Diquaternary Salts Research Articles

Balanced chemical reactivity, antimicrobial properties and biocompatibility of decellularized dermal matrices for wound healing.

The prevention of bacterial infection and prompt wound repair are crucial considerations when local skin tissue is compromised by burns, cuts, or similar injuries. Porcine acellular dermal matrix (pADM) is a commonly employed biological material in wound repair due to its inherent natural properties. Nonetheless, the pADM's primary constituent, collagen fibers, lacks antimicrobial properties and is vulnerable to bacterial infection when used in the treatment of incompletely debrided wounds. Meanwhile, conventional antimicrobial agents primarily consist of chemical compounds that exhibit inadequate biocompatibility and biological hazards. This research endeavors to create an antimicrobial collagen scaffold dressing utilizing the Schiff base reaction through the incorporation of oxidized chitosan diquaternary (ODHTCC) salt into the pADM. Compared with the unmodified pADM, ODHTCC-pADM (OD-pA) still retained the three-stranded helical structure of natural collagen. At an ODHTCC cross-linker concentration of 4%, the thermal denaturation temperature of OD-pA was 85 °C. According to the enzymatic degradation resistance test in vitro, the degradation resistance of OD-pA to type I collagenase was significantly improved compared with that of the uncross-linked pADM. In addition, OD-pA exhibited good antibacterial properties, with inhibition rates of 95.6% and 99.9% for E. coli and Staphylococcus aureus, respectively, and a cytotoxicity level 1, meeting the in vitro requirements of national biomedical materials. In vivo experiments showed that the OD-pA scaffold could better promote wound healing and more effectively promote the positive expression of bFGF, PDGF and VEGF. In conclusion, OD-pA has struck a balance between antibacterial properties, chemical reaction properties and biocompatibility, ultimately achieving controllability, and has broad application prospects in the field of antibacterial biomedical materials.

Compatibility of water treatment agents and produced water from oilfield

Aimed at corrosion inhibition and sterilization requirements from conventional produced water (CPW) and polymer-containing produced water (PCPW) in Shengli oilfield, functional agents screening was conducted through agent performance, suspended solids content (SSC), turbidity and filtration time. The interaction between polymer in PCPW and functional agent was discussed based on molecular structure and zeta potential of the functional agents. Results show that SSC of PCPW were significantly increased with addition of diquaternary ammonium salt, polyorganoguanidine and 9-octadecenoic acid imidazoline respectively, while slightly increased with addition of quaternary phosphonate and 9-octadecanoic acid epoxy imidazoline, respectively. Poor water-soluble aggregates were formed between anionic polymer and cationic agent with long chain alkyl groups through electrical attraction coming up with turbidity increased. Retention of aggregates and smaller suspended solid particles on filter membrane generated an increase on SSC, a prolonged filtration time and a darker color of filter membrane. “Deterioration” of water quality will happen with addition of such cationic agents with long chain alkyl groups. For the first time, the influence of polymer on selection of functional agents is figure out, and SSC should be taken into consideration besides functional performance when screening of water treatment agents. Also, the types of functional agents applicable to different produced water are proposed.

Synthesis, characterization and antitumor activity of two new dipyridinium ylide based lanthanide(III) complexes

Two new dinuclear lanthanide(III) complexes, La-DPY and Nd-DPY, with the stoichiometric formula [{Ln(Et3N)(SO4)}2(μ-DPY)(μ4-SO4)] (Ln = La, Nd; DPY = ylide form of DPB, Et3N = triethylamine), were obtained through the reaction of N-heterocylic diquaternary salt N,N’-diphenacyl-4,4′-dipyridinium dibromide (DPB) and lanthanide(III) sulfate in methanol, in the presence of triethylamine. The obtained complexes were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, elemental analysis, UV–vis spectroscopy, thermogravimetric analysis and powder X-ray diffraction. Scanning electron microscopy (SEM) was used to investigate the morphology and particles size of the complexes, confirming that their particles are quite homogenous and uniform. The antitumor activity of the complexes was evaluated in the human cancer cells MCF7 and A2780 and compared to cisplatin, the metal-based drug in cancer therapy. The complexes were found to induce apoptotic cell death and, to a lesser extent, production of ROS, although these are not the unique mechanisms of action. In conclusion, we anticipate that these types of Ln(III) complexes have potential and could be further explored for applications as antitumor agents.

Exploring the optoelectronic and charge transfer performance of diaza[5]helicenes at molecular and bulk level

Abstract Due to the unique structures of helicenes, we aim to probe their prospective as proficient optoelectronic and charge transfer materials. With the intention to shed light on both at the molecular and bulk levels various properties of interest have been studied. The optical (refractive indices, reflectivity, conductivity, absorption, dielectric constant and extinction coefficient) and electronic properties (total/partial density of states (T/PDOS) of some recently synthesized diquaternary salts of 4,4′-bipyridine helical viologens, i.e., 5,10-dimethyl-5,10-diaza[5]helicene bis-tetrafluoroborate 12+ (Compound1) and 3,8-dimethyl-3,8-diaza[5]helicene bis-tetrafluoroborate 22+ (Compound2) at the bulk level in solid-state have been reflected. The balanced values of hole and electron electronic coupling (Vh and Ve) for compound1 disclose that it might be good ambipolar material. For Compound2 Ve is greater than Vh enlightening that it might be good electron transfer contender. Furthermore, the electronic, photophysical (absorption, fluorescence, phosphorescence) and charge transfer properties (ionization potential (IP), electron affinity (EA) and hole/electron reorganization energy (λ(h)/(e)) of their bipyridine precursors (Compound3 and Compound4) as well as redox partners of Compound1 and Compound2 which are neutral forms of 12+ and 22+ named Compound5 and Compound6, respectively have been explored. The band gap, DOS, dielectric function, conductivity and refractive indices, IP, EA and λ(h)/(e) values revealed that these diaza[5]helicenes would be good contenders to be used in semiconductor devices. The dielectric functions also revealed that Compounds 1 and 2 retain energy holding ability which these systems absorb. It is also expected that absorption capability of photons would be enhanced in studied compounds especially Compounds 5 and 6 having narrow band gaps.

Solvent Effects on the Spectral and Electrochemical Properties of Some Pyridinium Quaternary Compounds

The physicochemical properties and the redox potential of two pyridinium compounds, a diquaternary salt of 4,4�-bipyridinium (BP) and one of 1,2-bis(4-pyridyl)ethane (BPE) were studied. Cyclic voltammetry on platinum electrode was used to evaluate the solvent influence on the redox properties of the pyridinium compounds. Electrochemical measurements were performed in aqueous media, ethanol and aprotic solvent. The solvent variation causes changes in the electro-oxidation processes of the heterogeneous electron transfer at the applied potential. The presence of the ethylenic group in the structure of BPE presents slightly different electrochemical behaviour compared to BP. The corroboration of the electrochemical data with absorption spectral results attests that it�s more likely that the ECE sequence is responsible for the reduction mechanism of pyridinium compounds.

Synthesis and Characterization of Piperazinium Polyelectrolytes Carrying Hydrophobic Functionalities: Effect of Counter Ion and Charge Density on Flocculation

Following our recent synthesis and characterization of three new cationic polyelectrolytes with subtle hydrophobic variability, this paper reports their physical and chemical properties in aqueous media in relation to their chemical structure. Aryl substituted cationic polyelectrolytes varying with their charge density are reported for the first time. Viscosity studies show that these polymers display typical polyelectrolytic behavior. The flocculation efficiency of the polyelectrolytes was investigated with different counter ions. The zeta potential of the polyelectrolytes indicates the charge of the mono and diquaternary ammonium salts which is supported by chloride analysis. The morphology of polymer before and after flocculation was investigated. The introduction of methylene group and quaternary nitrogen play an important role in the flocculation process. It was shown that increasing the hydrophobicity and charge density of the aryl substituted polymer affects the flocculation in the industrial tannery effluent and bentonite suspension.

Thermodynamics and Structures of Complexation between Tetrasulfonated 1,5-Dinaphtho-38-crown-10 and Diquaternary Salts in Aqueous Solution

The readily available recognition motifs with high affinity and selectivity can undoubtedly expedite the development of host-guest chemistry from fundamental research to practical application in miscellaneous fields. In this work, a series of guest-mediated [2]pseudorotaxanes are successfully constructed by the incorporation of tetrasulfonated 1,5-dinaphtho-38-crown-10 (1(4-)) with three kinds of dicationic substrates, i.e., the diquaternary salts of 4,4'-bipyridine, 1,10-phenanthroline, and 2,7-diazapyrene, which are comprehensively explored by means of UV/vis, (1)H NMR spectra, X-ray crystallography, and microcalorimetric titrations. Significantly, the interpenetration of 1(4-) with N,N'-dimethyl-2,7-diazapyrenium salt (DMDAP(2+)) gives an extraordinarily strong association constant (K(a)) up to 10(8) M(-1) order of magnitude in water. Moreover, the spectroscopic and crystallographic analyses jointly demonstrate that there is a competitive binding process in the complexation of 1(4-) with DMDAP(2+) and methyl viologen (MV(2+)), in which DMDAP(2+) is internally encapsulated in the cavity of 1(4-), whereas MV(2+) is externally embedded in the crystallographic lattice to form the ternary supramolecular assembly of MV(2+)·DMDAP(2+)⊂1(4-). We also envision that the Ka gradient obtained in our systematic work illustrates a new and elegant strategy for attaining multicomponent nanomaterials engineered at a molecualr level.

Chemically-Responsive Complexation of A Diquaternary Salt with Bis(m-phenylene)-32-Crown-10 Derivatives and Host Substituent Effect on Complexation Geometry

A chemically responsive diquaternary salt with π-extended surface was made. The host-guest complexation with chemo-responsiveness between three bis(m-phenylene)-32-crown-10 (BMP32C10) derivatives and this diquaternary salt guest was studied through the sequential addition of basic and acidic reagents (diethylamine and trifluoroacetic acid, respectively). Furthermore, the host-substituent effect on the complexation geometries of these three host-guest complexes, from taco to taco-type threaded to threaded structures by changing the substituent on BMP32C10 as shown by crystal structures, was also addressed.

Synthesis and photocatalytic performances of the TiO2 pillared montmorillonite

TiO2 pillared clay materials were prepared by montmorillonite (Mt) and acidic solutions of hydrolyzed Ti alkoxides in the presence of high-molecular-weight polyoxypropylene (POP)-backboned di-quaternary salts (POP). The as-prepared materials were characterized by means of XRD, FTIR, TG–DTA, XRF, specific surface area and porosity determinations, TEM and SEM, respectively. The experiments showed that the resulting material was a porous delaminated structure containing pillared fragments and nano-scaled TiO2 particles well dispersed among each other. Introducing polymer surfactant POP as an expanding agent of Mt cannot only promote the formation of the delaminated structure, but significantly improve the porosity and surface area of the composites. The resulting TiO2 pillared Mt exhibited a good thermal stability as indicated by its surface area after calcination at 800°C. No phase transformation from anatase to rutile was observed even under calcination at 900°C. The grain size of anatase in as-prepared sample decreased with the increase of the POP concentration, but increased with the increment of calcination temperature. The photocatalytic performances of these new porous materials were evaluated by using methylene blue degradation. The composite solid exhibited superior photocatalyic property and the maximum removal efficiency was up to 98% within 90min.

Complexation of Triptycene-Based Cylindrical Macrotricyclic Polyether toward Diquaternary Salts: Ion-Controlled Binding and Release of the Guests

Triptycene-based cylindrical macrotricyclic polyether 1 has been proved to be an efficient host for the complexation with diquaternary salts in solution and in the solid state. Moreover, it was also found that binding and release of the guest molecules could be easily controlled by the addition and removal of potassium ions.

Strategies Toward Syntheses of Triazolyl- or Triazolium-Functionalized Unsymmetrical Energetic Salts

Triazolyl-functionalized monocationic energetic salts (2a−m) were prepared through reactions of 1-(chloromethyl)-1H-1,2,4-triazole with 1-methylimidazole, 1-methyl-1,2,4-triazole, or 4-amino-4H-1,2,4-triazole in the presence of NaI, followed by metathetical reactions with equivalent silver salts. Subsequent protonation with corresponding acids gave rise to triazolium-functionalized diquaternary salts (3a−c). Direct treatment of neutral 1-(1H-imidazole-1-yl)methylene-1H-1,2,4-triazole, which was prepared by reaction of 1-(chloromethyl)-1H-1,2,4-triazole with imidazole in the presence of a base, with acids in methanol or metathesis with silver salts after quaternization with methyl iodide gave rise to the corresponding diquaternary energetic salts 5a−c and 7a−d, respectively. All of the energetic salts were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and density determinations. The majority of them exhibit good thermal stability and relatively high density. ...

Synthesis of 2,2′‐Biimidazolium‐Based Ionic Liquids: Use as a New Reaction Medium and Ligand for Palladium‐Catalyzed Suzuki Cross‐Coupling Reactions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of 2,2‘-Biimidazolium-Based Ionic Liquids: Use as a New Reaction Medium and Ligand for Palladium-Catalyzed Suzuki Cross-Coupling Reactions

Neat reactions of 2,2'-biimidazole with an excess of alkyl or polyfluoroalkyl iodides at 140 degrees C, followed by anion exchange with LiN(SO(2)CF(3))(2) or KPF(6), gave the diquaternary salts 3a-k in >80% yields. However, by controlling the reaction stoichiometry, 2,2'-biimidazole can also be monoquaternized with the same electrophiles at 100 degrees C under similar conditions. Subsequent metathesis reactions with LiN(SO(2)CF(3))(2) or KPF(6) resulted in the ionic liquids 4a-m in high yields. Thermal properties were determined with a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). Most of the monoquaternary salts are room-temperature ionic liquids. 1,3,1'-Tributyl-2,2'-biimidazolium hexafluorophosphate was demonstrated to be an excellent solvent and ligand for palladium-catalyzed Suzuki cross-coupling reactions. The catalytic ionic liquid system may be recycled at least 14 times without a significant decrease in catalytic performance.

Bridged tetraquaternary salts from N,N'-polyfluoroalkyl-4,4'-bipyridine.

4,4'-Bipyridine (1) with excess of polyfluoroalkyl bromide or iodides 2a-d at 100-110 degrees C without solvent gave the monoquaternary salts 3a-d in >90% yields. However, 1 with 2.5 equiv of 2a-c in DMF at 110 degrees C resulted in the diquaternary salts 5a-c in >85% yields. In DMF, 5a-c were obtained in comparable yields when a molar excess of 2a-c reacted with 3a-c. 1,4-Dibromobutane with 3a,b in DMF at 100 degrees C led to the tetraquaternary salts 7a,b in approximately 85% yields. In water or acetone/water as a solvent, salts 3a-d and 5a-c were metathesized with LiN(SO(2)CF(3))(2) and KSO(3)CF(3) to produce monoquaternary ionic liquids 4a-h in >88% yields and diquaternary ionic liquids 6a-f in >86% yields, respectively. Tetraquaternary ionic liquids 8a,b were obtained when LiN(SO(2)CF(3))(2) was reacted with salts 7a,b. These compounds were stable to 340 degrees C as determined by DSC. They are the first N-mono-, N,N'-di-, and N,N,N',N'-tetra-4,4'-polyfluoroalkylbipyridinium quaternary salts and ionic liquids.

Syntheses of the first N-mono- and N,N'-dipolyfluoroalkyl-4,4'-bipyridinium compounds.

Reactions of 4,4'-bipyridine (1) with excess of polyfluoroalkyl iodides (2a-d) at 100-110 degrees C, under neat conditions, led to the formation of monoquaternary salts (3a-d) in > 90% yields. Salts 3a-d were metathesized with LiN(SO2CF3)2 either in water or water/acetone mixtures to form ionic liquids (4a-d), respectively, in > 88% yields. When 1 was reacted with 2.5 equivalent of 2a-c in DMF at 110 degrees C, the diquaternary salts 5a-c were formed in > 85% yields. Alternatively, 5a-c were also synthesized by heating a mixture of 3a-c and 2a-c (1.25 equivalent) in DMF. The metathesis reaction of 5a-c with LiN(SO2CF3)2 produced dicationic ionic liquids (6a-c) in > 86% yield.

Tetracyanometalates of Ni, Pd, and Pt with cyclic diquaternary cations of 2,2'-bipyridine and 1,10-phenanthroline. A vibrational, crystallographic, and theoretical study of intermolecular weak interactions.

The compounds (bpy-dq)[Ni(CN)(4)].2H(2)O (1), (bpy-dq)[Pd(CN)(4)].2H(2)O (2), and ((bpy-dq)[Pt(CN)(4)].2H(2)O (3) (bpy-dq = (C(12)H(12)N(2))(2+), 6,7-dihydrodipyrido[1,2-a:2',1'-c]pyrazinediium) and (phen-dq)[Ni(CN)(4)] (4), (phen-dq)[Pd(CN)(4)].H(2)O (5), and (phen-dq)[Pt(CN)(4)].H(2)O (6) (phen-dq = (C(14)H(12)N(2))(2+), 5,6-dihydropyrazino[1,2,3,4-lmn]-1,10-phenanthrolinediium) have been synthesized and characterized by X-ray diffraction. The three bipyridinium diquaternary salt derivatives are isostructural. The crystal structures of these dihydrated compounds consist of columns formed by alternating anion complexes and diquaternary cations, pi-pi interacting through cyanide ligands and the aromatic rings, and stabilized by an extended hydrogen-bond network. On the other hand, the packing in the phenanthrolinium diquaternary salt derivatives is strongly dependent on the hydration degree. Thus, the anhydrous [Ni(CN)(4)](2-) compound presents a laminar arrangement and the hydrated salts show a columnar packing, similar but not the same as compounds 1-3. The anhydrous form of compound 5 is isostructural with compound 4. Vibrational (IR, Raman) and thermogravimetric studies of these compounds have been carried out. Finally, DFT calculations have been performed on the isolated tetracyanometalate anions and diquaternary cations to assign the fundamental modes in the vibrational spectra. The intermolecular weak interactions were studied through the analysis of the charge density by using the theory of atoms in molecules (AIM).

Synthesis and biological activities of diquaternary dipiperazinium salts containing dithiocarboxyl groups.

A series of diquaternary dipiperazinium salts containing dithiocarboxyl groups 6a-f and 9 were synthesized and evaluated for their analgesic and sedative activities. The result showed that the presence of two quaternary ammonium cations and the distance between them are very important for the activities of the salts. Compound 6b exhibited the best activities (at dose 2 mg/kg, analgesic, 57%; sedative, 59%) among compounds 6a-f. Compound 9 not only showed the most potent analgesic (85.4%, dose 1 mg/kg) and sedative (93.1%, dose 1 mg/kg) activities, but also exhibited anticancer activity against KB (68.7%, dose 10 microM).

Application of Calorimetry to Microbial Biodegradation Studies of Agrochemicals in Oxisols

Calorimetry was used to monitor the inhibitory effect caused by the bipyridynium diquaternary salts paraquat, diquat, and phosphamidon on microbial activity in a Red Latosol soil (Oxisol). The thermal effect was recorded on samples composed of 1.50 g of soil, 6.0 mg of glucose, 6.0 mg of ammonium sulfate, and different masses of an inhibitor ranging from zero to 8.00 mg, under a controlled moisture content of 35%. Thermal effects of each pollutant on the degradation curves of glucose in the soil were compared. Increasing amounts of the inhibitor caused a decrease in the thermal effect from -2234 to -1987 kJ mol(-1) for paraquat, -1670 to -1306 kJ mol(-1) for diquat, and -2239 to -589 kJ mol(-1) for phosphamidon. The last xenobiotic agent caused a significant inhibitory effect on the microbial activity of the soil. The results of relative efficiency, eta = deltaH/deltaH', referring to the enthalpic value with (deltaH) and without (deltaH') agrochemical in the soil, exhibited a significant correlation. From this correlation obtained for the ranges 2.00 to 8.00, 1.30 to 8.00, and 1.20 to 5.80 mg of the agrochemicals paraquat, diquat, and phosphamidon, respectively, the following eta values were calculated: 0.993 to 0.894, 0.668 to 0.522, and 0.896 to 0.236, respectively, during the degradation of glucose in the soil. The largest relative efficiency for paraquat implies that this agrochemical can be metabolized by microbial activity.

1,2,4-Triazolium-5-ylidene and 1,2,4-triazol-3,5-diylidene as new ligands for transition metals

Ab initio calculations show the 1,2,4-triazolium-5-ylidene ( 3a) and 1,2,4-triazol-3,5-diylidene ( 4a) are true minima on the potential surface. As expected, 4a is much higher in energy than its triazole isomers 5a, 6a and 8a and the 1,2,4-triazol-3-ylidene ( 7a). Sodium methoxyde adds to the diquaternary salt of 1,2,4-triazoles ( 9b,c) to give the corresponding monocationic heterocycles 10b,c in 70 and 50% yield, respectively. One equivalent of silver(I) acetate reacts with 9b leading to the bis(1,2,4-triazolium-5-ylidene)silver(I) complex ( 11b) in 80% yield. Under the same experimental conditions, but using two equivalents of silver(I) acetate, solid-state one-dimensional polymers 12′ b,c featuring the coplanar 1,2,4-triazol-3,5-diylidene ligands coordinated to silver(I) are obtained in 90% yield. 12′ c has been fully characterized including a single-crystal X-ray diffraction study.

Chemiluminescence of 1,1′-biisoquinolinium and 2,2′-biquinolinium salts. Reactions of electron-rich olefins with molecular oxygen

2,2′-Dialkyl-1,1′-biisoquinolylidenes (BIQ), having been prepared by two-electron reduction of the corresponding diquaternary salts BIQ2+(X–)2, react with triplet dioxygen to produce chemiluminescence (CL). In aprotic solvents, the kinetics of the reaction are first-order with respect to the concentrations of the substrate and of oxygen. The second-order rate constants at 25 °C increase in the order DMF < MeCN DMSO, which correlate with the free energy change for an electron-transfer (ET) from BIQ to O2, although this process is endothermic in all three solvents. In non-polar solvents such as benzene, the reaction proceeds much more slowly. From these results, a reaction mechanism is proposed as follows. An ET or partial charge-transfer gives a radical ion pair {BIQ˙+ · · · O2˙–} or a CT complex, in which intersystem crossing takes place from the triplet to the singlet state, and then radical coupling at the 1-position followed by cyclisation yields a 1,2-dioxetane, the postulated intermediate of the CL reaction. An electron-rich olefin having a closely related structure, 1,1′-dimethyl-2,2′-bisquinolylidene (BQ), shows a similar redox behaviour to that of BIQ. Reaction of BQ with O2 produces CL, and the emitter has been identified as the singlet excited state of 1-methyl-2(1H)-quinolinone 8a. The effects of substituents in the quinoline ring on the autoxidation rate have been investigated in MeCN and DMSO. An olefin having the more negative oxidation potential shows the higher reactivity to O2, suggesting that the autoxidation of BQ should take place via a similar reaction pathway as that of BIQ.