Secondary Ammonium Salt Research Articles

Long-term measurements of aerosol composition at rural background sites in France: Sources, seasonality and mass closure of PM2.5

Fine particulate matter (PM2.5) was monitored at five rural background locations in France from 2012 to 2021. Annual PM2.5 ranged from 5 to 15 μg m−3, all sites repeatedly exceeding the 2021 annual World Health Organization guideline. Chemical speciation including organic and elemental carbon (OC, EC), secondary inorganic aerosols (SIA: NO3−, SO42−, NH4+) and other major water-soluble ions (Cl−, Na+, Mg2+, Ca2+, K+) were monitored on 24-h filters covering 14% of the year. A source apportionment of OM was undertaken based on fine potassium and using representative ratios for domestic biomass burning (BB) and fossil fuel (FF) emissions. The latter dominated the EC fraction (55–60%) while BB was the main primary source of OM (27–54%). The average mass balance of PM2.5 at the French rural background atmospheric sites was: secondary organic aerosol (18–35%), BB (17–27%), non-sea-salt sulphate (12–17%), nitrate (6–22%), ammonium (7–11%), FF (4–6%), mineral dust (3–9%) and sea salt (1–2%). Secondary aerosols were the main component of PM2.5 through all seasons, with SIA dominating in spring episodes. The contribution of OM to PM2.5 was larger at the southern sites whereas the contribution of SIA was larger at the northern sites. The mean OC/EC ratio and the good correlations between OC, EC, and fine potassium suggested that BB was the main primary source contributing to carbonaceous aerosols, 27–54% to total OM depending on the site; and also, to PM2.5 (17–27%). Stronger regulations of OM sources including BB, nitrate from combustion, and ammonium from agricultural sources are needed to reduce PM2.5 at rural background sites on an annual and episodic basis, respectively.

Multistep sequence-controlled supramolecular polymerization by the combination of multiple self-assembly motifs

The precise sequence control of polymer chain is an important research topic of polymer chemistry. Although some methods such as iterative synthesis and supramolecular polymerization have been developed to fabricate sequence-controllable polymer, it is still a great challenge to consecutively prepare multiple supramolecular polymers with different sequence structures. In this work, through the reasonable utilization of assembly motifs, we integrated multiple host-guest recognitions and metal coordination interactions to prepare different sequence-controlled supramolecular polymers by a multistep assembly strategy. This research provides inspiration for the design and preparation of supramolecular polymers with different sequence structures.

Influence of cationic groups on the antibacterial behavior of cationic nano-sized hyperbranched polymers to enhance bacteria-infected wound healing.

With the continuous emergence of drug-resistant pathogens, new strategies with high antibacterial efficacy are urgently needed. Herein, five cationic nano-sized hyperbranched polymers (CNHBPs) with cationic functional groups have been constructed, and their antibacterial mechanism has been studied in detail. CNHBPs bearing secondary ammonium salt groups and long alkyl chains (S12-CNHBP) exhibited weak antibacterial and antibiofilm ability, while CNHBPs bearing quaternary ammonium salt groups and long alkyl chains (Q12-CNHBP) showed the highest antimicrobial and strongest antibiofilm activities. ζ potential and isothermal titration microcalorimetry (ITC) results suggest that the negatively charged surfaces of bacterial cells provided Q12-CNHBP with a higher intrinsic electrostatic driving force for bacterial killing than that with S12-CNHBP. Fluorescent tracing and morphological observations indicate that the bacterial genome might be another antibacterial target for S12-CNHBP in addition to the cell wall and membrane, which are mainly antibacterial targets for Q12-CNHBP, making it less likely to induce bacterial resistance. Surprisingly, Q12-CNHBP exhibited superior in vivo therapeutic efficacy in a mouse wound model of methicillin-resistant Staphylococcus aureus (MRSA) infection with low toxicity during treatment. These advantages and ease of preparation will undoubtedly distinguish Q12-CNHBP as a new class of suitable candidates to combat multidrug-resistant pathogen infections. This study opens up a new avenue for exploiting antibacterial biomaterials to treat infections caused by drug-resistant bacteria.

Construction of Supramolecular Polymers Based on Host‐Guest Recognition†

What is the most favorite and original chemistry developed in your research group?The establishment of two new types of host‐guest recognition building blocks (21‐crown‐7/secondary ammonium salt and pillar[5]arene/alkyl chain) for supramolecular polymers.How do you get into this specific field? Could you please share some experiences with our readers?I got my introduction to supramolecular chemistry during the postgraduate period. There are many phenomena closely related to the weak non‐covalent interactions in nature, such as the storage and transmission of genetic information through the DNA double helix structure. Inspired by these fascinating natural phenomena, scientists try to use non‐covalent interactions to prepare many very complex self‐assembled systems including supramolecular polymers from natural and artificially designed structural units. In 1987, Lehn, Cram, and Pederson won the Nobel Prize for their contribution to supramolecular chemistry. At present, supra‐molecular chemistry has developed into an emerging discipline formed by the intersection of chemistry, physics, life sciences, materials science, and electronic engineering.How do you supervise your students?Lead by example, teach students according to their aptitude, strive for excellence, and be a teacher and a friend.What is the most important personality for scientific research?Curiosity, thinking, hard work, and concentration.What's your hobbies? What's your favorite book(s)?Hiking and reading. Swordmen novels.How do you keep balance between research and family?Reasonable arrangement and choice.Who influences you mostly in your life?My grandmother. She taught me: “No pains, no gains”.Self‐assembly is a topic of intense scientific interest. Supramolecular polymers are one of the most important research directions in the field of chemical self‐assembly. As a novel kind of polymeric systems, supramolecular polymers are still in the early stage of their development. There are three fundamental scientific problems: How to expand host‐guest recognition building blocks? How to realize the control of the structures of supramolecular polymers at multiple levels? And how to realize multi‐stimuli responsivenesses of supramolecular polymers? To address these scientific problems, we constructed a series of novel supramolecular polymers based on host‐guest recognition.

Radical Cyclic [3]Daisy Chains

Summary Mechanically interlocked molecules (MIMs) that undergo controllable internal motions of their component parts in more than one dimension are rare entities in the molecular world. Cyclic [2]daisy chains ([c2]DCs) are a class of MIMs that have been identified as prototypes for molecular muscles. It remains, however, a challenge to synthesize [cn]DCs with n > 2 selectively and efficiently. Herein, we report the design and synthesis of [c3]DCs employing radical and anionic templates. Two mechanically interlocked [c3]DCs with 18 positive charges were obtained in >90% yields. One [c3]DC displayed good air stability in its radical cationic form, while the other underwent reversible “co-conformational” switching between open macrocyclic and closed trisarm-shaped forms under electrochemical control. These findings provide not only two-dimensional MIMs with attractive electronic and switchable properties, but also a starting point for the design of extended molecular arrays, which could become the forerunners of adjustable molecular nets and breathable molecular membranes.

Helic[1]triptycene[3]arene: Synthesis, Complexation, and Formation of [2]Rotaxane Shuttle.

A new macrocyclic arene, helic[1]triptycene[3]arene H, was conveniently synthesized in 37% yield by a one-pot reaction starting from 2,6-dimethoxyl-3,7-dihydroxymethyltriptycene. Macrocycle H showed fixed conformation in solution and could form 1:1 complexes with a series of neutral guests, secondary ammonium salts, and tertiary ammonium salts in both solution and solid states. The association constants between H and the neutral guests were between (1.23 ± 0.10) × 102 and (4.70 ± 0.47) × 103 M-1, while the association constants between H and the ammonium guests were between (1.35 ± 0.12) × 103 and (1.59 ± 0.14) × 105 M-1. Moreover, H showed bigger association constants with secondary ammonium salts than those with tertiary ammonium salts possibly because of the steric hindrance effect and multiple intermolecular interactions. The stimuli-responsive complexation between H and the ammonium salts could be controlled by the addition and removal of acids and bases as well. Based on the host-guest complexation between H and the secondary ammonium salt, [2]rotaxane was further synthesized, and its shuttling motion could be efficiently controlled by an acid and base.

Multistimuli-Responsive and Photocontrolled Supramolecular Luminescent Gels Constructed by Anthracene-Bridged Bis(dibenzo-24-crown-8) with Secondary Ammonium Salt Polymer.

A novel multistimuli-responsive and photcontrolled supramolecular luminescent gel is fabricated from anthracene-bridged bis(dibenzo-24-crown-8) (1) and secondary ammonium salt-functionalized graft polymer (3). X-ray crystallographic analysis reveals that the dibenzo-24-crown-8 (DB24C8) ring is located at the opposite site of 1, which will greatly hinder the mutual intermolecular π-π stacking between anthracene groups. By taking advantage of the controllable binding of 1 with 3, the unique gel-sol transition could occur under different temperatures, pH, and competitive guest bindings. Benefiting from the photo-oxygenation of anthracene, the luminescence behavior of the supramolecular gel could be switched off and on under UV light (365 nm) and heating treatment, which provides a new approach for constructing photocontrolled supramolecular luminescent gel.

Preparation of cross-linked supramolecular polymers based on benzo-21-crown-7/secondary ammonium salt host-guest interactions.

We found that TC7 not only self-assembles into one-dimensional supramolecular aggregates in chloroform, but also forms cross-linked supramolecular polymers via host-guest complexation between benzo-21-crown-7 and secondary ammonium salts. Compared with one-dimensional linear supramolecular polymers, soft and long viscous fibers were pulled out from a concentrated solution of cross-linked supramolecular polymers as a result of higher viscosity and lower diffusion coefficients.

Highly ortho‐Selective Chlorination of Anilines Using a Secondary Ammonium Salt Organocatalyst

AbstractAn organocatalytic, highly facile, efficient, and regioselective ortho‐chlorination of anilines is described. A secondary ammonium chloride salt has been employed as the catalyst and the reaction can be conducted at room temperature without protection from air and moisture. In addition, the reaction is readily scalable and the catalyst can be recycled and reused. This catalytic protocol has been applied to the efficient synthesis of a highly potent c‐Met kinase inhibitor. Mechanistic studies revealed that unique structural features of the secondary ammonium chloride salt are important for both the catalysis and regioselectivity of the electrophilic ortho‐chlorination.

Stepwise Unfolding of Single-Chain Nanoparticles by Chemically Triggered Gates.

The orthogonal, stepwise, and order-independent unfolding of single-chain nanoparticles (SCNPs) is introduced as a key step towards actively controlling the folding dynamics of SCNPs. The SCNPs are compacted by multiple hydrogen bonds and host-guest interactions. Well-defined diblock (AB) and tetrablock (ABCD) copolymers are equipped with orthogonal recognition motifs via modular ligation along the lateral chain. Initially, single-chain folding of the diblock copolymer was induced by the host-guest complexation of benzo-21-crown-7 (B21C7, host) and a secondary ammonium salt (AS, guest), representing an efficient avenue for single-chain collapse. Next, both orthogonal Hamilton wedge (HW) and cyanuric acid (CA) as well as B21C7-AS motifs were employed to generate SCNPs based on the ABCD polymer system. Subsequently, the stepwise dual-gated and order-independent unfolding of the SCNPs was investigated by the addition of external stimuli. The folding and unfolding were explored by 1D (1) H NMR spectroscopy, dynamic light scattering (DLS), and diffusion-ordered NMR spectroscopy (DOSY).

ChemInform Abstract: Synthesis of Linear [5]Catenanes via Olefin Metathesis Dimerization of Pseudorotaxanes Composed of a [2]Catenane and a Secondary Ammonium Salt

AbstractSeveral catenanes are synthesized by olefin metathesis dimerization.

Synthesis of linear [5]catenanes via olefin metathesis dimerization of pseudorotaxanes composed of a [2]catenane and a secondary ammonium salt.

[5]Catenanes were synthesized by olefin metathesis dimerization. The reaction of pseudorotaxanes, which were derived from a [2]catenane and one equivalent of an ammonium salt bearing two terminal olefins in dichloromethane, with a catalytic amount of Grubbs catalyst afforded linear [5]catenanes in 12% yield. Intermolecular and intramolecular olefin metathesis reactions were controlled by the length of the alkyl chain of the ammonium salts.

Mechanically linked poly[2]rotaxanes constructed from the benzo-21-crown-7/secondary ammonium salt recognition motif

Mechanically linked poly[2]rotaxanes have been designed and synthesized, which displays interesting thermal and rheological properties due to the integration of [2]rotaxane moieties into the polycaprolactone chains.

Sugar-based novel chiral macrocycles for inclusion applications and chiral recognition

A convergent template assisted synthesis of sugar-based chiral macrocycles has been achieved. The host–guest inclusion studies have revealed significant interactions of the synthesized macrocycle with primary over secondary ammonium salt. The chiral macrocyle also discriminates between D- and L-phenylalanine methyl ester hydrochlorides as revealed by 1H NMR spectral studies on the mixture of the host and the guest molecules.

Supramolecular Alternating Polymer from Crown Ether and Pillar[5]arene-Based Double Molecular Recognition for Preparation of Hierarchical Materials.

A novel supramolecular alternating polymer is constructed based on double molecular recognition events of benzo-21-crown-7 with a secondary ammonium salt and of pillar[5]arene with a neutral guest. The resulting polymer is utilized to prepare hierarchical materials with different dimensionalities for the first time. These materials included zero-dimensional spherical aggregates, one-dimensional nanofibers, two-dimensional microstructured films, and three-dimensional ordered glue. This development will be helpful for designing and preparing supramolecular hierarchical materials with different dimensionalities.

Complexations between Oxacalixcrowns and Secondary Ammonium Salts and ­Construction of an Oxacalixcrown‐Based [2]Rotaxane

AbstractPseudorotaxane type host–guest complex of a secondary ammonium salt and oxacalixcrown with the polyether linker as short as five ethylene glycol units was created. While an axle containing both ammonium and carbamate stations was installed in an oxacalixcrown‐6‐based [2]rotaxane through a threading‐followed‐by‐stoppering approach, translocation of the oxacalixcrown‐6 component of the [2]rotaxane from the secondary ammonium station to the carbamate station of the thread was achieved through blocking the amino moiety with a bulky Boc group.

Rapid and Efficient Acylative Active Transport on a Rotaxane

AbstractBiased Brownian movement, a key process of biological molecular motors, was achieved by the neutralization of a rotaxane consisting of a secondary ammonium salt, in which the ammonium group is located next to the terminal group, and crown ether. Active transport occurred kinetically upon fixation of the transient pseudorotaxane by the rapid acylation of the amino group. The bulky terminal group enhanced the biased Brownian movement, although it suppressed the formation of the pseudorotaxane. Efficient active transport was possible when a large excess of acylation agent and triethylamine were used at 0 °C with 1.5 equivalents of crown ether. The efficiency of active transport increased as the electrophilicity of the acylation agent increased. The highest efficiency of active transport was observed with the cyclopentyl terminal group with one methylene spacer. A simple, two‐step, unidirectional transport was carried out using the active transport system based on the cyclopentyl terminal group.

Polymeric Gel Electrolyte Based on a Rotaxane-Networked Polymer with Alkyl Magnesium Bromide and Ionic Liquid for Rechargeable Mg Batteries

Rechargeable magnesium (Mg) battery that uses metal Mg as the negative electrode is a potential candidate of the next-generation power sources for electric vehicles (EV) and other large scale applications. We previously reported that Mg is reversibly deposited and dissolved on a metal substrate in mixed solutions containing ionic liquid and alkyl magnesium bromide [1]. However, as the electrolyte system contains high vapor pressure THF, the resulting battery will have still practical problems in safety and reliability. Recently, we have synthesized a novel network polymer with a rotaxane structure, a complex consisting of secondary ammonium salt and 24-membered crown ether component [2]. In this study, a novel gel electrolyte based on a rotaxane-networked polymer has been prepared, in which ethyl magnesium bromide dissolved in triethylene glycol dimethyl ether (C2H5MgBr/Triglyme) and N,N-diethyl-N-methyl- N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl) imide (DEMETFSI) were included. The ionic conductance behavior and electrochemical behavior of the resulting gel electrolytes were investigated.A “rotaxane network” was synthesized in the same manner as our previous report [2] (Fig.1). The gel electrolytes were prepared by an impregnation method: the polymer film was immersed in the mixed solution of C2H5MgBr/Triglyme and DEMETFSI for 24 h. The resulting network polymer maintained the stable shape without decomposing after a month’s impregnation in 1M C2H5MgBr/Triglyme. The “rotaxane network” polymeric gel electrolyte impregnated in C2H5MgBr/ Triglyme + DEMETFSI exhibited an ionic conductivity of 2.8×10-4 S cm-1 at 20°C (swelling degree = ca. 60%). Highly reversible behavior was observed for cathodic deposition and anodic dissolution of Mg in this polymeric gel electrolyte system.AcknowledgmentThis research was financially supported by the Japan Science and Technology Agency (JST), Advanced Low Carbon Technology Research and Development Program (ALCA).

A supramolecular hyperbranched polymer based on molecular recognition between benzo-21-crown-7 and secondary ammonium salt.

A novel A2-B3-type supramolecular hyperbranched polymer was prepared based on the benzo-21-crown-7/secondary ammonium salt recognition motif. The resulting supramolecular polymer exhibited a reversible disassembled-assembled process by adding or removing potassium ions.

Main‐Chain Supramolecular Polymers Based on Orthogonal Benzo‐21‐Crown‐7/Secondary Ammonium Salt and Terpyridine/Metal Ion Recognition Motifs

Orthogonal self-assembly of multiple components represents an efficient strategy to afford hierarchical and multifunctional assemblies. Here, we demonstrate the orthogonal recognition behaviors between benzo-21-crown-7/secondary ammonium salt and terpyridine/metal ions (Fe(2+) or Zn(2+) ) recognition motifs. Main-chain supramolecular polymers are subsequently achieved via "one-pot" mixing of the three monomers together (heteroditopic monomer 1, homoditopic secondary ammonium salt monomer 2, and Fe(BF4 )2 •6H2 O or Zn(OTf)2 ), which are confirmed by (1) H NMR, UV-Vis, DOSY, and viscosity measurements. Moreover, different metal ions (Fe(2+) or Zn(2+) ) exert considerable effects on the size of the resulting supramolecular polymers. Integration of two different types of non-covalent interactions renders dynamic and responsive properties for the resulting supramolecular polymers, as triggered by a variety of external stimuli such as temperature, potassium cation, as well as stronger chelating ligands. Therefore, the current work is a prerequisite for the future application of such orthogonal assemblies as intelligent supramolecular materials.