Zwitterionic Salt Research Articles

Constructing Nitrogen-Rich Fused [5,6,5]-Tricyclic Frameworks Through Rearrangement: Heat-Resistant Zwitterionic Salt Energetic Materials.

This study synthesized nitrogen-rich [5,6,5] fused compounds through a novel rearrangement reaction. Owing to its unique zwitterionic salt structure, rearrangement product 4-1 exhibits high thermal stability (Td > 250 °C), low sensitivity (IS > 40 J, FS > 360 N), and acceptable detonation velocities and pressures (νD = 8520 m s-1 and P = 32.53 GPa, respectively), which are better than those of TNT and TATB. These indicate the potential of zwitterionic salts as thermally stable energetic materials and provide new synthesis strategies for constructing fused polycyclic heterocycles through rearrangement.

Solvent‐ or Base‐Controlled Diastereoselectivity and Chemoselectivity for the Reaction of Ketenimine Zwitterionic Salts

Comprehensive SummaryKetenimine zwitterionic salt (KZS), a novel and stable ketenimine precursor, is still underexplored in the realm of chemical synthesis. In this study, we demonstrate the transformation of pyrrole derivatives through the cyclization of KZS with α‐aminoketones. The diastereoselectivity of this reaction is influenced by the solvent, enabling the isolation of 3‐hydroxypyrrolidine diastereomers with the highest reported dr value of 21 : 1. Furthermore, the chemoselectivity is modulated by the choice of base, yielding 2‐aminopyrrole derivatives as the major products. This research offers a sustainable approach to harnessing the potential of KZS in organic synthesis, contributing to a greener chemical process.

A zwitterionic salt–cocrystal: in vitro insights from niraparib tosylate, an anti-cancer drug

Schematic representation showing nomenclature of different cocrystals.

A zwitterionic salt with one sulfonate and two ether functional groups as an additive for lithium-ion battery electrolyte

An imidazolium-based zwitterionic compound bearing two ether groups at the C-1 and C-2 positions and one sulfonate group at the C-3 position of the imidazolium ring was successfully synthesized. The compound was characterized using nuclear magnetic resonance spectroscopy and elemental analysis. The product (2.5 wt%) was added to a commercial electrolyte for lithium-ion batteries containing 1 M LiPF6 in ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (1:1:1 by volume). The resulting electrolyte had a slightly higher ionic conductivity in the range 10–70 °C than the model electrolyte, implying that the additive had a beneficial impact, possibly due to the C-2 rather than the C-1 ether group. Cyclic voltammetry analysis indicated that the electrochemical stability of the electrolyte did not change. The effect of the electrolyte additive on the cell’s 1C cycling performance was also examined: it was found that a stable discharge capacity was maintained for up to 100 cycles. Fourier transform infrared spectra of complexes formed by the synthesized product and LiPF6 at different ratios showed that the Li+ ions interacted with all the functional groups.

Characterization of the ionic liquid obtained by chlorosulfonation of 1-methylimidazole: 1-methyl-3-sulfonic acid imidazolium chloride, 1-methylimidazolium chlorosulfate or a zwitterionic salt?

A great number of organic reactions catalyzed by the ionic liquid product of chlorosulfonation of 1-methylimidazole have been reported recently. At the same time controversial assumptions have appeared on the real structure of the catalyst. In the present report the primarily formed chlorosulfonation product is proved to be 1-methylimidazolium chlorosulfate ([HMim]+[SO3Cl]−) instead of 1-methyl-3-sulfonic acid imidazolium chloride, reported previously. The former structure is confirmed by X-ray crystallography and NMR spectroscopy, including 1H-, 13C-, 17O- and 15N–1H HSQC measurements. 1H and 17O NMR experiments support fast hydrolysis of [HMim] [SO3Cl] resulting in the formation of [HMim][HSO4] in the presence of traces of water.

Tricyclic nitrogen-rich cation salts based on 1,2,3-triazole: Chemically stable and insensitive candidates for novel gas generant

A new tricyclic nitrogen-rich compound 4,5-bis(4,5-diamine-1,2,4-triazole-3-yl)-2H-1,2,3-triazole (2) was synthesized. Monovalent and divalent cations based on 1,2,3-triazole backbone were developed for energetic salts 3–13. It is worth mentioning that energetic salt 8 was obtained as a unique zwitterionic salt. These energetic compounds exhibit good thermal stability and positive heat of formation. Most of these newly synthesized compounds were insensitive to mechanical stimulation (IS ≥ 24 J, FS ≥ 252 N), while the sensitivity of compound 4 (IS = 7 J, FS = 120 N) is similar to that of RDX (IS = 7.4 J, FS = 120 N). Additionally, crystal analysis and theoretical calculations of crystals 2, 3, 4, 8 were carried to explore the relationship between strong hydrogen bonds and physicochemical properties. Furthermore, dinitramide salt 5 and zwitterionic salt 8 have relatively high theoretical detonation properties (5: D = 8770 m s−1, 8: D = 8545 m s−1), which are close to RDX (D = 8795 m s−1). The compounds 2–5, 8 possess outstanding combustion performance (Pmax: 4.57–13.38 MPa) tested by constant-volume combustion experiments, which are superior to frequently-used gas generant guanidine nitrate. All the results demonstrate that dinitramide salt 5 and zwitterionic salt 8 with high volumes of detonation gas (5: 826.74 L kg−1; 8: 799.77 L kg−1), moderate detonation performance and appropriate mechanical sensitivities (5: IS = 28 J, FS > 360 N; 8: IS > 40 J, FS > 360 N) may be useful as novel gas generant.

Effects of novel benzotriazole based zwitterionic salt as electrolyte additive for lithium ion batteries

A novel zwitterionic lithium-benzotriazole sulfobetaine is fabricated by grafting 1,3– propanesultone onto benzotriazole and then lithiating it. The resultant lithium-benzotriazole-sulfobetaine additive is used as an electrolyte additive in lithium ion batteries in 1 M LiPF6 (ethylene carbonate/dimethyl carbonate = 1:1). The electrolytes with the lithium-benzotriazole sulfobetaine shows higher ionic conductivities (2.18 × 10−2 S cm−1) compared to the bare electrolyte (1.07 × 10−2 S cm−1) and greater electrochemical stability (anodic limit at ~5.5 V vs. Li/Li+) than the pure electrolyte (anodic limit at ~4.6 V vs. Li/Li+). The discharge capacity of the lithium cobalt oxide/graphite cells is improved at higher C-rates with the addition of lithium-benzotriazole sulfobetaine due to increased ionic conductivity. The lithium cobalt oxide/graphite cells with the lithium-benzotriazole sulfobetaine additive also show stable cycling performance. These findings warrant the use of lithium-benzotriazole sulfobetaine as an electrolyte additive in lithium ion batteries.

Formation of trinitromethyl functionalized 1,2,4-triazole-based energetic ionic salts and a zwitterionic salt directed by an intermolecular and intramolecular metathesis strategy

Energetic trinitromethyl bistriazole and its ionic salts, as well as an unexpected energetic-zwitterion featuring trinitromethyl and diazonium moieties, were synthesized via an intermolecular and intramolecular metathesis strategy.

Mechanically strong ionogels formed by immobilizing ionic liquid in polyzwitterion networks

Recently, ionogels have obtained widespread attention as excellent functional materials due to their advantageous properties, such as nonvolatility, nonflammability, and good electrochemical properties. Herein, a novel two-component ionogel system exhibiting superior mechanical strength and flexibility, satisfactory self-healing property, as well as comparable electrochemical property is constructed through in situ photopolymerization. This kind of ionogels is free of any crosslinker and comprised of a polymerized imidazolium-type zwitterionic salt as polymer backbone and an ionic liquid 1-butyl-3-methylimidazolium chloride (bromide) as solvent. The zwitterionic groups interact strongly with each other and the ions of ionic liquid solvent, resulting in the formation of the physical crosslinking within the polymer chains and the ion-dipole interaction between the zwitterionic group in the polymer backbone and ionic liquid solvent which endow the ionogel with superior mechanical strength without any crosslinker. The compression strength and tensile strength can reach 58MPa and 2.3MPa, respectively. The mechanical performance of these polyzwitterion ionogels is even comparable to chemically crosslinked high strength ionogels reported. These tough ionogels also show good self-healing properties at their glass transition temperature and have 80% recovery of their original strength. Moreover, these ionogels exhibit comparable ionic conductivities and can be well-maintained even after successive bending or folding.

Zwitterionic Cyanine–Cyanine Salt: Structure and Optical Properties

Cyanines with long conjugation length such as heptamethines are well known to have strong intramolecular and/or intermolecular interactions (i.e., ion paring and aggregation), which can affect their structures (i.e., symmetry breaking) and optical properties remarkably. In this paper, we report a covalently linked complementary cyanine complex of cationic and anionic heptamethines forming a highly polarizable zwitterionic cyanine–cyanine salt. The effect of the modification was studied in detail on both its electronic structure and its optical properties. This novel zwitterionic salt was found to exhibit a decreased ion-pairing-induced charge localization but with an increased electronic coupling between the excited states of the cyanine cation and the anion, resulting in unusual optical properties compared to closely related noncovalent complementary cyanine salts. The dual-arm Z-scan technique was used to study their third-order NLO properties, suggesting the electronic coupling in such preorganized zwi...

ChemInform Abstract: Unveiling the Uncatalyzed Reaction of Alkynes with 1,2‐Dipoles for the Room Temperature Synthesis of Cyclobutenes.

AbstractA pyridiumethanide zwitterionic salt is used as dipole precursor for the metal‐free direct [2+2] cycloaddition with alkynes.

Synthesis, crystal structure and electrochemical study of (μ-κ2C:κ2S-NHC+-CS)[Fe2(CO)6]− generated from the reaction of NHC+-CS2− with Fe3(CO)12

Reaction of zwitterionic salt NHC+-CS2− (1), prepared from 1,3-diallylbenzimidazol-2-ylidene and CS2, with Fe3(CO)12 affords 2, (μ-κ2C:κ2S-NHC+-CS)[Fe2(CO)6]−. Two new compounds have been fully characterized by EA, IR, 1H NMR and 13C NMR spectroscopy and structurally determined by X-ray crystallography. Electrochemical study of 2 has demonstrated that using HOAc as a proton source complex 2 can efficiently catalyze H2 production.

An efficient approach for the synthesis of spirooxindole derivatives catalyzed by novel sulfated choline based heteropolyanion at room temperature

A new zwitterionic salt, sulfated choline based heteropolyanion, which was reported earlier by our group, has been found to be very effective for the synthesis of spirooxindole derivatives at room temperature. The heteropolyanion based on sulfated ionic liquid (HIL) showed promising features for the reaction, such as shorter reaction time, high product yields (about 90–95%), simple work up, easy removal, and reusability of the catalyst for several times without significant loss in its efficiency. This has made the protocol sustainable and economic.

1,3-Dimethylimidazolium-2-carboxylate: a zwitterionic salt for the efficient synthesis of vicinal diols from cyclic carbonates

The development of efficient, cheap and recyclable catalysts for reactions under mild reaction conditions is a very attractive topic in green chemistry. Herein, a series of basic ionic liquids (ILs) were investigated as catalysts for the synthesis of vicinal diols via the hydrolysis of cyclic carbonates in order to improve this kind of synthetic process. The effects of the IL structure, the molar ratio of cyclic carbonate to water, and various reaction parameters on the catalytic performance were investigated in detail. It was found that 1,3-dimethylimidazolium-2-carboxylate, a simple halogen-free zwitterionic catalyst, showed high activity (a space-time yield of 1086 h−1) and excellent selectivity for the preparation of ethylene glycol via the hydrolysis of ethylene carbonate. The catalyst could be reused over six times without obvious loss of catalytic activity. Also, it was applicable to a variety of cyclic carbonates for the production of their corresponding vicinal diols with high yields and selectivities. A possible catalytic cycle for this kind of catalytic process was proposed based on the experimental results, NMR spectroscopy and theoretical calculations. This reaction protocol opens a new possibility for chemical synthesis as a substitution for traditional base or basic ILs.

Frustrated Lewis Pair Chemistry of Chiral (+)‐Camphor‐Based Aminoboranes

Dimethylamino-(+)-camphorenamine reacted with an equimolar amount of Piers' borane, HB(C6F5)2, to give the corresponding iminium-hydroborate zwitterionic salt. Being in equilibrium with the parent enamine-HB(C6F5)2 N-B pair, this salt was able to split hydrogen heterolytically, hydrogenating the iminium group in the molecule. Detailed studies revealed that the hydrogen splitting in this reaction proceeded through an intermolecular pathway leading to a bornylamine-HB(C6F5)2 adduct. When the starting enamine is present in excess over HB(C6F5)2, the produced bornylamine-HB(C6F5)2 adduct breaks up, eliminating free bornylamine and forming the initial camphorenamine-HB(C6F5)2 pair. This results in hydrogenation of the camphorenamine framework in a catalytic fashion.

Dicyano(7‐methyl‐6‐oxo‐6H‐dibenzo[b,d]pyran‐9‐yl)methanide Salts via a Multicomponent Reaction

AbstractDialkylammonium dicyano(7‐methyl‐6‐oxo‐6H‐dibenzo[b,d]pyran‐9‐yl)methanides 4a–4j are obtained in good yields via a simple reaction between 3‐acetylcoumarins (=3‐acetyl‐2H‐1‐benzopyran‐2‐ones) 1 and malononitrile (2) in EtOH (Table 1). In this reaction, a charge‐separated zwitterionic salt is formed.

Peptide salt bridge stability: From gas phase via microhydration to bulk water simulations

The salt bridge formation and stability in the terminated lysine-glutamate dipeptide is investigated in water clusters of increasing size up to the limit of bulk water. Proton transfer dynamics between the acidic and basic side chains is described by DFT-based Born-Oppenheimer molecular dynamics simulations. While the desolvated peptide prefers to be in its neutral state, already the addition of a single water molecule can trigger proton transfer from the glutamate side chain to the lysine side chain, leading to a zwitterionic salt bridge state. Upon adding more water molecules we find that stabilization of the zwitterionic state critically depends on the number of hydrogen bonds between side chain termini, the water molecules, and the peptidic backbone. Employing classical molecular dynamics simulations for larger clusters, we observed that the salt bridge is weakened upon additional hydration. Consequently, long-lived solvent shared ion pairs are observed for about 30 water molecules while solvent separated ion pairs are found when at least 40 or more water molecules hydrate the dipeptide. These results have implications for the formation and stability of salt bridges at partially dehydrated surfaces of aqueous proteins.

Dimethylbut-2-ynedioate mediated esterification of acids via sp3 C–N bond cleavage of benzylic tertiary amines

A straightforward synthetic transformation of tertiary amines to the esterification of equimolar amounts of acids was demonstrated in this manuscript. The present protocol can be regarded as a straightforward synthetic transformation of tertiary amines to the esterification of equimolar amounts of acid. Moreover, the reaction is fundamentally new chemistry for the sp3 C–N bond cleavage coupled with esterification. The esterification reaction conditions are very mild and functional group-tolerated, such as hydrosilanes, alcohols, phenol, and amino acids. A mechanism is proposed in which the tertiary amine reacts with dimethyl but-2-ynedioate to form zwitterionic salt, and then the zwitterionic intermediate subsequently accept hydrogen to assist the nucleophilic attack of oxygen atom of carboxyl group at the benzyl group of tertiary amine, while a separate reaction pathway leads to esterification.

Gas Phase Hydrogen/Deuterium Exchange of Arginine and Arginine Dipeptides Complexed with Alkali Metals

The hydrogen/deuterium (H/D) exchange of protonated and alkali-metal cationized Arg-Gly and Gly-Arg peptides with D(2)O in the gas phase was studied using electrospray ionization quadropole ion trap mass spectrometry. The Arg-Gly and Gly-Arg alkali metal complexes exchange significantly more hydrogens than protonated Arg-Gly and Gly-Arg. We propose a mechanism where the peptide shifts between a zwitterionic salt bridge and nonzwitterionic charge solvated conformations. The increased rate of H/D exchange of the alkali metal complexes is attributed to the peptide metal complexes' small energy difference between the salt-bridge conformation and the nonzwitterionic charge-solvated conformation. Implications for the applicability of this mechanism to other zwitterionic systems are discussed.

Effect of zwitterionic salt on the electrochemical properties of a solid polymer electrolyte with high temperature stability for lithium ion batteries

In this study, we prepare a kind of solid polymer electrolyte (SPE) based on N-ethyl- N′-methyl imidazolium tetrafluoroborate (EMIBF 4), LiBF 4 and poly(vinylidene difluoride-co-hexafluoropropylene) [P(VdF-HFP)] copolymer. The resultant SPE displays high thermal stability above 300 °C and high room temperature ionic conductivity near to 10 −3 S cm −1. Its electrochemical properties are improved with incorporation of a zwitterionic salt 1-(1-methyl-3-imidazolium)propane-3-sulfonate (MIm3S). When the SPE contains 1.0 wt% of the MIm3S, it has a high ionic conductivity of 1.57 × 10 −3 S cm −1 at room temperature, the maximum lithium ions transference number of 0.36 and the minimum apparent activation energy for ions transportation of 30.9 kJ mol −1. The charge–discharge performance of a Li 4Ti 5O 12/SPE/LiCoO 2 cell indicates the potential application of the as-prepared SPE in lithium ion batteries.