Quinolinium Cations Research Articles

Quinolinium fumarate

In the title complex, C9H8N+·C4H3O4−, fumarate anions are linked by O—H⋯O hydrogen bonds, forming infinite supramolecular chains along the c axis. Quinolinium cations are attached to the anionic chains via N—H⋯O and C—H⋯O interactions. The crystal structure determination confirms the protonation of the quinoline N atom and deprotonation of one of the carboxyl­ic acid groups of fumaric acid.

Bisquinolinium tetrachlorocuprate dihydrate

The asymmetric unit of the title compound, 2C9H8N+·CuCl42−·2H2O, comprises one quinolinium cation, one water mol­ecule and one-half of the CuCl42− anion with the other half generated by crystallographic twofold symmetry. The water mol­ecules are linked to the anions through O—H⋯Cl hydrogen bonds to form two-dimensional molecular networks parallel to (110). The cations are arranged between two networks in parallel stacks. The N—H⋯O, C—H⋯O and C—H⋯Cl intermolecular hydrogen bonds link the cations and the anion networks to form a three-dimensional network.

Humic acid complexation of basic and neutral polycyclic aromatic compounds.

Complexation by humic acid (HA) of basic (quinoline) and neutral (naphthalene) polycyclic aromatic compounds (PACs) was compared using fluorescence spectroscopy and equilibrium dialysis (ED). These compounds sorb to HA via cation exchange and hydrophobic interactions, respectively. Ionization of quinoline strongly affects its sorption to HA; maximum sorption is observed at pH close to logKb (4.92), and competition with H+ and electrolyte cation (Li+) is evident. Spectroscopic experiments indicate that quinolinium (QH+) cation fluorescence is quenched via a static mechanism (i.e., a dark complex is formed) when the protonated form is adsorbed via ion exchange to HA. The extent of sorption, calculated from fluorescence data using the Stern-Volmer equation, was compared to independent ED measurements. Although both methods indicated the same trends with solution chemistry, fluorescence quenching data suggested more extensive complexation than that measured using ED. In contrast to ionizable PACs, studied here and previously, interaction of naphthalene with HA is unaffected by changes in solution conditions (pH, ionic strength).

Intramolecular Photoinduced Electron Transfer in Zwitterionic Quinolinium Dyes – Experimental and Theoretical Studies

Quinolinium cations and quinolinium betaines were investigated in the representative solvents water and acetonitrile at room temperature using stationary and time-resolved fluorescence spectroscopy (Experimental results reveal that sulfoalkyl- and carboxyalkyl-quinolinium compounds display a strikingly different behavior in the two solvents. Furthermore, the fluorescence lifetime depends on the length of the spacer for the sulfoalkyl compounds in acetonitrile and the carboxyalkyl compounds in water, respectively. This suggests an intramolecular interaction of the anionic headgroups with the quinolinium system in the excited state. To support this idea, different positions at the chromophore are substituted by a methylgroup in order to perturb the proposed interaction.With the intention to understand the dynamics of the postulated photoinduced electron transfer from the anionic group onto the excited quinolinium chromophore, semiempirical quantum chemical calculations were performed on the species using the PM3 hamiltonian including solvent effects by a self consistent reaction field (SCRF).We show that the Marcus theory of electron transfer may serve as a theoretical basis for a natural interpretation of the dynamic fluorescence quenching behavior.

Synthesis and characterization of di-, tri- and tetranuclear carboxylate complexes containing both lanthanide(III) and zinc(II) ions

Treatment of Ln(NO 3) 3·6H 2O, Zn(NO 3) 2·6H 2O and carboxylic acids with quinoline in stoichiometric molar ratios in ethanol produces four structural types of carboxylate-bridged lanthanide(III)zinc(II) complexes [C 9H 7N·H][LnZn(O 2CC 2H 5) 3(C 9H 7N)(NO 3) 3]·H 2O (Ln=Er 1 or Y 2), [DyZn 2(O 2CCMe 3) 6(C 9H 7N) 2(NO 3)] ( 3), [DyZn 2(μ-O 2CC 2H 5) 5(O 2CC 2H 5)(C 9H 7N) 2(NO 3)(H 2O)] ( 4) and [Gd 2Zn 2(O 2CC 2H 5) 8(C 9H 7N) 2(NO 3) 2(H 2O) 2] ( 5), all of which have been characterized by single-crystal X-ray diffraction. Complexes 1 and 2 are isostructural and comprise quinolinium cations, triply propionate-bridged dimeric LnZn anions and lattice water molecules. In 3 the central Dy ion and two terminal Zn ions are bridged by two sets of three equivalent bismonodentate pivalate ligands to form a symmetrical trinuclear DyZn 2 structure. While the Dy ion in 4 is connected to one Zn ion via three bismonodentate propionate ligands and connected to another Zn via only two bismonodentate propionate ligands generating a novel unsymmetrical trinuclear DyZn 2 structure. Complex 5 consists of two triply propionate-bridged dinuclear [GdZn(O 2CC 2H 5) 3(C 9H 7N)(NO 3)(H 2O)] subunits, being linked together by two tridentate propionate groups via two Gd ions. The magnetic properties of complex 5 containing a pair of Gd 3+ ions bridged by two carboxylate groups have been investigated. A quantitative analysis of the magnetic data shows the interaction is of antiferromagnetic type with a J constant of −0.042 cm −1.

Electrochemical Conversions of 2‐Methyl‐3‐nitro‐4‐phenylquinoline, Its Quinolinium Salts, and Hydrogenated Derivates.

Classical polarography, cyclic voltammetry, and EPR spectroscopy was used to study electrochemical reduction and oxidation of 3-nitro derivatives of 2-methyl-4-phenylquinoline, the corresponding quinolinium perchlorates, and 1,2- and 1,4-dihydroquinolines. The nitro derivatives of quinoline and 1,2-dihydroquinoline are reduced in the first step at the nitro group; the quinolinium cations are reduced at the heterocycle followed by reduction of the nitro group; and in 1,4-dihydroquinolines, the nitro group is not reduced. Electrochemical reduction processes associated with electron transfer in the heterocycle mainly display the same behavior as established for pyridine derivatives. But important differences were observed in electrochemical oxidation: the N-methyl derivative of 1,4-dihydroquinoline is oxidized significantly more easily than the corresponding N-unsubstituted derivative of 1,4-dihydroquinoline (in the 1,4-dihydropyridine series, the difference in pot! enti als is fairly small), and even more easily than the corresponding N-methyl derivative of 1,2-dihydroquinoline.

The HSAB principle in the description of the inhibitive effectiveness of heterocyclic N-bases

The structural effect of substituted pyridinium and quinolinium cations on the inhibition of acid corrosion was studied. It was shown to be advisable to apply the HSAB principle with taking in consideration the electronic parameters of these molecules.

Three-Dimensional Hexagonal Structures from a Novel Self-Complementary Molecular Building Block

Nitrilotri(methylphosphonic acid), 1H6, exists as a zwitter ion in its pure form and reveals a complex three-dimensional structure with no predictable structural patterns. However, when acid 1H6 is reacted with 1,7-phenanthroline, 2, 1,10-phenanthroline, 3, acridine, 6, and tripropylamine, 8, in a 1:1 molar ratio, monodeprotonation of 1H6 triggers a prototypal self-complementary 3D hexagonal architecture in complexes 9 (1H5·H·2H2O), 10 (1H5·3H), 11 (1·5H)·(5)0.5, and 12 (1·8H). The networks are stabilized by very strong ionic hydrogen bonds and offer a viable new strategy for the design of stable and predictable 3D open organic networks. However, monodeprotonation of acid 1H6 with quinoline, 6, does not lead to the expected open hexagonal structure in 13 (1·6H) as quinolinium cations cannot effectively fill the void space if open hexagonal open structures were formed. The unique three-dimensional connectivity of these open networks does not permit interweaving, and template effects play a critical role in...

Studies of 2,3′-biquinolyl. 6. Regioselectivity of nucleophilic addition of organometallic compounds to 1-aklyl-3-(2-quinolyl)quinolinium halides

Nucleophilic addition of organometallic lithium and magnesium compounds to 1-alkyl-3-(2-quinolyl)quinolinium cations produces a mixture of the corresponding 1′-alkyl-2′-R-1′,2′-dihydro-2,3′-biquinolyls and 1′-alkyl-4′-R-1′,4′-dihydro-2,3′-biquinolyls. The portion of the latter decreases with increasing “hardness” of the organometallic compound.

Tert-Butylation of Quinolinium Cations and Quinoline N-Oxides by tert-Butylmercury Halides

tert-Butylation of Quinolinium Cations and Quinoline N-Oxides by tert-Butylmercury Halides

Regioselectivity of the reactions of pyridinium and quinolinium salts with various nucleophiles (Review)

The factors determining the regioselectivily of nucleophilic addition to pyridinium and quinolinium cations are examined. Published data of the last IS years are summarized.

Intramolecular deactivation of substituted quinolinium cations. Time-resolved fluorescence and semi-empirical calculations

The fluorescence quenching of N-alkylated quinolinium ions with and without a sulfonato group at the chain end is investigated by measurement of their fluorescence lifetimes. The presence of the sulfonato group leads to a reduction of the fluorescence lifetime from 21.78 ± 0.12 ns for N-ethylquinolinium cation to 0.31 ± 0.05 ns for the sulfonatoethyl compound in CH 3CN. The high intramolecular quenching efficiency depends on the alkyl chain length in CH 3CN. However, in H 2O as solvent, there is no preferential quenching of fluorescence by the sulfonato group, which is strongly solvated. Semi-empirical calculations of sulfonatoalkylquinolinium betaines support the proposal of intramolecular ring formation as the cause of the strong quenching effects. The chain-length dependence of the fluorescence decay in CH 3CN is correlated with the different orientations of an interacting oxygen lone pair with the aromatic π system.

Structure-property relationships in Langmuir-Blodgett films of Zwitterionic D-π-A adducts of TCNQ

A range of Zwitterionic D-π-A adducts of TCNQ, where D is a long chain quinolinium cation, have been synthesized and characterized. Langmuir and Langmuir-Blodgett (LB) films have been fabricated for adducts having alkyl chain lengths varying from 8 to 20 carbon atoms. A study of the area per molecule values and the ultraviolet and visible spectra of the LB films shows an abrupt change in film behaviour occurring at alkyl chain lengths greater than or equal to 15 carbon atoms. Tentative explanations for this behaviour are given.

Syntheses, thermal behaviour, and spectroscopic and x-ray studies of quinolinium salts of nickel(II), palladium(II) and platinum(II), 1,2-dithiooxalato- S, S′ complexes. Packing and bonding of the quinolinium bis(1,2-dithiooxalato- S, S′)nickelate(II)

Three quinolinium (HC 9H 7N = Hquin) salts of planar inorganic dithiooxalato complexes: (Hquin) 2[Ni(S 2C 2O 2) 2] ( 1, (Hquin) 2[Pd(S 2C 2O 2) 2] ( 2) and (Hquin) 2[Pt(S 2C 2O 2) 2] ( 3) were synthesized and characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray diffraction techniques. Spectroscopic data support the presence of the aromatic cation and the complex anion. The complexes show a high thermal stability and the thermal studies give evidence that the onset temperatures of their thermal decompositions, the corresponding reaction mechanism and the final solid products are strongly influenced by the atmospheric conditions, as well as the chemical and structural features of the starting compounds. X-ray diffraction analyses show that 2 and 3 are isomorphous with 1, which crystallizes in the monoclinic space group P2 1/ n with Z = 2 so that the anion straddles a crystallographic centre of symmetry. The crystal structure of 1 is built up by layers of quasi-planar [Ni(S 2C 2O 2) 2] 2− complexes (A) and quinolinium cations (C) stacked along the c-axis, following an ⋯ACCACC ⋯ sequence, with alternative interplanar spacings of 3.3–3.8 Å (A ⋯ C) and 3.44 Å (C ⋯ C), which suggest the existence of significant π-π and d z 2 -π interactions between the cations and the complexes' anions. These interactions, together with the electrostatic forces and an extensive network of hydrogen contacts, ensure the lattice cohesion and give the compound a three-dimensional character.

Rate constants for the addition of the enolate ion of acetone to quinolinium and acridinium cations

The reaction of acetone with four heteroaromatic cations (10-methylacridinium (1), 3-aminocarbonyl-1-methylquinolinium (2a), 3-cyano-1-methylquinolinium (2b), and 3-bromo-1-methylquinolinium (2c)) has been investigated in basic aqueous solutions (pH 9–12, ionic strength 0.1, 25 °C). For each of 2a and 2b, the kinetically controlled product is a 35:65 mixture of the C-2 and C-4 enolate ion adducts; the C-2 adduct subsequently isomerizes to give the C-4 adduct as the only observable species under thermodynamic control. For 2c, the C-2 enolate adduct appears to be favoured both kinetically and thermodynamically. Under kinetic control, the pH-dependence of adduct formation from each cation is consistent with rate-determining attack of the enolate ion upon the heterocyclic cation. Comparisons of regiochemical control of acetone enolate ion attack with hydroxide ion attack upon these same cations indicate that acetone enolate ion shows a more pronounced preference for C-4 attack over C-2 attack than does hydroxide ion. The thermodynamically controlled regiochemistry is similar for each of these two nucleophiles. Keywords: nucleophilic addition, regioselectivity, kinetic control, thermodynamic control, quinolinium cations.

Ortho effects in organic molecules on electron impact. Part 15. Oxygen transfers from the nitro group to both sulphur and olefinic double bonds in allyl o‐nitrophenyl sulphide

AbstractAn oxygen transfer from the nitro group to the CC group, followed by a simple cleavage, afford intense fragments corresponding to o‐nitrosothiophenol at m/z 139 and o‐nitrosothiophenoxy cation at m/z 138 during mass spectral fragmentations of allyl o‐nitrophenyl sulphide. Further, a concerted double oxygen transfer from the nitro group to the sulphur is proposed for the ejection of ṠO2H from the molecular ion of this compound, leading to the quinolinium cation at m/z 130. These processes are supported by the high‐resolution data, collision‐induced dissociation linked‐scan spectra and chemical evidence.

Dual reactivity in 1,2-disubstituted dihydro-N-heteroaromatic systems. 12. Aromatization of 1-substituted-2-(indol-3-yl)-1,2-dihydroquinolines with 1,3,5-trinitrobenzene

As the electron-acceptor properties of the N-substituents in 1-R-2-(indol-3-yl)-1,2-dihydroquinolines decrease, their ability to undergo heterolysis of the internuclear C-C bond to give ion pairs of 1-R-quinolinium cations and indole anions decreases. Reaction of these ion pairs with 1,3,5-trinitrobenzene gives salts of 1-R-quinolinium cations and the 1-(indol-3-yl)-2,4,6-trinitrocyclohexadiene anion. With undissociated dihydroquinolines, aromatization under similar conditions gives salts of 1-R-2(indol-3-yl)quinolinium cations and the 1,1-dihydro-2,4,6-trinitrocyclohexadiene anion.

Dual type of reactivity op 1,2-disubstituted dihydro-N-heteroaromatic systems. 11. Aromatization of N-sulfonyl-1,2-dihydroquinolines and isoquinolines containing an ?-indolyl or pyrrolyl substituent

When N-sulfonyl-1,2-dihydroquinolines and isoquinolines, containing an indolyl or pyrrolyl substituent at the α-position, react with trityl perchlorate, this substituent is split off, and N-sulfonyl quinolinium and isoquinolinium cations and tritylindole or tritylpyrrole are formed. A similar reaction with 2,2,6,6-tetramethyl-1-oxopiperidinium perchlorate proceeds with splitting of hydrogen or retention of the α-substituent, which leads to the corresponding α-substituted N-sulfonylquinolinium and isoquinolinium cations.

Structural and Magnetic Investigation of BIS (Quinolinium) BIS (Maleonitrile Dithiolato) Cuprate (II) - (Quin)2Cu(mnt)2

Abstract The title compound (Quin)2Cu(mnt)2 was synthesized by metathesis of the sodium salt of Cu(mnt)2 2- with quinoline hydrochloride, and its structural and magnetic properties were examined. The X-ray crystal structure reveals the segregated stacking of the Cu(mnt)2 2- anions and the quinolinium cations and indicates anisotropic properties. The magnetic susceptibility studies show that the exchange interaction is very weak as the Curie-Weiss fit holds down to 2.5K. The dynamics of the exchange interaction as probed by EPR linewidth analysis yield detailed information about the strengths of the various magnetic interactions.

Kinetics of the reduction of 1-methylquinolinium cations by 1-benzyl-1,4-dihydronicotinamide

The reduction of a series of 3-W-1-methylquinolinium cations (1: W = H, Br, CONH2, CO2CH3, CN, NO2) by 1-benzyl-1,4-dihydronicotinamide has been investigated. In all cases the kinetically controlled product from these reactions is the appropriate 3-W-1,4-dihydro-1-methylquinoline. Only for W = Br is any significant amount of the 1,2-dihydro isomer obtained (15% in this case). This kinetic preference for C-4 attack over C-2 attack in dihydronicotinamide reductions contrasts with the kinetically preferred attack at C-2 by hydroxide ion and in borohydride reductions. Rates of reduction were measured for each 1 and also 1,2-dimethyl- and 1,4-dimethylquinolinium cations in 20% CH3CN – 80% H2O, ionic strength 1.0 at 25 °C, under pseudo-first-order conditions. Kinetic saturation due to nonproductive 1:1 complex formation was observed for several cations at high concentrations (> 0.1 M). Second-order rate constants [Formula: see text] were evaluated for each W, and also kinetic isotope effects from second-order rate constants [Formula: see text] for reduction by 1-benzyl-4,4-dideuterio-1,4-dihydronicotinamide. Second-order rate constants are correlated with σp− for W with ρ = 4.5, and are also closely correlated with [Formula: see text] for pseudobase formation at C-4 of these quinolinium cations by: [Formula: see text]. Values of [Formula: see text] vs. [Formula: see text] describe a Westheimer curve reaching a maximum of 5.8 for W = Br and falling to 1.5 for W = NO2 and 4.2 for W = H. These data are consistent with an intrinsic barrier of 2.9 ± 0.5 kcal/mol for hydride transfer between this 1,4-dihydronicotinamide and quinolinium cations. However, quinolinium cations display a dramatically enhanced rate of dihydronicotinamide reduction relative to hydroxide ion attack when compared with isoquinolinium cations. This observation, and the predominance of C-4 rather than C-2 reduction, suggests that these reactions may not be simple one-step hydride transfer processes.