- The comparative study of the DNA binding and biological activities of the quaternized dicnq as a dicationic form and its platinum(II) heteroleptic cationic complex
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The square-planar heteroleptic Pt(II) coordination compound [Pt(bpy)(dicnq)](NO3)2 (1) and the quaternized dicnq ligand, namely 12,13-dicyano-5,6-dihydrodipyrazino[2,3-f:1′,2′,3′,4′-lmn][1,10]phenanthroline-4,7-diium dibromide (2) (Fig. 1) were synthesized and fully characterized by means of FTIR, NMR, MALDI-TOF MS and the purity was confirmed by CHN analyses. The DNA binding profiles of 1 and 2 were identified in an identical condition. The biological activities of these compounds were investigated by the assays of transcription and replication inhibition, cytotoxic and antimicrobial activity. The result of this study indicates that, both compounds strongly bind to DNA via intercalation but only 1 has a strong nuclease activity. The coordination compound of dicnq (1) binds to the DNA only slightly stronger than the quaternized form of dicnq (2), and is more potent as an inhibitor of transcription and replication and therefore, 1 has more potential as an anticancer agent but the compounds did not show cytotoxic activity against MCF-7 and MDA-MB-231 breast cancer, and DLD-1 colon cancer cell lines it was found that they only had activities against HepG2 liver cancer cell line with following IC50 values; 94.75 and 159.60 μM for 1 and 2, respectively. In addition, tested bacteria are more susceptible to compound 1. These biological activities of 1 may strongly be due to its ability to digest DNA as a chemical nuclease. According to this study, the quaternization of the ligand does not make biologically more active than the coordination compound of the same ligand in this case. The compound (1) is worth further investigation for its antitumor activities.
- Y?ld?z, Ufuk,?engül, Abdurrahman,Kandemir, Irfan,C?mert, Füsun,Akko?, Senem,Coban, Burak
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- Ultrafast interfacial charge transfer from the LUMO+1 in ruthenium(II) polypyridyl quinoxaline-sensitized solar cells
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This paper describes the implementation of robust and modular sensitizers containing aromatic-amphiphilic ligands to provide new insights into the relationship between the molecular structure and electron injection process governing the efficiency of dye-sensitized solar cells (DSSCs). The significance of this work lies in the combination of favorable experimental and theoretical results in a new class of Ru(ii) polypyridyl complexes with the molecular formula of [Ru(E101)(Dicnq)x(Y)] which is named M101-M104 when X = 1 and Y = bpy, X = 1 and Y = phen, X = 2, and X = 1 and Y = 2 NCS, respectively. E101 and Dicnq ligands are 1,10-phenanthroline-5,6 heptan ammin and 6,7-dicyanodipyrido[2,2-d:2′,3′-f]quinoxaline, respectively. The good agreement between the experimental and the time-dependent density functional theory (TDDFT)-calculated absorption spectra of the M101-104 sensitizers allowed us to provide a detailed assignment of the main spectral features of the investigated dyes. M102 which contained phen as an ancillary ligand had the best photovoltaic performance which can be attributed to the higher light harvesting of M102 in the visible light region. A DSSC based on complex M102 without the E101 ligand did not show any observable power conversion efficiency (PCE), indicating the importance of the amphiphilic ligand, E101. Transient absorption studies indicated that the ratio of kreg/krec (krec = the rate constant of the recombination of the dye and kreg = the rate constant of regeneration in the presence of the electrolyte) for M101-104 is 1.1, 2.9, 1.3, and 1.2, clearly confirming a weak competition between dye regeneration and recombination. Therefore, because this ratio for M101, 103, and 104 is small, kreg ≈ krec, the operation of the device has been limited by back electron transports, subsequently enhancing the recombination process. However, the rate of recombination is relatively normal for an efficient DSSC, while the rate of regeneration is very low. Subsequently, the PCE will be poor, confirming the role of aliphatic chains in reducing the recombination process. To obtain a deeper insight into the charge transfer process in the investigated devices, ab initio DFT molecular dynamics simulations and quantum dynamics of electronic relaxation were carried out, clearly showing that the interfacial electron transfer (IET) time scale particularly depends on the type of ancillary ligand. The IET results substantially proved that M102 has the fast lifetime of 2.3 ps and 90 fs for the LUMO and LUMO+1, respectively, indicating the experimentally higher PCE of M102 compared to the other three investigated sensitizers.
- Shahroosvand, Hashem,Eskandari, Mortaza
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- Evaluation of the potential effectiveness of ruthenium(II) complexes with 2,3-disubtituted pyrazino[2,3-f][1,10]phenanthroline anchors, R2ppl (R = CN, COOH, COOEt, OH) as sensitizers for solar cells
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The ligands of type pyrazino[2,3-f][1,10]phenanthroline, R2ppl, with R = CN, COOH, COOEt or OH, were synthesized and used as precursors for obtaining the corresponding series of complexes of type [Ru(dmbpy) 2R2ppl](PF6)2, where dmbpy is 4,4′-dimethyl-2,2′-bipyridine. The compounds were prepared, characterized, and studied by theoretical DFT calculations in order to evaluate their potentiality as dyes in photoelectrochemical cells. The electron acceptor capacity of the R2ppl ligands was evaluated by analyzing parameters such as electrophilicity and charge distribution on the reduced ligand. Additionally, the R substituents on R2ppl were evaluated as anchoring groups, by variables such as highest spin occupied molecular orbital (HSOMO). Finally, the IT parameter was defined and calculated. This is related to the amount of energy that can be delivered to TiO2 from the acceptor anchoring ligand in the thexi state. According to this parameter, the [Ru(dmbpy)2(COOH)2ppl](PF6)2 complex is predicted to have the best response, among the compounds of the series, when used as dye in a solar cell.
- Francois, Angélica,Díaz, Ramiro,Ramírez, Angélica,Loeb, Bárbara,Barrera, Mauricio,Crivelli, Irma
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- Toward white electroluminescence by ruthenium quinoxaline light emitting diodes
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Ancillary ligand substitution in the new series [Ru(dicnq)(pyTz)(X)]+ {dicnq = 6,7-dicyanodipyrido[2,2-d:2′,3′-f]quinoxaline and X = 2,2-bipyridine (bpy), 1,10-phenanthroline (phen), 2-pyridine tetrazole (pyTz)} proves to be an effective way to create white electroluminescence with the Commission Internationale d'Eclairage Chromaticity Coordinates x = 0.40 and y = 0.39. These complexes were characterized by UV-visible and FT-IR spectroscopy, 1H-NMR, CHN and Mass spectroscopy analysis. The absorption and emission spectra are consistent with low-lying MLCT excited states, which are typical of Ru(ii) polypyridyl complexes. All the complexes exhibiting reversible metal-centered oxidation processes undergo a one-electron oxidation within the potential range +1.30 vs. SCE. Upon reduction, each compound undergoes several reversible or quasi reversible ligand-centered reduction processes (-1.65 V to -2.40 V). It was found that white light emission can be obtained from the device ITO/PEDOT:PSS/PVK/ruthenium complex/PBD/Al by combining Forster emission from Ru(dicnq) and Exciplex emission at the PVK/Ru(dicnq) interface, although the CIE chromaticity coordinates gradually change with applied voltages. The highest luminous efficiency and luminance and lowest turn-on voltage values are obtained from the 8 wt% Ru(dicnq)(pyTz)(bpy) doped device as 1.78 cd A-1 and 1030 cd m-2 at 16 V and 5.2 V, respectively. As an important result, the incorporation of pyTz as the ancillary ligand into [Ru(dicnq)] complexes was found to be the most beneficial ancillary substitution in terms of creating the white electroluminescence in ruthenium quinoxaline complexes.
- Shahroosvand, Hashem,Rezaei, Shiva,Mohajerani, Ezeddin,Mahmoudi, Malek
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- Spectroscopic and electrochemical properties of cyclopalladated complexes derived from 2,3-diphenylpyrazine
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A comparative study of complexes [Pd(dphpz)(N'N)]PF6 [dphpz - is the deprotonated form of 2,3-diphenylpyrazine; (N'N) is ethylenediamine (En), 2,2'-bipyridine (bpy), o-phenanthroline (phen), dipyrido[a,c]phenazine (dppz), 6,7-dicyanopyrido[f,h]quinoxaline (dicnq)] was made, using 1H NMR, electronic absorption, and emission spectroscopy, and also cyclic voltammetry. Steric interaction of the dphpz- phenyl rings leads to significant proton shielding in the carbanionic moiety of the cyclometallated ligand. Introduction of heterocyclic diimines instead of ethylenediamine decreases the desheilding of the dphpz- protons adjacent to the coordination center. Irrespective of the nature of the N'N ligands, the cyclopalladated complexes are characterized by specific parameters of photo-and electrostimulated electron transfer processes involving the Pd(dphpz) orbitals, namely, by the long-wave absorption band with λmax 395±6 nm and ε (2.2±1.2) × 103 1 mol-1 cm-1, the vibrationally structured low-temperature (77 K) luminescence resulting from the spinforbidden optical transfer from the excited to the ground state of the complex (energy E 00 19.27±0.07 kK, lifetime τ 160±30 μs), and the one-electron electroreduction wave with E 1-(2.0±0.1)V. For the [Pd(dphpz)?(N'N)]+ complexes containing diazine derivatives of phenanthroline (dppz, dicnq), the degradation of the photoexcitation energy from two electronically excited states can occur as isolated process with successive transfer of electrons to the π orbitals localized on the remote moieties: [Pd(dphpz)] and diazine fragments of the N'N ligands.
- Farus,Balashev
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p. 1410 - 1415
(2008/03/27)
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- Spectroscopic and electrochemical properties of dichlorodiimine complexes of Au(III) and Pt(II) with 1,4-diazine derivatives of o-phenanthroline
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A series of dichlorodiimine complexes [M(N∧N)Cl2] z of Au(III) and Pt(II) with 1,4-derivatives of o-phenanthroline [(N∧N) = o-phenanthroline (phen), dipyrido[f,h]quinoxaline (dpq), dipyrido[a,c]phenazine (dppz), 6,7-dicyanodipyrido[f,h]quinoxaline (dicnq)] were prepared and characterized by 1H NMR, electronic absorption, and emission spectroscopy and by cyclic voltammetry. In all the complexes, the 3(π-π*)-type transition is the spin-forbidden transition of the lowest energy, responsible for the luminescence. The longest wave bands in the absorption spectra of the Au(III) and Pd(II) complexes were assigned in accordance with the results of the electrochemical studies to the 1(d*)-and 1(d*)-type transitions, respectively. Pleiades Publishing, Inc., 2006.
- Ivanov,Puzyk,Balashev
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p. 843 - 848
(2008/02/02)
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- Hydrothermal syntheses of some derivatives of tetraazatriphenylene
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Some derivatives of tetraazatriphenylene can be synthesized readily by a hydrothermal synthetic method. Compared with the traditional technique, this method is effective and simple process, and much high yields of products with higher purity can be harvested. Copyright Taylor & Francis Group, LLC.
- Che, Guangbo,Li, Wenlian,Kong, Zhiguo,Su, Zisheng,Chu, Bei,Li, Bin,Zhang, Zhiqiang,Hu, Zhizhi,Chi, Haijun
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p. 2519 - 2524
(2007/10/03)
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- Luminescence modulation of a terbium complex with anions and its application as a reagent
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A terbium complex Tb(PMIP)3(PhCN), namely tris(1-phenyl-3- methyl-4-isobutyl-5-pyrazolone)-terbium-(pyrazino[2,3-f][1,10]phenanthroline-2, 3-dicarbonitrile), was synthesized as a reagent for anions. Compared with Tb(PMIP)3(H2/s
- Zhang, Dengqing,Shi, Mei,Liu, Zhiqiang,Li, Fuyou,Yi, Tao,Huang, Chunhui
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p. 2277 - 2284
(2007/10/03)
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- Tetraazatriphenylenes as extremely efficient antenna chromophores for luminescent lanthanide ions
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A series of tetraazatriphenylene derivatives is presented that constitutes a new and efficient class of sensitisers with significant complexing power for lanthanide ion. These tetraazatriphenylenes have the ability to sensitise the luminescence of different lanthanide ions simultaneously within a practically suitable exaltation window, and the 2:1 (ligand-ion) complexes are stable even at low concentrations in acetonitrile. The very high luminescence quantum yields obtained for both Eu3+ and Tb3+ (up to 0.41 and 0.67, respectively) in combination with the suitable excitation window and the appreciable molar extinction coefficient of tetraazatriphenylenes at λ>330 nm make these sensitisers very attractive for incorporation as antenna chromophores in luminescent lanthanide probes (e.g. for time-resolved fluorometry).
- Van der Tol, Erik B.,Van Ramesdonk, Hendrik J.,Verhoeven, Jan W.,Steemers, Frank J.,Kerver, Esther G.,Verboom, Willem,Reinhoudt, David N.
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p. 2315 - 2323
(2007/10/03)
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