, the redox behavior was investigated by using cyclic voltammetric techniques.
- Ortmeyer, Jochen,Vukadinovic, Yannik,Neuba, Adam,Egold, Hans,Fl?rke, Ulrich,Henkel, Gerald
-
-
Read Online
- Strong Electronic Coupling of Molecular Sites to Graphitic Electrodes via Pyrazine Conjugation
-
Glassy carbon electrodes were functionalized with redox-active moieties by condensation of o-phenylenediamine derivatives with o-quinone sites native to graphitic carbon surfaces. Electrochemical and spectroscopic investigations establish that these graphite-conjugated catalysts (GCCs) exhibit strong electronic coupling to the electrode, leading to electron transfer (ET) behavior that diverges fundamentally from that of solution-phase or surface-tethered analogues. We find that (1) ET is not observed between the electrode and a redox-active GCC moiety regardless of applied potential. (2) ET is observed at GCCs only if the interfacial reaction is ion-coupled. (3) Even when ET is observed, the oxidation state of a transition metal GCC site remains unchanged. From these observations, we construct a mechanistic model for GCC sites in which ET behavior is identical to that of catalytically active metal surfaces rather than to that of molecules in solution. These results suggest that GCCs provide a versatile platform for bridging molecular and heterogeneous electrocatalysis.
- Jackson, Megan N.,Oh, Seokjoon,Kaminsky, Corey J.,Chu, Sterling B.,Zhang, Guanghui,Miller, Jeffrey T.,Surendranath, Yogesh
-
-
Read Online
- New rhenium(I) complex with thiadiazole-annelated 1,10-phenanthroline for highly efficient phosphorescent OLEDs
-
A new neutral tricarbonyl rhenium(I) complex (Re-TDAP) was designed and synthesized by annelating a thiadiazole unit on the frame of 1,10-phenanthroline ligand. The optoelectronic properties of Re-TDAP were fully investigated. Compared to the 589 nm peak emission of a prototype Re-PHEN (PHEN = 1,10-phenanthroline) in CH2Cl2 solution, annelating thiadiazole group caused the peak emission of Re-TDAP to red-shift to 621 nm. The phosphorescent organic light-emitting diodes using Re-TDAP as dopant were fabricated with the structure of ITO/m-MTDATA (10 nm)/NPB (20 nm)/CBP: x wt% Re-TDAP nm)/TPBi (30 nm)/Alq3 (20 nm)/Liq (2 nm)/Al. The devices showed high performances with maximum efficiencies of 16.8 cd/A, 5.8 lm/W and 5.0%, which was better than that of a prototype Re-PHEN-doped device under the same conditions. These results suggest that rational molecular design is very beneficial to color tunability and photophysical regulation of the complex.
- Hu, Yong-Xu,Zhao, Guang-Wei,Dong, Yan,Lü, Yan-Li,Li, Xiao,Zhang, Dong-Yu
-
-
Read Online
- Binding of Fe(ii)-complex of phenanthroline appended glycoconjugate with DNA, plasmid and an agglutinin protein
-
The phenanthroline appended glycoconjugate (L) and its Fe(ii)-complex were synthesized and characterized using analytical and spectral methods. The complexation of Fe2+ with L has been shown using absorption and fluorescence spectral studies. 1H NMR titration of L with Fe2+ supports that the phenanthroline moiety acts as the metal binding core. The interaction and binding of the Fe-complex with calf thymus DNA (ct-DNA) were studied using spectral techniques, such as UV-Vis absorption, circular dichroism (CD) and DNA melting temperatures. The corresponding data supported the minor groove binding of ct-DNA by the Fe-complex along with electrostatic interactions. The gel electrophoresis studies carried out using pBR322 plasmid showed a tight binding of the iron complex with the plasmid and this resulted in the condensation of the pBR322 plasmid as revealed by the blob-like structures observed in the atomic force microscopy data. The binding of the Fe-complex by WGA was demonstrated by absorption, fluorescence and CD spectra, and the microstructures were observed via scanning electron microscopy (SEM). Star-like nanostructures observed via SEM support that the octahedral iron complex connects the protein molecules in three dimensions through their carbohydrate terminal moieties. Thus, a new Fe-complex possessing a biocompatible glucosyl moiety interacts and binds to biomolecules, such as DNA and protein, and the resulting species are of importance in biological applications.
- Dinda, Subrata Kumar,Polepalli, Sirilata,Rao, Chebrolu Pulla
-
p. 11727 - 11738
(2020/07/27)
-
- Flexible RuII Schiff Base Complexes: G-Quadruplex DNA Binding and Photo-Induced Cancer Cell Death
-
A series of new RuII Schiff base complexes built on the salphen moiety has been prepared. This includes four flexible monometallic RuII compounds and six rigid bimetallic analogues that contain NiII, PdII or PtII cations into the salphen complexation site. Steady state luminescence titrations illustrated the capacity of the compounds to photoprobe G-quadruplex (G4) DNA. Moreover, the vast array of the Schiff base structural changes allowed to extensively assess the influence of the ligand surface, flexibility and charge on the interaction of the compounds with G4 DNA. This was achieved thanks to circular dichroism melting assays and bio-layer interferometry studies that pointed up high affinities along with good selectivities of RuII Schiff base complexes for G4 DNA. In cellulo studies were carried out with the most promising compounds. Cellular uptake with location of the compounds in the nucleus as well as in the nucleolus was observed. Cell viability experiments were performed with U2OS osteosarcoma cells in the dark and under light irradiation which allowed the measurements of IC50 values and photoindexes. They showed the substantial role played by light irradiation in the activity of the drugs in addition to the low cytotoxicity of the molecules in the dark. Altogether, the reported results emphasize the promising properties of RuII Schiff base complexes as a new class of candidates for developing potential G4 DNA targeting diagnostic or therapeutic compounds.
- Gillard, Martin,Weynand, Justin,Bonnet, Hugues,Loiseau, Frédérique,Decottignies, Anabelle,Dejeu, Jér?me,Defrancq, Eric,Elias, Benjamin
-
p. 13849 - 13860
(2020/10/02)
-
- MOLECULARLY TUNABLE HETEROGENEOUS CATALYSTS BY EDGE FUNCTIONALIZATION OF GRAPHITIC CARBONS
-
Disclosed are surface immobilized (electro)catalysts that may be prepared by a condensation reaction that generates an aromatic unit that is robust to acid and base and elevated temperatures. Among their many desirable characteristics, the catalysts are far less prone to the bimolecular deactivation pathways commonly observed for homogeneous catalysts, and may be used in solvents with a range of polarities and dielectric strengths. The catalysts are suitable for a wide array of thermal catalytic reactions (polymerization, oxidation, hydrogenation, cross- coupling etc. ) and as anodes and or cathodes in fuel cells, electrolyzers, and in batteries and supercapacitors.
- -
-
Page/Page column 88
(2017/03/21)
-
- Preparation method and antineoplastic activity of novel Ru(II) complex containing 4-nitrobenzene
-
The invention provides a novel Ru(II) complex containing 2,3-bis(4-nitrophenyl)pyrazine[2,3-f][1,10] phenanthroline with antineoplastic activity and a preparation method thereof. The preparation method is characterized by comprising the following steps that 1, 1,10-o-phenanthroline and potassium bromide react to synthesize an intermediate product 1 according to the mole ratio of 1:2; 2, the intermediate product 1, hydroxylamine hydrochloride and sodium carbonate are synthesized into an intermediate product 2 according to the mole ratio of 1:3.5:1.5; 3, the intermediate product 2 and sodium dithionite are synthesized into an intermediate product 3 according to the mole ratio of 1:5; 4, the intermediate product 3 and 4'4-dinitrobenzil are synthesized into an intermediate product 4 according to the mole ratio of 1:1; 5, the intermediate product 4 and cis-bis-(2,2'-bipyridine)dichlororuthenium(II) dihydrate are synthesized into the Ru(II) complex according to the mole ratio of 1:1.3. The Ru(II) complex has planar aromatic heterocycle and has quite high DNA affinity, nitryl has the strong electrophilic effect, and the combining capacity of the complex and DNA is enhanced.
- -
-
-
- Two structurally analogous ruthenium complexes as naked-eye and reversible molecular "light switch" for G-quadruplex DNA
-
A pair of symmetrical furyl based ruthenium(II) complexes ([Ru(phen) 2dpq-df]2 + (1) and [Ru(bpy)2dpq-df] 2 + (2) (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine, dpq-df = dipyrido (3,2-a:2′,3′-c) quinoxaline-difuran) have been prepared and characterized. The binding properties of both complexes toward G-quadruplex DNA have been investigated by fluorescence spectroscopy, UV-Vis spectroscopy, circular dichroism (CD), fluorescence resonance energy transfer (FRET) melting assays and molecular docking studies. The experimental results indicated that both Ru-complexes exhibited a remarkable "light switch" effect in the presence of hybrid G-quadruplex DNA. Interestingly, the "light switch" can be repeated off and on through the successive addition of Cu2 + ions and EDTA, and all these behaviors can be observed even by the naked eyes. Moreover, FRET melting assay revealed that both complexes could be potential stabilizers for G-quadruplex architectures. The computational studies not only confirmed that the two complex molecules bound to one G-quadruplex DNA molecule, but also explained the "light switch" effect.
- Lu, Xiao-Hui,Shi, Shuo,Yao, Jun-Liang,Gao, Xing,Huang, Hai-Liang,Yao, Tian-Ming
-
-
- Tuning of photocatalytic activity by creating a tridentate coordination sphere for palladium
-
The synthesis and characterisation of an asymmetric potential bridging ligand bmptpphz (bmptpphz = 2,17-bis(4-methoxyphenyl)tetrapyrido[3,2-a:2′, 3′-c:3′′,2′′-h:2′′′, 3′′′-j] phenazine) is presented. This ligand contains a 1,10-phenanthroline (phen) and a 2,9-disubstituted phen sphere and possesses a strong absorbance in the visible. Facile coordination of the phen sphere to a Ru(tbbpy)2 core leads to Ru(bmptpphz) ([(tbbpy) 2Ru(bmptpphz)](PF6)2; tbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine). UV-vis, emission, resonance Raman and theoretical investigations show that this complex possesses all properties associated with a Ru(tpphz) ([(tbbpy)2Ru(tpphz)](PF 6)2; tpphz = tetrapyrido[3,2-a:2′,3′-c: 3′′,2′′-h:2′′′,3′′′- j] phenazine) moiety and that the ligand based absorbances in the vis-part also populate an MLCT like state. The coordination of a Pd-core in the new 2,9-disubstituted phen sphere is possible, leading to a cyclometallation. The tridentate complexation leads to changes in the UV-vis and emission behaviour. Furthermore, the stability of the Pd-coordination is significantly enhanced if compared to the unsubstituted Ru(tpphz). Ru(bmptpphz)PdCl proved to be an active photocatalyst for H2 evolution, albeit with lower activity than the mother compound Ru(tpphz)PdCl2. This journal is the Partner Organisations 2014.
- Pfeffer,Zedler,Kupfer,Paul,Schwalbe,Peuntinger,Guldi,Guthmuller,Popp,Graefe,Dietzek,Rau
-
p. 11676 - 11686
(2014/07/22)
-
- Chiral ruthenium(ii) complexes with phenolic hydroxyl groups as dual poisons of topoisomerases i and IIα
-
A series of novel chiral ruthenium(ii) complexes with phenolic hydroxyl groups were synthesized and characterized. These ruthenium(ii) complexes exhibited strong dual inhibition of topoisomerases I and IIα, with approximate IC50 values of 3-15 mM, which were more efficient than the widely clinically used single TopoI poison camptothecin (CPT) or TopoIIα poison etoposide (VP-16). Δ-1 and Λ-1 with more hydroxyls were observed to be more potent inhibitors. To further evaluate the mechanism of the complexes at a cellular level, these complexes were investigated for their effect on cell proliferation, cell cycle progression and induction of apoptosis. The results indicated that ruthenium(ii) complexes permeated the nuclei in cancer cells and inhibited the activities of nuclear enzymes topoisomerases I and IIα, then triggered DNA damage and induced apoptosis in the cancer cells. The simultaneous inhibition of TopoI and TopoIIα induced the death of cancer cells, which may be a promising and effective strategy for cancer therapy.
- Zhang, Pingyu,Wang, Jinquan,Huang, Huaiyi,Qiao, Liping,Ji, Liangnian,Chao, Hui
-
p. 8907 - 8917
(2013/07/27)
-
- DNA binding and cleavage properties of a newly synthesised Ru(II)-polypyridyl complex
-
The single crystal X-ray structure of the newly synthesized ruthenium (II)-polypyridyl complex, [(bpy)2Ru(L)](PF6)2 (1) (bpy is 2,2′-bipyridyl and L is 2-methyl-2H-1,3,7,8-tetraaza- cyclopenta[l]phenanthren-2-ol revealed a near planar conformation for the fused imidazole moiety, suggesting the complex may be capable of binding to duplex DNA. Binding-induced changes in spectral properties, along with thermal denaturation and viscosity measurement studies confirmed that the complex binds to CT-DNA with a moderately high binding constant value (4.1 × 10 5 M-1) through intercalation. Photocleavage studies with the pBR322 plasmid DNA were performed following excitation of this complex into the Ru(dπ) → bpy/L(π*)-based MLCT band and have shown that this complex cleaves the circular pBR322 DNA into linear DNA. Inhibitor studies revealed that the hydroxyl radicals were mainly responsible for the DNA photocleavage reaction. Preliminary studies indicate that the -OH functionality in 1 was also found to hydrolyse the phosphodiester linkage of pBR322 in the dark.
- Ghosh, Amrita,Mandoli, Amit,Kumar, D. Krishna,Yadav, Narendra Singh,Ghosh, Tamal,Jha, Bhavanath,Thomas, Jim A.,Das, Amitava
-
experimental part
p. 9312 - 9321
(2010/02/15)
-
- Synthesis of amino- and bis(bromomethyl)-substitued bi- and tetradentate N-heteroaromatic ligands: Building blocks for pyrazino-functionalized fullerene dyads
-
In this paper we describe the synthesis of amino- and bis(bromomethyl)- substituted derivatives of phenanthrofine (phen), pyrazino[2,3-f]-phenanthroline (pphen), dipyrido[3,2-a:2′,3′-c]phenazine (dppz), pyrazino[2,3-i]dipyrido[3,2-a:2′,3′-c]phenazine, 2,3-bis(2-pyridyl)pyrazine (dpp), 2,3-bis(2-pyridyl)quinoxaline (dpq) and 7,8-bis(2-pyridyl)pyrazino[2,3-g]quinoxaline. These substituted bi- and tetradentate N-heteroaromatic ligands are potential synthons for the preparation of the fullerene ligands 4-9. The diketones, 1,10-phenanthroline-5,6-dione 11a (phendione), 2,2-pyridyl 11b and 1,4-dibromo-2,3-butanedione 33 were used as starting materials. Phendione was converted into the phendiamine 13 by a two-step synthesis via the dioxime of the diketone 11a. Amino-substituted dppz and dpq derivatives were obtained by the reduction of the corresponding nitro compounds that were obtained by the Schiff base condensation of the diketones 11a and 11b and the appropriate o-phenylenediamine derivatives. An alternative synthetic route to the diamines 20a and 20b by detosylation of the diamino-substituted dppz and dpq ligands is also presented. Synthesis of the bis(bromomethyl)-substituted pphen, dpp, dppz and dpq derivatives was performed by the photochemical addition of bromine. Alternatively, synthesis of the bis(bromomethyl)-substituted pphen, pdppz and pdpq is also possible by the condensation of 1,4-dibromo-2,3-butanedione 33 and phendiamine or the diamino-substituted dppz and dpq derivatives. The latter two compounds can be also prepared by the condensation of diketones 11a and 11b with 6,7-diamino-2,3-bis(bromomethyl)-quinoxaline. Although the synthesis of some dppz and dpq ligands is already published, we herein present improved or alternative synthetic strategies leading to higher yields and/ or higher purity of these N-heteroaromatic ligands. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Kleineweischede, Andreas,Mattay, Jochen
-
p. 947 - 957
(2007/10/03)
-
- Low quantum yields of relaxed electron transfer products of moderately coupled ruthenium(II)-cobalt(III) compounds on the subpicosecond laser excitation
-
Photoinduced electron-transfer reactions of [(tpy)RuII(tpy-tpy) CoIII(tpy)]5+ (tpy = 2,2′:6′,2″-terpyridine and tpy-tpy = 6′,6″-bis(2-pyridyl)-2,2′:4′,4″: 2″,2″′-quarterpyridyne), [(tpy)RuII(tpy-ph-tpy) CoIII(tpy)]5+ (tpy-ptitpy = 1,4-bis[2,2′:6′,2″- terpyridine-4′-yl]benzene), and [(bpy)2RuII(tpphz) CoIII(bpy)2]5+ (bpy = 2,2′-bipyridine, and tpphz = tetrapyrido[3,2-a:2′,3′-c:3″,2″-h:: 2″′,3″′-j]phenazine) were studied in the range 140-298 K by means of subpicosecond transient absorption spectroscopy. 3MLCT(Ru) of [(tpy)RuII(L-L)CoIII(tpy)] 5+ (L-L: tpy-tpy and tpy-ph-tpy) underwent intramolecular electron-transfer (EET) reaction to form [2RuIII(tpy)(L-L) 2CoII(tpy)]5+ in a shorter time than 10 ps. Low quantum yields of the EET products (0.53 for tpy-tpy and 0.41 for tpy-ph-tpy in butyronitrile at 298 K) measured before the fast return electron-transfer were found as in the intermolecular electron-transfer quenching of 3MLCT(Ru) by [Co(tpy)2]3+. The quantum yield of [(tpy)-RuIII(tpy-tpy)CoII(tpy)]5+ (Φ) decreases to 0.38 in a slowly reorganizing solvent of propylene carbonate and that of [(tpy)RuII(tpy-ph-tpy)CoIII(tpy)]5+ to 0.21 at 180 K. The reductions in the EET yields, 1 - Φ, can be ascribed to a fast transition of the nonrelaxed EET product to the lowest triplet d-d* state of [CoIII(tpy)2] moiety during the solvent reorganization. A tunneling transition of the nonrelaxed EET products to the lowest lying d-d excited-state of [CoIII(tpy)2] moiety takes place as a hole transfer, HT, from the dπ-orbital of Ru(III) to that of Co(II) with a configuration of dπ6da*. An electronic coupling of dπ(Ru)-dπ(Co) estimated from the intensity of inter-valence transition of [(tpy)RuIII(L-L)RuII(tpy)]5+ (Collin, J.-P.; Laine, P.; Launay, J.-P.; Sauvage, J.-P.; Sour, A. J. Chem. Soc., Chem. Commun. 1993, 434) is large enough to carry out the HT. The weak coupling of dπ(Ru)-dπ(Co) in the case of [(bpy)2Ru(tpphz) Co(bpy)2]5+ attenuates the HT rate to bring about a high yield of EET (0.8). The possibility that energy-transfer of 3MLCT(Ru) to the Co(III) moiety via an intermediate super-exchange coupling between dπ(Ru) and dπ(Co) occurs in competition with the EET of [(tpy)Ru III(tpy-ph-tpy)CoII(tpy)]5+ is also pursued.
- Torieda, Hiroaki,Nozaki, Koichi,Yoshimura, Akio,Ohno, Takeshi
-
p. 4819 - 4829
(2007/10/03)
-
- Synthesis of novel substituted 1,10-phenanthrolines
-
The synthesis of both 5-amino-6-nitro-1,10-phenanthroline and 5,6-diamino-1,10-phenanthroline (starting from 5-nitro-1,10-phenanthroline) are described in detail.
- Camren, Heather,Chang, Mei-Yueh,Zeng, Liansheng,McGuire, Mark E.
-
p. 1247 - 1252
(2007/10/03)
-
- Stepwise Syntheses of Mono- and Di-nuclear Ruthenium tpphz Complexes 2- and 4+ phenazine>
-
The complex 2+ (tpphz = tetrapyridophenazine), is obtained by reaction of 2+ with 5,6-diamino-1,10-phenanthroline; upon reaction with 2+, the fully conjugated dimer 4+ is obtained.
- Bolger, Joseph,Gourdon, Andre,Ishow, Elena,Launay, Jean-Pierre
-
p. 1799 - 1800
(2007/10/02)
-
