- Unusual Photooxidation of S-Bonded Mercaptopyridine in a Mixed Ligand Ruthenium(II) Complex with Terpyridine and Bipyridine Ligands
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An unusual photooxidation of a coordinated 4-mercaptopyridine (SpyH) ligand in the [Ru(Hmctpy)(dmbpy)(κS-SpyH)]2+complex (Hmctpy = 4′-carboxy-2,2′6′,2″-terpyridine, dmbpy = 4,4′-dimethyl-2,2′-bipyridine) takes place under visible and UV irradiation, in aerated acetonitrile. The [Ru(mctpy)(dmbpy)(κS-SO2py)] sulfinato product has been characterized by a variety of methods, including X-ray diffraction which supports the presence of the Ru-κS-SpyH isomer in the starting complex. The photooxidation of the 4-mercaptopyridine ligand enhances the back-bonding interactions in the complex by means of the strongly acceptor 4-pyridinesulfinato-SO2py species, increasing the redox potential of the Ru(III)/Ru(II) couple significantly from 1.23 to 1.62 V. It also led to pronounced changes in the electronic and NMR spectra of the complexes, corroborated by DFT and ZINDO-S calculations. A possible mechanism based on referenced data of photooxidation has been proposed, which involves the formation of a reactive oxygen species and intermediate endoperoxide species, yielding a very stable Ru-sulfinato product. This novel species exhibits stronger luminescence (Φf = 0.004) than the starting complex under UV excitation.
- Da Silva, Maria Rosana E.,Auvray, Thomas,Laramée-Milette, Baptiste,Franco, Maurício P.,Braga, Ataualpa A. C.,Toma, Henrique E.,Hanan, Garry S.
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- Functionalization of Ruthenium(II) Terpyridine Complexes with Cyclic RGD Peptides To Target Integrin Receptors in Cancer Cells
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The lack of selectivity for cancer cells and the resulting negative impact on healthy tissue is a severe drawback of actual cancer chemotherapy. Tethering of cytotoxic drugs to targeting vectors such as peptides, which recognize receptors overexpressed on the surface of tumor cells, is one possible strategy to overcome such a problem. The pentapeptide cyc(RGDfK) targets the integrin receptor αvβ3, important for tumor growth and metastasis formation. In this work, two terpyridine-based RuII complexes were prepared and for the first time conjugated to cyc(RGDfK) through amide bond formation, which resulted in a monomeric and a dimeric bioconjugate. Both RuII complexes were found to bind strongly and selectively to integrin αvβ3, and the dimeric molecule displayed a 20-fold higher affinity to the receptor than the monomeric one. However, the cytotoxicity of the complexes and related bioconjugates against human A549 and SKOV-3 cell lines is still not sufficient for application as anticancer agents. Nevertheless, considering the high selectivity for integrin receptor αvβ3, the synthesis of Ru-based bioconjugates with cyc(RGDfK) paves a promising way towards the design of effective targeted anticancer agents.
- Hahn, Eva M.,Estrada-Ortiz, Natalia,Han, Jiaying,Ferreira, Vera F. C.,Kapp, Tobias G.,Correia, Jo?o D. G.,Casini, Angela,Kühn, Fritz E.
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- CO2-Induced Spin-State Switching at Room Temperature in a Monomeric Cobalt(II) Complex with the Porous Nature
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CO2-responsive spin-state conversion between high-spin (HS) and low-spin (LS) states at room temperature was achieved in a monomeric cobalt(II) complex. A neutral cobalt(II) complex, [CoII(COO-terpy)2]?4 H2O (1?4 H2O), stably formed cavities generated via π–π stacking motifs and hydrogen bond networks, resulting in the accommodation of four water molecules. Crystalline 1?4 H2O transformed to solvent-free 1 without loss of porosity by heating to 420 K. Compound 1 exhibited a selective CO2 adsorption via a gate-open type of the structural modification. Furthermore, the HS/LS transition temperature (T1/2) was able to be tuned by the CO2 pressure over a wide temperature range. Unlike 1 exhibits the HS state at 290 K, the CO2-accomodated form 1?CO2 (P (Formula presented.) =110 kPa) was stabilized in the LS state at 290 K, probably caused by a chemical pressure effect by CO2 accommodation, which provides reversible spin-state conversion by introducing/evacuating CO2 gas into/from 1.
- Hayami, Shinya,Kawaguchi, Shogo,Komatsumaru, Yuki,Kosaka, Wataru,Lindoy, Leonard F.,Miyasaka, Hitoshi,Nakamura, Masaaki,Nakaya, Manabu,Sugimoto, Kunihisa,Zhang, Yingjie
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- Chemistry of ternary monocarboxyterpyridine-bipyridine-trimercaptotriazine ruthenium complexes and application in dye sensitized solar cells
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The synthesis of the [RuII(Hmctpy)(H2O)(Cl2)], [RuII(Hmctpy)(dmbpy)Cl]Cl and [RuII(Hmctpy)(dmbpy)(H3tmt)](PF6)2 complexes (mctpy = monocarboxyterpyridine, dmbpy = dimethylbipyridine, tmt = trimercaptotriazine) was carried out based on a vectorial design for energy transfer in dye sensitized solar cells (DSSC). The [RuII(mctpy)(dmbpy)(Hxtmt)]n complexes were fully characterized and the electrochemical and absorption/emission properties corroborated their potentially as TiO2 photosensitizing agents. However, the observed current density and open circuit voltage were rather small, imparting a low efficiency for the assembled DSSCs. The results indicated a unexpected contribution of the charge recombination effects at the electrode surface. Such effects increased with the number of deprotonated groups in the tmt ligand as they interact with the nanocrystalline TiO2 surface, capturing electrons from the conduction band.
- Aguirre-Araque, Juan S.,Guimaraes, Robson R.,Toma, Henrique E.
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- Highly cytotoxic copper(II) terpyridine complexes as anticancer drug candidates
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Cancer is one of the deadliest diseases worldwide. Chemotherapy remains one of the frequently applied treatment modalities in the clinics. However, as the currently applied agents are associated with severe side effects, scientists are searching for novel chemotherapeutic drugs. Within the last decades, Cu(II) polypyridine complexes have received increasing attention as potential anticancer drug candidates. Herein, the biological activity of terminally functionalised mono- and bis-coordinated Cu(II)-2,2′:6′,2″-terpyridine complexes have been investigated. The bis-coordinated compounds were found to have a cytotoxic effect in the nanomolar range in human adenocarcinomic alveolar basal epithelial cells. Promisingly, the complexes were equally active in the corresponding cisplatin resistant cell line, indicating that they could potentially be useful for the treatment of drug resistant tumours.
- Karges, Johannes,Xiong, Kai,Blacque, Olivier,Chao, Hui,Gasser, Gilles
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supporting information
(2020/11/26)
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- Cobalt bis(2-ethylhexanoate) and terpyridine derivatives as catalysts for the hydrosilylation of olefins
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A simple method for the hydrosilylation of olefins by using air-stable cobalt catalysts is developed. The catalyst system is composed of simple, cheap, and readily available cobalt(II) salts and well-defined terpyridine derivatives as cocatalysts or ligands, and the hydrosilylation processes can be processed smoothly under mild conditions without either Grignard reagents or NaHBEt3 as activator.
- Dai, Zinan,Yu, Zehao,Bai, Ying,Li, Jiayun,Peng, Jiajian
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- Effect of push-pull ruthenium complex adsorption conformation on the performance of dye sensitized solar cells
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A new series of tris-(bipyridyl)ruthenium-like complexes based on the 4-tripheylamine-2,2':6',2''-terpyridine (TPA) push-pull ligand was prepared by incorporation of 4-carboxypyridine (cpy), 4,4'-dicarboxi-2,2'-bipyridine (dcbpy) and 4-carboxyterpyridine ligands (ctpy) ligands, in order to adsorb them on TiO2 in different anchoring conformations. The electron photoinjection and electron recombination processes of the respective dye-sensitized solar cells were greatly influenced by the molecular structure, which defined the surface concentration and surface charge on TiO2, such that the photoconversion efficiency was 10 times larger for [Ru(py)(dcbpy) (TPAtpy)] than for the [Ru(cpy)(bpy)(TPAtpy)](PF6) dye. Molecules anchoring in a more upright position and by a larger number of sites were shown to enhance the electron injection into TiO2 conduction band (CB) improving the short-circuit current (JSC), open circuit voltage (Voc) and the overall photoconversion efficiency. However, a positive net charge in the dye increased the back electron-transfer reactions and induced a decrease in both Voc and conversion efficiency.
- Araki, Koiti,Guimaraes, Robson R.,Matias, Tiago A.,Rosero, Wilmmer A. A.
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p. 2250 - 2264
(2020/10/13)
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- Covalent hybrids based on Re(i) tricarbonyl complexes and polypyridine-functionalized polyoxometalate: Synthesis, characterization and electronic properties
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A series of [Re(CO)3Br(N^N)] (N^N = substituted 2,2′-bipyridine ligand) complexes based on polypyridine-functionalized Dawson polyoxometalate (1-3) has been synthesized. The new hybrids (4-6) were characterized by various analytical techniques, including absorption, vibrational and luminescence spectroscopies as well as electrochemistry. Both units, the polyoxometalate and the transition metal complex, retain their intrinsic properties. Their combination in the newly prepared hybrids results in improved photosensitization in the high-energy visible region. However, a complete quenching of the emission for the [Re(CO)3Br(N^N)] complexes is observed due to formation of a charge separated state, Re(ii)-POM-, as shown by quenching experiments as well as theoretical modelling via DFT.
- Auvray, Thomas,Santoni, Marie-Pierre,Hasenknopf, Bernold,Hanan, Garry S.
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p. 10029 - 10036
(2017/08/10)
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- Synthesis and characterization of novel cyclometalated iridium(III) complexes for nanocrystalline TiO2-based dye-sensitized solar cells
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Four novel cyclometalated iridium(III) complexes with the following general formulas were synthesized and characterized using 1H NMR, { 1H-1H} COSY, ESI-MS spectral and elemental analysis data: [Ir(C∧N∧C)(ptpy-COOH)]+ (C ∧N∧C = 2,6-diphenylpyridinato (1); 2,4,6-triphenylpyridinato (2), ptpy-COOH = 4′-(4-carboxyphenyl)-2, 2′:6′,2"-terpyridine) and [Ir(C∧N ∧C)(tpy-COOH)]+ (C∧N∧C = 2,6-diphenylpyridinato (3); 2,6-ditolylpyridinato (4), tpy-COOH = 4′-carboxy-2,2′:6′,2″-terpyridine). The photophysical and redox properties and photovoltaic performance of the Ir(III) complexes as photosensitizers in nanocrystalline TiO2-based solar cells were studied and compared to those of cis-diisothiocyanatobis(4,4′-dicarboxy-2, 2′-bipyridine)ruthenium(II) (N3). Dye 4 exhibits the highest photovoltaic performance with an overall solar energy conversion efficiency of 2.16%.
- Shinpuku, Yoshiki,Inui, Fumiaki,Nakai, Misaki,Nakabayashi, Yasuo
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experimental part
p. 203 - 209
(2012/06/30)
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- Self-assembly of supramolecular architectures and polymers by orthogonal metal complexation and hydrogen-bonding motifs
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A modular construction kit with two orthogonal noncovalent binding sites for self-assembly of supramolecular architectures is presented. The heteroditopic building blocks contain a terpyridine (tpy) unit for coordination of metal ions and a Hamilton receptor for multiple H-bonding of cyanuric acid derivatives. The association constants of ligand binding of MII complexes (M=Ru, Zn, Fe, and Pt) with a dendritic end cap were determined to be in the range of 102 and 104 L mol-1 in chloroform. The capabilities for binding of metal ions were investigated by 1H NMR and UV/Vis spectroscopy. The Fe complexes are most appropriate for the generation of discrete and high-ordered architectures due to their strong tendency to form FeL2 complexes. Superstructures are readily formed in a one-pot procedure at room temperature. No mutual interactions between the orthogonal binding motifs were observed, and this demonstrates the highly specific nature of each binding process. Decomplexation experiments were carried out to examine the reversibility of Fe-tpy coordination. Substitution of the terminal end cap with a homoditopic bis-cyanurate linkage leads to formation of an iron-containing supramolecular strand. Formation of coordination polymers was confirmed by viscosity measurements. The supramolecular polymer strands can be reversibly cleaved by addition of a terminating cyanuric acid building block, and this proves the dynamic nature of this noncovalent polymerization process. Copyright
- Grimm, Felix,Ulm, Nadine,Groehn, Franziska,Duering, Jasmin,Hirsch, Andreas
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experimental part
p. 9478 - 9488
(2011/10/09)
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- Carboxylate derivatives of oligopyridines
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The key compound ethyl 2,6-dibromopyridine-4-carboxylate was prepared in two steps starting from the commercially available citrazinic acid. By using the Stille coupling reaction ethyl 2,6- dibromopyridine-4-carboxylate was converted to 2,2'-bipyridines, 2,2':6',2''-terpyridines and 2,2':6',2'':6'',2''':6''',2''''- quinquepyridines which bear a carboxylate functional group directly attached to the central pyridine ring.
- Fallahpour, Reza-Ali
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p. 1138 - 1142
(2007/10/03)
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