- Photocytotoxic oxovanadium(IV) complexes of ferrocenyl-terpyridine and acetylacetonate derivatives
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Oxovanadium(IV) complexes [VO(Fc-tpy)(acac)](C104) (1), [VO(Fc-tpy)(nap-acac)](C104) (2), [VO(Fc-tpy)(py-acac)](C104) (3) and [VO(Ph-tpy)(py-acac)](C104) (4) of 4'-ferrocenyl-2,2':6',2"-terpyridine (Fc-tpy) and 4'-phenyl-2,2':6',2"-terpyridine (Ph-tpy) having monoanionic acetylacetonate (acac), naph-thylacetylacetonate (nap-acac) or pyre ny lace ty lace to nate (py-acac) ligand were prepared, characterized and their photocytotoxicity in visible light studied. The ferrocenyl complexes 1-3 showed an intense charge transfer band near 585 nm in DMFand displayed Fc'/Fc and V(1V)/V(111) redox couples near 0.66 V and -0.95 V vs. SCE in DMF-0.1 M TBAP. The complexes as avid binders to calf thymus DNA showed significant photocleavage of plasmid DNA in green light (568 nm) forming "OH radicals. The complexes that are photocytotoxic in HeLa and MCF-7 cancer cells in visible light (400 700 nm) with low dark toxicity remain nontoxic in normal fibroblast 3T3 cells. ICP-MS and fluorescence microscopic studies show significant cellular uptake of the complexes. Photo-irradiation of the complexes causes apoptotic cell death by ROS as evidenced from the DCFDA assay.
- Balaji, Babu,Balakrishnan, Babita,Perumalla, Sravanakumar,Karande, Anjali A.,Chakravarty, Akhil R.
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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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- Living Long and Prosperous: Productive Intraligand Charge-Transfer States from a Rhenium(I) Terpyridine Photosensitizer with Enhanced Light Absorption
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The ground- and excited-state properties of six rhenium(I) κ2N-tricarbonyl complexes with 4′-(4-substituted-phenyl)terpyridine ligands bearing substituents of different electron-donating abilities were evaluated. Significant modulation of the electrochemical potentials and a nearly 4-fold variation of the triplet metal-to-ligand charge-transfer (3MLCT) lifetimes were observed upon going from CN to OMe. With the more electron-donating NMe2group, we observed in the κ2N complex the appearance of a very strong absorption band, red-shifted by ca. 100 nm with respect to the other complexes. This was accompanied by a dramatic enhancement of the excited-state lifetime (380 vs 1.5 ns), and a character change from 3MLCT to intraligand charge transfer (3ILCT), despite the remote location of the substituent. The dynamics and character of the excited states of all complexes were assigned by combining transient IR spectroscopy, IR spectroelectrochemistry, and (time-dependent) density functional theory calculations. Selected complexes were evaluated as photosensitizers for hydrogen production, with the κ2N-NMe2complex resulting in a stable and efficient photocatalytic system reaching TONRevalues of over 2100, representing the first application of the 3ILCT state of a rhenium(I) carbonyl complex in a stable photocatalytic system.
- Fernández-Terán, Ricardo,Sévery, Laurent
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supporting information
p. 1334 - 1343
(2020/10/09)
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- Coordination Environment Prevents Access to Intraligand Charge-Transfer States through Remote Substitution in Rhenium(I) Terpyridinedicarbonyl Complexes
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Six rhenium(I) κ3N-dicarbonyl complexes with 4′-(4-substituted phenyl)terpyridine ligands were evaluated in their ground and excited states. These complexes, bearing substituents of different electron-donating strengths - from CN to NMe2 - were studied by a combination of transient IR (TRIR), electrochemistry, and IR spectroelectrochemistry, as well as time-dependent density functional theory (TD-DFT). They exhibit panchromatic absorption and can act as stronger photoreductants than their tricarbonyl counterparts. The ground- and excited-state potentials, absorption maxima, and lifetimes (250-750 ps) of these complexes correlate well with the Hammett σp substituent constants, showing the systematic effect of remote substitution in the ligand framework. TRIR spectroscopy allowed us to assign the lowest singlet and triplet excited states to a metal-to-ligand charge-transfer (MLCT) character. This result contrasts our previous report on analogous κ2N-tricarbonyl complexes, where remote substitution switched the character from MLCT to intraligand charge transfer. With the help of TD-DFT calculations, we dissect the geometric and electronic effects of coordination of the third pyridine, local symmetries, and increasing conjugation length. These results give valuable insights for the design of complexes with long-lived triplet excited states and enhanced absorption throughout the visible spectrum, while showcasing the boundaries of the excited-state switching strategy via remote substitution.
- Fernández-Terán, Ricardo J.,Sévery, Laurent
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p. 1325 - 1333
(2021/01/11)
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- Osmium Complex-Chromophore Conjugates with Both Singlet-to-Triplet Absorption and Long Triplet Lifetime through Tuning of the Heavy-Atom Effect
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Os(II) complexes showing singlet-to-triplet absorption are of growing interest as a new class of triplet sensitizers that circumvent energy loss during intersystem crossing, and they enable effective utilization of input photon energy in various applications, such as photoredox catalysis, photodynamic therapy, and photon upconversion. However, triplet excited-state lifetimes of Os(II) complexes are often too short (τ a series of Os(II) and Ru(II) bis(terpyridine) complexes modified with perylene units. Phosphorescence lifetimes of these compounds strongly depend on the lifetimes of the perylenyl group-localized excited states that are shortened by the heavy-atom effect. The degree of heavy-atom effect can be largely circumvented by introducing meta-phenylene bridges, where the perylene unit retains its intrinsic long excited-state lifetime. The thermal activation to the short-lived excited states is suppressed, thanks to sufficient but still small energy losses during the IMET process. Involvement of the metal center was also confirmed by the prolonged lifetime by replacing Os(II) with Ru(II) that possesses a smaller spin-orbit coupling constant. These results indicate the importance of ligand structures that give a minimum heavy-atom effect as well as the sufficient energy gap among the excited states and fast IMET for elongating the triplet excited-state lifetime without sacrificing the excitation energy.
- Kimizuka, Nobuo,Sasaki, Yoichi,Yanai, Nobuhiro
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supporting information
(2022/02/09)
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- Chemical and photochemical behavior of ruthenium nitrosyl complexes with terpyridine ligands in aqueous media
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The synthesis and behavior in water of a set of various cis(Cl,Cl)-[R-tpyRuCl2(NO)](PF6) and trans(Cl,Cl)-[R-tpyRuCl2(NO)](PF6) (R = fluorenyl, phenyl, thiophenyl; tpy = 2,2′:6′,2′′-terpyridine) complexes are presented. In any case, one chlorido ligand is substituted by a hydroxo ligand and the final species arises as a single trans(NO,OH) isomer, whatever the nature of the starting cis/trans(Cl,Cl) complexes. Six X-ray crystal structures are presented for cis(Cl,Cl)-[thiophenyl-tpyRuCl2(NO)](PF6) (cis-3a), trans(Cl,Cl)-[thiophenyl-tpyRuCl2(NO)](PF6) (trans-3a), trans(NO,OH)-[phenyl-tpyRu(Cl)(OH)(NO)](PF6) (4a), trans(NO,OH)-[thiophenyl-tpyRu(Cl)(OH)(NO)](PF6) (4b), trans(NO,OEt)-[phenyl-tpyRu(Cl)(OEt)(NO)](PF6) (5a), and trans(NO,OH)-[phenyl-tpyRu(Cl)(OEt)(NO)](PF6) (5b) compounds. The different cis/trans(Cl,Cl) complexes exhibit an intense low-lying transition in the λ = 330-390 nm range, which appears to be slightly blue-shifted after Cl → OH substitution. In water, both cis/trans(Cl,Cl) isomers are converted to a single trans(NO,OH) isomer in which one chlorido- is replaced by one hydroxo-ligand, which avoids tedious separation workout. The water stable trans(NO,OH)-species all release NO with quantum yields of 0.010 to 0.075 under irradiation at 365 nm. The properties are discussed with computational analysis performed within the framework of Density Functional Theory.
- Labra-Vázquez, Pablo,Bocé, Mathilde,Tassé, Marine,Mallet-Ladeira, Sonia,Lacroix, Pascal G.,Farfán, Norberto,Malfant, Isabelle
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p. 3138 - 3154
(2020/03/19)
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- A convenient method for synthesis of terpyridines: Via a cooperative vinylogous anomeric based oxidation
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The presented study is the first report of the synthesis of terpyridines in the presence of a nanomagnetic catalyst instead of harmful reagents. Herein, Fe3O4&at;O2PO2(CH2)2NH3+CF3CO2- as a retrievable nanocatalyst with magnetic properties was applied for the multi-component reaction between acetylpyridine derivatives (2 or 3 or 4-isomer), aryl aldehydes and ammonium acetate under conventional heating conditions in the absence of any solvent. The derived terpyridines were obtained with acceptable yields and brief reaction times via a cooperative vinylogous anomeric based oxidation route. Fe3O4&at;O2PO2(CH2)2NH3+CF3CO2- showed a high capability for recovery and reuse in the mentioned reaction.
- Karimi, Fatemeh,Yarie, Meysam,Zolfigol, Mohammad Ali
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p. 25828 - 25835
(2020/07/28)
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- Rhodium-terpyridine catalyzed redox-neutral depolymerization of lignin in water
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Simple rhodium terpyridine complexes were found to be suitable catalysts for the redox neutral cleavage of lignin in water. Apart from cleaving lignin model compounds into ketones and phenols, the catalytic system could also be applied to depolymerize dioxasolv lignin and lignocellulose, affording aromatic ketones as the major monomer products. The (hemi)cellulose components in the lignocellulose sample remain almost intact during lignin depolymerization, providing an example of a "lignin-first" process under mild conditions. Mechanistic studies suggest that the reaction proceeds via a rhodium catalyzed hydrogen autotransfer process.
- Liu, Yuxuan,Li, Changzhi,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Zhang, Tao,Wang, Chao
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supporting information
p. 33 - 38
(2020/01/13)
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- Synthesis, characterization and anticancer mechanism studies of fluorinated cyclometalated ruthenium(ii) complexes
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The drug-resistance of cancer cells has become a major obstacle to the development of clinical drugs for chemotherapy. In order to overcome cisplatin-resistance, seven cyclometalated ruthenium(ii) complexes were synthesized with a varying degree of fluorine substitution, for use as anticancer agents. A cytotoxicity assay testified that the complexes possessed a more cytotoxic effect than cisplatin towards the cisplatin-resistant cell line A549R. The number of fluorine atoms regulated the lipophilicity of the complexes, but the relationship was not linear.Ru1containing one fluorine atom had the highest lipophilicity and the best therapeutic effect. The complexes enter cells through an energy-dependent pathway and then localize in the nuclei and mitochondria. The complexes induced nuclear dysfunction by the inhibition of DNA replication as well as mitochondrial dysfunction by the loss of membrane potential. The damage to these vital organelles leads to cell apoptosisviathe caspase 3/7 pathway. Our results indicated that the modulation of the number of fluorine atoms in therapeutic agents can have a profound effect andRu1is a complex with a high potential as a drug for the treatment of cisplatin-resistant cancer.
- Wen, Ya,Ouyang, Cheng,Li, Quanwen,Rees, Thomas W.,Qiu, Kangqiang,Ji, Liangnian,Chao, Hui
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supporting information
p. 7044 - 7052
(2020/06/04)
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- A Mitochondrion-Localized Two-Photon Photosensitizer Generating Carbon Radicals Against Hypoxic Tumors
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The efficacy of photodynamic therapy is typically reliant on the local concentration and diffusion of oxygen. Due to the hypoxic microenvironment found in solid tumors, oxygen-independent photosensitizers are in great demand for cancer therapy. We herein report an iridium(III) anthraquinone complex as a mitochondrion-localized carbon-radical initiator. Its emission is turned on under hypoxic conditions after reduction by reductase. Furthermore, its two-photon excitation properties (λex=730 nm) are highly desirable for imaging. Upon irradiation, the reduced form of the complex generates carbon radicals, leading to a loss of mitochondrial membrane potential and cell death (IC50light=2.1 μm, IC50dark=58.2 μm, PI=27.7). The efficacy of the complex as a PDT agent was also demonstrated under hypoxic conditions in vivo. To the best of our knowledge, it is the first metal-complex-based theranostic agent which can generate carbon radicals for oxygen-independent two-photon photodynamic therapy.
- Chao, Hui,Chen, Yu,Ji, Liangnian,Kuang, Shi,Liao, Xinxing,Rees, Thomas W.,Sun, Lingli,Zeng, Leli,Zhang, Xianrui,Zhang, Xiting
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supporting information
p. 20697 - 20703
(2020/09/07)
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- An efficient one pot three-component synthesis of 2,4,6-triarylpyridines using triflimide as a metal-free catalyst under solvent-free conditions
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A simple and efficient protocol developed for one pot three-component synthesis of 2,4,6-triarylpyridines from aromatic aldehydes, substituted acetophenones and ammonium acetate using the versatile super Br?nsted acid triflimide (HNTf2) as an effective catalyst is described. The reactions proceed well in the presence of 1 mol% of HNTf2 at 80 °c under solvent-free conditions and provide the corresponding triarylpyridines in good to excellent yields. The method reported has several advantages such as a metal-free and commercially available catalyst, mild reaction conditions and lower loading of catalyst.
- Wang, Hongshe,Zhao, Weixing,Du, Juan,Wei, Fenyan,Chen, Qi,Wang, Xiaomei
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p. 5158 - 5163
(2019/02/27)
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- Cationic organotin cluster [t-Bu2Sn(OH)(H2O)]2 2+2OTf?-catalyzed one-pot three-component syntheses of 5-substituted 1H-tetrazoles and 2,4,6-triarylpyridines in water
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The cationic organotin cluster [t-Bu2Sn(OH)(H2O)]2 2+2OTf? is easy to prepare and stable in air. The catalytic activity of [t-Bu2Sn(OH)(H2O)]2 2+2OTf? as a neutral organotin Lewis acid catalyst is probed through the one-pot three-component syntheses of 5-substituted 1H-tetrazoles from aldehydes, hydroxylamine hydrochloride and sodium azide, and of 2,4,6-triarylpyridines from aromatic aldehydes, substituted acetophenones and ammonium acetate. The reactions proceed well in the presence of 1?mol% of [t-Bu2Sn(OH)(H2O)]2 2+2OTf? in water and provide the corresponding 5-substituted 1H-tetrazoles and 2,4,6-triarylpyridines in good to excellent yields. The method reported has several advantages such as the catalyst being neutral, low catalyst loading and use of water as a green solvent.
- Wang, Hongshe,Zhao, Weixing,Du, Juan,Wei, Fenyan,Chen, Qi,Wang, Xiaomei
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- Synthesis, Structure, Electrochemical, and Spectroscopic Properties of Hetero-Bimetallic Ru(II)/Fe(II)-Alkynyl Organometallic Complexes
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A series of heterobimetallic wire-like organometallic complexes [(tpy-C6H4-R)(PPh3)2Ru-C-C-Fc]+ (tpy-C6H4-R = 4′-(aryl)-2,2′:6′,2′′-terpyridyl, Fc = [(η5-Cp)2Fe], R = -H, -Me, -F, -NMe2 in complexes 5-8, respectively) featuring ferrocenyl and 4′-(aryl)-2,2′:6′,2′′-terpyridyl ruthenium(II) complexes as redox active metal termini, have been synthesized. Various spectroscopic tools, such as multinuclear NMR, IR spectra, HRMS, CHN analyses, and single crystal X-ray crystallography have been utilized to characterize the heterobimetallic complexes. The electrochemical and UV-vis-NIR spectroscopic studies have been investigated to evaluate the electronic delocalization across the molecular backbones of the Ru(II)-Fe(II) heterobinuclear organometallic dyads. Electrochemical studies reveal two well-separated reversible redox waves as a result of successive oxidation of the ferrocenyl and Ru(II) redox centers. The spin density distribution analyses reveal that the initial oxidation process is associated with the Fe(II)/Fe(III) couple followed by one electron oxidation of the ruthenium(II) center. The high Kc value (0.11-1.73 × 1012) and intense NIR absorption, with molar absorption coefficient (in the order of 103 M-1 cm-1) for the RuIIFeIII mixed-valence species, signify strong electronic communication between the two metal termini. The electronic coupling constant (Hab) has been estimated to be 492 and 444 cm-1 for the structurally characterized complexes 6 and 7, respectively. The redox and NIR absorption features indicate that the mixed-valence system of the heterobinuclear dyads belongs to a Robin and Day "class II" system.
- Sil, Amit,Ghosh, Utsav,Mishra, Vipin Kumar,Mishra, Sabyashachi,Patra, Sanjib K.
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supporting information
p. 1155 - 1166
(2019/01/26)
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- Enhanced singlet oxygen generation of a soft salt through efficient energy transfer between two ionic metal complexes
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In this study, a soft salt complex based photosensitizer has been developed for photodynamic therapy (PDT) of cancer cells. The iridium(iii) complex [Ir(L)(L′)]3+(PF6-)3 (C1) with L and L′ being terpyridine ligands (L = 4′-phenyl-2,2′:6′,2′′-terpyridine, L′ = 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-9-hexyl-9H-carbazole) was chosen as the cationic component, and the iridium(iii) complex [Ir(dfppy)2CN2]-Bu4N+ (A1) was selected as the anionic component. Complexes C1 and A1 are directly connected through electrostatic interaction to form a soft salt based photosensitizer (S1), which exhibited an enhanced singlet oxygen generation rate because of efficient energy transfer between two ionic metal complexes. Furthermore, this novel photosensitizer was successfully applied in photodynamic therapy (PDT) of cancer cells for the first time.
- Ma, Yun,Zhang, Shujun,Wei, Huanjie,Dong, Yafang,Shen, Liang,Liu, Shujuan,Zhao, Qiang,Liu, Li,Wong, Wai-Yeung
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p. 5582 - 5588
(2018/04/30)
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- Ruthenium(II) Complexes of 4′-(Aryl)-2,2′:6′,2′′-terpyridyl Ligands as Simple Catalysts for the Transfer Hydrogenation of Ketones
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A series of cationic [Ru(L)(PPh3)2Cl]+ (1–3) and neutral [Ru(L)(PPh3)Cl2] (4–6) RuII complexes were synthesized by reacting [RuCl2(PPh3)2] with 4′-(aryl)-2,2′:6′,2′′-terpyridyl-based ligands (L1–L3) with various aryl groups (tolyl, phenyl and 4-fluorophenyl). The synthesized RuII complexes were unambiguously characterized by various spectroscopic techniques such as FTIR and multinuclear NMR spectroscopy as well as HRMS. The neutral complexes (4–6) were also structurally characterized by single-crystal X-ray diffraction studies. Photophysical and electrochemical studies of the RuII complexes were performed to elucidate the effects of the 4′-aryl substituents of L1–L3. These RuII complexes show good catalytic activities in the transfer hydrogenation (TH) of ketones with a wide substrates scope in 2-propanol under reflux. An optimization study revealed that the neutral RuII complexes are better catalysts than the cationic RuII complexes for TH reactions. Finally, [Ru(L1)(PPh3)2H]+ (7) with a [RuII–H] functionality was successfully synthesized and isolated and is proposed as the catalytically active species. A control experiment with the [RuII–H] complex in the absence of base was performed to establish the mechanism for the catalytic TH of ketones.
- Maity, Apurba,Sil, Amit,Patra, Sanjib K.
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supporting information
p. 4063 - 4073
(2018/09/11)
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- Experimental and computational exploration of photophysical and electroluminescent properties of modified 2,2′:6′,2″-terpyridine, 2,6-di(thiazol-2-yl)pyridine and 2,6-di(pyrazin-2-yl)pyridine ligands and their Re(I) complexes
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The excited-state characteristics of a series of 2,2′:6′,2″-terpyridine (terpy), 2,6-di(thiazol-2-yl)pyridine (dtpy) and 2,6-di(pyrazin-2-yl)pyridine (dppy) derivatives as well as their corresponding Re(I) complexes [ReCl(CO)3(Ln-κ2N)] were investigated both experimentally and theoretically, and the crucial effect of pyrrolidine substituent and peripheral rings on the optical and electrochemical properties was found evident. For Re(I) complexes bearing the ligands with electron-rich pyrrolidine substituent, different emission profiles were found in polar and non-polar solvents, indicating a change in the character of the excited state. Dual-emission effect of [ReCl(CO)3(L4-κ2N)] and [ReCl(CO)3(L5-κ2N)] in chloroform was attributed to the presence of two emitting states, identified as an 1ILCT excited state deactivated at higher energies and a longer-lived red-shifted phosphorescence assigned to the 3MLCT excited state. The triplet excited state was confirmed by recording the nanosecond time-resolved transient absorption spectra for the compound [ReCl(CO)3(L4-κ2N)]. To verify the charge transfer problem of low-lying excited states of the free ligands, the Λ parameter was calculated. In addition, the compounds were applied as emitting layers for both non-doped and doped single-layer organic light-emitting diodes fabricated by solution processing.
- Klemens, Tomasz,?witlicka, Anna,Szlapa-Kula, Agata,Krompiec, Stanis?aw,Lodowski, Piotr,Chrobok, Anna,Godlewska, Magdalena,Kotowicz, Sonia,Siwy, Mariola,Bednarczyk, Katarzyna,Libera, Marcin,Ma?kowski, Sebastian,P?dziński, Tomasz,Schab-Balcerzak, Ewa,Machura, Barbara
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- Preparation method of 2,4,6-triaryl substituted pyridine derivative
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The invention discloses a preparation method of a 2,4,6-triaryl substituted pyridine derivative. The preparation method comprises the following steps: taking a aryl methyl ketone compound and a benzylamine derivative as raw materials, taking tri(pentafluorobenzene)borane as a catalyst, and reacting for 6-24 hours under the oxygen condition at 80-160 DEG C to obtain the 2,4,6-triaryl substituted pyridine derivative. According to the preparation method has the main beneficial effects that the reaction raw materials are easily available; the consumption of the catalyst can be as low as 0.5%; theexperiment operation is simple; the target compound can be prepared by a one-pot process; the substrate universality is high; the 2,4,6-triaryl substituted pyridine derivative with different substituent groups can be built; the further derivatization research can be facilitated.
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Paragraph 0023
(2018/09/12)
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- B(C6F5)3-catalyzed oxidative deamination/cyclization cascade reaction of benzylamines and ketones for the synthesis of 2,4,6-triarylpyridines
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The B(C6F5)3-catalyzed oxidative deamination/cyclization cascade reaction of benzylamines and ketones for the construction of 2,4,6-triarylpyridines under metal-/solvent-free conditions has been successfully achieved. The advantages of this strategy include good functional group tolerance, low catalyst loading and high yields.
- Ling, Fei,Shen, Leixin,Pan, Zhentao,Fang, Lu,Song, Dingguo,Xie, Zhen,Zhong, Weihui
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supporting information
p. 3678 - 3682
(2018/09/11)
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- Synthesis, characterization, crystal structure, and DNA interaction of tin complexes containing pyridyl ligands
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Abstract: The reactions of 4′-aryl-2,2′:6′,2′′-terpyridines (aryl?=?phenyl, p-tolyl, p-anisyl, p-chlorophenyl, 4-pyridyl) and 3-phenyl-1,5-bis(2-pyridyl)-1,5-pentanedione with dimethyltin(IV) dichloride and tin(II) dichloride have been investigated. The resulting products have been fully characterized by elemental analysis and multinuclear (1H, 13C, 119Sn) NMR spectroscopy and X-ray crystal structure determination in the case of [SnCl2(pytpy)] (pytpy?=?4′-(4-pyridyl)-2,2′:6′,2′′-terpyridine). The crystal structure of [SnCl2(pytpy)] reveals that tin(II) is pentacoordinated in a highly distorted square pyramidal geometry. Moreover, the binding interaction of complex [SnCl2(pytpy)] with calf thymus-DNA (ct-DNA) has been investigated using UV–Vis spectroscopy. Data reveals that the groove binding is a mode of the interaction with a moderate binding constant of 7.2 (±0.2)?×?103?M?1. Graphical abstract: [Figure not available: see fulltext.]
- Momeni, Badri Z.,Noroozi, Vahid
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p. 893 - 900
(2017/04/14)
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- Transition-Metal-Free Oxidative C(sp2)?H Hydroxylation of Terpyridines: A HOMO-Raising Strategy for the Construction of a New Super-Stable Terpyridine Chromophores
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Direct functionalization of terpyridines is an increasingly important topic in the field of dyes and catalysis as well as supramolecular chemistry, but its synthesis and transformation is usually challenging. Herein, a HOMO-raising strategy is reported for the construction of a super-stable novel terpyridine chromophores, in which the selective oxidation of terpyridines at its 3-position was determined successfully to the synthesis of phenol-functionalization of terpyridines (TPyOHs) bearing a hydrogen bonding group. The corresponding TPyOHs displayed strong aggregation-induced emission and exhibited highly selective and visual detection of ZnII cation with a record green terpyridine-based luminophore with nanomolar sensitivity (125 nm).
- Huang, Jiang-Bo,Bai, Xing-Feng,Li, Li,Zheng, Zhan-Jiang,Xu, Zheng,Cui, Yu-Ming,Cao, Jian,Xu, Li-Wen
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supporting information
p. 4055 - 4059
(2017/03/31)
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- Iridium complex with phosphorescent ion pair structure as well as preparation method and application of iridium complex
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The invention discloses an iridium complex with a phosphorescent ion pair structure as well as a preparation method and an application of the iridium complex. The iridium complex is a phosphorescent anion and cation type soft salt iridium complex formed by bonding of a terpyridyl cation complex and a cation complex, wherein the cation complex contains a cyclometalated ligand, and a metal center and cyanogen are taken as auxiliary ligands. The structural general formula of the iridium complex is as shown in the specification. The iridium complex with the phosphorescent ion pair structure is capable of generating singlet oxygen under the radiation of white light, can be applied to the photodynamics treatment field and has very good application prospects in the photodynamics treatment.
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Paragraph 0029; 0030; 0031; 0034
(2017/10/31)
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- Unexpected lability of the [RuIII(phtpy)Cl3] complex
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Ruthenium(iii) complexes are known for their high stability and inertness. To the best of our knowledge, the only well-characterized example of a labile Ru(iii) complex is [RuIII(edta)(H2O)] as a consequence of an intramolecular hydrogen bonding leading to the formation of a large opening in the molecule front, thus changing the mechanism from dissociative to associative. Compelling experimental evidence is presented demonstrating that the [RuIII(phtpy)Cl3] complex is labile, also indicating that the Ru(iii)-phtpy bond is much weaker than expected, in contrast to the strongly π-back-bonding stabilized Ru(ii)-phtpy bond.
- Benavides, Paola A.,Matias, Tiago A.,Araki, Koiti
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p. 15567 - 15572
(2017/11/22)
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- Ruthenium-8-quinolinethiolate-phenylterpyridine versus ruthenium-bipyridine-phenyl-terpyridine complexes as homogeneous water and high temperature stable hydrogenation catalysts for biomass-derived substrates
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[(4′-Ph-terpy)(bipy)Ru(L)](OTf)n and [(4′-Ph-terpy)(quS)Ru(L)](OTf)n (n = 0 or 1 depending on the charge of L, L = labile ligand, e.g., H2O, CH3CN or OTf, bipy = 2,2′-bipyridine, quS = quinoline-8-thiolate) have been evaluated as catalysts for the hydrogenation of the biomass-derivable C6-substrates 2,5-dimethylfuran (obtainable from 5-hydroxymethylfurfural) and 2,5-hexanedione (the hydrolysis product of 2,5-dimethylfuran). Operating in aqueous acidic medium at T = 175-225 °C the bipy complex is only marginally active, while the quinoline-8-thiolate complex realizes yields of hydrogenated products up to 97% starting from 2,5-hexanedione and up to 66% starting from 2,5-dimethylfuran. The catalyst can also convert the 5-HMF derived acetone 4-(5-methyl-2-furanyl)-3-buten-2-one into 2,5,8-nonatriol, a potentially valuable cross-linker for polymer formulations. On the basis of DFT calculations, the higher activity of the quinoline-8-thiolate complex is proposed to be rooted in a metal-ligand bifunctional mechanism for the heterolytic activation and transfer of dihydrogen to the carbonyl substrate with the hydride-thiol complex [(4′-Ph-terpy)(quSH)Ru(H)]+ as the active catalyst.
- Sullivan, Ryan J.,Kim, Jin,Hoyt, Caroline,Silks, Louis A.,Schlaf, Marcel
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supporting information
p. 104 - 114
(2016/04/26)
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- Mitochondrial selectivity and remarkable photocytotoxicity of a ferrocenyl neodymium(iii) complex of terpyridine and curcumin in cancer cells
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A series of four novel neodymium(iii) complexes of the formulation [Nd(R-tpy)(O-O)(NO3)2] (1-4), where R-tpy is 4′-phenyl-2,2′:6′,2′′-terpyridine (Ph-tpy; 1, 2) and 4′-ferrocenyl-2,2′:6′,2′′-terpyridine (Fc-tpy; 3, 4); O-O is the conjugate base of acetylacetone (Hacac; 1, 3) or curcumin (Hcurc; 2, 4), are synthesized and characterized. The single crystal structure of 1 shows that the complex is a discrete mononuclear species with the Nd(iii) centre in a nine coordinate environment provided by a set of O6N3 donor atoms. Complexes 1 and 3 having the simple acac ligand are prepared as control compounds. Complex 4, possessing an appended ferrocenyl (Fc) and the curcumin moiety, is remarkably photocytotoxic to HeLa and MCF-7 cancer cells in visible light giving respective IC50 values of 0.7 μM and 2.1 μM while being significantly less toxic to MCF-10A normal cells (IC50 = 34 μM) and in the dark (IC50 > 50 μM). The phenyl appended complex 2, lacking a ferrocenyl moiety, is significantly less toxic to both the cell lines when compared with 4. Complexes 1 and 3, lacking the photoactive curcumin moiety, do not show any apparent toxicity both in light and in the dark. The cell death is apoptotic in nature and is mediated by the light-induced formation of reactive oxygen species (ROS). Fluorescence imaging experiment with HeLa cells reveals mitochondrial accumulation of complex 4 within 4 h of incubation. The complexes bind to calf thymus (ct) DNA with moderate affinity giving Kb values in the range of 104-105 M-1. The curcumin complexes 2 and 4 cleave plasmid supercoiled DNA to its nicked circular form in visible light via1O2 and ?OH pathways. The presence of the ferrocenyl moiety is likely to be responsible for the enhanced cellular uptake and photocytotoxicity of complex 4. Thus, the mitochondria targeting complex 4, being remarkably cytotoxic in light but non-toxic in the dark and to normal cells, is a potential candidate for photochemotherapeutic applications.
- Sarkar, Tukki,Banerjee, Samya,Mukherjee, Sanjoy,Hussain, Akhtar
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supporting information
p. 6424 - 6438
(2016/05/09)
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- Synthesis of heteroleptic terpyridyl complexes of Fe(II) and Ru(II): Optical and electrochemical studies
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We report the synthesis and characterization of heteroleptic terpyridyl complexes of d6 transition metal ions with Fe2+ and Ru2+ (1-3). Furthermore, we study the effect of substitution of either an electron donating group (-NH2) or electron withdrawing group (-NO2) at the 4′-position in the ligands by means of UV-vis, cyclic voltammetry, and differential pulse voltammetry measurements. The experimentally observed photophysical characteristics of the transition-metal based terpyridyl complexes are explained and supported by detailed quantum chemical calculations.
- Mondal, Prakash Chandra,Manna, Arun Kumar
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supporting information
p. 5775 - 5781
(2016/07/16)
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- Catalytic Water-Oxidation Activity of a Weakly Coupled Binuclear Ruthenium Polypyridyl Complex
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The catalytic oxidation of water by the binuclear complex [Ru2(H2O)2(bpy)2(tpy2ph)](PF6)4[bpy = 2,2′-bipyridine; tpy2ph = 1,3-bis(4′-2,2′:6′,2′′-terpyridin-4-yl)benzene] was investigated comparatively to its mononuclear counterpart [Ru(H2O)(bpy)(phtpy)](PF6)2(phtpy = 4′-phenyl-2,2′:6′,2′′-terpyridine). These catalysts were prepared from the synthesis of their precursor chloride complexes, which were also extensively characterized in this work. The H2O–RuIIcomplexes were found to undergo proton-coupled electron-transfer processes to generate the redox species HO–RuIII, O=RuIV, and O=RuV. The catalytically active species, [RuV2(O)2(bpy)2(tpy2ph)]6+and [RuV(O)(bpy)(phtpy)]3+, were generated electrochemically and by using cerium(IV) ammonium nitrate. In the presence of CeIV, the catalytic rates for O2production by the binuclear and mononuclear species were 1.9 × 10–3and 9.5 × 10–5s–1, respectively. This superior catalytic performance of the binuclear complex suggests that, despite weak electronic coupling between the Ru centers, the second site could play an important mechanistic role in the formation of the activated species [(bpy)(OO)RuIV(tpy2ph)RuIII(OH)(bpy)]4+.
- Matias, Tiago A.,Mangoni, Ana P.,Toma, Sergio H.,Rein, Francisca N.,Rocha, Reginaldo C.,Toma, Henrique E.,Araki, Koiti
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p. 5547 - 5556
(2016/12/26)
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- One-Pot Reactions for Modular Synthesis of Polysubstituted and Fused Pyridines
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A 2-fluoro-1,3-dicarbonyl-initiated one-pot Michael addition/[5 + 1] annulation/dehydrofluorinative aromatization reaction sequence is introduced for regioselective synthesis of di-, tri-, tetra-, and pentasubstituted pyridines as well as fused pyridines. This simple and modular synthesis is performed using readily available starting materials and under transition-metal catalyst-free conditions.
- Song, Zhidong,Huang, Xin,Yi, Wenbin,Zhang, Wei
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supporting information
p. 5640 - 5643
(2016/11/17)
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- Mononuclear manganese(II)/4′-Ar-2,2′:6′,2″-terpyridine complexes: Synthesis, characterization, and olefins oxidation study
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A series of mononuclear Mn(II)/terpyridine complexes were synthesized and characterized by elemental analysis, IR spectrum, and UV-vis spectrum. Catalytic activities of Mn(II)/4′-Ar-2,2′:6′,2″-terpyridine complexes were tested in the oxidation of cyclohexene or styrene in the presence of tert-butylhydroperoxide as oxidant. Significant catalytic effects of these complexes were observed in the oxidation of olefins, especially in the cyclo-oxidation of styrene.
- Liu, Bingqing,Luo, Wei,Li, Haixia,Qi, Xiaoyun,Hu, Quanyuan
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p. 1097 - 1101
(2015/04/14)
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- A selenium-containing ruthenium complex as a cancer radiosensitizer, rational design and the important role of ROS-mediated signalling
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A novel selenium-containing ruthenium complex Ru(phtpy)(phenSe)Cl(ClO4) (phtpy = 4-phenyl-2,2′:6′,2′′-terpyridine, phenSe = 2-selenicimidazole[4,5-f]1,10-phenanthroline) has been synthesized and found be able to enhance radiation-induced DNA damage through superoxide overproduction, which leads to G2/M arrest and apoptosis in cancer cells by activating ROS-mediated pathways. This journal is
- Deng, Zhiqin,Yu, Lianling,Cao, Wenqiang,Zheng, Wenjie,Chen, Tianfeng
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supporting information
p. 2637 - 2640
(2015/03/05)
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- Photoactivated cytotoxicity of ferrocenyl-terpyridine oxovanadium(IV) complexes of curcuminoids
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Oxovanadium(IV) complexes, viz. [VO(Fc-tpy)(Curc)](ClO4) (1), [VO(Fc-tpy)(bDHC)](ClO4) (2), [VO(Fc-tpy)(bDMC)](ClO4) (3) and [VO(Ph-tpy)(Curc)](ClO4) (4), of 4′-ferrocenyl-2,2′: 6′,2″-terpyridine (Fc-tpy) and 4′-phenyl-2,2′:6′, 2″-terpyridine (Ph-tpy) and monoanionic curcumin (Curc), bis-dehydroxycurcmin (bDHC) and bis-demethoxycurcumin (bDMC) were prepared, characterized and their photo-induced DNA cleavage activity and photocytotoxicity in visible light studied. The ferrocenyl complexes 1-3 showed an intense metal-to-ligand charge transfer band near 585 nm in DMF and displayed Fc+/Fc and V(IV)/V(III) redox couples near 0.65 V and -1.05 V vs. SCE in DMF-0.1 M TBAP. The complexes as avid binders to calf thymus DNA showed significant photocleavage of plasmid DNA in red light of 647 nm forming OH radicals. The complexes showed photocytotoxicity in HeLa and Hep G2 cancer cells in visible light of 400-700 nm with low dark toxicity. ICP-MS and fluorescence microscopic studies exhibited significant cellular uptake of the complexes within 4 h of treatment with complexes. The treatment with complex 1 resulted in the formation of reactive oxygen species inside the HeLa cells which was evidenced from the DCFDA assay.
- Balaji, Babu,Balakrishnan, Babita,Perumalla, Sravanakumar,Karande, Anjali A.,Chakravarty, Akhil R.
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p. 458 - 467
(2014/11/08)
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- An efficient synthesis of 2,4,6-triarylpyridines via solvent-free reaction between acetophenoneoximes and aldehydes
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An efficient synthesis of 2,4,6-triarylpyridines is described. Heating a mixture of an acetophenoneoxime and an aldehyde under solvent-free conditions afforded Kr?hnke pyridines in excellent yields. In this method acetophenoneoximes are directly used for the preparation of Kr?hnke pyridines under metal-free conditions. Georg Thieme Verlag Stuttgart New York.
- Mahernia, Shabnam,Mahdavi, Mohammad,Adib, Mehdi
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- A solvent-free reaction between acetophenone oximes and epoxy styrenes: An efficient synthesis of 2,4,6-triarylpyridines under neutral conditions
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An efficient synthesis of 2,4,6-triarylpyridines is described which involves heating a mixture of an acetophenone oxime and an epoxy styrene under neutral, solvent-free conditions. Kr?hnke pyridine products are obtained in excellent yields.
- Mahernia, Shabnam,Adib, Mehdi,Mahdavi, Mohammad,Nosrati, Meisam
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p. 3844 - 3846
(2014/07/08)
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- Facile synthesis of 5-substituted-1H-tetrazoles and 1-substituted-1H- tetrazoles catalyzed by recyclable 4′-phenyl-2,2′:6′,2″- terpyridine copper(II) complex immobilized onto activated multi-walled carbon nanotubes
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5-Substituted-1H-tetrazoles can conveniently be synthesized from the corresponding nitriles by reaction with NaN3 using the efficient and recyclable heterogeneous catalyst prepared by immobilization of copper(II) complex of 4′-phenyl-2,2′:6′,2″-terpyridine on activated multi-walled carbon nanotubes [AMWCNTs-O-Cu(II)-PhTPY]. Excellent results were obtained in each case affording the corresponding tetrazole adducts in good to excellent yields. In general, aromatic nitriles with electron-donating group could be accomplished as well as that with electron-withdrawing groups. By leaving out nitrile from the reaction and adding CH(OEt)3 and amines bearing various substituents, 1-substituted-1H-tetrazoles formed in water in high yields. The reported protocols have the advantages of rapid assembly of a host of heterocyclic systems in high yields with the added advantage of recycling and reuse of the catalyst.
- Sharghi, Hashem,Ebrahimpourmoghaddam, Sakineh,Doroodmand, Mohammad Mahdi
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- Cytotoxic, antibacterial, DNA interaction and superoxide dismutase like activities of sparfloxacin drug based copper(II) complexes with nitrogen donor ligands
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The novel neutral mononuclear copper(II) complexes with fluoroquinolone antibacterial drug, sparfloxacin and nitrogen donor heterocyclic ligand have been synthesized and characterized. An antimicrobial efficiency of the complexes has been tested against five different microorganisms and showed diverse biological activity. The interaction of complex with Herring sperm (HS) DNA was investigated using viscosity titration and absorption titration techniques. The results indicate that the complexes bind to DNA by intercalative mode and have rather high DNA-binding constants. DNA cleavage study showed better cleaving ability of the complexes compare to metal salt and standard drug. All the complexes showed good cytotoxic activity with LC50 values ranging from 4.89 to 11.94 μg mL-1. Complexes also exhibit SOD-like activity with their IC50 values ranging from 0.717 to 1.848 μM.
- Patel, Mohan N.,Joshi, Hardik N.,Patel, Chintan R.
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- Coordination chemistry of single-site catalyst precursors in reductively electropolymerized vinylbipyridine films
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Reductive electropolymerization of [RuII(PhTpy)(5,5′- dvbpy)(Cl)](PF6) and [RuII(PhTpy)(5,5′-dvbpy)(MeCN)] (PF6)2 (PhTpy is 4′-phenyl-2,2′:6′, 2″-terpyridine; 5,5′-dvbpy is 5,5′-divinyl-2,2′- bipyridine) on glassy carbon electrodes gives well-defined films of poly{[RuII(PhTpy)(5,5′-dvbpy)(Cl)](PF6)} (poly-1) or poly{[RuII(PhTpy)(5,5′-dvbpy)(MeCN)](PF6) 2} (poly-2). Oxidative cycling of poly-2 with added NO 3- results in the replacement of coordinated MeCN by NO3- to give poly{[RuII(PhTpy)(5,5′- dvbpy)(NO3)]+}, and with 0.1 M HClO4, replacement by H2O occurs to give poly{[RuII(PhTpy)(5, 5′-dvbpy)(OH2)]2+} (poly-OH2). Although analogous aqua complexes (e.g., [Ru(tpy)(bpy)(OH2)]2+) undergo rapid loss of H2O to MeCN in solution, poly-OH2 and poly-OH2+ are substitutionally inert in MeCN. The substitution chemistry is reversible, with reductive scans of poly-1 or poly-OH2 in MeCN resulting in poly-2, although with some loss of Faradaic response.
- Harrison, Daniel P.,Lapides, Alexander M.,Binstead, Robert A.,Concepcion, Javier J.,Mendez, Manuel A.,Torelli, Daniel A.,Templeton, Joseph L.,Meyer, Thomas J.
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supporting information
p. 4747 - 4749
(2013/06/26)
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- Photoactivated DNA cleavage and anticancer activity of pyrenyl-terpyridine lanthanide complexes
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Lanthanide(III) complexes [Ln(R-tpy)(acac)(NO3)2] (Ln = La(III) in 1, 2; Gd(III) in 4, 5) and [Ln(py-tpy)(sacac)(NO3) 2] (Ln = La(III), 3; Gd(III), 6), where R-tpy is 4′-phenyl-2, 2′:6′,2″-terpyridine (ph-tpy in 1, 4), 4′-(1-pyrenyl)-2, 2′:6′,2″-terpyridine (py-tpy in 2, 3, 5 and 6), acac is acetylacetonate and sacac is 4-hydroxy-6-{4-[(β-d-glucopyranoside)oxy] phenyl}hex-3,5-dien-2-onate, were prepared to study their DNA photocleavage activity and photocytotoxicity. Complexes [La(ph-tpy)(acac)(EtOH)(NO 3)2] (1a) and [Gd(ph-tpy)(acac)(NO3) 2] (4) were characterized by X-ray crystallography. The 1:1 electrolytic complexes bind to calf thymus DNA. The py-tpy complexes cleave pUC19 DNA and exhibit remarkable photocytotoxicity in HeLa cells in UV-A light of 365 nm with apoptotic cell death (IC50: ~40 nM in light, >200 μM in dark). Confocal microscopy using HeLa cells reveal primarily cytosolic localization of the complexes.
- Hussain, Akhtar,Gadadhar, Sudarshan,Goswami, Tridib K.,Karande, Anjali A.,Chakravarty, Akhil R.
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body text
p. 319 - 331
(2012/06/29)
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- Effect of substituent of terpyridines on the DNA-interaction of polypyridyl ruthenium(II) complexes
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An octahedral complexes of ruthenium with 2,9-dimethyl-1,10-phenanthroline (dmphen) and substituted terpyridine have been synthesized. The RuII complexes have been characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, FT-IR, electronic, 1H NMR and FAB mass spectra. The binding strength and mode of interaction of the complexes with Herring Sperm DNA has been investigated using absorption titration and viscosity measurement studies. Results suggest that the substituent on terpyridine ligand affects the binding mode and binding ability of the complexes. Effect of time and ionic strength on DNA cleavage ability of complex has also been studied by gel electrophoresis. Results suggest that more than 200 mM concentration of NaCl decreases the cleavage ability of complex.
- Patel, Mohan N.,Gandhi, Deepen S.,Parmar, Pradhuman A.
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experimental part
p. 243 - 248
(2011/12/03)
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- DNA interaction, free radical scavenging and in-vitro antibacterial activity of drug-based copper(II) complexes
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The Cu(II) complexes of type [Cu(cpf)(An)Cl] (An = terpyridines, cpf = ciprofloxacin) were synthesized and characterized using IR, mass and reflectance spectra. The free ligands and their complexes were evaluated for their in-vitro antimicrobial activity against a panel of Gram-positive and Gram-negative bacteria. The complexes exhibit better or equal inhibition in comparison to free fluoroquinolones. Binding interactions of the complexes with calf thymus (CT DNA) were investigated by absorption titration, viscosity studies and DNA melting temperature experiment. The cleavage reaction on pUC19 DNA was monitored by agarose gel electrophoresis. The lower concentration of the complexes was catalysed the dismutation of superoxide radical at biological pH, which indicates that the complexes can act as a possible model for superoxide dismutase. Copyright
- Patel, Mohan N.,Dosi, Promise A.,Bhatt, Bhupesh S.
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experimental part
p. 653 - 660
(2012/02/03)
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- High turnover remote catalytic oxygenation of alkyl groups: How steric exclusion of unbound substrate contributes to high molecular recognition selectivity
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H-bonding mediated molecular recognition between substrate and ligand -COOH groups orients the substrate so that remote, catalyzed oxygenation of an alkyl C-H bond by a Mn-oxo active site can occur with very high (>98%) regio- and stereoselectivity. This paper identifies steric exclusion - exclusion of non H-bonded substrate molecules from the active site - as one requirement for high selectivity, along with the entropic advantage of intramolecularity. If unbound substrate molecules were able to reach the active site, they would react unselectively, degrading the observed selectivity. Both of the faces of the catalyst are blocked by two ligand molecules each with a -COOH group. The acid p-tBuC6H4COOH binds to the ligand -COOH recognition site but is not oxidized and merely blocks approach of the substrate therefore acting as an effective inhibitor for ibuprofen oxidation in both free acid and ibuprofen ester form. Dixon plots show that inhibition is competitive for the free acid ibuprofen substrate, no doubt because this substrate can compete with the inhibitor for binding to the recognition site. In contrast, inhibition is uncompetitive for the ibuprofen-ester substrate, consistent with this ester substrate no longer being able to bind to the recognition site. Inhibition can be reversed with MeCOOH, an acid that can competitively bind to the recognition site but, being sterically small, no longer blocks access to the active site.
- Das, Siddhartha,Brudvig, Gary W.,Crabtree, Robert H.
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p. 1628 - 1637
(2008/09/18)
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- Diverse synthesis of novel bisterpyridines via Suzuki-type cross-coupling
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A new protocol is presented for the synthesis of novel bisterpyridine derivatives using palladium-catalyzed Miyaura- and Suzuki-type cross-couplings as the key reactions. This protocol is quick, efficient, mild, and broadly applicable for the construction of versatile bisterpyridines by symmetric and unsymmetric introduction of various substituants in the pyridine rings as well as by tuning the spacers for bridging the two terpyridine moieties.
- Fu, She Han,Higuchi, Masayoshi,Kurth, Dirk G.
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p. 559 - 562
(2007/10/03)
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- Kr?hnke reaction in aqueous media: one-pot clean synthesis of 4′-aryl-2,2′:6′,2″-terpyridines
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A clean aqueous Kr?hnke reaction process has been accomplished via a one-pot procedure of 2-acetylpyridine with aromatic aldehyde and ammonium acetate under microwave irradiation or conventional heating conditions. This method is convenient, economic and environmental friendly.
- Tu, Shujiang,Jia, Runhong,Jiang, Bo,Zhang, Junyong,Zhang, Yan,Yao, Changsheng,Ji, Shunjun
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p. 381 - 388
(2007/10/03)
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- A green and straightforward synthesis of 4′-substituted terpyridines
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A set of 4′-substituted 2,2′:6′,2″-terpyridines has been synthesized in a one-pot procedure under environmentally friendly reaction conditions using PEG and aqueous ammonia as solvents. This procedure features a short synthetic route, short reaction times, easy work-up, and good yields in comparison to conventional methods. The crystallographic data reveal the influence of the 4′-aryl substituent on the molecular structure and π-stacking behavior of the respective terpyridines. Georg Thieme Verlag Stuttgart.
- Winter, Andreas,Van Den Berg, Antje M. J.,Hoogenboom, Richard,Kickelbick, Guido,Schubert, Ulrich S.
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p. 2873 - 2878
(2008/02/05)
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- An efficient improve for the kroehnke reaction: One-pot synthesis of 2,4,6-triarylpyridines using raw materials under microwave irradiation
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A series of 2,4,6-triarylpyridines have been prepared by the one-pot reaction of aldehydes with aromatic ketones in the presence of ammonium acetate under microwave irradiation without catalyst. This method has the advantage of easier workup, shorter reaction time, higher yield, and environment-friendly. Copyright
- Tu, Shujiang,Li, Tuanjie,Shi, Feng,Fang, Fang,Zhu, Songlei,Wei, Xianyong,Zong, Zhimin
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p. 732 - 733
(2007/10/03)
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- A convenient one-pot synthesis of 4′-aryl-2,2′:6′, 2″-terpyridines and 2,4,6-triarylpyridines under microwave irradiation
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A series of 4′-aryl-2,2′:6′,2″-terpyridines have been prepared by the one-pot reaction of 2-acetylpyridine with aromatic aldehydes in the presence of ammonium acetate under microwave irradiation. This method has the advantages of shorter route, easier workup, shorter reaction time, higher yield and more environmentally friendly conditions, compared to the conventional ones. Georg Thieme Verlag Stuttgart.
- Tu, Shujiang,Li, Tuanjie,Shi, Feng,Wang, Qian,Zhang, Jinpeng,Xu, Jianing,Zhu, Xiaotong,Zhang, Xiaojing,Zhu, Songlei,Shi, Daqing
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p. 3045 - 3050
(2007/10/03)
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- A facile route to sterically hindered and non-hindered 4′-aryl-2, 2′:6′,2″-terpyridines
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A facile one-pot synthesis of 4′-aryl-2,2′:6′,2″- terpyridines from aryl aldehydes and 2-acetylpyridine is presented. The synthesis of terpyridines incorporating sterically hindered aryl groups, such as the 9-anthryl group, can also be readily synthesized using this method.
- Wang, Jianhua,Hanan, Garry S.
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p. 1251 - 1254
(2007/10/03)
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- The synthesis of 4′-aryl substituted terpyridines by Suzuki cross-coupling reactions: Substituent effects on ligand fluorescence
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Several 4′-aryl-substituted 2,2′:6′,2″-terpyridines (tpy-C6H4R) have been prepared by palladium-catalysed cross-coupling of 4′-bromoterpyridine or 4′-triflate-terpyridine (triflate = trifluoromethylsulfonyloxy) with aryl boronic acids or esters, RC6H4B(OR′)2 (R = H, m-NH2, p-CHO, -NO2, -CN, -NMe2, -NPh2). The new ligand 4′-mesityl-terpyridine (mesityl = 2,4,6-trimethylphenyl) was prepared in the same way. Similarly, 4′-bromophenylterpyridine (tpy-φ-Br) has been cross-coupled with aryl halides to generate several new biaryl-substituted terpyridines (tpy-φ-C6H4R where R = H, p-CN, NMe2, NPh2), together with two related compounds with pendent 3- or 4-pyridyl groups (tpy-φ-C6H4-py). For selected compounds, the alternative coupling strategy of reaction of a terpyridine-4-boronate or terpyridine-4-phenylboronate with the appropriate aryl halide has also been investigated (e.g. to prepare tpy-φ-C6H4NO2), but was generally found to be less satisfactory. All of the compounds are fluorescent in the UV region of the spectrum, the biaryl-substituted compounds being only slightly red-shifted compared to the monoaryl systems, but with the further red-shift that accompanies protonation being more significant for the former. Fluorescence lifetimes in solution are in the range 1-5 ns. The emission spectra of the aminobiphenyl-substituted compounds (tpy-φ-C6H4NR″2, where R″ = Me or Ph) display a large red-shift with increasing solvent polarity, suggesting the involvement of an intramolecular charge transfer state, as found previously for the two analogues omitting the phenyl ring (tpy-C6H4NR″2). In contrast to the latter, however, protonation or binding of a Lewis acidic metal ion to the aminobiphenyl compounds serves to quench almost completely their emission.
- Goodall, Wendy,Wild, Kerstin,Arm, Kathryn J.,Williams, J.A. Gareth
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p. 1669 - 1681
(2007/10/03)
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- Efficient synthesis of pyridines via a sequential solventless aldol condensation and Michael addition
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The synthesis of pyridines was conducted by using a sequential solventless aldol condensation and Michael addition. The conventional synthesis of enones from a benzaldehyde and an aryl ketone involved the synthesis of the enolate by solubilizing the ketone in a basic alcohol solution. The result showed that the aldol condensation of an enolisable ketone and a benzaldehyde followed by Michael addition of the enone with a second enolisable ketone under solvent free conditions lead to the quantitative formation of diketone.
- Cave, Gareth W. V.,Raston, Colin L.
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p. 3258 - 3264
(2007/10/03)
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- Synthesis, topoisomerase I inhibition and antitumor cytotoxicity of 2,2′:6′,2″-, 2,2′:6′,3″- and 2,2′:6′,4″-terpyridine derivatives
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For the development of new anticancer agents, 2,2′:6′,2″-, 2,2′:6′,3″- and 2,2′:6′,4″-terpyridine derivatives were designed and evaluated for their topoisomerase I inhibitory activity and antitumor cytotoxicity. Structure-activity relationship studies indicated that 2,2′:6′,2″-terpyridine derivatives were highly cytotoxic toward several human tumor cell lines, whereas 2,2′:6′,3″- and 2,2′:6′,4″-terpyridine derivatives were potent topoisomerase I inhibitors.
- Zhao, Long-Xuan,Kim, Tae Sung,Ahn, Soo-Hyun,Kim, Tae-Hyung,Kim, Eun-kyung,Cho, Won-Jea,Choi, Heesung,Lee, Chong-Soon,Kim, Jung-Ae,Jeong, Tae Cheon,Chang, Ching-jer,Lee, Eung-Seok
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p. 2659 - 2662
(2007/10/03)
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