Showing papers by "Rosario Scopelliti published in 2015"
TL;DR: In this paper, the authors showed that large Pd6L1212+ cages can be obtained by reaction of Pd(II) salts with metallo-ligands bearing terminal 3-pyridyl groups.
Abstract: Ditopic N-donor ligands with terminal 4-pyridyl groups are omnipresent in coordination-based self-assembly. The utilization of ligands with 3-pyridyl donor groups is significantly less common, because the intrinsic conformational flexibility of these ligands tends to favor the formation of small aggregates. Here, we show that large Pd6L1212+ cages can be obtained by reaction of Pd(II) salts with metallo-ligands L bearing terminal 3-pyridyl groups. The easy-to-access metallo-ligands contain an Fe(II) clathrochelate core. These sterically demanding clathrochelate complexes prevent the formation of smaller aggregates, which is observed for less bulky analogous building blocks. The cages were shown to bind BF4− and BPh4− anions in aqueous solvent mixtures, whilst the lateral size of the clathrochelate significantly affects their guest encapsulation behavior.
95 citations
TL;DR: In the new derivatives, the p-cymene ring and/or the chloride ligands are substituted by other ligands to modulate the steric bulk or aquation kinetics.
Abstract: Following the identification of [Ru(η6-p-cymene)Cl2(1H,1H,2H,2H-perfluorodecyl-3-(pyridin-3-yl)propanoate)], a ruthenium(II)–arene complex with a perfluoroalkyl-modified ligand that displays remarkable in vitro cancer cell selectivity, a series of structurally related compounds were designed In the new derivatives, the p-cymene ring and/or the chloride ligands are substituted by other ligands to modulate the steric bulk or aquation kinetics The new compounds were evaluated in both in vitro (cytotoxicity and migration assays) and in vivo (chicken chorioallantoic membrane) models and were found to exhibit potent antivascular effects
95 citations
TL;DR: The change of the symmetry from (a higher) C3 to (a lower) C1 alters the Luminescence spectrum, shortens the radiative lifetime, and increases the luminescence efficiency of the europium complexes.
Abstract: Homoleptic mononuclear nine-coordinate lanthanum(III) and europium(III) tris-complexes [Ln(N∧N∧O)3]·nH2O with two tridentate N-benzylbenzimidazole pyridine-2-carboxylates exhibit a rare C3-symmetry of the lanthanide coordination polyhedron in the solid state, as confirmed by luminescence spectroscopy and by X-ray crystallography (the three N∧N∧O ligands are arranged “up–up−up” around the lanthanide ion). The symmetry, however, is changed to the more common C1 upon dissolution of the complexes in dichloromethane, as revealed by luminescence spectroscopy (the three ligands are likely to be arranged “up–up–down”). The new europium complexes emit efficient ligand-sensitized metal-centered luminescence with excited-state lifetimes of 1.56–2.18 ms and quantum yields of 25–41% in the solid and in solution. The change of the symmetry from (a higher) C3 to (a lower) C1 alters the luminescence spectrum, shortens the radiative lifetime, and increases the luminescence efficiency of the europium complexes.
84 citations
TL;DR: In this paper, several Fe(II) complexes supported by a 2,6-bis(phosphinito)pyridine ligand (PONOP) have been synthesized.
69 citations
TL;DR: The design and development of a new nickel pincer complex that catalyzes the direct coupling of primary alkyl halides with terminal alkynes at room temperature is described, which has a good substrate scope and high functional group tolerance.
Abstract: Direct coupling of alkyl halides with terminal alkynes provides an efficient and streamlined access to alkyl-substituted alkynes, which are important synthetic intermediates, biologically active molecules, and organic materials. However, until now,there have been fewer than a handful of catalytic methods available for this reaction, and detailed mechanistic studies have not been reported. Herein, we describe the design and development a new nickel pincer complex that catalyzes the direct coupling of primary alkyl halides with terminal alkynes at room temperature. The catalysis has a good substrate scope and high functional group tolerance. Kinetic data suggest that the new pincer ligand is hemilabile, and the dissociation of a labile amine donor is the turnover-determining step of the catalysis. An intermediate Ni-alkynyl species has been isolated and structurally characterized. The reactivity of this species gives insight into the nature of the active species for the activation of alkyl halide.
66 citations
TL;DR: With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma cells and also to non-tumorigenic human embryonic kidney cells, but lack the cancer cell selectivity observed for related arene ruthenium(II) complexes.
Abstract: A series of half-sandwich cyclopentadienyl rhodium(III) and iridium(III) complexes of the type [Cp*M(curc/bdcurc)Cl] and [Cp*M(curc/bdcurc)(PTA)][SO3CF3], in which Cp* = pentamethylcyclopentadienyl, curcH = curcumin and bdcurcH = bisdemethoxycurcumin as O^O-chelating ligands, and PTA = 1,3,5-triaza-7-phosphaadamantane, is described. The X-ray crystal structures of three of the complexes, i.e. [Cp*Rh(curc)(PTA)][SO3CF3] (5), [Cp*Rh(bdcurc)(PTA)][SO3CF3] (6) and [Cp*Ir(bdcurc)(PTA)][SO3CF3] (8), confirm the expected "piano-stool" geometry. With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma (A2780 and A2780cisR) cells and also to non-tumorigenic human embryonic kidney (HEK293) cells, but lack the cancer cell selectivity observed for related arene ruthenium(II) complexes.
53 citations
TL;DR: In this article, a bis(oxazolinylphenyl)amido pincer ligand (Bopa) was applied to stabilize the catalytically active Fe center, resulting in isolation and characterization of well-defined iron complexes whose catalytic roles have been probed and confirmed.
51 citations
TL;DR: NMR spectroscopy and single-crystal X-ray diffraction show that extensive interactions between the imidazolium cation and the resulting polyiodide anion are present, which have the net effect of lengthening, polarizing, and weakening the I-I bonds in the anion.
Abstract: Ionic liquids doped with I2, usually resulting in the formation of polyiodide anions, are extensively used as electrolytes and in iodination reactions. Herein, NMR spectroscopy and single-crystal X-ray diffraction were used to rationalize the structures of imidazolium-based polyiodide ionic liquids in the liquid and solid states. Combined, these studies show that extensive interactions between the imidazolium cation and the resulting polyiodide anion are present, which have the net effect of lengthening, polarizing, and weakening the I–I bonds in the anion. This bond weakening rationalizes the high conductivity and reactivity of ionic liquids doped with I2.
39 citations
TL;DR: A series of cationic iridium(III) complexes with two carbene-based cyclometalating ligands and five different N^N bipyridine and 1,10-phenanthroline ancillary ligands is presented, suggesting promising potential for optoelectronic applications.
Abstract: A series of cationic iridium(III) complexes with two carbene-based cyclometalating ligands and five different N^N bipyridine and 1,10-phenanthroline ancillary ligands is presented. For the first time—in the frame of a rarely studied class of bis(heteroleptic) iridium complexes with two carbene-based cyclometalating ligands—a pair of cis and trans isomers has been isolated. All complexes (trans-1–5 and cis-3) were characterized by 1H NMR, 13C NMR, 31P NMR, and HRMS (ESI-TOF); in addition, crystal structures of cis-3 and trans-4 are reported and discussed. Cyclic voltammetric studies show that the whole series exhibits highly reversible oxidation and reduction processes, suggesting promising potential for optoelectronic applications. Ground-state DFT and TD-DFT calculations nicely predict the blue shift experimentally observed in the room-temperature absorption and emission spectra of cis-3, compared to the trans complexes. In CH3CN, cis-3 displays a 4-fold increase in photoluminescence quantum yield (PLQY)...
37 citations
TL;DR: This work quantified three types of CAHBs in both the condensed and gas phases for 1-(2'-hydroxylethyl)-3-methylimidazolium acetate ([C2OHmim][OAc]).
Abstract: Charge-assisted hydrogen bonds (CAHBs) play critical roles in many systems from biology through to materials. In none of these areas has the role and function of CAHBs been explored satisfactorily because of the lack of data on the energy of CAHBs in the condensed phases. We have, for the first time, quantified three types of CAHBs in both the condensed and gas phases for 1-(2'-hydroxylethyl)-3-methylimidazolium acetate ([C(2)OHmim][OAc]). The energy of conventional OH center dot center dot center dot[OAc](-) CAHBs is similar to 10 kcal. mol(-1), whereas nonconventional C(sp2)H center dot[OAc](-) and C(sp3)H center dot center dot center dot[OAc](-) CAHBs are weaker by similar to 5-7 kcal.mol(-1). In the gas phase, the strength of the nonconventional CAHBs is doubled, whereas the conventional CAHBs are strengthened by <20%. The influence of cooperativity effects on the ability of the [OAc](-) anion to deprotonate the imidazolium cation is evaluated. The ability to quantify CAHBs in the condensed phase on the basis of easier accessible gas-phase estimates is highlighted.
36 citations
TL;DR: Preliminary reactivity studies show that whereas the bis-TPA complexes of Eu (2+) and Yb(2+) do not show any reactivity with heteroallenes, the [Eu(BPA)2 ] complex reduces CS2 to afford the first example of a lanthanide trithiocarbonate complex.
Abstract: The preparation and characterization of a series of complexes of the Yb and Eu cations in the oxidation state II and III with the tetradentate N,O-donor tripodal ligands (tris(2-pyridylmethyl)amine (TPA), BPA(-) (HBPA=bis(2-pyridylmethyl)(2-hydroxybenzyl)amine), BPPA(-) (HBPPA=bis(2-pyridylmethyl)(3.5-di-tert-butyl-2-hydroxybenzyl)amine), and MPA(2-) (H(2)MPA=(2-pyridylmethyl)bis(3.5-di-tert-butyl-2-hydroxybenzyl)amine) is reported. The X-ray crystal structures of the heteroleptic Ln(2+) complexes [Ln(TPA)I-2] (Ln=Eu, Yb) and [Yb(BPA)I(CH3CN)](2), of the Ln(2+) homoleptic [Ln(TPA)(2)]I-2 (Ln=Sm, Eu, Yb) and [Eu(BPA)(2)] complexes, and of the Ln(3+) [Eu(BPPA)(2)]OTf and [Yb(MPA)(2)K(dme)(2)] (dme=dimethoxyethane) complexes have been determined. Cyclic voltammetry studies carried out on the bis-ligand complexes of Eu3+ and Yb3+ show that the metal center reduction occurs at significantly lower potentials for the BPA(-) ligand as compared with the TPA ligand. This suggests that the more electron-rich character of the BPA(-) ligand results in a higher reducing character of the lanthanide complexes of BPA(-) compared with those of TPA. The important differences in the stability and reactivity of the investigated complexes are probably due to the observed difference in redox potential. Preliminary reactivity studies show that whereas the bis-TPA complexes of Eu2+ and Yb2+ do not show any reactivity with heteroallenes, the [Eu(BPA)(2)] complex reduces CS2 to afford the first example of a lanthanide trithiocarbonate complex.
TL;DR: Three bifunctional organometallic osmium(II)‐p‐cymene complexes functionalized with alkyl or perfluoroalkyl groups display selectivity toward cancer cells, with moderate cytotoxicity observed against human ovarian carcinoma cells, whereas no cytot toxicity was observed on non‐cancerous human embryonic kidney cells and human endothelial cells.
Abstract: Osmium compounds are attracting increasing attention as potential anticancer drugs. In this context, a series of bifunctional organometallic osmium(II)-p-cymene complexes functionalized with alkyl or perfluoroalkyl groups were prepared and screened for their antiproliferative activity. Three compounds from the series display selectivity toward cancer cells, with moderate cytotoxicity observed against human ovarian carcinoma (A2780) cells, whereas no cytotoxicity was observed on non-cancerous human embryonic kidney (HEK-293) cells and human endothelial (ECRF24) cells. Two of these three cancer-cell-selective compounds induce cell death largely via apoptosis and were also found to disrupt vascularization in the chicken embryo chorioallantoic membrane (CAM) model. Based on these promising properties, these compounds have potential clinical applications.
TL;DR: A heterometallic Pt2Cu2-macrocycle which behaves as a molecular hinge is described which folds up to adopt a butterfly-like geometry in which the Pt centers approach each other.
Abstract: The ability to modify the structure of nanoscopic assemblies in a controlled fashion is an important prerequisite for the creation of functional supramolecular systems. Here, we describe a heterometallic Pt2Cu2-macrocycle which behaves as a molecular hinge. A square-planar Pt(II) complex with pendent 2-formylpyridine groups was synthesized and structurally characterized. Condensation of the complex with benzylamine followed by reaction with Cu(MeCN)4BF4 resulted in the formation of a rectangular Pt2Cu2-macrocycle. Upon chemical oxidation of the Cu centers, the macrocycle folds up to adopt a butterfly-like geometry in which the Pt centers approach each other. This process can be reversed by chemical reduction.
TL;DR: In this article, a new Methode zur Synthese of Triazenen is presented, i.e., Distickstoffmonoxid (N2O, “Lachgas”), which vermittelt the Kupplung von Lithiumamiden and Organomagnesiumverbindungen, wahrend es selbst als Stickstoffdonor.
Abstract: Triazene sind wertvolle Verbindungen in der organischen Chemie, fur die eine Vielzahl an Anwendungen dokumentiert ist. Ferner wurden Triazene ausgiebig als potenzielle Antitumorwirkstoffe getestet. Hier beschreiben wir eine neue Methode zur Synthese von Triazenen. Das Verfahren nutzt ein Reagens, das selten in der organischen Synthese verwendet wird: Distickstoffmonoxid (N2O, “Lachgas”). N2O vermittelt die Kupplung von Lithiumamiden und Organomagnesiumverbindungen, wahrend es selbst als Stickstoffdonor dient. Trotz des hochst inerten Charakters des Distickstoffmonoxids konnen die Reaktionen in Losung unter milden Bedingungen durchgefuhrt werden. Ein wesentlicher Vorteil der neuen Methode ist der Zugang zu Triazenen mit Alkenyl- und Alkinylsubstituenten. Diese Verbindungen sind mit herkommlichen Verfahren nur schwer erhaltlich, da die benotigten Ausgangsstoffe instabil sind. Einige der neuen Alkinyltriazene zeigten eine hohe Zytotoxizitat in Untersuchungen an Eierstock- und Brustkrebszellen in vitro.
TL;DR: The chlorendylimidyl moiety is introduced as a new temporary protecting group for the straightforward large-scale synthesis of protected quarter-, sexi-, octathiophene, and perylene bisimide diamine and dicarboxylic acid derivatives.
Abstract: Functional π-conjugated molecules are relevant for the preparation of new organic electronic materials with improved performance. However, their synthesis is often rendered difficult by their inherently low solubility, and the permanent attachment of solubilizing groups may change the properties of the material. Here, we introduced the chlorendylimidyl moiety as a new temporary protecting group for the straightforward large-scale synthesis of protected quarter-, sexi-, octathiophene, and perylene bisimide diamine and dicarboxylic acid derivatives. The obtained chlorendylimides and chlorendylimidyl active esters were highly soluble in organic solvents, and optical spectroscopy confirmed the low tendency of the compounds to aggregate in solution. At the same time, they could be conveniently purified by recrystallization or precipitation. Single-crystal X-ray structures obtained for most compounds showed supramolecular motifs highlighting the role of the rigid, polychlorinated chlorendyl moieties in their crystallization. The obtained protected diamine and dicarboxylic acid derivatives were easily deprotected and converted into various amide-substituted oligothiophenes and perylene bisimides that are of interest as new functional materials for organic electronic thin film or nanowire devices.
TL;DR: Correction for ‘Pattern-based sensing of aminoglycosides with fluorescent amphiphiles’ by Ziya Köstereli et al., Chem.
Abstract: Correction for ‘Pattern-based sensing of aminoglycosides with fluorescent amphiphiles’ by Ziya Kostereli et al., Chem. Sci., 2014, 5, 2456–2460.