Observation of CO2^++ dication in the dayside Martian upper atmosphere

Doubly charged positive ions(dications)are an important component of planetary ionospheres because of the large energy required for their formation.Observations of these ions are exceptionally difficult due to their low abundances;until now,only atomic dications have been detected.The Neutral Gas and Ion Mass Spectrometer(NGIMS)measurements made on board the recent Mars Atmosphere and Volatile Evolution mission provide the first opportunity for decisive detection of molecular dications,CO2^++in this case,in a planetary upper atmosphere.The NGIMS data reveal a dayside averaged CO2^++distribution declining steadily from 5.6 cm^−3 at 160 km to below 1 cm^−3 above 200 km.The dominant CO2^++production mechanisms are double photoionization of CO2 below 190 km and single photoionization of CO2^+at higher altitudes;CO2++destruction is dominated by natural dissociation,but reactions with atmospheric CO2 and O become important below 160 km.Simplified photochemical model calculations are carried out and reasonably reproduce the data at low altitudes within a factor of 2 but underestimate the data at high altitudes by a factor of 4.Finally,we report a much stronger solar control of the CO2^++density than of the CO2+density.

Gas Phase Activation of Methane Molecule with Lead Benzene Dication Complex Ion, [Pb(Benzene)₂]²⁺

Motivated by the search for ways of a more efficient usage of the ubiquitous, and unexploited resources of methane, recent progress in the gas-phase activation of methane by metal dication complex ion is discussed. The gas phase theoretical and experimental analysis on [Pb(Benzene)2]2+ was conducted. The [Pb(Benzene)2]2+ complex ions were prepared using a combination of the pick-up technique and high energy electron impact, and then held in a cold ion trap. Excitation with tuneable UV radiation resulted in the formation of [Pb(Benzene)2(H2O)]2+, [Pb(Benzene)2(H2O)2]2+, [Pb(Benzene)]+, Pb+ and Benzene+ ions when the experimental results were analysed. The two optimised geometries of [Pb(Benzene)2]2+ namely the C2V eclipse and C2 staggered were observed. Methane activation of [Pb(Benzene)2]2+ complex ion yielded [Pb(Benzene)2(Me)]2+. [Pb(Benzene)2(H2O)(Me)2]2+,? [Pb(Benzene)2(H2O)(Me)]2+, [PbBenzene(Me)3]2+ and [Pb(Benzene)(Me)]2+. The PEC calculated binding energy of methane to lead benzene dication complex ion was approximately 25.45% higher than the value recorded on DFT calculation. This difference was due to the charge differences on the lead metal centre. While the actual calculated charge on the Pb metal in the optimised geometry was 1.68 the charge of +2 on the Pb metal was considered in the PEC calculation.

Dication-accelerated anion transport inside micropores for the rapid decontamination of pertechnetate

Over 70%of the treated contaminated water at the Fukushima Daiichi Nuclear Power Station contains radionuclides beyond the regulatory standard for discharge that need to be re-purified.Technetium-99(^(99)Tc),mainly in the form of pertechnetate Tc(VII)O_(4)^(-),is one of the main sources of long-term radiotoxicity that jeopardizes the environment and human health.Herein,we used a series of dicationic pyridinium(DCP)derivative groups(–Py^(+)C_(n)H_(2n)N^(+)Me_(3),n=2,3,and 5)to modify commercial Reillex 425 resins containing tertiary pyridyl groups to improve the adsorption performance of rhenium(Re,an analog of radioactive Tc)and Tc.As the quaternary pyridinium and ammonium sites in one DCP group can adsorb ReO_(4)^(-) simultaneously,DCP-modified Reillex 425(Reillex-Cn)exhibited high maximum adsorption capacities for Re under neutral conditions.Adsorption capacities reached 344.8,416.7,and 588.2 mg g^(-)1 for Reillex 425-C2,Reillex 425-C3,and Reillex 425-C5,respectively.Intraparticle diffusion of ReO_(4)^(-)/TcO_(4)^(-) in Reillex 425-Cn was verified to be the rate-limiting step of adsorption.However,adsorption can be adjusted by the length of the alkyl spacers between the two positively charged N sites in DCP.–Py^(+)C_(2)H_(4)N^(+)Me_(3) significantly enhanced intraparticle diffusion compared to–Py^(+)C_(5)H_(10)N^(+)Me_(3).The two positive sites in–Py^(+)C_(2)H_(4)N^(+)Me_(3) would be laterally distributed,leading to a smaller steric hindrance for ReO_(4)–/TcO_(4)^(-) transport inside the microporous channels.Meanwhile,the longer alkyl spacers in–Py^(+)C_(5)H_(10)N^(+)Me_(3) formed hydrophobic microphases,repulsing the hydrated ReO_(4)–/TcO_(4)^(-) anions.Thus,the adsorptions of both ReO_(4)^(-) and TcO_(4)^(-) on Reillex 425-C2 were faster than those on Reillex 425-C5.Moreover,Reillex 425-Cn exhibited an exothermic nature,good selectivity,excellent reusability,and strong salinity tolerance.This study provides a simple strategy to enhance the Tc removal performance of adsorbents containing abundant micropores,which implies enormous environmental and economic benefits.

Highly efficient separation of benzene+cyclohexane mixtures by extraction combined extractive distillation using imidazolium-based dicationic ionic liquids

Benzene(BEN)and cyclohexane(CYH),which have very close boiling points and a binary azeotrope,are the most difficult binary components in the separation of aromatic and non-aromatic hydrocarbons.This study further explored the separation mechanism and industrial application prospects of BEN+CYH mixtures separated by a dicationic ionic liquid(DIL)[C_(5)(MIM)_(2)][NTf_(2)]_(2) based on experimental research.The calculation results of the Conductor-like Screening model Segment Activity Coefficient(COSMO-SAC)model show that selectivity and solvent capacity of the DIL are significantly improved.The effects of different anions and cations on the micro-structure distribution and diffusion behavior of BEN+CYH system were investigated by quantum chemistry(QC)calculations and molecular dynamics(MD)simulations.The results indicate that the anion[NTf_(2)]_(2)has low polarity,uniform charge distribution,and a dual role of hydrogen bonding andπ-πbonding,and the cation[C_(5)(MIM)_(2)]^(2+) has stronger interaction with BEN and higher selectivity than conventional cations.The liquid-liquid extraction and extractive distillation(LLE-ED)process using an optimized 65 mol/mol DIL+35 mol/mol H_(2)O mixed solution as the extractant was proposed,which solved the problem of low product purity in the LLE process and high energy consumption in the ED process.Under the best operating conditions,the purity of CYH product was 99.9%,the purity of BEN product was 99.6%,the recovery rate of BEN reached 99.9%,and the recovery rate of DIL reached 99.9%.The heat-integrated LLE-ED process reduced total annual cost by 21.6%,and reduced CO_(2) emissions by 48.0%,which has broad industrial application prospects.

Inclusion of methylviologen dication in a cadmium tetracyanoplatinate host clathrate showing photochromism and photoluminescence modulation

A cadmium tetracyanoplatinate host clathrate,(MV)[Cd_(2){Pt(CN)_(4)}_(3)]·2(H_(2)O)(1),including a methylviologen dication (MV^(2+)) was synthesized,and the crystal structures,photochromic and photoluminescence properties were investigated.In 1,the alternatively parallel stacking between the MV^(2+)dications as electron acceptors in the channels and the electron donors[Pt1(CN)_(4)]^(2-) units in the host frameworks give a unique donor-acceptor (DA) system.Under UV irradiation,the electron transfer between MV^(2+) and[Pt(CN)_(4)]^(2-) ions generates MV^(·+)radicals with a photochromic behavior from pale-yellow to blue.This process occurs through single-crystal-to-single-crystal (SCSC) transformation and obvious structure variation of viologen cations is successfully observed.Moreover,the spectral overlap between the emission bands of 1 and the absorption around 623 nm for the MV^(·+) radicals leads to a modulation of the photoluminescence.

Prevalence and Factors Associated with Dry Eyes Syndrome in Glaucomatous Patients on Anti-Glaucoma Eye Drops Followed up at the Garoua Regional Hospital-Northern Cameroon

Background: Dry eye and glaucoma are two common pathologies in the elderly, and are very often associated. This association suggests a link between them and between their treatments. Our purpose for this study is to determine the prevalence of dry eye in our glaucoma patients treated with eye drops and deduce the factors associated with it. Patients and Methods: We conducted a cross-sectional, analytical study from October 2022 to September 2023 in the ophthalmology department of Garoua Regional Hospital in glaucoma patients aged over 15 years able to answer the Ocular Surface Disease Index (OSDI) questionnaires and treated with antiglaucoma eye drops for more than 3 months. These patients underwent a complete ophthalmological examination and a tear film break-up time test. Results: A total of 73 patients (146 eyes) were examined. The average age of the patients was 47.2 ± 16.5 years, with a male predominance of 54.8%. The prevalence of dry eye syndrome in our patients according to the OSDI score was 56.2% (95% CI) (44.8;67.6). The prevalence of dry eye syndrome on clinical examination of the BUT in the right eye was 83.7% (95% CI) (75.1;92.1) and 79.4% (70.2;88.7) in the left eye. The duration of antiglaucoma treatment was the factor associated with dry eye syndrome (p < 0.05) in glaucoma patients in our setting. Conclusion: Dry Eye Syndrome is common in glaucoma patients on drops in our setting. Treatment duration of more than 1 year seems to be associated with dry eyes.

双阳离子液体分离甲苯-正庚烷共沸体系——综合实验的设计与探索

构建了一种全新的专业设计型实验体系:双阳离子液体的制备及萃取分离甲苯-正庚烷共沸体系。合成并表征新型“绿色溶剂”双阳离子液体;以双阳离子液体作为萃取剂,测定其对甲苯-正庚烷共沸体系的分离能力并进行相图绘制。通过该综合实验教学,既促进学生对多学科基础知识的掌握,又能激发学生科研探索兴趣,培养其绿色化学意识与理念。

Synthesis, characterization and tribological evaluation of novel1,4-diazabicyclo[2.2.2]octane based dicationic ionic liquids as efficient antiwear lubricant additives

Ionic liquids have developed and been applied in lubricant field since 2001. Nevertheless, it is little known about novel dicationic ionic liquids for tribology applications in the past several years. In this paper, a sequence of novel dicationic ionic liquids based on 1,4-diazabicyclo[2.2.2]octane cations(DABCO) and different anions have been designed and identified. The structures of ILs were confirmed by Fourier transform infrared(FTIR) spectra, multinuclear(~1H,^(13)C,^(11)B,^(31)P and ^(19)F) magnetic resonance and mass spectrometry. The effects of anion type on thermal properties, wettability, kinematic viscosity and tribological properties were studied. It is found that all of these dicationic ionic liquids as additives exhibit excellent anti-wear and friction-reducing properties in PEG synthetic base oil under boundary lubrication conditions for steel-to-steel contact, which offers great potential for the highly efficient lubricant additives. Simultaneously, novel 1,4-diazabicyclo[2.2.2]octane cation offers an exceptional chance for the research and development of dicationic ionic liquids in various applications.

Physicochemical and tribological properties of gemini-type halogen-free dicationic ionic liquids

A series of new halogen-free dicationic ionic liquids(ILs)with different alkyl chain lengths were prepared,and the relationship between the alkyl chain length,physicochemical and tribological properties of ILs,and their role as neat lubricant for steel–steel friction pairs,was investigated.Evaluation of stability during hydrolysis and copper strip corrosion test results show that synthetic ILs are stable and not corrosive to metal contacts,due to the halogen-free anions.The friction and wear test results indicate that ILs with long alkyl chains have excellent friction-reducing and anti-wear properties,especially at high temperatures.Based on the surface three-dimensional(3D)profiles,electrical contact resistance,scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),and the X-ray photoelectron spectrometry(XPS)analysis of the worn surfaces of steel discs,we can conclude that the efficiency of ILs is due to the formation of high quality tribofilms that consist of both tribochemical reaction and ordered absorption films.

Dicationic Ionic Liquid Mediated Synthesis of 5-Arylidine-2,4-thiazolidinediones

An efficient synthesis of 5-arylidine-2,4-thiazolidinediones has been developed using dicationic ionic liquid as green medium and catalyst. This method performed well for the condensation of both aryl as well as heteryl aldehydes with 2,4-thiazolidinedione and gave 5-arylidine-2,4-thiazolidinediones with excellent yields.

Air-stable diradical dications with ferromagnetic interaction exceeding the thermal energy at room temperature: from a monomer to a dimer

Two tetraazacyclophane dications(1^(2+) and 2^(2+)) with different remote substituents have been synthesized, isolated and characterized.Their electronic structures and physical property were studied by various spectroscopic techniques, single crystal X-ray diffraction,super conducting quantum interference device(SQUID) measurements and theoretical calculations. The dications have triplet ground states with ferromagnetic interaction exceeding the thermal energy at room temperature. The solid-state structures of these species were tunable by substituent effect, with 1^(2+) as a monomer and 2^(2+) as a dimer.

Host-guest complexes of a water soluble cucurbit[6]uril derivative with some dications of 1,ω-alkyldipyridines:~1H NMR and X-ray structures

Interactions between a symmetrical tetramethyl-substituted cucurbit[6]uril (host:TMeQ[6]) and 1,ω-alkylenedipyridine (ω = 2,4,6,8,10) dicationic guests were investigated using 1H NMR spectroscopy and single crystal X-ray crystallography. In these inclusion complexes,combined cavity and portal binding in TMeQ[6] were observed,and the length of the bridged alkylene was found to play an important role not only in balancing the overall hydrophilic/hydrophobic interaction between the host and the guest,but also in defining the structure of the resulting inclusion complexes. For the guest 1,2-ethylenedipyridine (Edpy),TMeQ[6] includes a positively charged pyridine ring of Edpy to form an unsymmetrical inclusion complex; for the guest 1,4-butylenedipyridine (Bdpy),TMeQ[6] includes a positively charged pyridine ring of Bdpy,but the different competitive interactions in and between the related inclusion complexes could lead to a fast exchange between the hosts and guests. For the guests with longer bridge chains,such as 1,6-hexamethylenedipyridine (Hdpy) or 1,8-octylenedipyridine (Odpy),a stable pseudorotaxane inclusion complex is formed by combining the hydrophobic cavity and the outer portal dipoleion interactions. However,for 1,10-decatylenedipyridine (Ddpy),the two TMeQ[6] host molecules include the two end pyridine rings of Ddpy and form a dumbbell inclusion complex.

A dicationic,podand-like,ionic liquid water system accelerated copper-catalyzed azide-alkyne click reaction

In this work,an effective,task specific,dicationic,podand-like ionic liquid was synthesized and applied to improve the capability features of click reaction.Moreover,to broaden the scope and decreasing the serious limitations of preparation methods of organic azides,a simple green procedure for the preparation of alkyl azides,the fundamental starting materials in click reactions,from alcohols under solvent-free conditions and microwave irradiation has been reported,for the first time.

双阳离子型离子液体在能量存储和转化体系中的应用进展

双阳离子型离子液体(DILs)由于具有极高的化学稳定性、电化学稳定性、热稳定性和环境友好等特点,引起了各个领域研究者的广泛关注。本文从DILs的结构特点出发,综述了不同阴阳离子和连接基团对DILs理化性质的影响,并对一些典型的合成路径进行了总结。本文重点对DILs在不同储能和转化器件的电解液体系中的研究现状进行总结和分析:在锂离子电池电解液中,基于DILs的电解液不仅具有高电位窗口和阻燃特性,还有助于稳定固态电解质膜的形成,能够更好地改善电池系统的稳定性和可逆性;在超级电容器电解液中,DILs具有宽的电化学窗口,但其较大的黏度严重阻碍了离子运动,尽管添加常规有机溶剂可降低黏度,但由于溶剂化效应而带来的溶剂分解等副反应也严重影响了电容器性能。除此之外,本文还总结了DILs在锌空气电池、质子交换膜燃料电池、染料敏化太阳能电池、氧化还原液流电池以及电催化中的探索研究,最后对目前DILs在电解液体系应用过程中存在的问题和将来主要的研究方向进行了总结。

基于双阳性离子液体-原位转化盐析增强型微萃取技术在液体基质宽极性激素类污染物检测中的应用

本研究利用亲水性双阳性离子液体[C_(6)(MIM)_(2)]Br_(2),以丙酮作为双功能溶剂,LiNTf_(2)作为亲-疏水转化试剂,开发了一种基于原位转化双阳性离子液体的盐析增强型分散微萃取方法,实现了离子液体一次萃取,可同时高效富集和提取多种宽极性激素和酚类污染物的目的。该方法成功地应用于检测环境水样和人体尿样中7种宽极性(logK_(ow)=1.61~5.00)激素和酚类污染物,对7种目标物(氢化可的松、雄烯二酮、雌酮、炔雌醇、雌二醇、三氯生及双酚Z)的检出限为0.028~0.43μg/L,加标回收率为72.5%~112.7%,相对标准偏差(RSD)在2.8%~6.2%。本研究可减少环境水样及尿液样品检测的工作量,是一种绿色、高效和简易的宽极性污染物前处理方法,在复杂液体基质样品领域显示出较好的应用前景。

反气相色谱测定双阳离子型离子液体的溶解度参数

采用反气相色谱法,于343.15K到363.15K温度下测定了双阳离子型离子液体1,10-双(N-甲基咪唑鎓)癸烷六氟磷酸盐[C10(MIM)2][PF6]2的溶解度参数。以正辛烷、正十二烷、正十四烷和正十六烷为探针溶剂,计算了探针溶剂的特性保留体积(V0g)、摩尔吸收焓(ΔH1S)、无限稀释摩尔混合焓(ΔH1∞)、摩尔蒸发焓(ΔHv)、无限稀释活度系数(γ1∞2)以及探针溶剂与[C10(MIM)2][PF6]2的Flory-Huggins相互作用参数(χ1∞2),测得该离子液体的溶解度参数(δ2)为15.01(J.cm-3)1/2。这一结果对研究离子液体的溶液性质和应用有指导作用。

双核离子液体-杂多酸催化剂上高选择性合成单十二烷基磷酸酯

采用两步法制备了功能化双咪唑核离子液体-杂多酸盐催化剂,并用FT-IR对催化剂的结构进行了表征,考察了其在正十二醇与磷酸(质量分数85%)直接酯化高选择性地合成单十二烷基磷酸酯反应中的催化性能。结果表明,所合成的催化剂中杂多酸的Keggin结构均得到了较好的保持。杂多酸-离子液体复合催化剂的催化性能优于传统的纯杂多酸催化剂,其中在双-(3-甲基-1-咪唑)亚丁基磷钨酸盐催化剂质量分数0.67%、反应温度90℃和反应时间1 h的条件下,单酯收率和选择性分别达到了43.5%和99.9%;加入甲苯携水剂后,在最佳催化剂用量0.8%(质量分数)和120℃下反应24 h,单酯收率为93.5%,选择性为99.8%;重复使用6次后,该催化剂的活性基本保持不变,表明该功能性双核杂多酸离子液体是一种有潜力的新型酯化有机-无机复合催化材料。

双子型Br?nsted酸性离子液体催化高级脂肪酸与醇反应合成生物柴油（英文）

合成了一系列双子型酸性离子液体,该类型离子液体以乙二铵为连接链,由碳链长度可调的双子型阳离子与不同的阴离子组成.因此,具有相分离催化剂的性质,并应用于高级脂肪酸与醇的酯化反应,以合成生物柴油.详细考察了各参数的影响.结果表明,[C12Sb][p-CH3C6H4SO3]表现出高催化活性及可重复使用性能.

双阳离子型离子液体的合成与性能

以N-甲基咪唑、吡啶和二溴代烷为原料合成了一系列α,ω-亚烷基-双(N-甲基咪唑鎓)型和α,ω-亚烷基-双(吡啶鎓)型离子液体,并对其结构、熔点、溶解性、吸湿性和热性能分别进行了表征。结果表明,随着连接两个阳离子联接基的碳氢链长度的增加,离子液体的熔点先降低后升高,联接基的碳氢链长度为5个碳原子时最低;α,ω-亚烷基-双(N-甲基咪唑鎓)型离子液体的熔点低于α,ω-亚烷基-双(吡啶鎓)型离子液体;双阳离子溴盐型离子液体溶于水,双阳离子六氟磷酸盐型离子液体溶于丙酮和乙腈等;双阳离子溴盐型离子液体有一定的吸湿性,所合成的双阳离子型离子液体具有较高的热稳定性。

磷酸酯类双离子液体的合成及摩擦学性能研究

以咪唑、1,6-二溴代己烷和磷酸三乙酯合成1,6-二(3-乙基-1-咪唑基)己烷二乙基磷酸盐双离子液体,采用核磁共振谱仪(NMR)和傅立叶变换红外光谱仪(FTIR)等对其结构及理化性能进行了分析;用SRV摩擦磨损试验机考察了其作为钢/钢体系润滑剂的减摩抗磨作用;用SEM和XPS对磨痕表面的形貌和元素组成进行了表征,并分析了其润滑机制.结果表明,该类双离子液体具有较好的低温流动性,作为润滑剂对钢/钢摩擦副具有优异的减摩抗磨性能.XPS分析结果表明,该离子液体在钢磨损表面形成了含FePO4和Fe4(P2O7)3等物质的边界润滑膜,从而有效地提高了摩擦副的承载能力和抗磨损性能.