Room Temperature In Solvents Research Articles

Morphology Controlling of All‐Inorganic Perovskite at Low Temperature for Efficient Rigid and Flexible Solar Cells

AbstractAll‐inorganic cesium lead halide (CsPbX3) perovskites have emerged as promising photovoltaic materials owing to their superior thermal stability compared to traditional organic–inorganic hybrid counterparts. However, the CsPbX3 perovskites generally need to be prepared at high‐temperature, which restricts their application in multilayer or flexible solar cells. Herein, the formation of CsPbX3 perovskites at room‐temperature (RT) induced by dimethylsulphoxide (DMSO) coordination is reported. It is further found that a RT solvent (DMSO) annealing (RTSA) treatment is valid to control the perovskite crystallization dynamics, leading to uniform and void‐free films, and consequently a maximum power conversion efficiency (PCE) of 6.4% in the device indium tin oxide (ITO)/NiO x /RT‐CsPbI2Br/C60/Bathocuproine (BCP)/Ag, which is, as far as it is known, the first report of RT solution‐processed CsPbX3‐based perovskite solar cells (PSCs). Moreover, the efficiency can be boosted up to 10.4% by postannealing the RTSA‐treated perovskite film at an optimal temperature of 120 °C. Profiting from the moderate temperature, flexible PSCs are also demonstrated with a maximum PCE of 7.3% for the first time. These results may stimulate further development of all‐inorganic CsPbX3 perovskites and their application in flexible electronics.

Rapid preparation of all-cellulose composites by solvent welding based on the use of aqueous solvent

In the present study, the dissolution of softwood fibers and fabrication of all-cellulose composites was investigated using aqueous tetraethylammonium hydroxide solution (TEAOH, 35wt%) at room temperature. The bulk of the cellulose fibers were instantly dissolved when mixed with the solvent, and suspensions up to 3wt% were fabricated with ease. During the dissolution, a few remaining larger fiber flocks were fully dissolved within 3h of mixing at room temperature. TEAOH was further studied in the production of all-cellulose composites by solvent welding (partial dissolution) of cellulose fiber sheets. Tensile strength of the original cellulose sheet increased from 3.3 to 55.0MPa only after 30s of room-temperature solvent welding, and an increase of over 23-fold (up to 76.7MPa) was obtained by high-pressure-aided hot-pressing of the partially dissolved sheets before drying. The demonstrated fabrication of all-cellulose composites yielded many benefits in comparison to the current dissolution systems, such as short treatment time, ambient operation conditions, and readily applicable processing solutions, which makes it a potential methodology applicable even at an industrial scale.

Nanofiber-based Matrimid organogel membranes for battery separator

Porous organogel membranes (POMs) composed of electrospun nanofibers with a crosslinking modification have demonstrated great potential as battery separators. As a proof of concept, we fabricated such membranes using electrospun Matrimid nanofibers crosslinked through a room temperature solvent immersion technique. The effects of the crosslinking modification on the chemical structure and mechanical properties of electrospun Matrimid mats were evaluated using Fourier transform infrared spectroscopy and dynamic mechanical analysis tests. Stability was tested on the resulting POMs showing that the crosslinking modification on Matrimid drastically improved fiber chemical and sovothermal resistance.A Matrimid organogel membrane with a 3-day crosslinking modification was tested as separator in a Li-ion battery. When soaked in dimethylformamide (DMF), no thermal shrinkage was observed at temperature up to 180°C. At 190°C and 200°C, Matrimid membranes showed shrinkage of 10% and 20% with respect to their original sample area, respectively. The discharge capacity of the battery was over 93% after 20 cycles with an average Coulombic efficiency above 98%. The membrane retained physical stability and flexibility after being in contact with the electrolyte LiPF6 in EC-DEC-DMC for three weeks of testing and demonstrated great potential as battery separators in applications involving strong solvents and high temperature.

Enhanced viscoelastic properties of graphene oxide membranes

Viscoelastic materials having high loss factor are receiving enormous importance in damping applications. In this report, several layers of graphene oxide (GO) stacked thick membranes are tuned for their viscoelastic properties, and studied the role of intercalated loosely bound water in deciding their damping ratios (tan δ, ratio of loss modulus to storage modulus). The loosely bound water present inside GO membranes, where the membranes are developed using flow assisted filtration, is removed by ethanol and diethyl ether based room temperature solvent drying technique to study the dynamic mechanical behaviour of the resultant membranes. A huge enhancement in tan δ (>160%) is observed in water removed GO membranes without compromising on its storage modulus, indicating the critical role of water in GO's viscoelastic properties. The in situ tan δ variation of GO paper immersed in ethanol bath is also studied using submersible clamp experiments in dynamic mechanical analyser, where the GO paper has undergone a dewetting phenomenon. These studies show the tunability in the viscoelastic properties of GO macroscopic structures by solvent assisted room temperature intercalation/de-intercalation techniques.

In situ GISAXS study of a Si-containing block copolymer under solvent vapor annealing: Effects of molecular weight and solvent vapor composition

The room-temperature solvent vapor annealing of polystyrene-b-polydimethylsiloxane (PS-b-PDMS) block copolymer films was studied in situ by grazing incidence small-angle X-ray scattering. Films of cylinder-forming PS-b-PDMS with molecular weight 16 kg/mol and 12.2 kg/mol, annealed under vapors of toluene:heptane with varying composition, exhibited swelling-ratio-dependent evolution of microdomain spacing and orientation. In a vapor made from a toluene:heptane 5:1 volumetric ratio liquid mixture, or from pure toluene, cylindrical microdomains reoriented from majority out-of-plane to in-plane during annealing, while drying led to shrinkage along the film normal and a large distortion of the hexagonal lattice of in-plane cylinders. Annealing under vapor from a toluene:heptane 1:5 volumetric ratio liquid produced a non-bulk lamellar structure in the 16 kg/mol PS-b-PDMS.

In Situ Characterization of the Self-Assembly of a Polystyrene–Polydimethylsiloxane Block Copolymer during Solvent Vapor Annealing

Grazing incidence X-ray scattering was used to follow the microphase separation during room-temperature solvent annealing of films of high interaction parameter cylinder-forming 16 kg/mol polystyrene-b-polydimethylsiloxane block copolymer in a toluene–heptane mixed solvent vapor. Microphase separation was observed for swelling ratios above 1.2, but swelling ratios above 1.9 caused the films to disorder. The films exhibited a thickness-dependent microdomain reorientation during annealing, with the initial out-of-plane cylinder orientation converting to an in-plane orientation as a result of preferential surface interactions. Drying led to a reduction in the out-of-plane cylinder spacing, with slower drying leading to greater deswelling and larger distortion of the hexagonal lattice.

Screening of Various Parts of P haleria macrocarpa Plant for α-Glucosidase Inhibitory Activity

Phaleria macrocarpa is an herbal plant used in Malaysia to enhance vitality. The aim of this study was to screen the α-glucosidase inhibitory activity of different parts (fruit flesh, leaves and stem) of P. macrocarpa. Methanol (polar) and n-hexane (nonpolar) extracts, obtained by room temperature solvent extraction, were evaluated for in vitro α-glucosidase activity inhibition. The compounds were identified by using gas chromatography-mass spectrometry (GC-MS) according to their similarity index of >70%, which might be responsible for α-glucosidase inhibitory activity. The methanol extract of the fruit flesh had the highest yield (25.6 ± 0.5%), whereas the n-hexane extract of the stem is more effective against α-glucosidase activity (IC50 0.8 ± 0.1 μg/mL). The fruit flesh (IC501.3 ± 0.2 μg/mL) and leaves (IC501.6 ± 0.6 μg/mL) had also well effectively. The identified metabolites are predominantly phenolics, carbohydrates, triterpenes and organic acids, such as D-fructose, squalene, α-linolenic acid and α-D-glucopyranoside. In-depth chemical profiling using GC-MS was performed for the first time for this plant to assess the likely compounds present in the extract that could be associated with anti-hyperglycemic activity. Of the three parts tested, every part indicates the potential α-glucosidase inhibitory activity and hexane extract of stem showed more inhibitory activity among all extracts. Thus, P. macrocarpa can attenuate hyperglycemia by potently inhibiting carbohydrate hydrolyzing enzymes, making it a viable plant as a source of natural compounds for the management of type 2 diabetes mellitus. Practical Application P. macrocarpa (Scheff.) Boerl. belongs to the Thymelaeaceae family, which is known as “Mahkota Dewa” is one of the well-known traditional herbs in South Asian countries. Every part of this plant has been reported to be used as a traditional medicine for diabetic treatment for many years. In the present study, the ability of this plant to inhibit carbohydrate hydrolyzing enzymes (α-glucosidase) was explored. All extracts tested exhibited the content to inhibit yeast α-glucosidase enzymes in vitro, and these beneficial effects appear to be due to some bioactive compounds in P. macrocarpa. Our preliminary investigation gives a principle for further animal and clinical studies of a possible use of P. macrocarpa for the management of diabetes mellitus.

Photo-Induced Intermolecular Electron Transfer from Donating Amines to Accepting Diarylethylenes in Different Solvents

The fluorescence quenching of newly synthesized diarylethylenes by some aliphatic and aromatic amines has been carried out at room temperature in solvents of various polarities and viscosities including acetonitrile, methanol, ethanol, and cyclohexane using steady-state measurements. Additionally, the cyclic voltammetric behavior of the investigated diarylethylenes has been studied, in order to determine their reduction potentials, which are necessary for calculation the Gibbs energy change for the photoinduced, electron transfer (ET) reactions in diarylethylene–amine systems. No change in the shape of the fluorescence spectra was observed, except for diarylethylenes–N,N-dimethyl aniline pairs in cyclohexane at which an exciplex was observed. The quenching mechanism is due to the ET from the ground state amines to the excited diarylethylenes. Both linear and non-linear Stern–Volmer behaviors have been encountered. The observed k q values for different diarylethylenes–amine pairs do not correlate with the basicity (pK b) of the amines but decrease with increasing the oxidation potentials of the amines. The bimolecular quenching rate constants have been correlated with ∆G° values for the ET reactions according to the Marcus outer-sphere ET theory.

Roles of Fullerene‐Based Interlayers in Enhancing the Performance of Organometal Perovskite Thin‐Film Solar Cells

To surmount these obstacles, conventional PHJ PVSCs with the confi guration of substrate/HTL (p)/perovskite (i)/fullerene derivative (n) has been developed. [ 9 ] PEDOT:PSS or NiO X are the commonly employed HTLs to date while the electron-transporting layers (ETLs) employed are mainly based on fullerene derivatives. [ 7c,9c,d,10 ] It is worth noting that room temperature and orthogonal solvent processability of fullerene derivatives can successfully prevent the degradation of the underlying perovskite layer. In addition, the decent electron mobility of most fullerene derivatives makes them promising ETLs for high-performance PVSCs. Guo et al. fi rst demonstrated the feasibility of such a conventional PHJ confi guration, realizing a PCE of 3.9% by employing a phenyl-C 61 -butyric acid methyl ester (PC 61 BM) ETL. [ 9c ] Although three different fullerene derivatives (C 60 , PC 61 BM, and indene-C 60 bisadduct (IC 60 BA)) were investigated as ETLs, the functions of these fullerene-based interlayers were not fairly explored due to the inferior quality of the perovskite thin fi lm grown atop them. Soon after, a PC 61 BM ETL was used in a similar PHJ structure by Lam et al. to further improve the device performance to 7.4% by optimizing the perovskite precursor solution concentration and the blending ratio of PbI 2 and methylammonium iodide (MAI). [ 9a ] Lately, Jen and co-workers have signifi cantly enhanced the PCE to 12%–13%, respectively, by optimizing perovskite deposition either by controlling annealing conditions or adding a solvent additive.[11] Most recently, Seok and co-workers have reported an over 14% PCE through solvent engineering and thickness optimization of PC 61 BM. [ 12 ]

Solvent effect on absorption and fluorescence spectra of cinchonine and cinchonidine dications: Estimation of ground and excited state dipole moments by experimental and numerical studies

Absorption and fluorescence spectra of dications of cinchonine (C2+) and cinchonidine (Cd2+) have been measured at room temperature in solvents of different polarities. Ground and excited state electric dipole moments are determined experimentally using solvatochromic shift method based on bulk solvent properties. Theoretical calculations are done using B3LYP/6-31G(D) and CIS/6-31G(D) levels of theory for ground and excited states, respectively. Both experimental and theoretical studies reveal that excited state dipole moment (μe) values are higher than corresponding ground state dipole moment (μg) value of C2+ and Cd2+, which is attributed to the higher polarity of excited states compared to the ground state polarity of these molecules.

Manganese dioxide nanoparticles-silver-Y zeolite as a nanocomposite catalyst for the decontamination reactions of O, S-diethyl methyl phosphonothiolate

The decontamination reactions of O,S-diethyl methyl phosphonothiolate, as an agricultural organo-phosphorous pesticide onto 20 wt% loaded manganese dioxide nanoparticles-silver-Y zeolite as a nanocomposite catalyst in different solvents, were evaluated and monitored by means of gas chromatography–flame ionization detector and gas chromatography–mass spectrometry. Prior to the reaction, the catalyst was synthesized in three steps: at first, sodium-Y zeolite was prepared by hydrothermal method; then, silver-Y zeolite was prepared from sodium-Y zeolite using ion exchange procedure; and finally, manganese dioxide nanoparticles were synthesized by in situ impregnation method by pouring the pre-prepared silver-Y zeolite into manganese(ΙΙ) nitrate solution and loaded as 20 wt% onto silver-Y zeolite structure. The formation of the synthesized units and final nanocomposite catalyst was verified through scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry and Fourier transform-infrared spectroscopy techniques. Gas chromatography chromatograms showed that O,S-diethyl methyl phosphonothiolate was decontaminated perfectly by the catalyst in n-heptane solvent after 8 h, at room temperature, while chloroform and isopropanol solvents and other reaction times gave lower decontamination results. Moreover, gas chromatography–mass spectrometry chromatograms confirmed the formation of ethyl methyl phosphonic acid as a major and final product, which exemplifies the role of hydrolysis reaction during the degradation progress.

Catalytic Synthesis of α-Aminonitriles Using Nano Copper Ferrite CuFe2O4 under Green Conditions

Copper ferrite nanomaterial CuFe2O4 as reusable heterogeneous initiator in the synthesis of α-aminonitriles. The nanocatalyst is easily recovered and its reusability is recorded. Synthesis of α-aminonitriles derivatives by one-pot reaction of different aldehydes with amines and trimethylsilyl cyanides has been developed using nano copper ferrite CuFe2O4 catalyst under room temperature and green solvent (water as solvent) conditions. α-aminonitriles are important in preparing a wide variety of amino acids, amides, diamines, and nitrogen containing heterocycles.

Excited-State Structure, Vibrations, and Nonradiative Relaxation of Jet-Cooled 5-Fluorocytosine

The S0 → S1 vibronic spectrum and S1 state nonradiative relaxation of jet-cooled keto-amino 5-fluorocytosine (5FCyt) are investigated by two-color resonant two-photon ionization spectroscopy at 0.3 and 0.05 cm(–1) resolution. The 0(0)(0) rotational band contour is polarized in-plane, implying that the electronic transition is (1)ππ*. The electronic transition dipole moment orientation and the changes of rotational constants agree closely with the SCS-CC2 calculated values for the (1)ππ* (S1) transition of 5FCyt. The spectral region from 0 to 300 cm(–1) is dominated by overtone and combination bands of the out-of-plane ν1′ (boat), ν2′ (butterfly), and ν3′ (HN–C6H twist) vibrations, implying that the pyrimidinone frame is distorted out-of-plane by the (1)ππ* excitation, in agreement with SCS-CC2 calculations. The number of vibronic bands rises strongly around +350 cm(–1); this is attributed to the (1)ππ* state barrier to planarity that corresponds to the central maximum of the double-minimum out-of-plane vibrational potentials along the ν1′, ν2′, and ν3′ coordinates, which gives rise to a high density of vibronic excitations. At +1200 cm(–1), rapid nonradiative relaxation (k(nr) ≥ 10(12) s(–1)) sets in, which we interpret as the height of the (1)ππ* state barrier in front of the lowest S1/S0 conical intersection. This barrier in 5FCyt is 3 times higher than that in cytosine. The lifetimes of the ν′ = 0, 2ν1′, 2ν2′, 2ν1′ + 2ν2′, 4ν2′, and 2ν1′ + 4ν2′ levels are determined from Lorentzian widths fitted to the rotational band contours and are τ ≥ 75 ps for ν′ = 0, decreasing to τ ≥ 55 ps at the 2ν1′ + 4ν2′ level at +234 cm(–1). These gas-phase lifetimes are twice those of S1 state cytosine and 10–100 times those of the other canonical nucleobases in the gas phase. On the other hand, the 5FCyt gas-phase lifetime is close to the 73 ps lifetime in room-temperature solvents. This lack of dependence on temperature and on the surrounding medium implies that the 5FCyt nonradiative relaxation from its S1 ((1)ππ*) state is essentially controlled by the same ~1200 cm(–1) barrier and conical intersection both in the gas phase and in solution.

Solvent effect on the dipole moments and photo physical behaviour of 2,5-di-(5-tert-butyl-2-benzoxazolyl) thiophene dye

The absorption and emission spectra of fluorescent thiophene dye, namely, 2,5-di-(5-tert-butyl-2-benzoxazolyl) thiophene, have been recorded at room temperature in solvents of different polarities. The excited state dipole moments (μe) were estimated from Lippert’s, Bakhshiev’s, and Kawski–Chamma–Viallet’s equations using the variation of Stoke’s shift with the solvent dielectric constant and refractive index. The optimized geometry of the molecule and μgwere calculated theoretically by Gaussian 03 software using B3LYP/6-31g* level of theory. The μgand μewere calculated by means of solvatochromic shift method and μewas determined in combination with μg. It was observed that μewere higher than those of the μg, indicating a substantial redistribution of the π-electron densities in a more polar excited state for the selected thiophene dye. Further, the change in the dipole moment (Δμ) was calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter [Formula: see text] and values are compared.

Synthesis, Characterization, Photoluminescence and Photocatalytic Properties of CeO2 Nanoparticles by the Sonochemical Method

Uniform CeO2 nanoparticles were synthesized via a facile sonochemical reaction between ceric ammonium nitrate and ammonia. Nanoparticles were synthesized via a surfactant free reaction at room temperature in solvent of water. Products were characterized using X-ray diffraction, scanning electron microscopy, photoluminescence (PL) spectroscopy, and energy dispersive X-ray analysis. The effect of different parameters such as precursor, power of pulsation, surfactant and reaction time on the morphology of the products was investigated. It was found that the as-obtained CeO2 nanoparticles exhibit a strong PL peak at 381 nm at room temperature that can be ascribed to the high level transition in the CeO2 semiconductor. The photocatalytic behavior of CeO2 nanoparticles was evaluated using the degradation of a methyl orange aqueous solution under ultraviolet light irradiation. The results show that CeO2 nanoparticles are promising materials with excellent performance in photocatalytic applications.

Evolution of Polyvinylidene Fluoride (PVDF) Hierarchical Morphology during Slow Gelation Process and Its Superhydrophobicity

In the paper, we proposed an evolution process of polyvinylidene fluoride (PVDF) macromolecular aggregation in a mixed solvent through the simple and slow gelation process at room temperature. The mixed solvent is prepared with a room-temperature solvent and a high-temperature solvent. The evolution process can be terminated by quenching and exchanging with nonsolvent in a nonsolvent coagulation bath properly, and then the vivid petal-like nanostructure and microspherulite is formed simultaneously. This hierarchical morphology endows PVDF with superhydrophobic and self-cleaning properties, which is useful to PVDF coating and membrane materials. The evolution processes are investigated through the measurements of differential scanning calorimetry (DSC), X-ray diffraction (XRD). In addition, the rheological properties of solution, dry gel and wet gel, are explored.

Estimation of ground and excited state dipole moments of quinidine and quinidine dication: Experimental and numerical methods

Absorption and fluorescence spectra of quinidine (QD) and quinidine dication (QD2+) have been measured at room temperature in solvents of different polarities. Ground and excited state electric dipole moments are determined experimentally using solvatochromic shift method based on bulk solvent properties. Numerical calculations are also performed using B3LYP/6-31G(D) level of theory for ground state and CIS/6-31G(D) level of theory for first excited singlet state. From both experimental and numerical studies it has been observed that dipole moment values of excited states (μe) are higher than corresponding ground state value (μg), of QD and QD2+, which is attributed to the higher polarity of excited states of QD and QD2+ molecules.

Solvent Effects on the Steady State Photophysics of Estrone and 17β‐Estradiol

Absorption and emission yields for estrone and 17β-estradiol were measured in a variety of room temperature solvents. Molar extinction coefficients were found to not vary as a function of solvent, while fluorescence yields were found to be significantly affected by the polarity and hydrogen-bond accepting ability of the solvent, with the yield for 17β-estradiol being highest in nonpolar, hydrogen-bond donating solvents, and lowest in the nonpolar, hydrogen-bond accepting solvent ethyl acetate. Estrone's emission yield was found to be a factor of ten smaller than 17β-estradiol's. Strong solvent and excitation wavelength dependences were found for the relative amounts of emission between estrone's two emission bands, with increased relative emission occurring in nonpolar aprotic solvents, and under higher excitation energies. These results are interpreted with the aid of vertical excitation energies from time-dependent density functional calculations using both explicit and implicit solvation models.

In vitro Anthelmintic effect of Melia azedarach L. and Trichilia claussenii C. against sheep gastrointestinal nematodes

The control of parasitic diseases in small ruminants is mainly done with the use of synthetic anthelmintics. However, incorrect and indiscriminate use of these products has caused the emergence of parasite resistance. Plants with anthelmintic activity are used in folk veterinary medicine, but it is necessary to investigate and scientifically validate low-cost phytotherapeutic alternatives for future use to control gastrointestinal nematodes in small ruminants by family farmers. Thus, the aim of this study was to evaluate the in vitro anthelmintic effect of plant extracts from Melia azedarach and Trichilia claussenii by the egg hatch test (EHT) and larval development test (LDT) against sheep gastrointestinal nematodes. The hexane extract of M. azedarach fruits was extracted through cold percolation and the methanol extract of T. claussenii leaves was obtained by extraction at room temperature in solvents in order of increasing polarity. The efficacy results were analyzed using the Probit program of SAS. The M. azedarach extract showed a LC50 of 572.2μg/mL and LC99 of 1137.8μg/mL in the EHT, and LC50 of 0.7μg/mL and LC99 of 60.8μg/mL in the LDT. In turn, the T. claussenii extract presented a LC50 of 263.8μg/mL and LC99 of 522.5μg/mL in the EHT and LC50 of 1.1μg/mL and LC99 of 26.4μg/mL in the LDT. Comparing the extracts of the species from the Meliaceae family, T. claussenii showed greater anti-parasite potential in vitro than M. azedarach. However, studies on the isolated compounds, toxicity and administration forms to animals are also needed to validate low-cost alternative herbal remedies for use to control gastrointestinal nematodes by family farmers.

Stereoselective reduction of 1-acyl-2-phenylacetylenes with triphenylphosphine in water: efficient synthesis of E-chalcones

1-Acyl-2-phenylacetylenes are reduced with triphenylphosphine in water under mild conditions (room temperature, without catalyst and organic solvent, 3 h) to afford (E)-1-acyl-2phenylethenes (chalcones) in high yields (83-91%).