Diquaternary Salts Research Articles

Diamine and Diammonium Extractants

The application of di-tertiary amines and di-quaternary ammonium salts as extractants for metal ion separation is discussed. The versatility of the di-tertiary amines is illustrated. In these cases, two extraction mechanisms are postulated to coincide with the low and high pH conditions employed in the aqueous phases. The advantages in applying these two mechanisms for the selective extraction of metals from, and stripping to aqueous media are outlined. The potential advantages of these reagents over monoamines are discussed. Other features unique to diamine/diammonium extractants, e.g., differences in “acid effects” associated with these extractants, their differing tendencies towards third phase formation, etc., will be illustrated with extraction isotherms.

Electron transfer between viologen derivatives and the flavoprotein ferredoxin-NADP + reductase

The mechanism of electron transfer of several diquaternary salts of 4,4′-bipyridine and 2,2′-bipyridine with the FAD which is the prosthetic group of the protein ferredoxin-NADP + reductase from the cianobacterium Anabaena PCC 7119 was studied. Two different reactions involving the same compounds were studied: (i) the reduction of NADP + by the enzyme using reduced viologens; (ii) reduction of the viologens using NADPH and the enzyme. Different catalytic rates were obtained in each case, with values very similar to the turnover numbers reported for other enzymatic reactions described for this enzyme. In all cases a correlation between the second-order rate constant and the difference in redox potential of the groups exchanging electrons was obtained in agreement with the outer-sphere electron transfer theory. Those cases in which anomalous behavior was observed corresponded to viologens with an electrical charge quite different from the rest. The reaction between a highly charged viologen and the enzyme was much more dependent on the ionic strength of the medium than is the case for those having lower or no charge, which is an indication of the modulating effect of the electrical nature of the reactant on the electron transfer process.

Crystal structure of N(1)-methyl-α-isosparteine iodide and 1,16-endomethylene-α-isosparteine diiodide

The crystal and molecular structures of mono- and di-quaternary salts ofa-isosparteine have been determined by X-ray analysis. Both N(1)-methyl-α-isosparteine iodide and 1,16-endomethyleneα-isosparteine diiodide crystallize in the space groupC2221. The N-methylation does not change the configuration of parenttrans-cisoid-trans-α-isosparteine. The crystallographic twofold symmetry axis coincides with molecular symmetry of the diquaternary cation. Thetrans-cisoid-trans-1,16-endomethylene-α-isosparteine diiodide and its stereoisomer,trans-cisoid-cis-1,16-endo-methylenesparteine diiodide, form isomorphous crystals. Short cation-anion contacts in crystal structures suggest existence of C-H-⋯-I− hydrogen bonds in the solid state. In the N(1)-methyl-α-isosparteine iodide crystal, 7C⋯I− distances in the range 3.85-4.15 A have been found, while 17 distances of this type have been observed in 1,16-endomethylene-α-isosparteine diiodide.

Spontaneous Color Development Encountered for Diquaternary Salts of 1,10-Phenanthrolines in Various Media

Abstract Diquaternary salts of 1,10-phenanthroline or, 2,9-dimethyl-1,10-phenenthroline (viologen), prepared according to the Menshutkin rection, developed intense colors spontaneously, presumably due to high reduction potentials. The extent and λmax of the colors developed were dependent upon both the kind of viologen and the media such as solvents and polymer matrices.

Quaternary Salts of 1,2‐Bisazolyl‐ and 1,2‐Bisbenzazolylethanes

AbstractEleven new heterocyclic mono‐and diquaternary salts have been prepared by reaction of 1,2‐bisazolyl‐ and 1,2‐bisbenzazolyl‐ethanes with methyl sulfate or methyl fluorosulfonate. Their structure has been established by means of 1H and 13C NMR spectroscopy. Homonuclear COSY and NOESY experiments and 2D‐heteronuclear correlations have been performed when necessary to assign all NMR signals.

ChemInform Abstract: Diquaternary Salts of 4,4′‐Bipyridine as Electron Relays for the Photoreduction of Water

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Diquaternary Salts of 4,4′‐Bipyridine as Electron Relays for the Photoreduction of Water

Journal of Heterocyclic ChemistryVolume 28, Issue 4 p. 827-842 Review Diquaternary Salts of 4,4′-Bipyridine as Electron Relays for the Photoreduction of Water Lindsay A. Summers, Lindsay A. Summers Department of Chemistry, The University of Newcastle, 2308 New South Wales, AustraliaSearch for more papers by this author Lindsay A. Summers, Lindsay A. Summers Department of Chemistry, The University of Newcastle, 2308 New South Wales, AustraliaSearch for more papers by this author First published: June/July 1991 https://doi.org/10.1002/jhet.5570280401Citations: 21AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume28, Issue4June/July 1991Pages 827-842 RelatedInformation

Elektrochemische und spektroskopische Charakterisierung von N,N′‐Dialkylchinoxalinium‐Redoxsystemen

Electrochemical and Spectroscopic Characterization of N,N′‐Dialkylquinoxalinium Redox SystemsThe outstanding position of the 1,4‐isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations. Diquaternary salts [(R+)2(quin)](X−)2, R = Me, Et; quin = quinoxaline, 2,3‐ and 6,7‐dimethyl‐ and 2,3,6,7‐tetramethylquinoxaline, X− = BF4‐ or SbCl6‐ (4a – g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis. Cyclic voltammetry of the two‐step redox systems of the Weitz type showed two reversible one‐electron reductions with an extraordinarily stable radical cation intermediate (lg Kc 12). The redox potentials are less negative than those of the 4,4′‐bipyridinium systems but also less positive in comparison to the values of N,N′‐dialkylphenazinium compounds. The radical cation intermediates which include a TCNQ− salt cannot only be characterized by ESR, but also by absorption spectroscopy in comparison to the respective dications.

ChemInform Abstract: Crystal Structure, Raman and Resonance Raman Spectroscopic Studies of the Dimethyl Diquaternary Salt of 2,2′‐Dicyano‐4,4′‐bipyridine and Its Radical Monocation

Abstract The crystal structure of the dimethyl diquaternary salt of 2,2′-dicyano-4,4′-bipyridine is reported. Crystal data: C14H12Br2N4, Mr = 396.1, a = 7.1934(9), b = 10.192(1), c = 10.715(1) A, β = 103.89(1)°, V = 762.61 A3, monoclinic, space group P21/n, Z = 2, Dm = 1.70, Dc = 1.73 g cm−3, Mo Kα, λ = 0.71069 A, μ = 56.24 cm−1, F(000) = 388, T = 293 ± 1 K, R = 0.028, Rw = 0.029 for 1156 (I > 2.50σ(I)) reflections. The cation straddles a crystallographic centre of symmetry with the two pyridine rings being coplanar. The bromide ion is in a general position. Bond lengths and angles are normal. Raman spectra of the parent dication and resonance Raman spectra of the coloured radical monocation are also reported. The CN stretching frequency for the radical monocation is only weakly enhanced and is displaced only 12 cm−1 from the corresponding feature for the parent dication.

Crystal structure, Raman and resonance Raman spectroscopic studies of the dimethyl diquaternary salt of 2,2′-dicyano-4,4′-bipyridine and its radical monocation

The crystal structure of the dimethyl diquaternary salt of 2,2′-dicyano-4,4′-bipyridine is reported. Crystal data: C 14H 12Br 2N 4, M r = 396.1, a = 7.1934(9), b = 10.192(1), c = 10.715(1) Å, β = 103.89(1)°, V = 762.61 Å 3, monoclinic, space group P2 1/ n, Z = 2, D m = 1.70, D c = 1.73 g cm −3, Mo Kα, λ = 0.71069 Å, μ = 56.24 cm −1, F(000) = 388, T = 293 ± 1 K, R = 0.028, R w = 0.029 for 1156 ( I > 2.50σ(I)) reflections. The cation straddles a crystallographic centre of symmetry with the two pyridine rings being coplanar. The bromide ion is in a general position. Bond lengths and angles are normal. Raman spectra of the parent dication and resonance Raman spectra of the coloured radical monocation are also reported. The CN stretching frequency for the radical monocation is only weakly enhanced and is displaced only 12 cm −1 from the corresponding feature for the parent dication.

Synthesis of Quaternary Salts from 3,3′ -Bipyridine and Dibromoalkanes

Abstract Reaction of 3,3'-bipyridine with 1,3-dibromopropane, 1,4-dibromobutane, 1.5-dibromo-pentane, 1,6-dibromohexane. 1,7-dibromoheptane and 1.8-dibromooctane affords the corresponding bridged diquaternary salts, the structures of which were confirmed by fast atom bombardment mass spectrometry. Reaction with 1,2-bromoethane gives instead 1.1"-(1,2-ethanediyl)-bis-3.3'-bipyridinium dibromide.

ChemInform Abstract: Bridged Diquaternary Salts from 3,3′‐Bipyridine.

AbstractThe bipyridine (I) reacts with α,ω‐dibromoalkanes such as (II) to give the bridged diquaternary salts (III).

Bridged diquaternary salts of di-2-pyridyl ketone and their radical cations: crystal structure, raman and resonance raman studies

Raman spectra are reported for two bridged diquaternary salts of di-2-pyridyl ketone. The crystal structure of one parent dication is also reported. Crystal data: C 13H 12Br 2N 2O, M r = 372.05, a = 9.369(1), b = 11.036(4), c = 7.115(1) Å, α = 97.60(2), β = 90.12(1), γ = 67.79(1)°, V = 674.20 Å 3, triclinic, space group P 1 ; Z = 2, D m = 1.83, D x = 1.832 g cm −3, MoKα, λ = 0.71069, Å, μ = 63.54 cm −1, F(000) = 364, T = 292 ± 1 K, R = 0.033, R w = 0.032 for 1330 ( I &> 2.5σ) reflections. Resonance Raman spectra of the coloured radical cations obtained from the diquaternary salts by one-electron reduction are also reported. Changes in the frequency of the carbonyl stretching vibration of the parent dications are correlated with changes in the conformation of the conjugated system. Changes in the Raman spectrum of a parent dication between the solid state and aqueous solution appear to arise from a modification of molecular geometry in solution. The decrease in frequency of the carbonyl stretching mode on radical formation is attributed to a decrease in the carbonyl bond order, due to delocalisation of the odd electron.

The Phase Transition of 1,4-Dialkyl-1,4-diazoniabicyclo[2.2.2]octane Dibromides, Cn–DABCO–Cn+2–Br

Abstract The phase transition of 1,4-dialkyl-1,4-diazoniabicyclo[2.2.2]octane dibromide (diquaternary salt) in which the difference in the carbon numbers of the two alkyl groups is two, was studied by means of differential scanning calorimetry, infrared absorption spectroscopy, and a study of the bromide-anion conductivities. DSC measurements revealed the existence of the metastable phase. The conversion rate from the metastable phase to the stable phase was too slow to be followed. The phase transition could be explained by the free energy-temperature relation. The temperature-dependence of the infrared absorption spectra showed that the band progressions due to two different alkyl chains disappeared at the transition temperature. This shows that the trans-zigzag conformation in the low-temperature phase is destroyed by the conformational change of the alkyl chain at the transition temperature. The free energy-temperature relation was also confirmed by the IR spectra. Discontinuous increases in the bromide-anion conductivities were observed at the transition temperatures. The conductivity jump was explained by the voids caused by the conformational change in the alkyl chain.

Synthesis of Quaternary Salts from 2,3ʹ-Bipyridine and Dibromoalkanes

Reaction of 2,3ʹ-bipyridine with dibromoalkanes affords both 1ʹ-bromoalkyl-2,3ʹ-bipyridinium bromides and 1ʹ,1‴-(alkanediyl)-bis-2,3ʹ-bipyridinium dibromides. The latter diquaternary salts react with dimethyl sulfate to afford 1ʹ,1‴-(alkanediyl)-bis-(1-methyl-2,3ʹ-bipyridinium) tetraquaternary salts which are reduced to diradical dications at potentials (E0) of about -0.47 V to -0.62 V.

ChemInform Abstract: Synthesis of Thieno[2,3‐c:5,4‐c]dipyridine and the One Electron Transfer Properties of Its Dimethyl Diquaternary Salt.

Abstract3,3′‐Thio‐bis‐pyridin (I) kann mit Natrium in Ammoniak mit schlechter Ausbeute zum Thjeno‐dipyridin (II) cyclisiert werden.

Resonance Raman spectra of radical cations of bridged diquaternary salts of 2,2′‐bipyridine

AbstractRaman spectra are reported for several bridged diquaternary salts of 2,2′‐bipyridine. Resonance Raman spectra and some excitation profiles of the coloured radical monocations obtained from the diquaternary salts by one‐electron reduction are also reported. Selected frequencies of the parent dications are correlated with changes in the torsional angle between the aromatic rings of the bipyridinium moiety. These correlations, when applied to the spectra of the radical monocations, suggest that the radicals exhibit reduced torsional angle and increased inter‐ring bond order, compared with the parent dications. These changes are consistent with predictions of increased inter‐ring π‐electron delocalization, associated with radical formation. The torsional angle appears to decrease for the radical monocations with increasing number of bridging methylene groups. This is opposite to the trend known to occur in the parent dications.

Synthesis of thieno[2,3‐c:5,4‐c]dipyridine and the one electron transfer properties of its dimethyl diquaternary salt

AbstractThieno[2,3‐c:5,4‐c]dipyridine is synthesised by reaction of 3,3′‐thiobispyridine with sodium and liquid ammonia in dimethylformamide. It forms a diquaternary salt with excess methyl iodide. The salt is reversibly reduced to a stable blue‐green radical cation in aqueous solution at a potential (Eσ) of ‐0.38V.

Synthesis and mass spectrum of 3‐(3′‐pyridinyloxymethyl)pyridine and polarography of its dialkyl diquaternary salts

Abstract3‐(3′‐Pyridinyloxymethyl)pyridine is prepared by reaction of 3‐hydroxymethylpyridine with 3‐bromopyridine and converted to the 1,1′‐dimethyl and 1,1′‐diethyl diquaternary salts with alkyl iodides. The salts are reduced polarographically at a potential (Eo) of about ‐ 1.02 to ‐ 1.10 V in the pH range of 5.5‐8.5.

Synthesis and mass spectrum of 3,3′‐thiobispyridine and polarographic reduction of 1,1′‐dimethyl‐3,3′‐thiobispyridinediium diiodide

Abstract3,3′‐Thiobispyridine is prepared by reaction of pyridine‐3‐thiol with 3‐bromopyridine. The base peak in the mass spectrum of 3,3′‐thiobispyridine is due to the molecular ion which fragments by loss of H, HCN and CS as well as by central bond rupture. The 1,1′‐dimethyl diquaternary salt of 3,3′‐thiobispyridine is reduced polarographically by a one electron transfer not involving hydrogen to an unstable radical cation at a potential (Eo) of −0.72 V in the pH range 7.4–11.2.