Tertiary Ammonium Groups Research Articles

Can Copper(I) and Silver(I) be Hydrogen Bond Acceptors?

Gold(I) centers can form moderately strong (Au⋅⋅⋅H) hydrogen bonds with tertiary ammonium groups, as has been demonstrated in the 3AuCl+ (3+ =1-(tert-butyl)-3-phenyl-4-(2-((dimethylammonio)methyl)phenyl)-1,2,4-triazol-5-ylidene) complex. However, similar hydrogen bonding interactions with isoelectronic silver(I) or copper(I) centers are unknown. Herein, we first explored whether the Au⋅⋅⋅H bond originally observed in 3AuCl+ can be strengthened by replacing Cl with Br or I. Experimental gas-phase IR spectra in the ∼3000 cm-1 region showed only a small effect of the halogen on the Au⋅⋅⋅H bond. Next, we measured the spectra of 3AgCl+ , which exhibited significant differences compared to its 3AuX+ counterparts. The difference has been explained by DFT calculations which indicated that the Ag⋅⋅⋅H interaction is only marginal in this complex, and a Cl⋅⋅⋅H hydrogen bond is formed instead. Calculations predicted the same for the 3CuCl+ complex. However, we noticed that for Ag and Cu complexes with less flexible ligands, such as dimethyl(2-(dimethylammonio)phenyl)phosphine (L7 H+ ), the computations predict the presence of the respective Ag⋅⋅⋅H and Cu⋅⋅⋅H hydrogen bonds, with a strength similar to the Au⋅⋅⋅H bond in 3AuCl+ . We, therefore, propose possible complexes where the presence of (Ag/Cu)⋅⋅⋅H bonds could be experimentally verified to broaden our understanding of these unusual interactions.

Amphoteric waterborne polyurethane with unsaturated carboxyl group as crosslinker to improve cohesive strength of soybean protein-based adhesive for excellent cold-pressing adhesion

The cold-pressing performance of adhesives is important for the preparation of wood-based panels. Adhesives for wood-based panels must have appropriate viscosity, strong interfacial adhesion to wood substrates with hydration layers, and excellent cohesive strength at ambient temperature for cold-pressing adhesion. However, bio-based adhesives synthesized using conventional modification approaches still struggle to meet these standards. Herein, an amphoteric waterborne polyurethane with an unsaturated carboxyl group (AWPU-UC) is prepared as a crosslinker to modify soybean meal (SM) matrix, and prepare a soybean protein-based adhesive with excellent cold-pressing adhesion and mildew resistance. The unsaturated carboxyl groups form electrostatic interactions with tertiary ammonium groups of polyurethane and amino groups of protein molecules in the SM matrix. These bonds enhance both the cohesion of adhesive molecular network and the interaction between the adhesive and wood surface with “hydration layers”. Consequently, the cold-pressing bonding strength of the adhesives SM/AWPU-UC-4 reaches 271% of that of pure SM adhesive. In addition, the quaternary ammonium structure formed by electrostatic interactions in the AWPU-UC system endows the adhesive with mildew resistance. This study provides a simple and effective method for producing high-performance protein-based adhesives with outstanding cold-pressing adhesion and mildew resistance. • An amphoteric waterborne polyurethane emulsion with unsaturated carboxyl groups was synthesized. • The emulsion facilitated diffusion and creation of interaction of adhesives with the wood substrate. • The electrostatic interaction between unsaturated carboxyl groups and aminos on protein promoted cohesive crosslinking. • The quaternary ammonium structure produced by electrostatic interaction made it possess bactericidal ability. • The bio-adhesives had excellent cold-pressing performance and mildew resistance with AWPU-UC as a crosslinker.

An Operative Electrostatic Slipping Mechanism along Macrocycle Flexibility Accelerates Guest Sliding during pseudo-Rotaxane Formation.

A pseudo‐rotaxane is a host−guest complex composed of a linear molecule encircled by a macrocyclic ring. These complexes can be assembled by sliding the host over the guest terminal groups. If there is a close match between the molecular volume of the flanking groups on the guest and the cavity size of the macrocycle, the slipping might occur slowly or even become completely hindered. We have previously shown that it is possible to overcome the restraints imposed by steric effects on the sliding process by integrating electrostatic attractive interactions during the slipping step. In this work, we extend our electrostatically assisted slipping approach (EASA) to a new host−guest system featuring a flexible macrocyclic ring and a series of asymmetric guests containing a cyclic tertiary ammonium group. Compelling evidence for pseudo‐rotaxane formation is presented, along with thermodynamic and kinetic data. Experimental results suggests that the higher conformational flexibility of 24‐crown‐8 significantly increases the sliding rate, compared with the more rigid dibenzo‐24‐crown‐8, without affecting complex stability. Furthermore, by combining the EASA and macrocycle flexibility, we were capable to slip a large eight‐membered cyclic group across the 24‐crown‐8 annulus, setting a new limit on the ring molecular size that can pass through a 24‐membered crown ether.

Spectral Stable Blue-Light-Emitting Diodes via Asymmetric Organic Diamine Based Dion-Jacobson Perovskites.

The spectral instability issue is a challenge in blue perovskite light-emitting diodes (PeLEDs). Dion–Jacobson (DJ) phase perovskites are promising alternatives to achieve high-quality blue PeLEDs. However, the current exploration of DJ phase perovskites is focused on symmetric divalent cations, and the corresponding efficiency of blue PeLEDs is still inferior to that of green and red ones. In this work, we report a new type of DJ phase CsPb(Br/Cl)3 perovskite via introduction of an asymmetric molecular configuration as the organic spacer cation in perovskites. The primary and tertiary ammonium groups on the asymmetric cations bridge with the lead halide octahedra forming the DJ phase structures. Stable photoluminescence spectra were demonstrated in perovskite films owing to the suppressed halide segregation. Meanwhile, the radiative recombination efficiency of charges is improved significantly as a result of the confinement effects and passivation of charge traps. Finally, we achieved an external quantum efficiency of 2.65% in blue PeLEDs with stable spectra emission under applied bias voltages. To our best knowledge, this is the first report of asymmetric cations used in PeLEDs, which provides a facile solution to the halide segregation issue in PeLEDs.

Electrochemical Degradation of a Dicationic Rhenium Complex via Hoffman-Type Elimination.

Electrocatalytic reduction of carbon dioxide (CO2) by transition-metal catalysts is an attractive means for storing renewably sourced electricity in chemical bonds. Metal coordination compounds represent highly tunable platforms ideal for studying the fundamental stepwise transformations of CO2 into its reduced products. However, metal complexes can decompose upon extended electrolysis and form chemically distinct molecular species or, in some cases, catalytically active electrode deposits. Deciphering the degradative pathways is important for understanding the nature of the active catalyst and designing robust metal complexes for small-molecule activation. Herein, we present a new dicationic rhenium bipyridyl complex capable of multielectron ligand-centered reductions electrochemically. Our in-depth experimental and computational study provides mechanistic insight into an unusual reductively induced Hoffman-type elimination. We identify benzylic tertiary ammonium groups as an electrolytically susceptible moiety and propose key intermediates in the degradative pathway. This investigation highlights the complex interplay between the ligand and metal ion and will guide the future design of metal-organic catalysts.

Proton blockage membrane with tertiary amine groups for concentration of sulfonic acid in electrodialysis

The weak base of tertiary amine groups was introduced into poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) anion exchange membranes (AEMs) by Cu(I)-catalyzed “click chemistry” in order to fabricate proton blockage membranes for sulfonic acid concentration in electrodialysis (ED). The degree of functionalization has been confirmed quantitatively by 1H NMR spectroscopy. Fourier transform infrared spectroscopy (FTIR) was also used to confirm the functional groups in the membranes matrix. The prepared proton blockage membrane with tertiary ammonium groups showed lesser swelling and water uptake ratios than the typical AEMs with strong organic base of quaternary ammonium groups. It is believed that the strong organic base of quaternary ammonium has a stronger hydration effect on water than that of tertiary amine groups. Interestingly, the concentration limitation of membranes with tertiary amine groups was higher than that of the membrane with quaternary ammonium groups, indicative of the proton blocking capabilities of the AEMs as a result of the weak base introduced into the matrix. Moreover, it was found that the concentration limitation of tertiary amine based AEMs was also influenced by the weight-based ion exchange capacities (IECw), essentially the water uptake and swelling ratios of the membranes. The highest concentration limitation of AEMs with tertiary ammonium groups for H+ was 3.02 mmol/L with IECw value of 1.67 mmol/g, which is slightly higher than the 3.00 mol/L reported for the commercial AEM (Neosepta ACM). Therefore, AEMs containing weak base groups are potential candidates for proton blockage membrane for acid recovery applications by ED process.

Synthesis of actinomycin analogs: XXIV. Non-symmetric derivatives of actinocin containing benzo-18-crown-6 moiety and tertiary ammonium group

Non-symmetric derivatives of actinocin containing fragments of benzo-18-crown-6 and dimethylaminopropylamine (with the crown ether group separated from the heterocyclic chromophore by β-alanine moiety) have been prepared as models of actinomycin D.

Interaction between linear PEGylated cationic block copolymers and human serum albumin

Interaction of proteins with synthetic polyelectrolytes is significant with respect to various biological applications. In this work, a detailed spectroscopic study of the binding between a series of PEGylated linear cationic block polymers (BCPs) and human serum albumin (HSA) at physiological pH has been carried out. Techniques like steady-state fluorescence spectroscopy, life-time measurements by time-correlated single photon counting (TCSPC) method and protein conformation analysis by circular dichroism (CD) measurements were employed at different temperatures. Analysis of the quenching data indicated a static quenching mechanism occurring during polymer–protein interaction. The electrostatic interaction between cationic tertiary ammonium groups of the BCPs and negatively charged amino acid residues present in HSA is the predominant force contributing to the binding process. On the other hand, the presence of PEG units in the BCPs significantly influenced the overall binding process. Conformational analysis of HSA using CD studies suggested that the linear PEG units resisted changes in the secondary structure of HSA to a significant extent, resulting in weakening of the overall binding of cationic BCPs and HSA. Detailed analysis of the thermodynamic parameters like∆G0, ∆H0and ∆S0 indicated that the binding process was entropy driven spontaneous in nature.

Hydrogen bonds and steric effects induced structural modulation of three layered iodoplumbate hybrids from nonperovskite to perovskite structure.

Directed by diprotonated organic diamines containing both primary and tertiary ammonium groups, three layered iodoplumbate hybrids, {[H2DMPDA][PbI4]}n (1), {[H2DEPDA]4[Pb5I18]}n (2) and {[H2TMEDA][Pb3I8]}n (3) (DMPDA = N,N-dimethyl-1,3-propanediamine, DEPDA = N,N-diethyl-1,3-propanediamine, TMEDA = N,N,N',N'-tetramethylethylenediamine), have been synthesized solvothermally. 1 presents a layered perovskite structure based on corner-sharing PbI6 octahedra, compound 2 consists of a Pb4I20 perovskite motif and a Pb2I10 dimeric motif and compound 3 comprises Pb3I13 units connected by face-sharing and edge-sharing modes. Structural modulations from nonperovskite to perovskite structure are strongly correlated to steric effects and hydrogen bonding interaction at the organic-inorganic interface. Band gaps for 1-3 , estimated as 2.21, 2.58 and 2.73 eV, respectively, also reveal an interesting correlation with structural modulation, and the red shift for 1 is attributed to large Pb-I(equatorial)-Pb bond angles.

Surface modification of poly(ethylene terephthalate) fabric via photo-chemical reaction of dimethylaminopropyl methacrylamide

Photo-chemical reactions and surface modifications of poly(ethylene terephthalate) (PET) fabrics with the monomer dimethylaminopropyl methacrylamide (DMAPMA) and benzophenone (BP) as photo-initiator using a broad-band UV lamp source were investigated. The tertiary amino groups of the grafted poly(DMAPMA) chains were subsequently quaternized with alkyl bromides of different chain lengths to establish antibacterial activity. The surface composition, structure and morphology of modified PET fabrics were characterized by Fourier transform infrared spectroscopy (FTIR/ATR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). To evaluate the amount of quaternary and tertiary ammonium groups on the modified surface, PET was dyed with an acid dye which binds to the ammonium groups. Therefore, the color depth is a direct indicator of the amount of ammonium groups. The resulting antibacterial activity of the modified PET fabrics was tested with Escherichia coli. The results of all experiments show that a photochemical modification of PET is possible using DMAPMA, benzophenone and UV light. Also, the quaternization of tertiary amino groups as well as the increase in antibacterial activity of the modified PET by the established quaternary ammonium groups were successful.

Sorption concentration of IO3 − and I− on anion exchangers AV-17 and silicas modified with tertiary ammonium groups

We have studied the possibility of using new anion exchangers based on silica with covalently-immobilized trimethyl ammonium propyl and dimethyloctadecyl ammonium propyl groups for sorption concentration of trace amounts of iodine iodide ions followed by their spectrophotometric determination. Sorption properties of new anion exchangers were compared with the properties of the industrial anion exchangers AV-17.

Syntheses, Specific Interactions, and pH-Sensitive Micellization Behavior of Poly[vinylphenol-b-2-(dimethylamino)ethyl methacrylate] Diblock Copolymers

We have used anionic polymerization to prepare a series of poly[vinylphenol-b-2-(dimethylamino)ethyl methacrylate] (PVPh-b-PDMAEMA) block copolymers. These block copolymers are miscible, with strong specific interactions occurring between the OH groups of the PVPh segments and the tertiary ammonium groups of the PDMAEMA segments. These PVPh-b-PDMAEMA diblock copolymers exhibit higher glass transition temperatures than do the corresponding PVPh/partially protonated PDMAEMA blends obtained from DMSO solution, which we suspect exist in the form of separate coils. The blocks of the PVPh-b-PDMAEMA diblock copolymers interact strongly, resulting in polymer complex aggregation similar to the behavior of PVPh/partially protonated PDMAEMA blend complexes obtained from methanol solution. The spin−lattice relaxation times in the rotating frame, determined through solid state NMR spectroscopic analysis, provided clear evidence that the polymer complex aggregates formed from the diblock copolymers have shorter values of T1ρH than do the corresponding separated coils in the miscible blends. In addition, these PVPh-b-PDMAEMA diblock copolymers exhibit a novel type of pH sensitivity: at low pH, compact spherical micelles are formed possessing PDMAEMA coronas and PVPh cores; at medium pH, vesicles are observed, consisting of partially protonated hydrophilic PDMAEMA shells and hydrophobic PVPh cores; at high pH, the spherical micelles that formed comprised ionized PVPh coronas and deprotonated hydrated-PDMAEMA cores, i.e., phase inversion of the micelles formed at pH 2.

Synthesis and evaluation of functional hyperbranched polyether polyols as prospected gene carriers

Hyperbranched polyether polyols have been partially functionalized with quaternary or tertiary ammonium groups. Five derivatives have been prepared bearing 4, 8 and 12 quaternary or 4 and 21 tertiary ammonium groups. The resulting dendritic polymers interact with plasmid DNA affording the corresponding polyplexes. The complexes were physicochemically characterized while their transfection ability was assessed by gel retardation assay, ethidium bromide exclusion assay and cell culture transfection. All the investigated polymers were shown to have marginal to low cytotoxicity in mammalian cells. Transfection efficiency comparable to that of polyethylenimine was exhibited by selected quaternized polymers. However, the introduction of tertiary amino groups on polyglycerol did not improve the transfection of the ineffective parent polymer, despite the fact that the derivatives obtained exhibited additional buffering capacity (sponge effect). The observed transfection efficiency for the quaternized polymers has been attributed to the destabilization of the lysosomal membrane originating from the interaction between the cationic polymers and the anionic moieties located at the membrane. These results are encouraging for the prospective application of these polyols as gene delivery vectors.

Preparation and electrochemical properties of SAM of alkanethiols functionalized with 2-aza[3]ferrocenophane on gold electrode

Thiols functionalized with N-aryl[3]azaferrocenophane formulated as HS-(CH 2) n -N(CH 2Cp) 2Fe ( 1: n = 6, 2: n = 8, 3: n = 10, 4: n = 12) and disulfide obtained by oxidation of 4 ( 5) were synthesized via three or four steps reactions starting from 1,1′-ferrocenedimethanol, 4-aminophenol, and α,ω-aklanedithiol. Self-assembled monolayers (SAMs) of these thiols and disulfide on gold electrode were prepared by immersing the electrode in MeCN solutions of the compounds. Cyclic voltammograms of the SAM of 1 ( n = 6) exhibited reversible redox of the Fe center at E 1/2 = 0.26 V (vs. Ag +/Ag) in the presence of Et 4NBF 4 in MeCN and at E 1/2 = 0.40 V (vs. AgCl/Ag) in the presence of NaClO 4 in H 2O. Addition of HClO 4 to the solutions shifted the redox peaks to higher potentials, E 1/2 = 0.51 V (vs. Ag +/Ag) in MeCN and E 1/2 = 0.48 V (vs. AgCl/Ag) in H 2O, respectively, which was ascribed to positive charge of tertiary ammonium group formed by protonation of the amino group of the azaferrocenophane. E 1/2 of SAM of 1 in H 2O solution varies depending on the anion contained in the electrolyte, NaClO 4 (0.40 V), NaBF 4 (0.46 V), Na 2SO 4 (0.53 V), and NaCl (0.55 V). Kinetic data of electron transfer between the Fe center and the gold surface of the SAM of 2– 4 were obtained with variable scanning rate. Laviron’s analysis provided tunneling constant β, 0.05 Å −1, suggesting that the structural changes in the SAMs on oxidation/reduction undergoes the insignificant change of the kinetic constants of the electron transfer depending on the range of the spacer length. In the acidic aqueous media, the kinetic parameters indicated that the imbalanced electron transfer between oxidized and reduced states of the Fe center was caused by the protonation of bridged amine group of azaferrocenophane.

Fundamental studies on a novel series of bipolar membranes prepared from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO): II. Effect of functional group type of anion-exchange layers on I–V curves of bipolar membranes

In this paper, the water splitting properties of bipolar membranes with different types of functional groups are discussed. To do this, the anion-exchange layers with different ammonium groups were prepared in advance which can be controlled by reacting the bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) base membrane with different amines such as methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), triethylamine (TEA), tri- n-propylamine (TPA), tri- n-butylamine (TBA) and dimethyethanolamine (DMEA) to form the corresponding secondary, tertiary and different quaternary ammonium groups. And then the corresponding bipolar membranes were prepared by casting the sulphonated PPO solution on these anion-exchange layers. The fundamental characteristics of bipolar membranes, current–voltage curves, are fully discussed based on the functional group type of anion-exchange layers. The results demonstrate that the bipolar membrane with strongly basic groups has larger water dissociation ability than those with weakly basic groups. For membranes with weakly basic groups (secondary or tertiary ammonium groups) or strongly basic groups (quaternary ammonium groups), water dissociation mainly depend on the p K b value of amines to form the anion-exchange layers if the mono-polar ion-exchange layers processes the close intrinsic properties such as water uptake and conductivity: voltage at a given current density roughly decreases with an increase in p K b values.

A female with central anticholinergic syndrome responsive to neostigmine

Central anticholinergic syndrome is a rarely observed condition in children. The occurrence of this syndrome after ingestion of Solanum pseudocapsicum is infrequent because findings tend to be milder and localized to the gastrointestinal system, without central nervous system involvement. Most patients do not present with diagnostic problems because their relatives can usually report any ingestion of poisonous agents; however, when drug poisoning or plant ingestion is uncertain, a differential diagnosis with encephalitis must be considered. Physostigmine salicylate is the specific antidote because it crosses the blood-brain barrier because of its tertiary ammonium group. Neostigmine methylsulfate has a quaternary ammonium group, which prevents its penetration through the blood-brain barrier; hence its primary influence is believed to be due to its action on the peripheral nervous system. We describe a female with central anticholinergic syndrome caused by ingestion of Solanum pseudocapsicum . A slow intravenous infusion of neostigmine methylsulfate (0.03 mg/kg) immediately resolved the clinical picture. To our knowledge, this case is the first reported of central anticholinergic syndrome occurring after ingestion of Solanum pseudocapsicum in a child and the first report of a complete and rapid remission after intravenous neostigmine methylsulfate administration.

New polyurethane compositions able to bond high amounts of both albumin and heparin: II: Copolymers and polymer blends

Haemocompatible new urethane copolymers and polymer blends containing, in the chain extender, a long chain alkyl group (able to bond albumin) or a tertiary ammonium group able, after suitable quaternization reaction, to bind ionically significant amounts of heparin, were prepared. The copolymers were characterized by differential scanning calorimetry, intrinsic viscosity determinations, infrared spectroscopy and nuclear magnetic resonance ( 1H and 13C). Biological in vitro evaluation has shown that the adsorption sequence for albumin and heparin, respectively, onto films of the various copolymers and blends, exerts a great influence. From scanning electron microscopy measurements it was seen that the bonding type of albumin to the polymer films plays a determining role on the platelet activation. A phase segregation occurring on the polymer blends surface was demonstrated by X-ray photoelectron spectroscopy measurements.

Synthesis and characterization of new amphiphilic polyurethane compositions

New segmented polyurethanes containing in the chain extender molecule (dihydroxyethyl- n-hexadecylamine, DHHA) both a hydrophobic long alkyl group and a tertiary ammonium group (whose polarity was further increased by quaternization reaction), are described. In order to evaluate the influence of the chain extender content on the polymer properties, also polymers containing DHHA and 1,4 butanediol at different molar ratios have been prepared. The obtained polymers were characterized by i.r., NMR, DSC, viscometry and water swelling measurements.

New polyurethane compositions able to bond high amounts of both albumin and heparin: Part I

In order to prepare polymers provided with better haemocompatibility with respect both to the coagulative cascade and to platelet aggregation and activation, we have synthesized new polyurethanes containing in the chain-extender [di(2-hydroxyethyl)hexadecylamine] both a long chain alkyl group (able to bond albumin) and a tertiary ammonium group able, after suitable quaternization reaction, to bind ionically significant amounts of heparin. The amounts of heparin and albumin bonded to the polymer films were determined spectrophotometrically. A biological in vitro evaluation of the heparinized and albuminized films was also carried out with respect to blood coagulation factors (by activated partial thromboplastin time measurements) and to platelet adhesion and activation (by platelet count and scanning electron microscopy examination). It was seen that the type of adsorption sequence for albumin and heparin, respectively, onto the various homo- and copolymer films, plays an important role on their biological properties; the possible mechanisms involved are also discussed on the basis of X-ray photoelectron spectroscopy and attenuated transmission reflectance evaluation of the polymer surfaces.

New polyurethane compositions able to bond high amounts of both albumin and heparin

In order to prepare polymers provided with better haemocompatibility with respect both to the coagulative cascade and to platelet aggregation and activation, we have synthesized new polyurethanes containing in the chain extender [di-(2-hydroxyethyl) hexa-decylamine (DHHA)] both a long chain alkyl group (able to bond albumin) and a tertiary ammonium group able, after suitable quaternization reaction, to bind ionically significant amounts of heparin. The amounts of heparin and albumin bonded to the polymer films were determined spectrophotometrically. A biological in vitro evaluation of the heparinized and albuminized films was also carried out, with respect to the blood coagulation factors (by APTT measurements) and to platelet adhesion. For the sake of comparison, polyurethanes containing as chain extenders two different monomers (containing, respectively, the long alkyl and the quaternary ammonium group), and polymer blends consisting of these copolymers, were also prepared and evaluated as above. It was seen that the type of the adsorption sequence for albumin and heparin, respectively, onto films of the various homopolymers, copolymers and blends, plays an important role in their biological properties.