Terminal Ammonium Research Articles

Luminescent Dansyl-Calix[5]arene for the Recognition of Biogenic Amines

: A luminescent calix[5]arene with a covalently linked dansyl chromophore substituent has been successfully used, both in solution and in the gas phase (ESI-MS), for the recognition of biogenic amines that contain linear alkylammonium structural unit. Binding constant values, determined by fluorescence spectroscopy, revealed a greater affinity for cadaverine, spermidine, and L-lysine, in which the terminal ammonium group allows for additional stabilizing interactions with the dansyl moiety.

Designing Surface Passivators Through Intramolecular Potential Manipulation for Efficient and Stable Perovskite Solar Cells.

The conjugation of terminal ammonium salt groups with perovskite surfaces is a frequently employed technique that aims to enhance the overall performance of perovskite materials, encompassing both bulk and surface properties. Particularly, it exhibits heightened efficacy when applied to surface modification, due to its ability to mitigate defect accumulation and facilitate facile binding with the receptive sites inherent to the perovskite structure. However, the interaction of the bulk ammonium group with PbI2 has the potential to form a low-dimensional phase of perovskite, which may obstruct carrier extraction at the interface. Therefore, the surface passivators (MeO-PFACl) are designed through intramolecular potential manipulation. The combinations of the electron-donating methoxy group and π-π conjugation of the phenyl ring reduce the local potential at the reactive site of formamidinium group, making it less likely to form a low-dimension phase with perovskite. This surface passivation strategy effectively suppresses the surface nonradiative recombination and promotes the interface carrier extraction. The devices treated with MeO-PFACl have demonstrated exceptional performance, achieving a peak power conversion efficiency (PCE) of 25.88%, with an average PCE of 25.37%. These works offer a novel principle for enhancing both the efficiency and stability of PSCs using ammonium-incorporated molecules without the induction of an additional phase layer.

Novel Natural Compounds and Their Anatomical Distribution in the Stinging Fireworm Hermodice carunculata (Annelida).

Increasing evidence in the field of bioprospection fosters the necessity of studying poorly investigated poisonous marine invertebrates to expand knowledge on animal venom biology. Among marine annelids, amphinomid fireworms are notorious for their bearded trunk equipped with a powerful stinging capacity. Here, a methodological workflow based on analytical chemistry techniques (compound isolation followed by mass spectrometry and spectroscopy analyses) was applied to gain new insights, leading to the identification and structural elucidation of an array of natural products from Mediterranean specimens of Hermodice carunculata. Eight betaine-derived unprecedented compounds, named “carunculines”, were detected, bearing two terminal ammonium groups tri-and disubstituted at the Cα (A, B) and a series of different alkyl chains (I–VIII). The mixture of chemicals was found in all the body parts of H. carunculata, supporting a mechanism of action triggered by their vehiculation inside the dorsal chaetae, and subsequent injection when chaetae break off on contact. Preliminary investigations to understand adaptive features were also performed, showing a trend in carunculine abundance that fits into the evolutionary history of these worms. These findings shed light on the chemical ecology of amphinomids, giving reasons for the success of H. carunculata in benthic environments and providing promising novel metabolites for biotechnological implications.

Novel ether-free membranes based on poly(p-terphenylene methylimidazole) for vanadium redox flow battery applications

The fabrication of low-cost and high-performance membranes is one of the most critical issues for vanadium redox flow batteries (VRFBs). Herein, a novel ether-free poly(p-terphenylene methylimidazole) (PTMIm) is synthesized by a facile one-pot Friedel-Crafts polyhydroxyalkylation of p-terphenyl and 1-methyl-2-imidazolecarboxaldehyde. The PTMIm has excellent organic solubility and good chemical stability towards high valence vanadium ions. Meanwhile, due to the present pendant imidazole groups, the PTMIm membrane exhibits a high sulfonic acid absorption capability, achieving a suitable area resistance (AR). In order to further enhance the performance of the PTMIm membrane, side-chain quaternization is carried out by using 1-bromopropane, 3-bromo-N,N,N-trimethylpropan-1-aminium bromide and 3-chloro-2-hydroxypropyltrimethyl ammonium chloride as quaternized reagents. Comparing with pure PTMIm membrane and propyl group grafted membrane (i.e. PTMIm-C3), terminal quaternary ammonium side chain grafted membranes of PTM-C3-QA and PTMIm-C3-OH-QA possess lower AR and better vanadium ion resistance simultaneously. Consequently, the ion selectivity value of the PTMIm-C3-QA membrane is 8.7 × 105 S min cm−3, which is approximately 130 times higher than that of Nafion 115 (6.6 × 103 S min cm−3), mainly resulting from its low AR (0.68 Ω cm2) and ultralow vanadium ion permeability (9.5 × 10−9 cm2 min−1). Meanwhile, both PTMIm and its grafted membranes exhibit excellent chemical stabilities within 400 h chemical stability test. Owing to the superior restriction on vanadium migration, the single cell with PTMIm-C3-QA displays an excellent self-discharge duration of 500 h, which is greatly longer than that of Nafion 115 (58 h). In the range of 40–160 mA cm−2, the PTMIm-C3-QA based cell expresses higher coulombic efficiencies (>99.5%) and larger energy efficiencies than the cell with Nafion 115. For the cycling test of VRFB during 500 cycles, the PTMIm-C3-QA based cell displays excellent cycle stability and good discharge capacity retention, indicating a great application potentiality of the PTMIm-C3-QA membrane for VRFBs.

Reaction of Amino-Terminated PAMAM Dendrimers with Carbon Dioxide in Aqueous and Methanol Solutions.

Polyamines have been used as active materials to capture carbon dioxide gas based on its well-known reaction with amines to form carbamates. This work investigates the reactions between three amino-terminated poly(amidoamine) (PAMAM) dendrimers (G1, G3 and G5) and CO2(g) in aqueous (D2O) and methanolic (CD3OD) solutions. The reactions were monitored using 1H NMR spectroscopy, and yielded dendrimers with a combination of terminal carbamate and terminal ammonium groups. In aqueous media the reaction was complicated by the generation of soluble carbonate and bicarbonate ions. The reaction was cleaner in CD3OD, where the larger G5 dendrimer solution formed a gel upon exposure to CO2(g). All reactions were reversible, and the trapped CO2 could be released by treatment with N2(g) and mild heating. These results highlight the importance of the polyamine dendrimer size in terms of driving changes to the solution’s physical properties (viscosity, gel formation) generated by exposure to CO2(g).

A water soluble hydrazone probe for subsequent fluorescent detection of Zn2+ and S2− in neat aqueous solution and imaging in mitochondria of living cells

A simple water soluble hydrazone sensor (1·Cl) has been developed to selectively chelate with Zn2+ via an O2N donor set, leading to specific fluorescence enhancements. The highly emissive 1-Zn2+ complex can serve as a reversible on-off sensor for S2−. The detection limits of 1·Cl for Zn2+ and S2− are 66.0 and 32.6 nM, respectively. The recognition mechanism was carefully investigated through FL, UV-vis, 1H NMR, ESI-MS, time-resolved fluorescence, and density functional theory (DFT) calculations. Owing to the mitochondria-targeting ability of the terminal quaternary ammonium moiety, 1·Cl was successfully applied to image mitochondrial Zn2+ and S2−.

Modulating the Stability of Collagen Triple Helices by Terminal Charged Residues.

Cationic or anionic residues are frequently located at the termini of proteins because their charged side chain can form electrostatic interactions with a terminal carboxylate or ammonium group to stabilize the structure under physiological conditions. Here, we used collagen-mimetic peptides (CMPs) to examine how the terminal charge-charge interactions affect the collagen triple helix stability. We designed a series of CMPs with either a Lys or Glu incorporated into the terminus and measured their pH-dependent stability. The results showed that the terminal electrostatic attractions stabilized the triple helix, while the terminal electrostatic repulsions destabilized the trimer. The data also revealed that the repulsions imposed a greater effect than did the attractions on the triple helix. An amino acid with a shorter side chain, such as aspartate and ornithine, was also installed to investigate the length effect on electrostatic interactions, which was found to be insignificant. Meanwhile, simultaneously incorporating cationic and anionic residues into the termini showed slight additive stabilization effects but pronounced additive destabilization consequences. We have demonstrated that the collagen triple helix stability can be modulated by introducing a cationic or anionic residue into the terminus of a peptide, giving useful information for the design of collagen-associated materials.

Synthesis, crystal structures, Hirshfeld surface analysis and physico-chemical characterization of two new ZnII and CdII halidometallates

Two new organic–inorganic hybrid materials, based on 1,3-CycloHexaneBis-(Methyl Amine), abbreviated CHBMA, namely (H2CHBMA)ZnCl4·2H2O (CP1) and (H2CHBMA)CdI4·2H2O (CP2), have been synthesized under mild conditions in acidic media and characterized by single-crystal X-ray diffraction, spectroscopic techniques (13C NMR, FTIR, RAMAN) and thermal analysis. The crystal structures of the two compounds were solved by single-crystal X-ray diffraction methods. Both compounds show a 3-dimensional supramolecular structure directed by various interactions between tetrahalidometallate anions (ZnCl42−, CdI42−), water molecule and organic cations (H2CHBMA)2+. For both compounds, the cyclohexane ring of the template cation is in a chair conformation with the methylammonium substituent in the equatorial positions and the two terminal ammonium groups in a cis conformation but with two different orientations (upward for CP1 and downward for CP2) which influences the supramolecular architecture of the two structures. Hirshfeld surface analysis and the associated two-dimensional finger print plots were used to explore and quantify the intermolecular interactions in the crystals.

Janus charged polyamide nanofilm with ultra-high separation selectivity for mono-/divalent ions

Nanofiltration (NF) membranes with ultra-high separation selectivity to both mono-/divalent anions and cations are desirable for treatment of practical water with complex composition of ions. In this work, a facile and universal method for fabricating polyamide (PA) NF membranes with both ultra-high separation selectivity to mono-/divalent anions and cations was developed. Cationic poly(amido-amine) (PAMAM) dendrimers with different numbers of terminal quaternary ammonium groups were synthesized and incorporated into the polyamide (PA) matrix by interfacial polymerization (IP) to modulate both charge properties and network structures of the PA nanofilms. Contributed by the heterogenous distribution of PAMAM G5-TAC2, a Janus charged PA nanofilm was successfully fabricated. The negatively charged top surface of the PA nanofilm leads to a high electrostatic repulsion to divalent anions while its positively charged back surface exerts a high electrostatic repulsion to divalent cations. Moreover, the network structures of the PA nanofilms are precisely modulated to accelerate the transport of water molecules (103.5 L m−2h−1 MPa−1). Based on the synergistic effect of steric and Donnan effects, the transports of both divalent anions and cations through the G5-TAC2/PIP membrane are hindered, while the transports of monovalent ions are free, so that both ultra-high separation selectivity to mono-/divalent anions and cations (both above 65) can be achieved. Compared to PIP only membrane, G5-TAC2/PIP membrane exhibits high-efficiency in mixed ion separation process.

(S)-5′-C-Aminopropyl-2′-O-methyl nucleosides enhance antisense activity in cultured cells and binding affinity to complementary single-stranded RNA

Antisense oligonucleotides (ASOs) are a promising clinical tool that could be applied for unmet medical needs, but there are several limitations for their therapeutic application. Here, we designed and synthesized (S)-5′-C-aminopropyl-2′-O-methylcytidine, and oligonucleotides containing (S)-5′-C-aminopropyl-2′-O-methyluridine and -methylcytidine. We then investigated the properties of ASOs containing these nucleoside analogs. (S)-5′-C-Aminopropyl modifications enhanced the thermal stability of DNA/RNA duplexes when compared to other commercially available 2′-O-methyl modifications. This suggested that the terminal ammonium cation on the alkyl side chains neutralized the negative charge of the phosphates in the duplex. Additionally, the overall conformation of ASO/RNA duplexes was retained with the modified ASOs. Thus, these duplexes exhibited the ability to elicit RNase H activity. Furthermore, we found that ASOs containing the (S)-5′-C-aminopropyl modification exhibited higher antisense potency than those containing the 2′-O-methyl modification in cultured cells. Therefore, the (S)-5′-C-aminopropyl-2′-O-methyl nucleosides synthesized in this study are promising candidates for developing antisense therapeutics.

A Molecular Crystal Shows Multiple Correlated Magnetic and Ferroelectric Switchings

Simultaneous control of the magnetic and electric properties of materials is crucial for their application in next-generation memory and sensor devices. Herein, we report a single-crystal Co(II) co...

Impact of Chain Length on Release Behavior of Modified Polyethylene Glycol Intercalated-Montmorillonite Nanocomposite.

A new drug delivery nanocomposite system was prepared from sodium montmorillonite (Na+Mt) intercalated with modified polyethylene glycol (PEG). PEGs of different molecular weights (400, 4000, and 8000) were modified with glycidyltrimethylammonium chloride (GTMAC) to provide terminal quaternary ammonium sites capable for attaching with Mt or other materials through ion exchange. The modified PEG-GTMAC derivatives were reacted in excess amount with Na+Mt through ion exchange. The remaining quaternary sites were used for the attachment of sodium diclofenac as a model drug. The structures of the prepared clay-modified PEG-diclofenac systems were characterized using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The release behavior of diclofenac from the different nanocomposites was studied at different pH values. With regard to the PEG chain length, the drug release increased with increasing PEG molecular weight (GCDIII > GCD-III > GCDII > GCDI). The kinetics of the release models was discussed using Korsmeyer-Peppas, Higuchi, and zero- and first-order models. The results of the kinetics study revealed that modified samples with PEG 400 and PEG 4000 (GCD-I and GCDII) exhibited non-Fickian diffusion (anomalous transport) while modified samples with PEG 8000 (GCDIII) exhibited super case-II transport.

Quantum mechanical study of human carbonic anhydrase II in complex with polyamines as novel inhibitors: Kinetic and thermodynamic investigation

Spermine and spermidine polyamines are investigated as a new class inhibitors of different carbonic anhydrase (CA) isoforms using DFT calculations. Our results indicate these two polyamines, inhibited the human carbonic anhydrase with very different inhibition profiles compared to other inhibitors. According to calculated results, studied polyamines are anchored to the non-protein zinc ligand (hydroxyl ion) by means of a hydrogen bond of 2.6 Å involving one of terminal ammonium group and an intermediate complex is formed, [(his)3Zn(II)(OH)/polyamine], which is in good agreement with experimental data. By transferring a proton from the terminal ammonium group of polyamine inhibitor to the oxygen atom of the hydroxyl group, the active form of the CA enzyme converted to the inactive form. Finally, the HOMO-LUMO and AIM analysis have been done to understand the details of interaction between studied polyamines and CA active center in intermediate complex in water phase.

P.671 Efficacy and safety of lumateperone tosylate 42mg in the treatment of schizophrenia: A pooled analysis of phase 2 and 3 studies

Transient absorption spectroscopy in combination with in silico methods has been employed to study the interactions between human serum albumin (HSA) and the anti-psychotic agent chlorpromazine (CPZ) as well as its two demethylated metabolites (MCPZ and DCPZ). Thus, solutions containing CPZ, MCPZ or DCPZ and HSA (molar ligand:protein ratios between 1:0 and 1:3) were submitted to laser flash photolysis and the ΔAmax value at λ = 470 nm, corresponding to the triplet excited state, was monitored. In all cases, the protein-bound ligand exhibited higher ΔAmax values measured after the laser pulse and were also considerably longer-lived than the non-complexed forms. This is in agreement with an enhanced hydrophilicity of the metabolites, due to the replacement of methyl groups with H that led to a lower extent of protein binding. For the three compounds, laser flash photolysis displacement experiments using warfarin or ibuprofen indicated Sudlow site I as the main binding site. Docking and molecular dynamics simulation studies revealed that the binding mode of the two demethylated ligands with HSA would be remarkable different from CPZ, specially for DCPZ, which appears to come from the different ability of their terminal ammonium groups to stablish hydrogen bonding interactions with the negatively charged residues within the protein pocket (Glu153, Glu292) as well as to allocate the methyl groups in an apolar environment. DCPZ would be rotated 180° in relation to CPZ locating the aromatic ring away from the Sudlow site I of HSA.

An Amphiphilic Pyridinoyl-hydrazone Probe for Colorimetric and Fluorescence pH Sensing.

A new pH sensor based on a substituted aroylhydrazide with a flexible side chain and a terminal trimethyl ammonium group (PHA+) was designed and synthesized. The terminal quaternary ammonium guarantees excellent solubility in water. At the same time, the probe is very soluble in hydrophobic envirornments. The pyridinoyl-hydrazone moiety acts as the pH-sensitive fluorophore/chromophore probe. Extensive physicochemical characterization has been performed on the bromide salt PHABr. DFT calculations, based on single-crystal X-ray data, permitted to rationalize the optical behavior. Molecular dynamics simulations permitted to clarify the mode of interaction with lipid membrane. The ability of the probe to change color and fluorescence in response to different pH and media of different polarity has been investigated. PHABr shows a remarkable pH-dependent behavior in both absorption and fluorescence spectra with high sensitivity and strong on-off switch effect at neutral pH, perceptible even to the naked eye.

Investigation of metabolite-protein interactions by transient absorption spectroscopy and in silico methods.

Transient absorption spectroscopy in combination with in silico methods has been employed to study the interactions between human serum albumin (HSA) and the anti-psychotic agent chlorpromazine (CPZ) as well as its two demethylated metabolites (MCPZ and DCPZ). Thus, solutions containing CPZ, MCPZ or DCPZ and HSA (molar ligand:protein ratios between 1:0 and 1:3) were submitted to laser flash photolysis and the ΔAmax value at λ = 470 nm, corresponding to the triplet excited state, was monitored. In all cases, the protein-bound ligand exhibited higher ΔAmax values measured after the laser pulse and were also considerably longer-lived than the non-complexed forms. This is in agreement with an enhanced hydrophilicity of the metabolites, due to the replacement of methyl groups with H that led to a lower extent of protein binding. For the three compounds, laser flash photolysis displacement experiments using warfarin or ibuprofen indicated Sudlow site I as the main binding site. Docking and molecular dynamics simulation studies revealed that the binding mode of the two demethylated ligands with HSA would be remarkable different from CPZ, specially for DCPZ, which appears to come from the different ability of their terminal ammonium groups to stablish hydrogen bonding interactions with the negatively charged residues within the protein pocket (Glu153, Glu292) as well as to allocate the methyl groups in an apolar environment. DCPZ would be rotated 180° in relation to CPZ locating the aromatic ring away from the Sudlow site I of HSA.

Uniform, High-Aspect-Ratio, and Patchy 2D Platelets by Living Crystallization-Driven Self-Assembly of Crystallizable Poly(ferrocenyldimethylsilane)-Based Homopolymers with Hydrophilic Charged Termini

Two-dimensional (2D) seeded growth of poly(ferrocenyldimethylsilane) (PFS) homopolymers that possess hydrophilic charged termini in solution has been investigated using the living crystallization-driven self-assembly method. The charge-terminated homopolymers, PFSn[NMe3]I, were synthesized through a combination of living anionic polymerization and post-polymerization thiol–ene “click” chemistry. Uniform and patchy high-aspect-ratio 2D structures were obtained by seeded growth in solution. We show that the aspect ratio of the resultant 2D platelets could be controlled over a wide range (ca. 2–20) by changing either the solvent polarity of the medium in which seeded growth was conducted, the substituents on the charged terminal group, or the characteristics of the seed micelle. The counteranion associated with the charge-terminated PFS[NMe3]+ homopolymers was found to have a substantial effect on the resulting morphology and colloidal stability of the resulting 2D platelets, which may be a consequence of relatively high charge density of the terminal quaternary ammonium cation.

1-nm-Wide Hydrated Dipole Arrays Regulate AuNW Assembly on Striped Monolayers in Nonpolar Solvent

Summary We show that striped phases of horizontally oriented phospholipids presenting 1-nm-wide orientable dipole arrays can order and straighten flexible 2-nm-diameter gold nanowires (AuNWs) with lengths (up to 1 μm) that greatly exceed the template pitch (∼7.5 nm). AuNW ordering can extend over areas > 100 μm2. Whereas wires bundle in solution, with contact between ligand shells, wires adsorbing to the template separate to much larger center-to-center distances (e.g., 12–30 nm) near multiples of the template pitch, consistent with repulsive interactions between wires emerging during interactions with dipole arrays in the template. AuNW assembly was carried out in cyclohexane, a nonpolar solvent. Interestingly, we found that wire ordering was contingent on the extent of phospholipid headgroup hydration and the presence of excess oleylamine, which assembled into hemicylindrical micelles around the hydrated headgroups. Together, these components generated a protected polar environment that enabled the phospholipid headgroups to function collectively to regulate AuNW assembly.

Non-covalently crosslinked anion exchange membranes: Effect of urea hydrogen-bonding group position

To investigate the effects of noncovalent intermolecular interaction on the performance of anion exchange membranes (AEMs), two types of side chain urea-containing poly(phenylene oxide)-based AEMs, namely, benzyl urea-linkaged terminal quaternary ammonium (QA)-containing AEMs (bU-AEMs) and benzyl QA-linkaged urea-containing AEMs (sU-AEMs), were synthesized and comparatively studied. The analyses by solubility test and variable-temperature infrared spectroscopy showed that the urea-based hydrogen-bonding strength in bU-AEMs was higher than that of sU-AEMs. The bU-AEMs were characterized with a stable water uptake (WU), as well as high swelling resistance relative to that of the sU-AEM counterparts, as the temperature increases. A high chloride conductivity of 50.3 mS cm−1 was achieved for bU-AEM-0.45 at 90 °C, while its WU maintained a moderate value (80.6 wt%). The H2-O2 single fuel cell performance using the bU-AEM-0.35 membrane as a separator reached a peak power density of 68 mW cm−2, which was higher than that of the sU-AEM-0.35 sample with 48 mW cm−2. More importantly, there was less than 10% conductivity loss for the bU-AEMs after incubation in 1 M NaOH at 60 °C after 7 days, while approximately 30% loss was observed for the sU-AEMs. The results indicated that the hydrogen-bonding crosslinking strategy, as well as the configuration of H-bonding groups, provides a platform to tune the properties of AEMs suitable for fuel cell applications.

Unveiling Noncovalent Interactions in Imidazolium, Pyrrolidinium, or Quaternary Ammonium Cation and Acetate Anion Based Protic Ionic Liquids: Structure and Spectral Characteristics.

In the present work protic ionic liquids (PILs) composed of imidazolium-, quaternary ammonium-, or pyrrolidinium-dications and acetate (OAc-) anion have been modeled as the dication-anion complexes through the M06-2x based density functional theory. It has been shown that cation-anion interaction energies are larger for the PILs containing the quaternary ammonium cation, which can be attributed to strong hydrogen bonding from the terminal ammonium protons. Underlying N-H···O and C-H···O hydrogen bonding, electrostatic, and van der Waals interactions are unraveled using the natural bond orbital analyses in conjunction with the quantum theory of atoms in molecules (QTAIM) and noncovalent interaction index reduced density gradient methods. The ramifications of noncovalent binding to 1H NMR and vibrational spectra are presented. The calculations further demonstrate a linear correlation of the kinetic energy density parameter G( r) in QTAIM analysis with the characteristic frequency shift of -NH3+ stretching in the dication-anion complexes. Moreover, the chemical shifts (δH) in 1H NMR spectra from theory reveal larger deshielding; the corresponding δH value correlates well with proton affinities and cation-anion binding energies as well. Effect of solvent (DMSO) on structure, binding energies, and 1H NMR are presented. The shifts of the characteristic carbonyl and the terminal ammonium stretching vibrations accompanying the dication-anion complexes from gas phase calculations are in consonance with the self-consistent reaction field theory.