Interfacial engineering through lead binding using crown ethers in perovskite solar cells

In the domain of perovskite solar cells(PSCs),the imperative to reconcile impressive photovoltaic performance with lead-related issue and environmental stability has driven innovative solutions.This study pioneers an approach that not only rectifies lead leakage but also places paramount importance on the attainment of rigorous interfacial passivation.Crown ethers,notably benzo-18-crown-6-ether(B18C6),were strategically integrated at the perovskite-hole transport material interface.Crown ethers exhibit a dual role:efficiently sequestering and immobilizing Pb^(2+)ions through host-guest complexation and simultaneously establishing a robust interfacial passivation layer.Selected crown ether candidates,guided by density functional theory(DFT)calculations,demonstrated proficiency in binding Pb2+ions and optimizing interfacial energetics.Photovoltaic devices incorporating these materials achieved exceptional power conversion efficiency(PCE),notably 21.7%for B18C6,underscoring their efficacy in lead binding and interfacial passivation.Analytical techniques,including time-of-flight secondary ion mass spectrometry(ToF-SIMS),ultraviolet photoelectron spectroscopy(UPS),time-resolved photoluminescence(TRPL),and transient absorption spectroscopy(TAS),unequivocally affirmed Pb^(2+)ion capture and suppression of non-radiative recombination.Notably,these PSCs maintained efficiency even after enduring 300 h of exposure to 85%relative humidity.This research underscores the transformative potential of crown ethers,simultaneously addressing lead binding and stringent interfacial passivation for sustainable PSCs poised to commercialize and advance renewable energy applications.

Density Functional Theory Study of Marine Polybrominated Diphenyl Ethers in Anaerobic Degradation

Polybrominated diphenyl ethers(PBDEs)are a kind of serious pollutants in the ocean.Biodegradation is considered as an economical and safe way for PBDEs removal and reductive debromination dominates the initial pathway of anaerobic degradation.On the basis of experimental study,Octa-BDE 197,Hepta-BDE 183,Hexa-BDE 153,Penta-BDE 99 and Tetra-BDE 47 were selected as the initial degradation objects,and their debromination degradation were studied using density functional theory.The structures were optimized by Gaussian 09 program.Furthermore,the molecular orbitals and charge distribution were analyzed.All C-Br bond dissociation energies at different positions including ortho,meta and para bromine atoms were calculated and the sequence of debromination was obtained.There is a close relationship between molecular structure,charge,molecular orbital and C-Br bond.All PBDEs exhibited similar debromination pathways with preferential removal of meta and para bromines.

Synthesis of mordenite by solvent-free method and its application in the dimethyl ether carbonylation reaction

Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sites were systematically investigated.The characterization results showed that with the increase of Si/Al ratio in the feedstock,part of silicon species fail to enter the skeleton and the specific surface area and pore volume of the samples decreased.The amount of weak acid and medium strong acid decreased alongside with the increasing Si/Al ratio,and the amount of strong acid slightly increased.The Al atoms preferentially enter the strong acid sites in the 8 member ring(MR)channel during the crystallization process.The high Si/Al ratio sample had more acid sites located in the 8 MR channel,leading to more active sites for carbonylation reaction and higher catalytic performance.Appropriately increasing the Si/Al ratio was beneficial for the improvement of carbonylation reaction activity over the mordenite(MOR)catalyst.

Synthesis and Properties of New-type Troponoid Dithio-Crown Ethers

Condensation of 3,7-dichloromethyl-5-isopropyl-2-methoxytropane 4 with bis (mercaptoethyl) ether 5a and mono, di, and tri-ethylene glycol bis(mercaptoethyl) ethers 5b-5d gave troponoid-annexed dithiocrown ethers 6a-6d. Compounds 6a-6d have selective and reversible mercury salt capturing ability.

Mechanism of chain propagation for the synthesis of polyoxymethylene dimethyl ethers

Polyoxymethylene dimethyl ethers(PODE)were synthesized from the reaction of paraformaldehyde with dimethoxymethane(DMM)over different acid catalysts at different conditions.Products were found to follow the Schulz-Flory distribution law.The chain propagation proceeds through the insertion of an individual segment of CH2O one by one,while the simultaneous insertion of a few CH2O segments or their assembly is unlikely.Due to the restriction of this law,it is difficult to increase the selectivity to the desired products(e.g.,PODE3 4).

Chemical equilibrium controlled synthesis of polyoxymethylene dimethyl ethers over sulfated titania

The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers （DMMn） were investigated over sulfated titania in order to reveal the decisive factor controlling the reaction. The results showed that the molar ratio of adjacent DMMn products in equilibrium solution had the same value, which depended absolutely on the reaction temperature. Meanwhile, the reactions had the same DMMn products distributions under varied reaction conditions. The equilibrium constants of the related step-wise reactions for DMMn formation were equal, which were calculated based on the bulk compositions of the reaction solution. And thus, the selectivity to DMMn was mainly controlled by the chemical equilibrium, i.e., thermodynamic control. In brief, the present results provide some guidance for future synthesis of DMMn.

Ecotoxicological effects of mixed pollutants resulted from e-wastes recycling and bioaccumulation of polybrominated diphenyl ethers in Chinese loach(Misgurnus anguillicaudatus)

To understand potential ecotoxicological effects of electrical and electronic equipment waste （e-waste） recycling and polybrominated diphenyl ethers （PBDEs） bioaccumulation in loaches, a semi-field experiment using Chinese loach （Misgurnus anguiUicaudatus） as experimental fish was performed. Larval loaches were kept in net-cage for three months in an e-wastes recycling site and a reference site in Southeastern China. There was significant difference of the survival rate between the loaches from the e-wastes recycling site （27%, 19/70） and from reference site （70%, 49/70）. Histopathological responses were also found in all the livers examined in loaches from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological effects on loaches. The bioaccumulation of polybrominated diphenyl ethers （PBDEs）, the main pollutants in e-waste, in loaches was also studied, the mean concentration of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L （dissolved phase）. BDE 209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low concentration of BDE 209 （less than 0.01% of total PBDEs） and high concentration of BDE47 （up to 39.34% of total PBDEs） were detected in loaches.

A comparative study of four 20-membered N_2S_4-crown ethers as ionophores for polymeric membrane silver selective electrodes

Four 20-membered N_2S_4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag^+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag^+ ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine 6,13-(7H,14H)-dione(C) with 2-nitrophenyl octyl ether(o-NPOE) as solvent in a poly(vinyl chloride)(PVC) membrane matrix sho...

A Synthesis, Process Optimization, and Mechanism Investigation for the Formation of Polyoxymethylene Dimethyl Ethers

Polyoxymethylene dimethyl ethers(DMM_n) are promising diesel additives. The synthesis of DMM_n from methylal(DMM) and paraformaldehyde over the NKC-9 acidic ion-exchange resin catalyst was investigated. Many unrecyclable by-products such as methyl formate, dimethyl ether and formic acid were produced in the reaction. To increase the selectivity of the desired products DMM_(3-6) and reduce the amount of unrecyclable by-products, the effects of reaction temperature, time, pressure and the molar ratio of the raw materials were evaluated through a series of single factor experiments. Experiments revealed that trace amount of water could suppress the formation of unrecyclable by-products, and the optimum initial water content(less than 2 wt%) was investigated. In addition, the synthetic process needs to go through the polyoxymethylene hemiformals intermediate stage, and then the DMM_n were obtained when polyoxymethylene hemiformals reacted with methanol. Ultimately, a possible mechanism is proposed to describe the formation of DMM_n from polyoxymethylene hemiformals in detail, in which it is revealed that the formation of carbocation intermediates is important in the reaction processes.

Occurrence of polybrominated diphenyl ethers in fish and shellfish downstream from electronic-waste recycling plants

We measured 39 polybrominated diphenyl ethers （PBDEs） in the muscle tissue of three species of fish （Sciaenops ocellatus,Sparus macrocephalus,and Lateolabrax japonicus） and four species of shellfish （Tegillarca granosa,Cyclina sinensis,Sinonovacula constricta,and Ostrea cucullata） that were collected downstream of electronic-waste recycling plants in Taizhou,China.A total of 24 PBDE congeners （PBDE 24） in the samples were detected.The PBDE 24 （total PBDE） ranged from 545.4 to 1688.7 ng/kg ww （wet weight）.The mean PBDE 24 concentration was 1382.6 ng/kg ww in fish and 858.1 ng/kg ww in shellfish.The lower brominated congeners were detected at relatively high concentrations in all species.The penta-products,produced from e-waste,were found at relatively low levels.A principal component analysis suggested a significant correlation among di-,tri-,tetra-,and hepta-BDEs for the three species of fish.Similarly,we found a significant correlation between mono-and tri-BDEs in the shellfish.Our results suggested that the processes of PBDE metabolism and elimination were similar in both fish and shellfish.In addition,the primary source of PBDEs appeared to be from the debromination of high brominated PBDEs.

Synthesis of New Aza-crown Ethers Containing Pyridine Ring and their Liquid Membrane Transport of Alkali Cations

Five new aza-crown ethers have been prepared by the condensation of 2,6-bis[(2-formylphenyl)oxymethyl] pyridine with different diamino compounds in hot methanol, the bis-Schiff bases without isolation were reduced with NaBH4 to afford the corresponding aza-crown ethers. The liquid membrane transport or alkali cations using the five new macrocycles as the ion-carriers was also studied.

Analysis of Air Voids Evolution in Cement Pastes Admixed with Non-ionic Cellulose Ethers

Four cellulose ethers（CEs） were compared for their effects on the pore structure of cement paste using mercury intrusion porosimetry. The experimental results show that the total pore volume and porosity of cement pastes containing the four cellulose ethers are significantly higher than that of the pure cement pastes and the total pore volume and porosity of cement pastes containing HEC（hydroxyethyl cellulose ether） or low viscosity cellulose ethers are low in four CEs. By changing the surface tension and viscosity of liquid phase and the strengthening of liquid film between air voids in cement pastes, CEs affect the formation, diameter evolution and upward movement of air voids and the pore structure of hardening cement paste. For the four CEs, the pore volume of cement pastes containing HEC or low viscosity cellulose ethers is higher with the diameter of 30-70 nm while lower with the diameter larger than 70 nm. CEs affect the pore structure of cement paste mainly through their effects on the evolvement of the small air voids into bigger ones when the pore diameter is below 70 nm and their effects on the entrainment and stabilization of air voids when the pore diameter is above 70 nm.

A QSRR Study on the Relative Retention Time of Halogenated Methyl-phenyl Ethers

Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.

A Convenient and Efficient Procedure for Oxime Ethers

Acetophenone oxime and benzaldehyde oxime were converted to oxime ethers in the presence of alkyl halide or methyl sulfate and KOH in aqueous DMSO in 5 to 70 min. The yields of oxime ethers were 70 - 96%.

An Efficient Synthesis of Diaryl Ethers by Coupling Aryl Halides with Substituted Phenoxytrimethylsilane in the Presence of TBAF

A general synthesis of diaryl ethers via coupling of aryl halides with substituted phenoxytrimethylsilane in the presence of TBAF is described. The protocol is simple and mild, and gives good to excellent yields.

Predicting the Relative Retention Time (RRT) of Polybrominated Diphenyl Ethers (PBDEs)

Using the molecular electronegativity distance vector descriptors derived directly from the molecular topological structures, the relative retention time （RRT） of polybrominated diphenyl ethers （PBDEs） were predicted. A four-variable regression model （M30） with the correlation coefficient of 0.9816 and the root mean square errors of 0.061 was developed using a training set including 30 PBDEs. The correlation coefficient of 0.9841 and the root mean square errors of 0.054 between the values of RRT predicted by M30 and the RRT observed for 16 external PBDEs show a good predictive potential of M30. The descriptors included in the M30 represent four interactions between four pairs of atom types, i.e., atom -C= and -C=, -C= and 〉C=, 〉C= and 〉C=, -C= and -Br.

Studies on the Synthesis and Complexing Behavior of Crown Ethers with External Coordination Center

The synthesis, characterization of five ditopic or tritopic crown compounds were reported in this paper together with the preparation of the corresponding hetero-dinuclear and hetero-trinuclear complexes with different metal cations.

Study on Molecular Recognition of Crown Ethers to Aniline and Monosaccharides

Theoretical study on coordinates between crown ethers and aniline as well as monosaccharides is performed by AM1, MNDO and PM3 methods. It is indicated that crown ethers possess ability to recognize polar guests especially ionic guests and monosaccharides. Electronic spectra of coordinates are computed by the INDO/SCI method. The reason of the blue-shift for UV absorption of complexes relative to that of hosts is discussed and electronic transition is theoretic- cally assigned.

Polybrominated Diphenyl Ethers in Surface Sediment from Songhua River Basin,Northeast of China

Sixty sediment samples were collected from the main Songhua River in three years. Twelve polybrominated diphenyl ether( PBDE) congeners( BDE17,28,47,66,99,100,153,154,138,183,and BDE-209) were detected to state the pollution situation. The results showed that the total concentration of total PBDEs ranges from 0. 424 to 23. 0 ng / g dry weight,with the mean of 3. 02 ng / g,and the total PBDEs concentration is at relative low level compared with those worldwide. The congener profile showed that BDE-209 is the dominant congener that accounts for more than 80. 1% of total PBDEs in sediments,followed by BDE-47 and BDE-99. These profiles are consistent with a high consumption of Deca-BDEs for the brominated flame retardant market in China. The results of spatial and seasonal observations indicated that local sources,temperature variation, and hydrologic conditions are significant factors on PBDEs concentrations. Hazard quotients suggested that PBDEs pose no potential risk to benthic organisms in detected area at present.

Influence of Cellulose Ethers on Hydration Products of Portland Cement

Cellulose ethers are widely used to mortar formulations,and it is significant to understand the interaction between cellulose ethers and cement pastes.FT-IR spectra,thermal analysis and SEM are used to investigate hydration products in the cement pastes modified by HEMC and HPMC in this article.The results show that the hydration products in modified cement pastes were finally identical with those in the unmodified cement paste,but the major hydration products,such as CH（calcium hydroxide）,ettringite and C-S-H,appeared later in the modified cement pastes than in the unmodified cement paste.The cellulose ethers decrease the outer products and increase inner products of C-S-H gels.Compared to unmodified cement pastes,no new products are found in the modified cement pastes in the present experiment.The HEMC and HPMC investigation shows almost the same influence on the hydration products of Portland cement.