Aminium Group Research Articles

Conformational change of L-phenylalanine in fluorinated alcohol-water mixed solvents studied by IR, NMR, and MD simulations

To clarify the unique solvation properties of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) on a biomolecule of L-phenylalanine (Phe), the solvation structure of Phe in HFIP-water mixed solvents at 70 mmol dm−3 has been observed over the entire range of HFIP mole fraction xHFIP using infrared (IR), 1H and 13C NMR techniques with a help of molecular dynamics (MD) simulation. The solvation structure of Phe in the HFIP solvents has been compared with that in 2-propanol (2-PrOH)-water mixed solvents and the structure of L-leucine (Leu) in both alcohol-water mixed solvents previously reported. The results from IR, NMR, and MD simulations showed that water molecules hydrogen-bonded with the Phe carboxylate group are gradually replaced by HFIP with increasing xHFIP. In contrast, the replacement of water molecules by HFIP on the Phe aminium group does not easily take place. These findings arise from the high electron acceptability and the very low electron donicity of the HFIP hydroxyl group due to the electron drawing of the six fluorine atoms. In the 2-PrOH solutions, the replacement of water on the carboxylate group by 2-PrOH less easily occurs with increasing x2-PrOH compared to HFIP because of the lower electron acceptability of 2-PrOH. The solvation for the Phe hydrophilic parts is similar to that of Leu. The most significant difference between HFIP and 2-PrOH was observed for the solvation of the Phe phenyl group. The hydrophobic hydration shell around the phenyl group is collapsed with increasing alcohol content in both alcohol solutions. Instead of water, the HFIP fluorine atoms significantly interact with the phenyl hydrogen atoms, whereas 2-PrOH molecules do not markedly approach the hydrogen atoms. The conformational change of Phe molecule against the dihedral angle of Cγ-Cβ–Cα-COO− takes place with increasing HFIP content, but does not with the increase in 2-PrOH. This is attributed to the steric hindrance between the large phenyl group and the carboxylate group remarkably solvated by HFIP molecules.

Synthesis of monocationic β-cyclodextrin derivatives

Reactions of 6-bromo- and 6-iodo-6-deoxy-β-cyclodextrin with organic amines of diverse nature afforded a series of monocationic derivatives with aminium groups located in the cyclodextrin scaffold on the side of the primary hydroxy groups. The structure and composition of the obtained cationic β-cyclodextrin derivatives were confirmed by 1H and 13C NMR data.

Solvation power of HFIP for the hydrophilic and the hydrophobic moieties of l-leucine studied by MD, IR, and NMR techniques

Abstract The solvation properties of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) in its aqueous binary solvents have been evaluated using l -leucine (Leu) as a probe molecule by both theoretical and experimental approaches. Thus, molecular dynamics (MD) simulations, infrared (IR) and 1 H and 13 C NMR spectroscopic experiments have been conducted on Leu-HFIP-water solutions with varying the HFIP mole fraction from x HFIP = 0 to 1. Spatial distribution functions (SDFs) obtained from the MD simulations showed that the Leu carboxylate group is gradually solvated by HFIP molecules with increasing x HFIP , instead of water molecules. Thus, the replacement of water by HFIP for the carboxylate group progresses as the x HFIP rises. This was proved by the C O stretching vibrations and the 13 C chemical shift of the carboxylate group. On the contrary, the Leu aminium group is preferentially solvated by water below x HFIP = 0.7. However, HFIP molecules begin to solvate the aminium group above this mole fraction. The trifluoromethyl groups of HFIP significantly enclose the alkyl group of Leu even at the low x HFIP . By surrounding the Leu alkyl group with the HFIP trifluoromethyl groups, the C H stretching vibrations of Leu blueshift with increasing x HFIP . Simultaneously, the hydrogen and carbon atoms of the Leu alkyl group are electronically shielded as the x HFIP rises. The MD pair correlation function g ( r ) HCLeu-FHFIP showed the H F interactions between the Leu alkyl hydrogen and the HFIP fluorine atoms with the distance of 2.75 A. Consequently, the present results proved that the HFIP trifluoromethyl groups may interact with the Leu alkyl group through the blueshift hydrogen bonds of C H ⋯ F C.

Hydrogen bonds and van der Waals forces as tools for the construction of a herringbone pattern in the crystal structure of hexane-1,6-diaminium hexane-1,6-diyl bis-(hydrogen phospho-nate).

The asymmetric unit of the title salt, [H3N(CH2)6NH3][(HO)O2P(CH2)6PO2(OH)], consists of one half of a hexane-1,6-diaminium dication and one half of a hexane-1,6-diyl bis-(hydrogen phospho-nate) dianion. Both are located around different centres of inversion (Wyckoff sites: 2a and 2d) of the space group P21/c. The shape of the hexane-1,6-diaminium cation is best described as a double hook. Both aminium groups as well as the two attached CH2 groups are turned out from the plane of the central four C atoms. In contrast, all six C atoms of the dianion are almost in a plane. The hydrogen phospho-nate (-PO3H) groups of the anions and the aminium groups of the cations form two-dimensional O-H⋯ and O-H⋯N hydrogen-bonded networks parallel to the ac plane, built up from ten-membered and twelve-membered ring motifs with graph-set descriptors R33(10) and R54(12), respectively. These networks are linked by the alkyl-ene chains of the anions and cations. The resulting three-dimensional network shows a herringbone pattern, which resembles the parent structures 1,6-di-amino-hexane and hexane-1,6-di-phospho-nic acid.

Crystal structure of N,N-di-ethyl-benzene-1,4-diaminium dinitrate.

In the structure of the title mol­ecular salt, C10H18N2 2+·2NO3 −, the dinitrate salt of 4-(N,N-di­ethyl­amino)­aniline, the two ethyl groups lie almost perpendicular to the plane of the benzene ring [the ring-to-ethyl C—C—N—C torsion angles are −59.5 (2) and 67.5 (3)°]. The aminium groups of the cation form inter-species N—H⋯O hydrogen bonds with the nitro O-atom acceptors of both anions, giving rise to chain substructures lying along c. The chains are linked via further N—H⋯O hydrogen bonds, forming two-dimensional networks lying parallel to (010). These sheets are linked by C—H⋯O hydrogen bonds, forming a three-dimensional structure.

Synthesis, Spectroscopy and Crystal Structure of a New Copper Complex Built Up by Cationic (Dimethylphosphoryl)methanaminium Ligands

A new transition metal complex of the mono-protonated ligand (dimethylphosphoryl)methanamine (dpmaH+) was obtained by equimolar reaction of copper(II) chloride dihydrate and dpma in concentrated hydrochloric acid. The asymmetric unit of the title structure, [CuCl2(C3H11NOP)4][CuCl4]2, consists of one half of a fourfold charged trans-dichloridotetrakis[(dimethylphosphoryl)methanaminium]copper(II) complex with the copper atom located on an inversion centre and one tetrachloridocuprate(II) dianion found in a general position. The copper centre in the cationic complex shows a tetragonally distorted octahedral environment composed of four oxygen atoms in a square plane and two trans-coordinated chlorido ligands. This 4+2-coordination causes elongated Cu-Cl distances because of the Jahn-Teller effect. The geometry of the tetrachloridocuprate(II) dianion is best described as a seriously distorted tetrahedron. Analysis of the hydrogen bonding scheme by graph-set theory shows three patterns of rings in the title compound. The cationic copper complex reveals intramolecular hydrogen bonds between two aminium groups and the two axial chlorido ligands. Further hydrogen bonding among the cations and anions, more precisely between four aminium groups and the chlorido ligands of four adjacent tetrachloridocuprate(II) anions, lead to a chain-type structure. Comparing the coordination chemistry of the title structure with an analogue cobalt(II) compound only disclose differences in hydrogen bonding pattern resulting in an unusual chain propagation. Besides the crystal structure received spectroscopic data are in accordance with appropriate literature.

Anilides and quinolones with nitrogen-bearing substituents from benzothiophene and thienothiophene series: Synthesis, photochemical synthesis, cytostatic evaluation, 3D-derived QSAR analysis and DNA-binding properties

A series of new anilides (2a–c, 4–7, 17a–c, 18) and quinolones (3a–b, 8a–b, 9a–b, 10–15, 19) with nitrogen-bearing substituents from benzo[b]thiophene and thieno[2,3-c]thiophene series are prepared. Benzo[b]thieno[2,3-c]- and thieno[3′,2′:4,5]thieno[2,3-c]quinolones (3a–b, 8a–b) are synthesized by the reaction of photochemical dehydrohalogenation from corresponding anilides. Anilides and quinolones were tested for the antiproliferative activity. Fused quinolones bearing protonated aminium group, quaternary ammonium group, N-methylated and protonated aminium group, amino and protonated amino group (8a, 9b, 10–12) showed very prominent anticancer activity, whereby the hydrochloride salt of N′,N′-dimethylaminopropyl-substituted quinolone (14) was the most active one, having the IC50 concentration at submicromolar range in accordance with previous QSAR predictions. On the other hand, flexible anilides were among the less active. Chemometric analysis of investigated compounds was performed. 3D-derived QSAR analysis identified solubility, metabolitic stability and the possibility of the compound to be ionized at pH 4–8 as molecular properties that are positively correlated with anticancer activity of investigated compounds, while molecular flexibility, polarizability and sum of hydrophobic surface areas were found to be negatively correlated. Anilides 2a–b, 4–7 and quinolones 3a–b, 8a–b, 9b and 10–14 were evaluated for DNA binding propensities and topoisomerases I/II inhibition as part of their mechanism of action. Among the anilides, only compound 7 presented some DNA binding propensity whereas the quinolones 8b, 9b and 10–14 intercalate in the DNA base pairs, compounds 8b, 9b and 14 being the most efficient ones. The strongest DNA intercalators, compounds 8b, 9b and 14, were clearly distinguished from the other compounds according to their molecular descriptors by the PCA and PLS analysis.

Trans-Dichloridotetrakis[(dimethylphosphoryl)methanaminium-κO]cobalt(II) tetrachloridocobaltate(II)

The asymmetric unit of the title structure, [CoCl2(C3H11NOP)4][CoCl4]2, consists of one half of the trans-dichlorido­tetra­kis­[(di­methyl­phosphor­yl)methanaminium]cobalt(II) tetra­cation lying on an inversion center and one tetra­chloridocobaltate(II) dianion on a general position. Four O-coordinated cationic (di­methyl­phosphor­yl)methanaminium (dpmaH+) ligands occupy the equatorial coordination sites, whereas the chloride ligands occupy axial positions of the roughly o­cta­hedral coordination polyhedron of the cobalt metal center. Intra­molecular hydrogen bonds between the aminium groups and the O atom of the phosphoryl groups and additional hydrogen bonds between the aminium groups and the chloride ligands are present. Furthermore, four of the six H atoms not involved in intra­molecular bonding of each cobalt(II) tetra­cation form weak hydrogen bonds to four adjacent tetra­chloridocobaltate(II) counter-anions. By these inter­molecular hydrogen bonds, one-dimensional polymeric strands are formed along the b-axis direction. The hydrogen bonding is analyzed using the graph-set method and the structural similarity with dpmaHCl is discussed.

Crystallographic characterization of the first reported crystalline form of the potent hallucinogen (R)-2-amino-1-(8-bromobenzo[1,2-b;5,4-b′]difuran-4-yl)propane or `bromodragonfly': the 1:1 anhydrous proton-transfer compound with 3,5-dinitrosalicylic acid

The 1:1 proton-transfer compound of the potent substituted amphetamine hallucinogen (R)-2-amino-1-(8-bromobenzo[1,2-b;5,4-b']difuran-4-yl)propane (common trivial name 'bromodragonfly') with 3,5-dinitrosalicylic acid, namely 1-(8-bromobenzo[1,2-b;5,4-b']difuran-4-yl)propan-2-aminium 2-carboxy-4,6-dinitrophenolate, C(13)H(13)BrNO(2)(+).C(7)H(3)N(2)O(7)(-), forms hydrogen-bonded cation-anion chain substructures comprising undulating head-to-tail anion chains formed through C(8) carboxyl-nitro O-H...O associations and incorporating the aminium groups of the cations. The intrachain cation-anion hydrogen-bonding associations feature proximal cyclic R(3)(3)(8) interactions involving both an N(+)-H...O(phenolate) and the carboxyl-nitro O-H...O associations and aromatic pi-pi ring interactions [minimum ring centroid separation = 3.566 (2) A]. A lateral hydrogen-bonding interaction between the third aminium H atom and a carboxyl O-atom acceptor links the chain substructures, giving a two-dimensional sheet structure. This determination represents the first of any form of this compound and is in the (R) absolute configuration. The atypical crystal stability is attributed both to the hydrogen-bonded chain substructures provided by the anions, which accommodate the aminium proton-donor groups of the cations and give crosslinking, and to the presence of the cation-anion aromatic ring pi-pi interactions.

2,2′,4,4′-Tetramethyl-7,7′-diazenediylbis(1,8-naphthyridin-1-ium) bis(perchlorate)

In the title salt, C20H20N6 2+·2ClO4 −, the cation is disposed about a center of symmetry at the mid-point of the N=N bond. The 1,8-naphthyridine systems are planar and the ten atoms have a mean deviation of 0.01 Å from the least-squares plane. The two planar 1,8-naphthyridine units are parallel but extend in opposite directions from the diazene bridge. The 1,8-naphthyridine aminium groups inter­act with perchlorate O atoms through N—H⋯O hydrogen bonds.

3-Methoxyanilinium 3-carboxy-4-hydroxybenzenesulfonate dihydrate

The 1:1 proton-transfer compound of m-anisidine with 5-sulfosalicylic acid, 3-methoxy­anilinium 3-carb­oxy-4-hydroxy­benzene­sulfonate dihydrate, C7H10NO+·C7H5O6S−·2H2O, is a three-dimensional framework structure built from hydrogen-bonding inter­actions involving the aminium group of the cation, the two water mol­ecules of solvation and the sulfonate, carboxyl­ate and phenolic substituent groups of the anion.

5-Nitrosalicylic Acid and its Proton-Transfer Compounds with Aliphatic Lewis Bases

The crystal structures of the proton-transfer compounds of 5-nitrosalicylic acid (5-nsa) with morpholine (morph), hexamethylenetetramine (hmt), and ethylenediamine (en) have been determined and their solid-state packing structures described. The compounds are [(morph)+(5-nsa)–] 1, [(hmt)+(5-nsa)–·H2O] 2, and [(en)2+2(5-nsa)–·H2O] 3. In all compounds, protonation of the hetero-nitrogen of the Lewis base occurs. With 1, the 5-nsa anions and the morpholine cations lie, respectively, in or across crystallographic mirror planes and are linked within the planes by hydrogen-bonding interactions through the aminium group and the carboxylic and phenolic oxygens of the anionic 5-nsa species giving a two-dimensional sheet polymer. Compound 2 is an unusual structure with the planar 5-nsa anions lying within pseudo mirror planes and cyclically linked by duplex water bridges through a single carboxylate oxygen into centrosymmetric dimers. The hmt cation molecules are disordered across the pseudo mirror and are strongly linked by N+–H···O hydrogen bonds only to the water molecules with peripheral weak hmt C–H···O hydrogen bonds extending the dimer within and between the dimer planes. Compound 3 is a network polymer comprised of the 5-nsa anions, the en dianions, and the water molecule in an extensive hydrogen-bonded structure.

Zwitterionic 5-amino-2-naphthalenesulfonic acid

The crystal structure of 5-amino-2-naphthalene­sulfonic acid (1,6-Cleve's acid), C10H9NO3S, shows the presence of a sulfonate–aminium group zwitterion, viz. 5-ammonio-2-naphthalene­sulfonate. All aminium H atoms are involved in head-to-tail intermolecular hydrogen-bonding interactions with separate sulfonate O-atom acceptors, giving a three-dimensional framework polymer structure.

Quinolin-8-aminium toluene-4-sulfonate

The crystal structure of the 1:1 proton-transfer compound of 8-amino­quinoline with toluene-4-sulfonic acid, viz. quinolin-8-aminium toluene-4-sulfonate, C9H9N2+·C7H7O3S−, is different from previously characterized proton-transfer compounds of 8-amino­quinoline, in that the 8-amino group rather than the quinoline N atom is protonated. All H atoms of this aminium group are subsequently involved in intermolec­ular hydrogen-bonding interactions with sulfonate O-atom acceptors, linking the cationic and anionic species and forming a linear polymer structure.

Dithiocarbamates as Innocent Anions: The Synthesis and Structural Properties of (8-Methyl-3,6,10,13,16,19-hexaazabicyclo[6.6.6]-icosan-1-amine)cobalt(Ii I) Tris(N,N-diethyldithiocarbamate), [Co(AMMEsar)][Et2dtc

Sodium diethyldithiocarbamate, Na[Et2dtc], reacts with (8-methyl-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosan-1-aminium)cobalt(III) chloride, [Co( AMMEsarH )]Cl4, in aqueous solution to form the compound [Co( AMMEsar )][Et2dtc]3 which is readily soluble in organic solvents. Crystals are trigonal, space group R3c (3m, No. 167) with a 13.864(4), c 36.42(2)Ǻ, Z 6. A full-matrix least-squares refinement on 952 reflections, with I > 2.5σ(I), converged with final R of 0.037. The structure consists of the [Co( AMMEsar )]3+ cation and three [Et2dtc]- anions. The primary aminium group on one trigonal cap of the cage is deprotonated to an amine. Strong hydrogen bonds exist between the sulfur atoms of the diethyldithiocarbamate anions and the protons of the secondary amines of the complex cation, which is stabilized in the lel conformation.

Specific interaction of spermine with cibacron blue F3GA

The polyamines, spermine, spermidine, and putrescine, have been shown to bind to Cibacron blue F3GA generating a difference spectrum with a maximum at 685 nm and a minimum at 585 nm, which is characteristic of ionic interactions between the dye and the polyamines. The difference spectral signal vanishes when the charges on the amino groups of the polyamines are neutralized. The magnitude of perturbation of the dye spectrum by the polyamines and, by inference, the capacity to bind to the dye, decrease in the order spermine > spermidine > putrescine. For spermine, the spectral signal of the dye-spermine complex is dependent on the charge state of an aminium group with a p K a = 8.2.