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The similar reactivity of lanthanides generally leads to statistically populated polynuclear complexes, making the rational design of ordered hetero-lanthanide compounds extremely challenging. Here we report on the site selectivity in hetero-lanthanide tetranuclear complexes afforded by the relatively simple ditopic pyterpyNO ligand (4'-(4-pyridil)-2,2':6',2"-terpyridine N-oxide). The sequential room temperature reaction of RE

A family of homodinuclear Ln3+ (Ln3+ = Gd3+, Eu3+) luminescent complexes with the general formula [Ln2(β-diketonato)6(N-oxide)y] has been developed to study the effect of the β-diketonato and N-oxide ligands on their thermometric properties. The investigated complexes are [Ln2(tta)6(pyrzMO)2] (Ln = Eu (1·C7H8), Gd (5)), [Ln2(dbm)6(pyrzMO)2] (Ln = Eu (2), Gd (6)), [Ln2(bta)6(pyrzMO)2] (Ln = Eu (3), Gd (7)), [Ln2(hfac)6(pyrzMO)3] (Ln = Eu (4), Gd (8)) (pyrzMO = pyrazine N-oxide, Htta = thenoyltrifluoroacetone, Hdbm = dibenzoylmethane, Hbta = benzoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone, C7H8 = toluene), and their 4,4′-bipyridine N-oxide (bipyMO) analogues. Europium complexes emit a bright red light under UV radiation at room temperature, whose intensity displays a strong temperature (T) dependence between 223 and 373 K. This remarkable variation is exploited to develop a series of luminescent thermometers by using the integrated intensity of the 5D0 → 7F2 europium transition as the thermometric parameter (Δ). The effect of different β-diketonato and N-oxide ligands is investigated with particular regard to the shape of thermometer calibration (Δ vs T) and relative thermal sensitivity curves: i.e.. the change in Δ per degree of temperature variation usually indicated as Sr (% K–1). The thermometric properties are determined by the presence of two nonradiative deactivation channels, back energy transfer (BEnT) from Eu3+ to the ligand triplet levels and ligand to metal charge transfer (LMCT). In the complexes bearing tta and dbm ligands, whose triplet energy is ca. 20000 cm–1, both deactivation channels are active in the same temperature range, and both contribute to determine the thermometric properties. Conversely, with bta and hfac ligands the response of the europium luminescence to temperature variation is ruled by LMCT channels since the high triplet energy (>21400 cm–1) makes BEnT ineffective in the investigated temperature range., A family of homodinuclear Eu3+ luminescent complexes with the general formula [Ln2(β-diketonato)6(N-oxide)y] (y = 2, 3) was developed to study the effect of the β-diketonato and N-oxide ligands on the thermometric properties of the complexes. In this way, an effective tuning of the system’s thermometric properties can be achieved.

Mononuclear rare-earth tris-β-diketonato complexes RE(tta)

Two homometallic Coordination Polymers (CPs) with composition [Ln(hfac)3bipy]n (Ln3+ = Eu3+, 1, and Tb3+, 2, hfac = hexafluoroacetylacetonato, bipy = 4,4′-bipyridine) were used to develop a family of ratiometric luminescent thermometers containing Eu3+ and Tb3+ as red and green emitters, respectively. The thermometric properties of pure CPs and of their mixtures having an Eu3+/Tb3+ molar ratio of 1:1, 1:3, 1:5, and 1:10 (samples: Eu1Tb1, Eu1Tb3, Eu1Tb5, and Eu1Tb10) were studied in the 83–383 K temperature range. Irrespective of the chemical composition, we observed similar thermometric responses characterized by broad applicative temperature ranges (from 100 to 165 K wide), and high relative thermal sensitivity values (Sr), up to 2.40% K−1, in the physiological temperature range (298–318 K). All samples showed emissions endowed with peculiar and continuous color variation from green (83 K) to red (383 K) that can be exploited to develop a colorimetric temperature indicator. At fixed temperature, the color of the emitted light can be tuned by varying composition and excitation wavelength.

Resistance to platinum‐based anticancer drugs represents an important limit for their clinical effectiveness and one of the most important field of investigation in the context of platinum compounds. From our previous studies, PtII complexes containing the triphenylphosphino moiety have been emerging as promising agents, showing significant cytotoxicity to resistant ovarian carcinoma cells. Two brominated triphenylphosphino trans‐platinum derivatives were prepared and evaluated on human tumor cell lines, sensitive and resistant to cisplatin. The new complexes exert a notable antiproliferative effect on resistant ovarian carcinoma cells, showing a remarkable intracellular accumulation and the ability to interact with different intracellular targets. The interaction with DNA, the collapse of mitochondrial transmembrane potential, and the impairment of intracellular redox state were demonstrated. Moreover, a selectivity towards the selenocysteine of thioredoxin reductase was observed. The mechanism of action is discussed with regard to the resistance phenomenon in ovarian carcinoma cells., Increase targets, decrease resistance: Two new brominated trans‐PtII complexes show an interesting cytotoxicity on ovarian carcinoma resistant cells. Study of the mechanism of action reveals the ability to affect different biomolecular targets: interaction with DNA, inhibition of thioredoxin reductase and impairment of mitochondria were demonstrated.

Despite the generally accepted inertness of platinum(IV) complexes towards nucleophilic substitution, the title compound promptly reacts with nucleophiles L (L = pyridine, quinoline, isoquinoline, benzothiazole, o-, m-, p-toluidine) affording the corresponding acetonitrile substitution products. To follow the reaction spectroscopically, a series of platinum(IV) standards were prepared by bridge splitting of trans-[Pt(μ-Cl)Cl(PPh3)]2, followed by oxidation by PhICl2. All the new platinum(II) and platinum(IV) complexes were fully characterized, and, in some cases, the structure was studied by single crystal X-ray diffraction. Even when protic o-, m- and p-toluidines were used, chemoselectivity towards substitution was observed, with addition products formed in less than 10% extent.

A series of iminopyridine complexes of platinum(II), bearing a flexible diethereal, aryl terminated residue, where the size of aryl group is varied from phenyl to 9-anthracenyl, was synthesized. The new complexes are soluble and stable in DMSO/H2O mixtures. Besides the metal center, aryl groups are available for further interactions with DNA, due to the good side chain flexibility. The new aryl functionalized iminopyridine dichlorido platinum(II) complexes show a significant antiproliferative activity on ovarian carcinoma cells and notably, complex 13 is able to overcome cisplatin resistance. The study of the interaction mode of 13 with DNA highlighted the ability to form a molecular complex characterized by a dual (intercalative and groove binding) geometry. The complex is also able to covalently add to DNA even though interstrand cross-links appear significantly hampered with respect to cisplatin. The interactions with the macromolecule are discussed in view of the observed cell effect.

Single-crystal-to-single-crystal post-synthetic modifications (PSMs) of Lanthanide Organic Frameworks (LOFs) {[Ln2(H2L)3(DMF)4]·2DMF}n (Ln = Gd, 1 and Eu, 2; H4L = 2,5-dihydroxyterephthalic acid; DMF = dimethylformamide), carried out by treatment with (a) chloroform or (b) an imidazole solution in chloroform, yielded respectively isostructural {[Ln2(H2L)3(DMF)4]·CHCl3}n (Ln = Gd, 3; Eu, 4) or {[Ln2(H2L)3(Im)4][Ln2(H2L)3(Im)2(H2O)2]·6Im·2CHCl3}n (Ln = Gd, 5; Eu, 6). Single crystal X-ray diffraction studies of 5 showed two different regularly alternating dimeric units in the LOF and two regularly alternating cavities with different guest molecules. All compounds revert to the parent LOF, 1 or 2, when treated with DMF at 90 °C for 8 h. Europium-LOFs (2, 4 and 6) showed a faint red emission that progressively gained intensity upon cooling from RT to liquid nitrogen temperature. This behaviour was exploited to develop a family of luminescent thermometers whose characteristics were affected by the structural and coordinative modifications induced by PSMs.

New pyridinimino complexes of platinum(II) [PtCl2(N^N-R)] (N^N = 2-pyridylmethanimino, R = -(CH2)2O(CH2)2OH, -(CH)2O(CH2)2OCH2Pyr), Pyr = pyren-1-yl) have been prepared. They are characterized by a dioxygenated alkyl side chain and, in one case, by a fluorescent terminal 1-pyrenyl residue. The complexes were characterized by elemental analysis, IR, 1H–, 13C–and 195Pt NMR spectroscopies. For [PtCl2(N^N-(CH2)2O(CH2)2OH] the molecular structure was determined by single crystal X-ray diffraction. The complexes are soluble and stable in DMSO/H2O (80/20, v/v). The pyrenyl terminated compound was tested as antiproliferative agent against selected human cancer cell lines. Comparable cytotoxic effect was obtained on human ovarian carcinoma A-2780 and A-2780cis cells, thus suggesting a certain ability to circumvent cisplatin resistance. The interaction of this complex with DNA was investigated by linear flow dichroism and by spectrophotometric (absorbance and fluorescence) titrations. Both techniques enlightened the presence of a complex mode of interaction with DNA, involving both groove binding and intercalation.

Neutral complexes with generic formula [PtCl2(PPh3)(L)] were efficiently oxidized to [PtCl4(PPh3)(L)] (L = dibenzylamine, p-toluidine, diethanolamine, pyridine and acetonitrile) using PhICl2 The anionic complex [TBA][PtCl3(PPh3)] (TBA = Tetrabutylammonium) was also oxidized to [TBA][PtCl5(PPh3)] with this method. The obtained products were fully characterized by 1H, 13C, 31P and 195Pt NMR, IR-ATR spectroscopy, elemental analysis and, for complexes cis-([PtCl4(PPh3)(p-toluidine)]·CHCl3 and trans-[PtCl4(PPh3)(NCCH3)]·CH3CN, also by single crystal X-ray diffraction.

[Y(O 2 CNBu 2 ) 3 ], has been prepared by extraction of the Y 3+ ions from aqueous solution into heptane by the NHBu 2 /CO 2 system. Exhaustive hydrolysis of [Y(O 2 CNBu 2 ) 3 ] produced the yttrium carbonate [Y 2 (CO 3 ) 3 ⋅n H 2 O] (n = 2–3), that was converted to Y 2 O 3 by thermal treatment at 550 °C for 12 h. The exhaustive hydrolysis of [Y(O 2 CNBu 2 ) 3 ] and [Al(OBu) 3 ] (Y/Al molar ratio = 3/5) carried out at room temperature yielded an intermediate mixed carbonate, that, upon heating at 950 °C for 12 h, was converted to Y 3 Al 5 O 12 . The exhaustive hydrolysis of [Y(O 2 CNBu 2 ) 3 ] and [Al(OBu) 3 ] was repeated in the presence of [Nd(O 2 CNBu 2 ) 3 ] (Nd/Y molar ratio = 0.07;(Nd + Y)/Al molar ratio = 3:5). The neodymium doped garnet Nd:Y 3 Al 5 O 12 was obtained, through the intermediate formation of a mixed hydroxo-carbonate. For comparison, the neodymium doped garnet was prepared also starting from N,N -dialkylcarbamato complexes of all three metals, [Y(O 2 CNBu 2 ) 3 ], [Nd(O 2 CNBu 2 ) 3 ] and [Al 2 (O 2 CN i Pr 2 ) 6 ] (Nd/Y molar ratio = 0.07;(Nd + Y)/Al molar ratio = 3:5). Also in this case the intermediate mixed hydroxo-carbonate, after heating at 950 °C for 12 h, evolved to Nd:Y 3 Al 5 O 12 . FTIR, XRD, SEM, TGA measurements were used for the characterization of the obtained materials. Preliminary studies of the photoluminescent emission properties were carried out on Nd:Y 3 Al 5 O 12 . Photoluminescence dynamics have been investigated by means of femtosecond laser pulses and nanosecond temporal resolution up to the millisecond range after excitation. All the luminescence traces have shown a decay time of the order 200 microseconds indicating its potential as a laser medium for infrared emission at 1064 nm.

Exhaustive hydrolysis of a mixture of [La4(CO3)(O2CNBu2)10] and [Cu(O2CNBu2)(py∗)2] (py∗ = 4-dimethylamino pyridine) in molar ratio 1/2 corresponding to a La/Cu molar ratio 2/1 was carried out in toluene at room temperature. The carbamato derivatives of lanthanum and copper can be easily prepared by extraction of the metal ions from aqueous solution into heptane by the NHBu2/CO2 system, according to a method previously reported. The copper precursor was selected amongst a number of derivatives in respect of its easy tractability. The tetragonal modification T′ of La2CuO4 was obtained by treatment at 600 °C of the intermediate mixed carbonate. The thermal treatment of T′-La2CuO4 at 850 °C, followed by cooling down to room temperature, afforded the orthorhombic modification of the mixed oxide.

Red crystals of [TBA]2[Pt5Cl20] were obtained by reacting [TBA]2[PtCl6] with an excess of AlCl3 at room temperature in CH2Cl2. The salt [PPN]2[Pt5Cl20] containing the same anion was prepared by reaction of platinum tetrachloride with a small excess of [PPN]Cl in 1,2-dichloroethane at room temperature. Single crystal X-Ray diffraction studies confirmed that both species contained the mixed-valence [Pt5Cl20]2− anion with two dinuclear platinum(IV) Pt2Cl10 fragments organized around a central square planar platinum(II) in a chair arrangement.

A sound synthetic procedure for the preparation of trans‐[PtBr(µ‐Br)(PPh3)]2 is described. The species was fully characterized and used to obtain [PtBr2(PPh3)(L)] complexes (L = DMSO, p‐toluidine, pyridine) by a bridge‐splitting reaction. All products were fully characterized by NMR spectroscopy, together with cis‐[PtBr2(PPh3)(NCCH3)], obtained as an intermediate in the synthesis of the dinuclear precursor. Cis‐[PtBr2(PPh3)(NCCH3)] was also studied by X‐ray diffraction.

We present an approach toward sequence-dependent materials based on a stepwise assembly on a silica surface of rare earth cations (RE: Y3+, Eu3+ and Tb3+) and the 1,4-benzenedicarboxylate (terephthalate, T2-) ligand, organized in an ordered sequence RE1-T-RE2. The first RE was grafted to silica through a reaction of its N,N-dibutylcarbamato derivative, [RE1(O2CNBu2)(3)], with the surface silanols. The residual carbamato groups in the metal coordination sphere were then substituted by HT- through a reaction with H2T in pyridine. The BrOnsted acidity of the pendant COOH groups was successively exploited for the anchorage of the second metal ion (RE1 = Eu, RE2 = Tb; RE1 = Y, RE2 = Tb). The choice of pyridine as the solvent, able to dissolve both H2T and the secondary product [NH2Bu2](2)[T]H2T, was crucial for achieving success with this method. The emission properties of the materials were modulated by modifying the order of the synthetic steps. Metal complexes and materials were characterized by IR, EDX, ICP and photoluminescence. We used Tb3+ to Eu3+ energy transfer (ET) to study the RE3+ spatial distribution and intermetal distances to prove the formation of a RE1-T-RE2 sequence. Photoluminescence was used as a multi-tool technique to characterize the functional properties of the materials and to obtain structural information supporting the sequence growth.

The reaction of a lanthanide precursor with 2,5-dihydroxyterephthalic acid (H4L) yields different MOFs, having [H2L]2− and [L]4− as anionic spacers, in different synthetic conditions. The interconversion conditions have been established for some of them. The known gadolinium coordination polymer (CP) {[Gd2(H2L)3(DMF)4]·2DMF}n (DMF = N,N-dimethylformamide), 1, was prepared in DMF, either at 90 °C or also at room temperature, if assisted by a base diffusion. NMR monitoring for the synthesis of the analogous yttrium system (DMF, 90 °C) showed that the reaction progress relates with the formation of NHMe2 by DMF decomposition. {[Y2(H2L)3(DMF)4]·2DMF}n, 2, isotypic with 1, was obtained. The new structurally characterized CP {[Gd2(H2L)3(H2O)6]·2H2O}n 3, has been prepared by initial thermal (T = 170 °C) desolvation of 1 in vacuo (P = 1·10−3 Torr), followed by a hydrothermal treatment. Interestingly, 3 reverted back to 1 by treatment in DMF at 90 °C. Moreover 3 has been obtained starting from the metal nitrate and H4L in hydrothermal conditions (140 °C; 12 h) in the presence of the stoichiometric amount of NaOH. Long reaction times produced the intermediate formation of a mixture where it was possible to identify the new structurally characterized {[Gd2(H2L)3]·2H2O}n, 4, the known {[Gd2(H2L)2(L)0.5(H2O)3]·4H2O}n, 5 and {[Gd2(H2L)(L)(H2O)5]·2H2O}n, 6, while at higher temperature (160 °C; 24 h) the pure 6 was obtained. The observed transformations of 1 into 6 in H2O involve H4L elimination. On the other hand, it was found that the treatment of 6 in DMF in the presence of H4L leads back to 1. Single Crystal X Ray Diffraction (SCXRD) studies were carried out on the new species 2, 3 and 4.

The coordination chain {[Dy(dbm)3bpy]·C7H8}n (1) having only 4,4′-bipyridine as connector has been prepared in high yield and its structural and magnetic properties have been investigated. It is isostructural with the terbium analogue {[Tb(dbm)3bpy]·C7H8}n (2) and features units repeating in a 1D-zigzag fashion, where the metal is octa-coordinated in a distorted square antiprism geometry. Despite the 1D structure, the absence of paramagnetic connectors prevents the direct magnetic intrachain interaction among the lanthanide ions. In zero magnetic field, only a small fraction of the magnetization of 1 displayed slow dynamics with no dependence on temperature. Upon application of a 1 kOe magnetic field, a relaxation process appears, compatible with a mixed Raman/Direct mechanisms. Magnetic dilution in the diamagnetic Y(III)-based analogue revealed that actually two distinct relaxation processes are active for 1, whose temperature dependence can be interpreted again with a mixed Raman/Direct relaxation model. Compound 2 displayed only in-field slow relaxation, compatible with the models employed for 1.

The coordination polymers [ Ln ( β - dik ) 3 bpy ] ∞ 1 ·C7H8 (Ln = Eu, β-dik = dbm, tta, hfac; Ln = Tb; β-dik = dbm; Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac: hexafluoroacetylacetone) were easily assembled in mild conditions and high yields starting from the anhydrous lanthanide β-diketonates as nodes and 4,4′-bipyridine (bpy) as connector. X-ray single crystal studies have shown zigzag extended chains where lanthanide centres are 8-coordinated in a distorted square-antiprismatic geometry. Photoluminescence studies show bright red europium emission and spectral features dependent on the topology of the polymeric chains.

Partial hydrolysis (H2O/Ln molar ratio = ¼) of lanthanum di-iso-propylcarbamato complex, [La(O2CNiPr2)3], 1, afforded the tetranuclear μ-oxo derivative [La4O(O2CNiPr2)10], 2, which was structurally characterized by single crystal X-ray diffraction studies. The carbonato–carbamato derivative of lanthanum, [La4(CO3)(O2CNBu2)10], 3, was prepared by extraction of lanthanum ions from aqueous solution into heptane by the NHBu2/CO2 system. Partial hydrolysis (H2O/Ln molar ratio = ½) of N,N-di-iso-propylcarbamato complexes of neodymium, europium, gadolinium and terbium, [Ln(O2CNiPr2)3], yielded the derivatives [Ln2(CO3)(O2CNiPr2)4] (Ln = Nd, 4, Eu, 5, Gd, 6). Exhaustive hydrolysis of [Ln(O2CNR2)3] (Ln = Nd, Tb, R = Bu; Ln = Eu, Gd, R = iPr, Bu) produced hydrated lanthanide carbonates, Ln2(CO3)3·nH2O. For sake of comparison with a block d metal, the exhaustive hydrolysis of two copper(II) carbamato complexes, [Cu(O2CNEt2)2(NHEt2)]2 and [Cu(O2CNiPr2)2], was carried out with formation in both cases of the hydrated basic carbonate Cu2(OH)2(CO3)·nH2O. The exhaustive hydrolysis of mixtures of cerium and lanthanum or cerium and terbium N,N-dibutylcarbamato complexes allowed the preparation of mixed oxides containing the two metals in the desired molar ratio, via the intermediate formation of the corresponding mixed carbonates.

The synthesis of dinuclear molecular complexes [Eu2(dbm)6(bipyMO)2], 1, [Tb2(dbm)6(bipyMO)2], 2, [Eu2(tta)6(bipyMO)2], 3 [Eu2(hfac)6(bipyMO)3], 4, [Tb2(hfac)6(bipyMO)3], 5 is here reported (bipyMO = 4,4?-bipyridine N-oxide, Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone). The products were obtained in mild conditions and with high yields reacting anhydrous lanthanide ?-diketonates and bipyMO in 1:1 or 1.5 molar ratio in toluene. X-ray single crystal studies on 2, 3, 4 showed that the heterotopic ligands are hypodentate, bridging the two lanthanide centres exclusively through the oxygen atom. Photoluminescence studies show bright red emissions from europium derivatives with absolute quantum yields up to 44 %.

Heterotopic divergent ligand N-oxide-4,4'-bipyridine (bipyMO) has been herein exploited for the preparation of hetero-bimetallic coordination polymers where Ln(hfac)(3) and M(hfac)(2) nodes regularly alternate (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), bipyMO being able to selectively use its two potential coordination sites to discriminate the metal ions. The synthesis of three coordination polymers, [Ln(hfac)(3)M(hfac)(2) (bipyMO)(2)](n) (Ln = Eu, M = Zn, 1; Ln = Eu, M = Cu, 2, Ln = Dy, M = Co, 3), was carried out by reacting the appropriate [M(hfac)(2)(bipyMO)](n) and [Ln(hfac)(3)] precursors in toluene in the presence of a given stoichiometric amount of bipyMO. The products were characterized by elemental analysis, X-ray powder diffraction, and FTIR spectroscopy. Single crystal X-ray diffraction studies carried out on 2 showed that it was formed by chains containing the hexa-coordinated 3d metal (Cu(hfac)(2)[N](2)) and the octa-coordinated lanthanide (Eu(hfac)(3)[O](2)) nodes, where [N] and [O] stand for the donor atom of the bridging divergent ligand. The X-ray powder diffraction patterns of the three compounds and the comparison of their cell constant values allowed establishing that the derivatives were isotypic. Photoluminescence (PL) studies on microcrystalline sample powders evidenced a bright red emission for 1 with an absolute PL quantum yield of 0.24. The sensitized emission of Eu3+ can be excited in a wide wavelength range, from UV to visible, up to approximate to 450 nm. Conversely, europium emissions are not detectable in 2 due to the presence of Cu(hfac)(2)(bipyMO) moieties whose strong absorption overlaps Eu3+ transitions. Magnetic measurements conducted on 3 revealed the presence of a weak ferromagnetic interaction below 2.1 K. An ac susceptibility study highlighted a slow relaxation of the magnetization of 3 with an applied static magnetic field of 0.1 T, which could be equally fitted with a Orbach-direct or a Raman-direct mechanism. No relaxation dynamics was detected without the application of a static magnetic field.

trans -[Pt(μ-Cl)Cl(PPh 3 )] 2 reacted with arylaldoximes in 1,2-dichloroethane to afford [PtCl 2 (PPh 3 ){N(OH) CHAr}] (Ar = 3,4-dimethoxyphenyl, 1-naphthyl, 9-anthryl) where aldoxime ligands are N-coordinated to platinum. The obtained complexes are soluble in chlorinated solvents, where they afford equilibrium mixtures of cis,trans and/or ( E ),( Z ) isomers. Equilibria in solution were studied by 31 P-NMR spectroscopy and solid state structural data were obtained by single crystal X ray diffraction studies. The reactivity of [PtCl 2 (PPh 3 ){N(OH) CHAr}] complexes with basic aqueous solutions was studied, under liquid-liquid phase transfer catalysis conditions. The outcome of the reaction depends on the stereochemistry of the precursors: cis, ( Z )-isomers promptly undergo cyclization to the corresponding dinuclear derivatives [Pt{μ-(κ 2 -N,O)}-{N(O) CHAr}Cl(PPh 3 )] 2 , where two aldoximate ligands symmetrically bridge two metal centers.

The simple but rarely used heterotopic divergent ligand N-oxide-4,4′-bipyridine (bipyMO) has been exploited, for the first time, for the preparation of heterometallic derivatives, showing the ability to selectively use its two potential coordination sites in dependence of the metal ion nature. By reacting in refluxing acetonitrile ∞ 1 [Cu(hfac) 2 (bipyMO)] with ∞ 1 [Mn(hfac) 2 (bipyMO)] (herein completely characterized), the heterometallic self-assembled monodimensional coordination polymer containing the two regularly alternated moieties Cu(hfac) 2 [N] 2 and Mn(hfac) 2 [O] 2 was obtained in high yield and purity and structurally characterized. On the other hand, a molecular heterometallic compound was obtained using, as a ligand, the here prepared mononuclear complex trans -[PtCl 2 (bipyMO)(PPh 3 )], with the hypodentate bipyMO ligand coordinated to platinum through the nitrogen atom. Reaction with [Zn(hfac) 2 (DME)] afforded the heterometallic trinuclear complex trans [Zn(hfac) 2 { trans -PtCl 2 (PPh 3 )(bipyMO)} 2 ] that was structurally characterized.

We describe a new organic/inorganic material emitting circularly polarized luminescence (CPL). The hybrid system was obtained by the following steps: (i) preliminary grafting of the europium N,N-dibutylcarbamate [Eu(O2CNBu2)3] complex onto silica, (ii) substitution of the residual carbamato groups with anionic 1,3-diphenyl-1,3-propanedionato ligands (dbm), and (iii) subsequent introduction of the neutral tridentate chiral ligand 2,6-bis(isopropyl2-oxazolin-2-yl)pyridine (iPr-PyBox) in the metal coordination sphere. The solid material is stable to air and does not leach either the metal or the ligand. Samples of both enantiomers have been studied, showing mirror-image CPL spectra. The molecular compounds [Eu(dbm)3-(S)-(iPr-PyBox)] and [Eu(dbm)3-(R)-(iPrPyBox)] were prepared for comparison purposes and their molecular structures studied by single-crystal X-ray diffraction, showing mononuclear derivatives with a coordination number of 9 for europium. Powder X-ray diffraction showed a single crystalline phase. Photoluminescence and CPL evidenced the presence of a single emitting species.

A convenient synthetic route and the characterization of complexes trans-[PtCl2(L)(PPh3)] (L=Et2NH (2), (PhCH2)2NH (3), (HOCH2CH2)2NH) (4) are reported. The antiproliferative activity was evaluated on three human tumor cell lines. The investigation on the mechanism of action highlighted for the most active complex 4 the capacity to affect mitochondrial functions. In particular, both the induction of the mitochondrial permeability transition phenomenon and an aspecific membrane damage occurred, depending on concentration.

The reactivity of ( cis - + trans -)[Pt(μ-Cl){(κ 2 -P,C)P(OC 6 H 4 )(OPh) 2 }] 2 ( 1 ) towards several ligands L (L = RCN, P(OMe) 3 , DMSO, NHEt 2 , py, CO, C 2 H 4 , C 8 H 16 ) has been studied. Ethylene and 1-octene do not react while the other reactions proceed with cleavage of the halide bridge and formation of one or both geometrical isomers of [PtCl{(κ 2 -P,C)P(OC 6 H 4 )(OPh) 2 }L] ( 2 – 8 ) depending on the nature of the entering ligand. In some cases equilibrium reactions (L = RCN, DMSO, CO, py) were observed. The structures of [SP4-3]-[PtCl{(κ 2 -P,C)P(OC 6 H 4 )(OPh) 2 }(S)DMSO] ([SP4-3]- 4 ) and [SP4-4]-[[PtCl{(κ 2 -P,C)P(OC 6 H 4 )(OPh) 2 }py] ([SP4-4]- 6 ) are reported.

The reactivity of mixed complexes [PtCl2(L)(L′)] (L = MeCN, EtCN, CO), L′ = PPh3; L = η2-C2H4, CO; L′ = MeCN, EtCN) towards diethylamine has been investigated. The processes are chemo- (substitution versus addition) and stereo-selective in dependence of the stereochemistry of the precursor. The structures of [SP4-4]-[PtCl(CONEt2)(NHEt2)(PPh3)], [SP4-4]-1, trans-[PtCl2(NHEt2)(PPh3)], trans-2, and cis-[PtCl2{(E-)HN C(NEt2)Me}(PPh3)], cis-3a, are reported.

Some new platinum(II) complexes have been prepared, of general formula trans-[PtCl2(PPh3){NH(Bu)CH2Ar}], where the dimension of the Ar residue in the secondary amines has been varied from small phenyl to large pyrenyl group. The obtained complexes, tested in vitro towards a panel of human tumor cell lines showed an interesting antiproliferative effect on both cisplatin-sensitive and -resistant cells. For the most cytotoxic derivative 2a the investigation on the mechanism of action highlighted the ability to induce apoptosis on resistant cells and interestingly, to inhibit the catalytic activity of topoisomerase II.

The grafting and the postgrafting functionalization of lanthanide ions on commercial amorphous silica have been herein carried out by using as a precursor the terbium N,N-dibutylcarbamato derivative [Tb(O2CNBu2)3]. The reaction of the complex with the surface silanols involved only a fraction of the carbamato ligands. The following protolytic substitution of the residual carbamato ligands was carried out by exploiting the Bronsted's acidity of the beta-diketone dibenzoylmethane (Hdbm), in view of the antenna effect of the beta-diketonato groups, which are commonly used in lanthanide photoluminescence studies. The reaction proceeded at room temperature in a clean and easy way affording the introduction of the chosen functionality in the lanthanide coordination sphere. The same procedure has been followed by using as a precursor the X-ray characterized heterometallic N,N-dibutylcarbamato complex [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] (Ln = Eu, Tb, Tm). In both cases, X-ray photoelectron spectroscopy evidenced the chemical implantation of the lanthanide ions on the silica surface, and photoluminescence studies pointed out the potentiality of the proposed synthetic approach in the preparation of highly luminescent materials.

Ionic platinum(II) complexes [PtCl(PPh3)(L∧L)][BF4] {L∧L = 2,2′-bipyridyl (1) 1,10-phenanthroline (2)} and [PtCl(PPh3)(L)2][BF4] {L = pyridine (3), dimethyl sulfoxide (4)} were synthesized by dehalogenation of cis-[PtCl2(PPh3)(NCMe)], followed by reaction with the suitable ligand. Chelating nitrogen ligands L∧L afforded single products, which were structurally characterized. In the other cases mixtures of geometric (L = pyridine) and/or coordination (L = dimethyl sulfoxide) isomers were observed in solution. In these cases the structures of the less soluble isomers were obtained via single crystal X-ray diffraction. All the complexes were tested in vitro for their antiproliferative activity on three human tumor cell lines: MSTO-211H, HeLa and HepG2.

Dinuclear platinum(II) complexes [{PtCl2(PPh3)}2(μ-N–N)], where N–N is a divergent bidentate nitrogen ligand, were prepared by reacting cis-[PtCl2(PPh3)(NCMe)] with N–N in a Pt/N–N molar ratio 2. The (trans,trans)-isomers were obtained as kinetic products and recovered in good yields and high purity {1, N–N = pyrazine (pyrz); 2, N–N = 4,4′-bipyridyl (bipy); 3, N–N = piperazine (pipz); 4, N–N = p-xylylendiamine (xylN2)}. Cis-[PtCl2(PPh3)(NCMe)] was also reacted with the tridentate divergent ligand 2,4,6-tris-(pyrid-4′-yl)1,3,5-triazine (py3TRIA) in molar ratio 3 with formation of the trinuclear (trans,trans,trans)-[{PtCl2(PPh3)}3(μ-py3TRIA)], 5. On the other hand, the treatment of cis-[PtCl2(PPh3)(NCMe)] with the monodentate pyridine (py) produced a mixture of both trans-[PtCl2(PPh3)(py)] (6a) and cis-[PtCl2(PPh3)(py)] (6b). The reactions of cis-[PtCl2(PPh3)(NCMe)] with N–N = pyrz, bipy, pipz, carried out with a Pt/N–N molar ratio 1, were monitored by 31P NMR spectroscopy. Equilibria were observed in solution, involving dinuclear (trans–trans)-[{PtCl2(PPh3)}2(μ-N–N)], mononuclear [PtCl2(PPh3)(N–N)] and free N–N. The addition of an excess of the divergent ligand allowed the complete conversion to the corresponding mononuclear complexes. With the heteroaromatic ligands both geometric isomers were observed (7a, 7b and 8a, 8b, for pyrz and bipy derivatives, respectively) while with pipz the trans-isomer only was detected, 9. In the system involving bipy, the scarcely soluble dinuclear (cis,cis)-[{PtCl2(PPh3)}2(μ-bipy)], 2b, was also obtained. Products 2, 2b, 3·2(CHCl3) and 6a·0.5(C2H4 Cl2) were structurally characterized by single crystal X-ray diffraction methods.

Dimethoxy-2,5-dihydrofuran is a synthetic equivalent of 2(5H)-furanone or 2-trimethylsilyloxyfuran, useful C4 synthons in the prepara- tion of 5-substituted-2(5H)-furanone derivatives. The reaction conditions adopted allow to obtain different classes of complex and biologically interesting compounds, in only one step, with high yields. 2008 Elsevier Ltd. All rights reserved.

The hexanuclear Pd6Cl12, i.e., the crystal phase classified as β-PdCl2, was obtained by reacting [TBA]2[Pd2Cl6] with AlCl3 (or FeCl3) in CH2Cl2. The action of AlCl3 on PtCl42-, followed by digestio...

Neodymium and terbium pentafluorophenolates, containing 1,10-phenanthroline as ancillary ligand, [Ln(OC6F5)3(phen)3], (1 Ln = Nd, 2 Ln = Tb) have been synthesized by reacting the N,N-dibutylcarbamato complexes, [Ln(O2CNBu2)3], easily obtained from aqueous solutions of lanthanide salts, with C6F5OH in the presence of 1,10-phenanthroline. The formation of the sparingly soluble hydrated compound [Tb(OC6F5)3(phen)2(H2O)·phen], 3, was observed, due to fortuitous presence of water. Single crystal X-ray diffraction studies on compounds 1, 3 and 3·DME (DME = dimethoxyethane) showed coordination numbers (CN) 9 for neodymium in 1 and 8 for terbium in 3 and 3·DME, where only two 1,10-phenanthroline ligands are coordinated to terbium, the third forming two hydrogen bonds with the coordinated water. The structural characterisation of [NH2Bu2][C6F5O], 4, showed the organisation of the product in ionic quartets. The photoluminescence spectra of 1 and 2 displayed the typical emissions related to the lanthanide centre in the NIR and visible region, respectively.

International audience; We present the X-ray diffraction, polarizing optical microscopy and electrooptic response studies of the chiral liquid crystal siloxane DSi3-MR11 [1] with a de Vries-type behavior. In a wide temperature range (b.Delta T sim 50°C) the material shows no layer shrinkage but a weak nearly linear layer spacing variation with temperature. Neither discontinuity nor slope change occurs at the SmA*-SmC* transition. In addition, using the X-ray data, the unusual electrooptic response in both 1st and 2nd harmonics together with known thermal behavior of birefringence, we evidence the cross-over from the classical orthogonal to the de Vries-like SmA* regime in DSi3-MR11 siloxane.

Two new chiral liquid crystalline monomers with bilactate or trilactate chiral units were synthesized and studied. The monomers show the paraelectric SmA and ferroelectric SmC∗ phases. The antiferroelectric phase was detected only for the monomer possessing the bilactate unit. The temperature dependences of the spontaneous polarization and spontaneous tilt angle were measured. Real and imaginary parts of the complex permittivity were studied as a function of frequency and temperature. The synthesized monomers contain a double bond at the end of the achiral terminal chain, and were used to prepare liquid crystalline polysiloxanes.

The ability of some 2-alkyl(aryl)-4,6-dimethoxy-1,3,5-triazine derivatives to interfere with production of reactive oxygen species (ROS) by human phagocytes was evaluated in an in-vitro cell model. Superoxide anion (O2−.) production by human polymorphonuclear cells (PMNs), challenged by the chemotactic agent N-formylmethionyl-leucyl-phenylalanine (FMLP), was inhibited in a dose-dependent manner by all the compounds tested, compounds 3, 4 and 5 being statistically the most active. Adhesion of PMNs to vascular endothelial cells (ECs) is a critical step in recruitment and infiltration of leucocytes into tissues during inflammation, and the effects of 1,3,5-triazine derivatives on PMN adhesion to ECs from the human umbilical vein (HUVEC) were also investigated. Triazines were incubated with PMNs and HUVEC; adhesion was quantitated by computerized micro-imaging fluorescence analysis. The 1,3,5-triazines tested inhibited the adhesion evoked by pro-inflammatory stimuli, such as platelet activating factor (PAF), FMLP, phorbol myristate acetate (PMA), tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in a dose—response manner over the concentration range 10−9 to 10−4 m, compounds 5 and 6 being the most active. Both of these compounds inhibited PMN adhesion to HUVEC, even when endothelial or PMN stimuli were used. Indeed, when both cell populations were activated contemporarily, the anti-adhesive effect was enhanced. The study suggests that 2-aryl-4,6-dimethoxy-1,3,5-triazines deserve further evaluation as anti-inflammatory agents.

Systematic studies on symmetric twin molecules composed of two bent-core mesogenic units are reported for the first time. It is shown that the formation of mesophases mainly depends on the chemical structure of the spacer. A sufficiently flexible spacer containing dimethylsiloxane units allows a decoupling of the mesogenic moieties; the related compounds exhibit a ferroelectric SmCP phase proved by electro-optical measurements. On the basis of X-ray data, a plausible structure model is presented. The connection of two bent-core mesogenic units by means of a tetraethylene glycol spacer results in dimers, which are able to form columnar phases. For twins containing a simple hydrocarbon chain as spacer, in most cases liquid-crystalline behavior could not be detected. These general tendencies remain valid if the bent-core unit is changed, e.g., by increasing the number of aromatic rings, by lateral substitution, and by inversion of the direction of one of the connecting groups between the aromatic rings, resp...