Bipyridyl Derivatives Research Articles

“Turn-on” fluorescent sensor for the selective detection of zinc ion by a sterically-encumbered bipyridyl-based receptor

A sterically-encumbered 5,5'-distyryl-2,2'-bipyridyl derivative that enforces a 1:1 metal-to-ligand ratio acts as a selective turn-on sensor for Zn(2+) in THF.

Structure−Activity Relationships for Cytotoxic Ruthenium(II) Arene Complexes Containing N,N-, N,O-, and O,O-Chelating Ligands

We report structure-activity relationships for organometallic RuII complexes of the type [(eta6-arene)Ru(XY)Cl]Z, where XY is an N,N- (diamine), N,O- (e.g., amino acidate), or O,O- (e.g., beta-diketonate) chelating ligand, the arene ranges from benzene derivatives to fused polycyclic hydrocarbons, and Z is usually PF6. The X-ray structures of 13 complexes are reported. All have the characteristic "piano-stool" geometry. The complexes most active toward A2780 human ovarian cancer cells contained XY=ethylenediamine (en) and extended polycyclic arenes. Complexes with polar substituents on the arene or XY=bipyridyl derivatives exhibited reduced activity. The activity of the O,O-chelated complexes depended strongly on the substituents and on the arene. For arene=p-cymene, XY=amino acidate complexes were inactive. Complexes were not cross-resistant with cisplatin, and cross-resistance to Adriamycin was circumvented by replacing XY=en with 1,2-phenylenediamine. Some complexes were also active against colon, pancreatic, and lung cancer cells.

Hydridodimethylplatinum(IV) Complexes with Bis(pyridine) Ligands: Effect of Chelate Ring Size on Reactivity

The effect of changing the bite angle of the dipyridyl ligand LL on the reactivity of the dimethylplatinum(II) complexes [PtMe2(LL)] has been studied, by comparing complexes with the ligands LL = di-2-pyridylamine (DPA) or di-2-pyridyl ketone (DPK), which form a six-membered chelate ring, to compounds with 2,2‘-bipyridyl derivatives, which form a five-membered chelate ring. The complex [PtMe2(DPA)] undergoes easy oxidative addition of methyl iodide to give the corresponding platinum(IV) complex [PtIMe3(DPA)]. Both [PtMe2(DPA)] and [PtMe2(DPK)] are protonated by acids HX at low temperature to give the hydridodimethylplatinum(IV) complexes [PtHXMe2(NN)] and [PtH(S)Me2(NN)]X (S = solvent), which can exist in two isomeric forms with H trans to X or N. The structure of the complex [PtHClMe2(DPK)] was determined crystallographically. In a solution containing excess CD3OD, extensive hydrogen/deuterium exchange occurs into the methylplatinum groups and methane product at low temperature, indicating very easy reversibility of the exchange between hydridomethylplatinum(IV) and (methane)platinum(II) complexes. The hydridomethylplatinum(IV) complexes reductively eliminate methane at room temperature in solution but have significantly higher thermal stability and undergo more extensive H−D exchange than when NN = 2,2‘-bipyridyl. The reaction of [PtMe2(DPA)] with excess HCl gave [PtCl2(DPA)], and the reaction of [PtMe2(DPK)] with excess CF3SO3H gave the aqua complex [Pt(OH2)2(DPK)](CF3SO3)2 or the binuclear hydroxo complex [Pt2(μ-OH)2(DPK)2](CF3SO3)2, depending on the experimental conditions.

Synthesis and Structural Characterization of Macrocyclic Half-Sandwich Rhodium(III) and Iridium(III) Complexes Bearing Bipyridyl Derivatives and Terephthalate

The reactions of half-sandwich rhodium and iridium complexes [Cp‘MCl(μ-Cl)]2 with bidentate ligands (L) such as pyrazine, 4,4‘-bipyridine (bpy), and trans-4,4‘-azopyridine gave the corresponding binuclear complexes [{Cp‘MCl2}2(L)] (M = Ir, Cp‘ = Cp* = η5-C5Me5, L = pyrazine (3a), bpy (3b); M = Rh, Cp‘ = Cpt = η5-1,3-tBu2C5H3, L = bpy (3c), 4,4‘-azopyridine (3d)), which can be converted into tetranuclear complexes [{Cp‘2M2(μ-Cl)2}2(L)2]4+ (M = Ir, Cp‘ = Cp*, L = bpy (4a and 4b); M = Rh, Cp‘ = Cpt, L = bpy (4c, 4e), L = 4,4‘-azopyridine (4d)) on treatment with Ag(OTf) or AgBF4 (OTf = CF3SO3). Treatment of Cl-bridged complexes 4c and 4e with terephthalate (L‘) resulted in replacing the Cl bridges to produce macrocyclic complexes [(Cp‘M)4{(L)(L‘)}2]4+ (M = Rh, Cp‘ = Cpt, L = bpy, L‘ = terephthalate (5)). The molecular structures of [{Cp*IrCl2}2(μ-pyrazine)] (3a), [{Cp*Ir}4(μ-Cl)4-(μ-bpy)2](BF4)4·6(CH2Cl2) (4a), [(Cp*Ir)4(μ-Cl)4(μ-bpy)2](OTf)4·5(CH2ClCH2Cl) (4b), [(CptRh)4(μ-Cl)4(μ-bpy)2](OTf)4 (4c), [(CptRh)4...

Selective hydrogen transfer reduction of ketones by recyclable ruthenium complex catalysts containing a ‘ROMP polymer-attached’ ligand

Various pyridine and 2,2′-bipyridyl ligands attached to the polymer chain end of ring-opened poly(norbornene) were prepared by living ring-opening metathesis polymerization (ROMP) using Mo(CHCMe 2Ph)( N-2,6- i Pr 2C 6H 3)(O t Bu) 2. The prepared pyridine and 2,2′-bipyridyl derivatives were examined for their use as ligands for catalytic hydrogen transfer reduction of cyclohexanone in the presence of Ru(acac) 3 (in toluene/ i PrOH in the presence of NaO i Pr, at 50 °C, acac: acetylacetonato). The catalytic activity increased upon addition of the above polymer as the ligand, and the prepared catalyst could be recovered by filtration as the precipitate, by pouring the reaction mixture into methanol. The recovered catalyst could be reused without decrease in the activity. Since the olefinic double bond in the ROMP polymer was not hydrogenated under these reaction conditions, exclusive reduction of carbonyl group in various ketones, such as acetophenone, 5-hexen-2-one, 2-allylhexanone could be achieved in this catalysis.

Intramolecular Metal···Sulfur Interactions of Platinum(II) 1,4,7-Trithiacyclononane Complexes with Bipyridyl Ligands: The Relationship between Molecular and Electronic Structures

Five platinum(II) 1,4,7-trithiacyclononane (ttcn) complexes with bidentate-substituted 2,2'-bipyridine ligands have been prepared and structurally characterized: [Pt(bpy)(ttcn)](PF6)2 (bpy = 2,2'-bipyridine), triclinic, P1, a = 10.2529(3) A, b = 10.7791(3) A, c = 10.7867(3) A, alpha = 83.886(1) degrees, beta = 87.565(1) degrees, gamma = 84.901(1), V = 1179.99(6) A3, Z = 2; [Pt(4,4'-dmbpy)(ttcn)](PF6)2 x CH3CN x H2O (4,4'-dmbpy = 4,4'-dimethyl-2,2'-bipyridine), triclinic, P1, a = 10.1895(3) A, b = 11.8566(4) A, c = 13.1004(4) A, alpha = 77.345(1) degrees, beta = 79.967(1) degrees, gamma = 72.341(1) degrees, V = 1461.56(8) A3, Z = 2; [Pt(5,5'-dmbpy)(ttcn)](PF6)2 (5,5'-dmbpy = 5,5'-dimethyl-2,2'-bipyridine), triclinic, P1, a = 10.6397(4) A, b = 10.8449(4) A, c = 11.2621(4) A, alpha = 90.035(1) degrees, beta = 98.061(1) degrees, gamma = 91.283(1) degrees, V = 1286.32(8) A3, Z = 2; [Pt(dbbpy)(ttcn)](PF6)2 x CH3NO2 (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine), triclinic, P1, a = 11.5422(7) A, b = 11.6100(7) A, c = 13.6052(9) A, alpha = 85.902(1) degrees, beta = 89.675(1) degrees, gamma = 74.942(1) degrees, V = 1755.90(19) A3, Z = 2; and [Pt(dtfmbpy)(ttcn)](PF6)2 x CH3CN (dtfmbpy = 5,5'-di-trifluoromethyl-2,2'-bipyridine): monoclinic, P2(1)/c, a = 13.1187(9) A, b = 20.9031(15) A, c = 11.3815(8) A, beta = 105.789(2) degrees, V = 3003.3(4) A3, Z = 4. For each salt, the platinum(II) center of the cation is bonded to two nitrogen atoms of the chelating diimine and two sulfur atoms of the thioether macrocycle. The third sulfur atom of ttcn forms a long apical interaction with the metal center (2.84-2.97 A), resulting in a flattened square pyramid structure. An examination of these and 17 other structures of platinum(II) ttcn complexes reveals a correlation between the apical Pt...S distance and the donor properties of the ancillary ligands, suggesting a means for using variations in ligand electronic properties to tune molecular structure. The room-temperature absorption spectra in acetonitrile solution show a broad and comparatively low-energy MLCT band maximizing near approximately 390 nm for the bpy and dialkyl-substituted bipyridyl derivatives. The maximum is dramatically red-shifted to 460 nm in the spectrum of the dtfmbpy complex as a result of the electron-withdrawing properties of the -CF(3) groups. The 3:1 EtOH/MeOH 77 K glassy solution emission spectra exhibit low-energy emission bands (lambdamax, 570-645 nm), tentatively assigned as originating from a lowest, predominantly spin-forbidden MLCT excited state that is stabilized by apical Pt...S interactions.

Cp*(eta2-bipy)(MeCN)RuII][PF6] catalysts for regioselective allylic substitution and characterization of dicationic [Cp*(eta2-bipy)(eta3-allyl)RuIV][PF6]2 intermediates.

The coordination of a 2,2′-bipyridyl derivative to a (C5Me5)RuII fragment provides both a facile route to unprecedented dicationic (allyl)RuIV complexes (see picture) and new highly efficient catalysts for the regioselective allylic substitution from unsymmetrical allylic carbonates.

Mono- and binuclear bipyridyl derivatives of the Mo(η 3-C 3H 5)(CO) 2 fragment: structural studies and fluxionality in solution

New mono- and binuclear complexes of the Mo(η 3-C 3H 5)(CO) 2 fragment, containing bipyridyl ligands (2,2′-bpy, 4,4′-Me 2-2,2′-bpy) as chelates, and mono- (4-CNpy, 4-Mepy, NCMe, Br) or bidentate nitrogen ligands (4,4′-bpy, bipyridylethylene, pyrazine) as terminal or bridging ligands, respectively, were prepared. The binuclear complex [{Mo(η 3-C 3H 5)(CO) 2(2,2′-bpy)} 2(μ-4,4′-bpy)][PF 6] 2 ( 2) was shown by X-ray diffraction to assemble in the crystal forming large channels with a rectangular section. A longer bridge, such as bipyridylethylene, led to a different structure ( 3). 4-CNpy behaved as monodentate ligand ( 4), coordinating through the pyridine nitrogen as a terminal ligand. NMR spectroscopy studies showed that the complexes exhibited a fluxional behavior in solution, the endo and exo forms of the more symmetrical equatorial isomers being usually present and interconverting in solution. The solid state structures of the complexes revealed a preference for the more symmetrical equatorial isomer, with the two chelate ligands in trans positions in the binuclear species. The rings tended to become parallel in the organized crystal.

Cu(II)-Self-Assembling Bipyridyl-Glycoclusters and Dendrimers Bearing the Tn-Antigen Cancer Marker: Syntheses and Lectin Binding Properties.

Abstract Using the carbohydrate cancer marker, T N -antigen (α-GalNAc-OR), covalently linked to a bipyridine core, square planar complexes were formed by self-assembly upon simple addition of Cu(II) sulfate. The required α- d -GalNAc-OR building block was constructed from 2-azidoethyl 2-acetamido-2-deoxy-α- d -glucopyranoside (GlcNAc) by epimerization at C-4 of a suitably protected derivative followed by conventional modifications to provide 2-aminoethyl 2-acetamido-3,4,6-tri- O -acetyl-2-deoxy-α- d -galactopyranoside. The 2-aminoethyl aglycone was further elongated into a key monomer having an aminocaproic acid spacer together with their corresponding dimers using a double N-alkylation strategy of their N -bromoacetyl derivatives using mono-Boc-1,4-diaminobutane, respectively. The building blocks containing the bipyridyl dimers, having either a short or a long spacer arm, together with the tetramer built from the short spacer derivative were prepared in a convergent manner using 2,2′-bipyridine-4,4′-dicarboxylic acid chloride and the aminated sugar derivatives, respectively. Copper(II)-nucleated GalNAc derivatives containing four and eight residues were obtained from an aqueous solution of the bipyridyl derivatives. The relative inhibitory potencies of these glycodendrimers were evaluated against monomeric allyl α- d -GalNAc using a solid-phase competition assay with asialoglycophorin and horseradish peroxidase-labeled lectin Vicia villosa . The di- and tetra-valent bipyridyl clusters showed up to 87-fold increased inhibitory properties (IC 50 7.14, 1.82, 4.09 μM, respectively) when compared to the monomer (IC 50 158.3 μM) while the Cu(II)-complexes showed up to a 259-fold increase potencies (IC 50 0.61 μM) with the octamer showing the highest affinity. However, when expressed on a per-saccharide basis, the tetramer Cu(II) nucleated derivative, possessing the longest inter-sugar distances showed the highest affinity (IC 50 0.63 μM).

Reactions of Tris(2‐pyridyl)phosphine Oxides with Electrophiles: Formation of 5‐Substituted 2,2′‐Bipyridyls.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cu(II)-Self-assembling bipyridyl-glycoclusters and dendrimers bearing the Tn-antigen cancer marker: syntheses and lectin binding properties

Using the carbohydrate cancer marker, T N-antigen (α-GalNAc-OR), covalently linked to a bipyridine core, square planar complexes were formed by self-assembly upon simple addition of Cu(II) sulfate. The required α- d-GalNAc-OR building block was constructed from 2-azidoethyl 2-acetamido-2-deoxy-α- d-glucopyranoside (GlcNAc) by epimerization at C-4 of a suitably protected derivative followed by conventional modifications to provide 2-aminoethyl 2-acetamido-3,4,6-tri- O-acetyl-2-deoxy-α- d-galactopyranoside. The 2-aminoethyl aglycone was further elongated into a key monomer having an aminocaproic acid spacer together with their corresponding dimers using a double N-alkylation strategy of their N-bromoacetyl derivatives using mono-Boc-1,4-diaminobutane, respectively. The building blocks containing the bipyridyl dimers, having either a short or a long spacer arm, together with the tetramer built from the short spacer derivative were prepared in a convergent manner using 2,2′-bipyridine-4,4′-dicarboxylic acid chloride and the aminated sugar derivatives, respectively. Copper(II)-nucleated GalNAc derivatives containing four and eight residues were obtained from an aqueous solution of the bipyridyl derivatives. The relative inhibitory potencies of these glycodendrimers were evaluated against monomeric allyl α- d-GalNAc using a solid-phase competition assay with asialoglycophorin and horseradish peroxidase-labeled lectin Vicia villosa. The di- and tetra-valent bipyridyl clusters showed up to 87-fold increased inhibitory properties (IC 50 7.14, 1.82, 4.09 μM, respectively) when compared to the monomer (IC 50 158.3 μM) while the Cu(II)-complexes showed up to a 259-fold increase potencies (IC 50 0.61 μM) with the octamer showing the highest affinity. However, when expressed on a per-saccharide basis, the tetramer Cu(II) nucleated derivative, possessing the longest inter-sugar distances showed the highest affinity (IC 50 0.63 μM).

Synthesis of 2,2′‐Bipyridyl Derivatives Using Aza Diels—Alder Methodology.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of 2,2′-bipyridyl derivatives using aza Diels–Alder methodology

Amidrazone 1 and the tricarbonyl derivatives 2a– c gave the triazines 3a– c , respectively, which reacted with 2,5-norbornadiene 4 in boiling ethanol yielding the corresponding novel 2,2′-bipyridines 5a– c in good yield. Triazine 6 gave the 2,2′-bipyridyl derivative 7 (65%) with compound 4 in 1,2-dichlorobenzene at 140°C.

Reactions of tris(2‐pyridyl)phosphine oxides with electrophiles: Formation of 5‐substituted 2,2′‐bipyridyls

AbstractThe reaction of tris(2‐pyridyl)phosphine oxides with benzeneselenenyl chloride in methanol gave the corresponding 5‐phenylseleno‐2,2′‐bipyridyls together with a small amount of 2,2′‐bipyridyls. Similarly, the reaction with arenesulfenyl chlorides in aqueous acetonitrile afforded two kinds of coupling products, 5‐phenylthio‐2,2′‐bipyridyls and 2,2′‐bipyridyls. While in the reaction with arenesulfinyl chlorides in aqueous acetonitrile, four corresponding bipyridyl derivatives, 2,2′‐bipyridyls, 5‐arylthio‐2,2′‐bipyridyls, 5‐arylsulfinyl‐2,2′‐bipyridyls, and 5‐arylsulfonyl‐2,2′‐bipyridyls, were formed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:72–81, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10085

Polyhalogenated heterocyclic compounds. Part 48. Synthesis of perfluoroisopropyl-2,2'-bipyridyl derivatives

The synthesis of a highly halogenated 2,2'-bipyridyl system using organometallic methodology is reported.

Synthesis of novel nematic liquid crystals containing 3,3'-dimethyl-2,2'-bipyridyl

Liquid-crystalline 3,3′-dimethyl-2,2′-bipyridyl derivatives with long 4-(alkoxyphenyl)ethynyl (-C≡C-C6H4-OR) groups in the 5,5′-positions were synthesized by palladium-catalysed crosscoupling reactions. The compounds exhibit exclusively nematic behaviour; for example, the hexyl derivative showed a nematic phase over the temperature range 145.2–205.0°C. On increasing the length of the terminal chain, the transition temperatures were lowered; for example, the hexadecyl derivative was nematic in the range 117.0–126.8°C.

Organic/inorganic nanocomposite gels employed as electrolyte supports in Dye‐sensitized Photoelectrochemical cells

Dye‐sensitized photoelectrochemical cells based on TiO2 mesoporous films, a ruthenium bipyridyl derivative as photosensitizer and a SiO2/poly(ethylene glycol)‐200 nanocomposite thin film as electrolyte support, have been constructed. TiO2 films have been deposited on conductive transparent Indium‐Tin Oxide glass slides by means of a sol‐gel procedure carried out in reverse‐micellar solutions. The photosensitizer has been adsorbed on titania films from ethanolic solutions while the electrolyte layer has been synthesized by a sol‐gel procedure. The presence of silica in the nanocomposite electrolyte gel provides the gelifying agent, the compound that holds the cell together in a sandwich form and the sealing agent that protects the cell and secures its long‐term function. PEG‐200 makes the organic subphase which provides the ionic conductivity. The present work describes the construction of the cell and the study of its efficiency. A variant of the cell has also been made by incorporating Ag+ and Ru3+ ions into titania particles, but these dopants did not improve cell efficiency, either in their oxidized or in their reduced form.

Dye-Sensitized Photoelectrochemical Cell Using a Nanocomposite SiO2/Poly(Ethylene Glycol) Thin Film as Electrolyte Support. Characterization by Time-Resolved Luminescence and Conductivity Measurements

A dye-sensitized photoelectrochemical cell has been constructed by using a TiO2 mesoporous film, a ruthenium bipyridyl derivative as photosensitizer, and a SiO2/poly(ethylene glycol)-200 (SiO2/PEG-200) nanocomposite thin film as electrolyte support. The TiO2 film has been made by hydrolysis of titanium isopropoxide in Triton X-100 reverse micelles. In the present work, emphasis has been given to the nature and the applicability of the SiO2/PEG-200 film, which has been characterized by conductivity and, mainly, time-resolved luminescence quenching techniques. It has been found that optimal cell function is obtained with a SiO2/PEG-200 film where the PEG-200 content is about 10 wt %, a composition which is above and close to the percolation threshold for the PEG subphase.

New Simple and One-Pot Synthetic Routes to Polyfunctionally Substituted Pyridines; 1,4-Dihydropyridazines and 4H-1,2-Oxazine

Reactions of arylidenemalononitriles la-d with 2-cyano-1,1-diaminoethene (5); arylhydrazones 14a,b and syn-2-pyridinealdoxime 15 afforded the title derivatives 3a-d; 16a,b and 17, respectively. Bipyridyl derivatives 11-13 were also synthesized. Unambiguous syntheses and/ or spectral analyses confirmed the suggested structures of 3a-d, 11-13, 16a,b and 17.

Synthesis, X-ray crystal structures and characterization of copper(II)-2,2′-bipyridyl derivatives of (4-amino)-hippuric acid and of l-proline

In this paper the synthesis and the characterization of two complexes of copper and 2,2′-bipyridyl with amino acids 4-aminohippuric acid and l-proline are reported. The X-ray structure reveals for the first complex, [Cu 2(OH)(OH 2)(bipy) 2(Am-hip)](NO 3) 2·4H 2O, dinuclear copper(II) cations with nitrate counterions and lattice water molecules. The two metal centres are linked together by a water molecule, a hydroxyl group and the carboxylic moiety of the 4-amino-hippuric acid, the remaining two positions on both metal centres are occupied by bipyridyl molecules. The second compound consists of monomeric [Cu(OH 2)(bipy)( l-pro)] + cations and perchlorate anions. Also in this case copper is five-coordinated in a distorted square pyramidal geometry with the bipyridine nitrogens, one carboxylate oxygen atom and the amino nitrogen of the l-proline ion on the basal plane.