Chromium(VI) oxide-mediated oxidation of polyalkyl-polypyridines to polypyridine-polycarboxylic acids with periodic acid

4,4′-Dicarboxy-2,2′-bipyridine was synthesized quantitatively by chromium(VI) oxide-mediated oxidation of 4,4′-dimethyl-2,2′-bipyridine or 4,4′-diethyl-2,2′-bipyridine with periodic acid as the terminal oxidant in sulfuric acid. 5,5′-Dicarboxy-2,2′-bipyridine and 6,6’-dicarboxy-2,2′-bipyridine were also synthesized by the method from the corresponding dimethyl bipyridines in excellent yields. 4,4′,4″-Tricarboxy-2,2′:6′,2″-terpyridine was obtained in 80% yield from 4,4′,4″-triethyl-2,2′:6′,2″-terpyridine, and 4,4′,4″,4′″-tetracarboxy-2,2′:6′,2″:6″,2′″-quaterpyridine was obtained in 72% yield from 4,4′,4″,4′″-tetraethyl-2,2′:6′,2″:6″,2′″-quaterpyridine by the same procedure.     

An Efficient and Easy Synthesis of Tetrasubstituted 2,2′:6′,2″-Terpyridines

An efficient synthesis of 4,4″-dinitro-5,5″-dimethyl-2,2′:6′,2″-terpyridine was accomplished. The crystal structures of three different 2,2':6’,2″-terpyridines were determined by x-ray analysis.     

Chiral ligands with pyridine donors in transition metal catalyzed enantioselective cyclopropanation and hydrosilylation reactions

Copper(I) and rhodium(I) complexes prepared in situ from [Cu(OTf)(C₆H₆)_0.5] and [Rh(cod)Cl]₂ with a range of chiral 2,2′-bipyridines, 5,6-dihydro-1,10-phenanthrolines, 1,10-phenanthrolines and 2,2′:6′,2′′-terpyridines were assessed as chiral catalysts for the enantioselective cyclopropanation of styrene with diazoacetates and for the hydrosilylation of acetophenone with diphenylsilane. Enantioselectivities up to 68% in the cyclopropanation and up to 32% in the hydrosilylation were obtained.     

Synthesis and Ni(0)-catalyzed oligomerization of isomeric 4,4‴-dichloroquaterphenyls

4,4?-Dichloro-1,1′ : 2′,1″ : 2″,1?-quaterphenyl ( 9 ), 4,4?-dichloro-1,1′ : 3′,1″ : 3″,1?-quaterphenyl ( 10 ), and 4,4?-dichloro-1,1′ : 4′,1″ : 4″,1?-quaterphenyl ( 11 ) were synthesized by Pd (0) catalyzed cross-coupling reaction of 4-chlorobenzeneboronic acid with 2,2′-, 3,3′-, and 4,4′-bis (trifluoromethanesulfonyloxy)biphenyl respectively. 4,4?-Dichloro-1,1′ : 2′,1″ : 2″,1?-quaterphenyl ( 9 ) and 4,4?-dichloro-1,1′ : 3′,1″ : 3″,1?-quaterphenyl ( 10 ) were oligomerized by Ni(0) catalyzed homocoupling reaction to yield white and soluble oligophenylenes. © 1993 John Wiley & Sons, Inc.     

Direct synthesis of disubstituted aromatic polyimine chelates

The reaction of an alkyl- or aryl-lithium with 1,10-phenanthroline followed by hydrolysis and rearomatisation with manganese dioxide gives good yields of the 2,9-disubstituted product. This synthetic method has been extended to other polyimines such as 2,2′-bipyridine, 2,2′,6′, 2″-terpyridine and 1,8-naphtyridine.     

New Approaches to the Synthesis of 2,2′: 6′,2″-Terpyridine and Some of Its Derivatives

A new two-step procedure has been developed for the synthesis of 2,2′: 6′,2″-terpyridine and 4′-methylsulfanyl-2,2′: 6′,2″-terpyridine in more than 70% yield on the basis of Potts’ condensation. Efficient methods have been proposed for purification of all condensation products.     

Condensation metallosupramolecular polymers containing main-chain 2,2′-bipyridine and 2,2′:6′,2″-terpyridine moieties

Methods of preparing diverse metallosupramolecular polymers containing 2,2′-bipyridine and 2,2′:6′,2″-terpyridine moieties in main chains and their properties have been considered and analyzed. It has been shown that these polymers offer new possibilities for the design of materials possessing valuable specific characteristics.     

Enantioselective reduction of acetophenone with PMHS and tin(II) complexes of chiral pyridine ligands

A number of tin(II) complexes, prepared in situ from tin(II) triflate and pyridine derivatives (2,2′:6′,2″-terpyridine, 1,10-phenanthroline, 2,2′-bipyridine, dipyridylmethane, 2-(thiophen-2-yl)pyridine and 2-(2-diphenylphosphinophenyl)-5,6,7,8-tetrahydroquinoline), have been used as chiral catalysts for the reduction of acetophenone in the presence of polymethylhydrosiloxane (PMHS). Yields up to 82% and enantioselectivities up to 19% have been obtained.     

Synthetic, spectral and catalytic activity studies of ruthenium bipyridine and terpyridine complexes: Implications in the mechanism of the ruthenium(pyridine-2,6-bisoxazoline)(pyridine-2,6-dicarboxylate)-catalyzed asymmetric epoxidation of olefins utilizing H2O2

Various Ru(L₁)(L₂) (1) complexes (L₁ = 2,2′-bipyridines, 2,2′:6′,2″-terpyridines, 6-(4S)-4-phenyl-4,5-dihydro-oxazol-2-yl-2,2′-bipyridinyl or 2,2′-bipyridinyl-6-carboxylate; L₂ = pyridine-2,6-dicarboxylate, pyridine-2-carboxylate or 2,2′-bipyridinyl-6-carboxylate) have been synthesized (or in situ generated) and tested on epoxidation of olefins utilizing 30% aqueous H₂O₂. The complexes containing pyridine-2,6-dicarboxylate show extraordinarily high catalytic activity. Based on the stereoselective performance of chiral ruthenium complexes containing non-racemic 2,2′-bipyridines including 6-[(4S)-4-phenyl-4,5-dihydro-oxazol-2-yl]-[2,2′]bipyridinyl new insights on the reaction intermediates and reaction pathway of the ruthenium-catalyzed enantioselective epoxidation are proposed. In addition, a simplified protocol for epoxidation of olefins using urea hydrogen peroxide complex as oxidizing agent has been developed.     

Synthesis and characterization of alkyl-, alkenyl-, acyl- and nitrogen-substituted derivatives of the potent phototoxin α-terthiophene

Some alkyl-, alkenyl-, acyl- and nitrogen- derivatives of α-terthienyl 1 have been synthesized in an effort to expand the potential insecticidal activity profile of this compound. The introduction of substituents was carried out directly on the α-terthienyl molecule. Three compounds were isolated in the nitration reaction and the compounds have been identified as 5-nitro-2,2′:5′,2″-terthiophene 5 , 3′-nitro-2,2′:5′,2″-terthiophene 6 and 3-nitro-2,2′:5′,2″-terthiophene 7 respectively. Preliminary results of biological acitivity are reported.     

Engineering with metallo-supramolecular polymers: linear coordination polymers and networks

Here we demonstrate the synthesis of telechelics with different spacer units and different numbers of metal-complexing units, like α-methoxy-ω-(2,2′:6′,2″-terpyrid-4′-yl)-poly(ethylenoxide)₇₈ ( 1 ), bis(2,2′:6′,2″-terpyrid-4′-yl) di(ethylene glycol) ( 2 ), bis(2,2′:6′,2″-terpyrid-4′-yl)-poly(ethylene oxide)₁₈₀ ( 3 ) and tris[(2,2′:6′,2″-terpyrid-4′-yl)-oligo (ethylenoxy-)_3.33]glycerin ( 4 ) utilizing 4-chloro-2,2′:6′,2″-terpyridine. The complexation behaviour of a variety of metal-salts towards the telechelics was studied and different supramolecular architectures were investigated, such as symmetric polymeric complexes and linear coordination polymers. Furthermore, attempts have been undertaken to prepare metallo-supramolecular cross-linked systems.     

Efficient Preparative Rentes to 6,6′-Dibromo-2-2′-bipyridine and 6-Bromo-2,2′-bipyridine

The preparation of 6,6′-dibromo-2,2′-bipyridine and 6-bromo-2,2′-bipyridine are described. The dibromo compound was prepared by way of an improved cuprate synthesis resulting in a 72% yield. The monobromo species was prepared from the dibromo compound by way of metal-halogen exchange in 88% yield.     

4,4′,4″-Tris(5-nonyl)-2,2′ : 6′,2″-terpyridine as ligand in atom transfer radical polymerization (ATRP)

The bulk atom transfer radical polymerization (ATRP) of styrene or methyl acrylate was carried out in the presence of CuCl or CuBr complexed by equimolar amounts of 2,2′: 6′,2″-terpyridines (tpy) as ligands. Uncontrolled reactions were observed in the presence of unsubstituted ligands whereas relatively fast but controlled polymerization of styrene and methyl acrylate was observed for CuCl and CuBr complexed by tpy with three 5-nonyl substituents (tNtpy). Molecular weights evolved linearly with conversion and polymers with relatively low polydispersities were formed (M_w/M_n < 1.2).     

The Synthesis and Characterization of New Optically Active ‘dimeric’ ‘pineno’-[4,5]-fused 2,2′-bipyridines linked without spacer or by small spacer groups

Linked chiral bipyridines 2–4 are prepared by combining two optically active ‘pineno’-[4,5]-fused 2,2′-bipyridines in a stereoselective reaction (Scheme 1). These potential ligands are new members of the ‘chiragen’ family, and are characterized by NMR spectroscopy and, in the case of 2 and 3 by single-crystal X-ray analysis. A new synthesis of ‘dipineno’-[4,5;4′,5′]-fused 2,2′ -bipyridine 8 is described, which, when coupled, gives additional four chiral centres to the analogous ‘chiragen’ series ( → 9 ). Analysis of the CD spectra allowed conformational information about the solution species to be determined.     

Terpyridines as supramolecular initiators for living polymerization methods

Bis(5,5″-bis(bromomethyl)-2,2′:6′,2″-terpyridine), bis-4′-(4-bromomethylphenyl)-2,2′:6′,2″-terpyridine and 4-hydroxymethyl-5′,5″-dimethyl-2,2′:6′,2″-terpyridine metal complexes have been used as initiators for the living polymerization of 2-oxazolines and L-lactides. In both cases polymers with controlled molecular weights and narrow molecular weight distributions have been obtained. In-line diode array GPC measurements of iron(II) complexed poly(ethyloxazoline)s showed an unexpected absence of fragmentation. Viscosity experiments demonstrated the differences of the complexed and uncomplexed systems.     

The preparation and coordination chemistry of 2,2′:6′,2″-terpyridine macrocycles—1

A range of 6,6″-disubstituted derivatives of 2,2′: 6,2″-terpyridine have been prepared with the intention of forming macrocycles incorporating the 2,2′: 6′,2$\text{-}\text{?}$terpyridyl moiety. A high yield route to 6,6″-bis(methylhydrazino-4′-phenyl-2,2′:6′,2″-terpyridine is described, and a number of complexes of this novel pentadentate ligand have been prepared.     

Further Determination of Cadmium Ions in Water by an Electrochemiluminescence Method

ABSTRACT

Two new electrochemiluminescence (ECL) reactions in aqueous solution involving cadmium(II) ions are reported. The ECL reaction occurs in the presence of a common co-reactant, tripropylamine (TPA), and either of two organic ligands, 2,2′:6′,2″-terpyridine or 2,2′-bipyridine. The reaction is presumed to arise from the metal-ligand complex and the co-reactant. Conditions for ECL emission were optimised and a calibration graph constructed. Emission was linear over the range 10-1 000 ppb. The calculated limits of detection (LOD) were 8 and 50 ppb using terpyridine and bipyridine, respectively. Comparison with a previously reported reaction involving cadmium(II) ions and 1, 10-phenathroline is made.     

A new terpyridine tethered polythiophene: Electrosynthesis and characterization

A novel polythiophene bearing a pendant terpyridine moiety has been synthesized by electrochemical polymerization of a new thiophene monomer, namely 4′‐(2,2′:5′,2″‐terthien‐3′‐ethynyl)‐2,2′:6′,2″‐terpyridine (TAT). The insertion of a conjugated ethynyl spacer between the terthiophene and the terpyridine fragments provides for an effective extension of the delocalization of electrons within the structural unit and the polymer as a whole. The synthesis and characterization of the relevant monomer, the electrosynthesis of the corresponding polymer and its electrochemical, UV–visible spectroelectrochemical and IR characterization are described. Finally, a comparison between the electrochemical, spectroscopic, and spectroelectrochemical properties of PTAT and the analogue, saturated‐spacer PTTT (TTT = 4′‐[(2,2′:5′,2″‐terthien‐3′‐yl)methoxy]‐2,2′:6′,2″‐terpyridine) polymer is discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A new method of using supercritical carbon dioxide as a green solvent for synthesis and purification of 5,5‴-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2‴-quaterthiophene,which is one of n-type organic semiconducting materials

We have investigated synthesis as well as purification of 5,5?-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2?-quaterthiophene (BFH-4?T, n-type organic semiconducting material) using supercritical carbon dioxide (scCO₂) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdCl₂-catalyzed reductive coupling reaction of 5-bromo-5′-(tridecafluorohexyl)-2,2′-bithiophene in scCO₂. We have also successfully established purification of the reaction mixture by passing scCO₂ in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained.     

Synthesis of Bis(Trifluoromethyl)-2,2′- Bipyridines by Nickel Catalysed Homocoupling Reactions

Bis(trifluoromethyl)-2,2′-bipyridines have been synthesized in moderate yields by nickel or palladium catalysed homocoupling of 2-chloro(trifluoromethyl) pyridines.