Cyclohexane Solution Research Articles

ESIPT-induced intersystem crossing leads to tautomer fluorescence quenching for 3-mercapto-2-(4-(trifluoromethyl)phenyl)-4H-chromen-4-one molecule

The excited-state intramolecular proton-transfer (ESIPT) dynamics of 2-(4-(diethylamino)phenyl)-3-mercapto-4H-chromen-4-one (3NTF) and 3-mercapto-2-(4-(trifluoromethyl)phenyl)-4H-chromen-4-one (3FTF) have been investigated using time-dependent density functional theory (TDDFT). Upon photoexcitation, 3NTF exhibits a single fluorescence emission while 3FTF is fluorescence quenched when dissolved in cyclohexane solution. The present study reveals that both species undergo barrierless ESIPT process, and the underlying reason for fluorescence quenching in 3FTF has been elucidated. Specifically, it is concluded that intersystem crossing (ISC) is responsible for the fluorescence quenching in the 3FTF molecule due to the energy gap between the S1 and T2 states is only 0.12 eV plus large S1 → T2 spin–orbit coupling resulting in a strong interaction between the singlet and triplet states. The present study provides a reference for the fluorescence quenching associated with thiol-hydrogen bond molecules, and it is helpful for further research on ESIPT reactions of sulfur-containing molecules.

Capture of Iodine in Vapor and Solution Phases by a Th-Based Metal-Organic Framework.

The efficient capture of radioactive iodine is of paramount importance due to its harmfulness. In this work, a new Th-based metal-organic framework (ECUT-Th-11) for iodine capture was reported. ECUT-Th-11 exhibited a relatively high capacity of capturing vapor iodine (2.03 g/g). Besides, the maximal adsorption capacity of iodine in a cyclohexane solution reaches 258.03 mg/g. All of the results demonstrated that ECUT-Th-11 could be a candidate material for the effective removal of waste iodine.

Constructing covalent organic frameworks with dense thiophene S sites for effective iodine capture

Developing versatile sorption materials for radionuclide capture (e.g. iodine) is critical for nuclear energy and environmental science. Covalent organic frameworks (COFs) have recently become a new platform for developing sorption materials because of their high surface area and functionalised skeleton structure. Herein, two types of COF materials containing thiophene were designed as iodine sorbents and synthesised via a Schiff base reaction of benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene-2,5,8-tricarbaldehyde, benzidine (DADP) and p-phenylenediamine (DAB): DADP-COF and DAB-COF. DAB-COF exhibits a unique granular-rod-like morphology and has a higher surface area (1775 m2/g) than DADP-COF (1140 m2/g), which is clearly beneficial for the physical adsorption of iodine. Meanwhile, the COF backbone is rich in N and S sites, which are advantageous for the chemical adsorption of iodine. These two features make the two prepared COFs ideal iodine sorption materials. DAB-COF demonstrates an excellent gaseous iodine adsorption capacity of 4.2 g/g, ranking it as one of the most effective iodine sorption materials, while DADP-COF exhibits a good adsorption capacity of over 235 mg/g for iodine in cyclohexane solutions. Density functional theory calculations prove that imine N and thiophene S serve as active sites during the iodine adsorption. DAB-COF exposes more active sites because of its higher surface area, leading to a higher iodine adsorption capacity than DADP-COF. The results of this study indicate that introducing thiophene to COFs improves sorption efficacy for sorption applications in general and particularly paves the way for developing stable and effective COF sorbents for iodine capture from various environments.

Synthesis of bulk foam-like palygorskite based adsorbent for efficient and convenient recyclable removal of radioactive iodine and iodide

Radioactive iodine is the inevitable product of nuclear fission, and the types and valence states of iodine are relatively rich and easy to convert to each other. Therefore, the synthesis of a material that can be easily recovered and efficiently remove polyvalent radioactive iodine has great strategic significance for the safe use of nuclear power. Bulk foam-like palygorskite based adsorbents (PDMA-PAL) with the macroscopic pore size of 40 to 150 μm were synthesized by the emulsion template method using dimethylaminoethyl methacrylate (DMAEMA) as the functional monomer and cheap palygorskite (PAL) as the matrix material. The excessive addition of DMAEMA and PAL will lead to the collapse of the porous structure. Optimized PDMA2-PAL shows excellent adsorption capacity (2.14 g/g) for iodine in cyclohexane solution with the equilibrium time of 5 h. PDMA2-PAL also exhibits an excellent adsorption capacity for gaseous iodine (308 wt%), and the I2 adsorption mechanism is the strong affinity and charge transfer of electron-rich N heteroatoms for electron-deficient iodine. PDMA2-PAL also achieves an outstanding iodide adsorption capacity (2.1mmol/g) within 5 min, and the I− adsorption mechanism is the electrostatic interaction between I− and the derivatization of tertiary amine under acidic conditions. Moreover, the deprotonation in alkaline solution can desorb iodide efficiently, which makes PDMA-PAL exhibit excellent recyclability. Importantly, PDMA-PAL also shows excellent simultaneous adsorption ability of iodide and iodine, and also exhibits stable adsorption activity in actual water. This study provides promising results for the removal of polyvalent radioactive iodine by bulk foam-like palygorskite based adsorbent in environmental remediation.

A mixed polynuclear clusters-based Y-MOF with an unprecedented (12, 12, 18)-c topology: highly efficient propylene/ethylene separation and iodine adsorption

The design and synthesis of highly stable metal–organic frameworks (MOFs) bearing unpredictable polynuclear clusters and new topologies are important for the development of novel and complicated MOFs. Herein, the polynuclear rare-earth (RE) clusters with more coordination modes and the small V-shaped ligand (2,5-thiophenedicarboxylic acid) were chosen, and subsequently JLU-MOF132 with three different yttrium clusters (two independent Y6 and one Y9 clusters) and a novel (12, 12, 18)-connected topology was successfully synthesized. Notably, JLU-MOF132 exhibits high porosity, excellent thermal, acid-base, and solvent stabilities. JLU-MOF132 shows considerable potential in methanol-to-olefins (MTO) products (C3H6 and C2H4) separation. The high ideal adsorbed solution theory C3H6/C2H4 selectivities (9.2, 10.6, and 15.1) and the breakthrough experiments results, including the high C2H4 purity (>99.9 %) and productivities (26.1, 73.1, and 101.0 L·kg-1), demonstrate its practical purification capability. Semi-empirical tight binding (xTB) quantum chemical calculations explain the mechanisms that differentiate C2H4 and C3H6 adsorption in JLU-MOF132. In addition, JLU-MOF132 also displays outstanding radioactive iodine adsorption performance, with an iodine uptake of 750 mg·g-1 in vapor and 153 mg·g-1 in cyclohexane solutions. Briefly, this work not only demonstrates the viability of employing the V-shaped ligand to increase the structural diversity of highly stable MOFs, but also enhances the application potential of MOFs in the fields of the MTO products separation and radioactive iodine adsorption.

Electron-rich COFs with a bis-triphenylamine structure as the main chain: Ultrafast and ultrahigh iodine capture

The construction of ideal adsorbents for the capture of radioiodine usually requires high adsorption capacity and high adsorption rate. However, this is still a challenging problem. The advantages of COFs based on their good crystallinity, pore order, and structural diversity make COFs ideal adsorbents. Here, we developed three novel electron-rich COFs based on the triphenylamine, which have good chemical, thermal, and radiation-resistant stability and are suitable for the harsh environment of radioactive iodine therapy. Upon the introduction of heteroatom N/S, TAPD-PDB and TAPD-TDB exhibited amazing adsorption capacities (75 °C: 7.88 g g−1 and 6.98 g g−1, 25 °C: 4.46 g g−1 and 3.62 g g−1), while the adsorption rates, K80%, are significantly increased to 5.34 g g−1h−1 and 4.22 g g−1h−1, which is higher than most of the reported iodine adsorbents. It was surprising that COFs also have excellent adsorption properties for iodine in cyclohexane solution up to 1260 mg L−1. FT-IR, XPS, Raman and electrostatic potential calculations indicate that the ultrafast and ultrahigh iodine uptake of COFs can be attributed to the interplay of their rich electronic structure, efficient adsorption sites, helical conformation and charge transfer. This study shows the efficient and ultrafast removal of iodine from nuclear wastewater and nuclear exhaust gas by electron-rich COFs.

Kinetic Analysis for Selective Semi-Hydrogenation of Diphenylacetylene on Pt1Pd99/C Catalyst by PEM Electrolysis

Introduction For carbon neutrality, organic synthesis should utilize renewable electricity. Alkyne semi-hydrogenation has been researched for a long time to prevent a side reaction: over-hydrogenation to produce alkane. Although the Lindlar catalyst, composed of Pd/CaCO3 added with lead acetate and quinoline, has been a dominant catalyst for stereoselective Z-alkene synthesis, lead toxicity is a concern. In contrast, PEM electrolysis enables synthesis under mild conditions without lead and hydrogen gas as a reactant, unlike the Lindlar catalyst.Our previous research revealed that Pt1Pd99/C (at%) catalyst had high activity and selectivity towards the semi-hydrogenation of diphenylacetylene (DPA) to form cis-stilbene due to the high proton reduction activity of Pt even with a small amount and the selective hydrogenation of DPA at Pd sites.1,2) It also qualitatively figured that electrolysis conditions that reduce residence time in the catalyst layer (low catalyst loading, high flow rate, high temperature) enhance selectivity.3) This study conducted essential quantitative kinetic analyses to evaluate performance under specific conditions and develop practical conditions. Experimental DSE® (De Nora Permelec Ltd) was used for the oxygen evolution as the anode and Nafion® 117 (DuPont) as the PEM, respectively. Carbon paper (39BB, SGL Carbon), loaded with 0.14 mg-PtPd cm−2 of Pt1Pd99/C (ISHIFUKU Metal Industry Co., Ltd.) and cut into 3.3 cm × 3.5 cm, was employed as the cathode. The cathode was hot-pressed on the PEM at 120 ℃, 6 MPa, for 3 min to make a membrane cathode assembly. In the anode compartments, 1 M (= mol dm−3) sulfuric acid circulated, and 1 M cyclohexane solution of DPA in the cathode compartments either flowed once-through or circulated.As electrochemical measurements, chronoamperometry at 1.3―2.1 V for once-through experiments and chronopotentiometry at 18 mA cm−2 for batch electrolysis were conducted. The concentrations of cis-stilbene and dibenzyl in electrolytes were quantified with high-performance liquid chromatography (HPLC) after collection during the last 2 min out of 5 min of electrolysis at 80 ℃. The partial currents were calculated by eqns. 1, derived from Faraday’s laws of electrolysis. Results and Discussion Figure 1 shows Tafel plots of the total and each partial current density derived by eqns. 1 at a 1 M DPA once-through flow rate of 2 mL min−1 and 80 ℃. The kinetic parameters, i 0 and α, were determined by the fitting lines of mass transport corrected Tafel equation (eqns. 2), shown in Table 1. The solid lines in Figure 1 represent the calculated partial current densities from the parameters, describing their behavior well.Figure 2 shows concentration-time profiles of 12-h batch electrolysis of 1 M DPA 30 mL at 18 mA cm−2 and 80 ℃. Initially, the concentration of DPA steeply decreased as the semi-hydrogenation to form cis-stilbene proceeded mainly. As a result, cis-stilbene at 65% concentration was produced with approximately 80% selectivity. The reactivity significantly changed around 9 h of electrolysis since the concentration of DPA became deficient, and thus the semi-hydrogenation rate dropped and the over-hydrogenation rate increased.The solid lines in Figure 2 were simulated from the estimated once-through partial current densities of 1 M DPA at 18 mA cm−2 in total by Figure 1, using eqns. 3. The rate constants k 1 and k 2 were respectively obtained by dividing the estimated once-through partial current density i 1 and i 2 by 2Fc A and 2Fc B . The computed kinetic parameters are shown in Table 2. The parameters derived by once-through electrolysis data described the concentration profiles in Figure 2 until 7.5 h of the batch electrolysis, when sufficient DPA existed. The high selectivity was quantitively explained by the high k 1/k 2 value at 18 mA cm−2. In addition, this simple kinetic model would predict products under a variety of operating conditions. Conclusion The kinetic analysis quantitively described the once-through partial current densities and the batch electrolysis concentration profiles. The high k 1/k 2 enabled cis-stilbene formation at 65% concentration with approximately 80% selectivity with the batch electrolysis. The suggested concise kinetic model would be beneficial to estimate the compositions in a batch electrolysis with once-through data. Acknowledgment This work was financially supported by CREST (JST Grant 18070940). The authors are grateful to ISHIFUKU Metal Industry Co., Ltd. for providing the cathode catalysts. References 1) S, Nogami, K. Nagasawa, A. Fukazawa, K. Tanaka, S. Mitsushima, M. Atobe, J. Electrochem. Soc., 167, 155506 (2020).2) S. Nogami, N. Shida, S. Iguchi, K. Nagasawa, H. Inoue, I. Yamanaka, S. Mitsushima, M. Atobe, ACS Catal., 12, 5430 (2022).3) H. Nakamura, J. Harada, N. Shida, K. Nagasawa, Y. Kuroda, M. Atobe, S. Mitsushima, ECS Meet. Abstr., MA2023-01, 2703 (2023). Figure 1

Amino-Functionalized NDI-Based MOFs as Unusual "Turn On" and "Turn Off" Fluorescent Sensors for Phenolic Pollutants with Double Solvent Channel Response and Iodine Adsorbents.

Regulating mixed ligands to change the functional properties of metal-organic frameworks (MOFs) has been an important topic; especially, the structural changes have significant implications for the transformation of sensing response in different solvent channels. Herein, two [Cd (DPNDI) (NH2-BDC)0.5(NO3)]·2.25DMF (1) and [Cd(DPNDI)(NH2-AIPA)]·0.5DMF (2) (DPNDI = N,N-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide, NH2-BDC = 2-amino terephthalic acid, NH2-AIPA = 5-aminoisophthalic acid) were synthesized by the solvothermal method. Structural analysis shows that complex 1 has a two-dimensional planar network structure and complex 2 exhibits a three-dimensional network structure, endowing its potential as an efficient fluorescence sensor for phenolic compound detection under different solvent environments. Both complexes showed high fluorescence quenching sensitivity to phenolics in a water medium. Conversely, complex 1 showed a fluorescence enhancement response to phenolic pollutants in an ethanol system with significantly low detection limits and recyclability. The detection limits were 0.58 μM for TNP, 1.3 μM for DNP, and 2.43 μM for PCP. In addition, the uncoordinated amino groups in the complexes promote them to exhibit excellent iodine adsorption performance. Especially, complex 2 can serve as an adsorbent for iodine in cyclohexane solution with better adsorption efficiency than that of complex 1, and its adsorption capacity can reach 505 mg/g. The mixed ligands regulation strategy of NDI-based MOFs will open up an effective avenue for the conversion of fluorescence signals in dual-solvent channels and play simultaneously important roles in multiple applications.

Fluorescent octahydrophenazines as novel inhibitors against herpes simplex viruses

A new series of racemic fluorescent octahydrophenazines (rac-PZ1–11) have been designed and synthesized via the efficient nucleophilic aromatic substitution (SNAr) of tetrafluorobenzenedinitriles (1a–c) and racemic cyclohexane-1,2-diamines (rac-2a and b). The bioactivities of these racemic rac-PZs (20 μM) against herpes simplex virus type-1 (HSV-1) were evaluated by the relative cell viability of Vero cells infected with HSV-1. It was found that rac-PZ3 shows much higher anti-HSV-1 activity than others, with EC50 = 9.2 ± 1.4 μM. Further investigation into the anti-HSV activities of rac-PZ3 and its enantiomers RR- and SS-PZ3 indicates that rac-PZ3 can also efficiently inhibit HSV-2 and even ACV-resistant HSV-2 (EC50 = 11.0 ± 2.3 and 14.9 ± 2.8 μM, respectively), SS-PZ3 has better activities against HSV-1, HSV-2 and ACV-resistant HSV-2 (EC50 = 4.1 ± 1.1, 5.8 ± 1.0 and 7.9 ± 1.2 μM, respectively), but RR-PZ3 has almost no antiviral activities. The primary mechanism study indicates that rac-PZ3 efficiently reverses the HSV-1/2-induced cytopathic effect and suppresses the expression of viral mRNA and proteins. In addition, rac-, RR- and SS-PZ3 possess excellent fluorescence properties with almost the same emission wavelength and high fluorescence quantum yields (ΦF = 90.3–92.3 % in cyclohexane solutions and 54.4–57.3 % in solids) and can target endoplasmic reticulum and cell membrane. The efficient anti-HSV bioactivities and excellent fluorescence of PZ3 prove its potential applications in antiviral therapy and biological imaging.

Biomass betulin-based porous aromatic frameworks nanomicrospheres as adsorbents for reversible capture of iodine

Betulin with a modifiable hydroxyl group and a rigid backbone is a kind of natural triterpene product that extracted from white barked birch bark with up to 30 % of its dry weight. Herin, we prepared a series of betulin-based porous aromatic frameworks (BEPAFs) nanomicrospheres by [Rh(nbd)Cl]2 polymerization or Sonogashira-Hagihara coupling reaction for iodine vapor capture and adsorption. The resulting BEPAFs nanomicrospheres presented perfect thermal stability and high specific surface areas that up to 324.6 m2 g−1, 506.3 m2 g−1 and 320.5 m2 g−1 for BEPAF-1, BEPAF-2 and BEPAF-3, respectively. Based on the above characteristics, the BEPFAs nanomicrospheres showed an excellent iodine capture performance with the volatile iodine capture ability reached 3.79 g g−1 and iodine adsorption in cyclohexane solution up to 389.9 mg g−1. The iodine capture behavior is consistent with the pseudo-second-order model, indicating that the iodine adsorption process of BEPAFs microspheres belongs to multilayer heterogeneous surface chemical adsorption. Furthermore, the BEPFAs nanomicrospheres could maintained 88.26 % of the absorption capacity after four cycles that endow them a great potential in practical application. This research provides a facile synthesis of biomass porous aromatic framework nanomicrospheres adsorbents based on the natural product.

Unraveling the Ultrafast Photochemical Dynamics of Nitrobenzene in Aqueous Solution.

Nitroaromatic compounds are major constituents of the brown carbon aerosol particles in the troposphere that absorb near-ultraviolet (UV) and visible solar radiation and have a profound effect on the Earth's climate. The primary sources of brown carbon include biomass burning, forest fires, and residential burning of biofuels, and an important secondary source is photochemistry in aqueous cloud and fog droplets. Nitrobenzene is the smallest nitroaromatic molecule and a model for the photochemical behavior of larger nitroaromatic compounds. Despite the obvious importance of its droplet photochemistry to the atmospheric environment, there have not been any detailed studies of the ultrafast photochemical dynamics of nitrobenzene in aqueous solution. Here, we combine femtosecond transient absorption spectroscopy, time-resolved infrared spectroscopy, and quantum chemistry calculations to investigate the primary steps following the near-UV (λ ≥ 340 nm) photoexcitation of aqueous nitrobenzene. To understand the role of the surrounding water molecules in the photochemical dynamics of nitrobenzene, we compare the results of these investigations with analogous measurements in solutions of methanol, acetonitrile, and cyclohexane. We find that vibrational energy transfer to the aqueous environment quenches internal excitation, and therefore, unlike the gas phase, we do not observe any evidence for formation of photoproducts on timescales up to 500 ns. We also find that hydrogen bonding between nitrobenzene and surrounding water molecules slows the S1/S0 internal conversion process.

Interface self-assembly of plasmonic nanolayer for sensitive detection of heavy metals in water using NELIBS

Nowadays, high-stable and ultrasensitive heavy metal detection is of utmost importance in water quality monitoring. Nanoparticle-enhanced laser-induced breakdown spectroscopy (NELIBS) shows high potential in hazardous metal detection, however, encounters unstable and weak signals due to nonuniform distribution of analytes. Herein, we developed an interface self-assembly (ISA) method to create a uniformly distributed gold nanolayer at a liquid-liquid interface for positive heavy metal ions capture and NELIBS analysis. The electrostatically self-assembled Au nanoparticles (NPs)-analytes membrane was prepared at the oil-water interface by injecting ethanol into the mixture of cyclohexane and Au NPs-analytes water solution. Then, the interface self-assembled Au NPs-analytes membrane was transformed onto a laser-processed superhydrophilic Si slide for detection. Three heavy metals (cadmium (Cd), barium (Ba), and chromium (Cr)) were analyzed to evaluate the stability and sensitivity of the ISA method for NELIBS. The results (Cd: RSD ​= ​3.6 ​%, LoD ​= ​0.654 ​mg/L; Ba: RSD ​= ​3.4 ​%, LoD ​= ​0.236 ​mg/L; Cr: RSD ​= ​7.7 ​%, LoD ​= ​1.367 ​mg/L) demonstrated signal enhancement and high-stable and ultrasensitive detection. The actual sample detection (Cd: RE ​= ​7.71 ​%, Ba: RE ​= ​6.78 ​%) illustrated great reliability. The ISA method, creating a uniform distribution of NP-analytes at the interface, has promising prospects in NELIBS.

Hydrogen-Bonded Thiol Undergoes Unconventional Excited-State Intramolecular Proton-Transfer Reactions.

The chapter on the thiol-related hydrogen bond (H-bond) and its excited-state intramolecular proton-transfer (ESIPT) reaction was recently opened where compound 4'-diethylamino-3-mercaptoflavone (3NTF) undergoes ESIPT in both cyclohexane solution and solid, giving a 710 nm tautomer emission with an anomalously large Stokes shift of 12,230 cm-1. Considering the thiol H-bond to be unconventional compared to the conventional Pauling-type -OH or -NH H-bond, it is thus essential and timely to probe its fundamental difference between their ESIPT. However, thiol-associated ESIPT tends to be nonemissive due to the dominant nπ* character of the tautomeric lowest excited state. Herein, based on the 3-mercaptoflavone scaffold and π-elongation concept, a new series of 4'-substituted-7-diethylamino-3-mercaptoflavones, NTFs, was designed and synthesized with varied H-bond strength and 690-720 nm tautomeric emission upon ultraviolet (UV) excitation in cyclohexane. The order of their H-bonding strength was experimentally determined to be N-NTF < O-NTF < H-NTF < F-NTF, while the rate of -SH ESIPT measured by fluorescence upconversion was F-NTF (398 fs)-1 < H-NTF (232 fs)-1 < O-NTF (123 fs)-1 < N-NTF (101 fs)-1 in toluene. Unexpectedly, the strongest H-bonded F-NTF gives the slowest ESIPT, which does not conform to the traditional ESIPT model. The results are rationalized by the trend of carbonyl oxygen basicity rather than -SH acidity. Namely, the thiol acidity relevant to the H-bond strength plays a minor role in the driving force of ESIPT. Instead, the proton-accepting strength governs ESIPT. That is to say, the noncanonical thiol H-bonding system undergoes an unconventional type of ESIPT.

Validasi Metode Analisis Iodin Secara Spektrofotometri UV-Vis pada Dua Variasi Pelarut

In this study, the method of analysis of iodine by UV-Vis spectrophotometry was validated. Two other solvents, ethanol, and cyclohexane were used to validate this approach. The UV-Vis Spectrophotometer method's linearity, detection, and quantization limitations, precision, and accuracy were investigated as variables. The results of the linearity tests indicated that the method was proportionally verified because the r values for the two iodine solutions in ethanol and cyclohexane varied between 0.990 and 0.999, respectively. This suggests that the values were higher than 0.99. The LOD values for the ethanol solvent were 4.441 mg/kg and the LOQ was 14.802 mg/kg, whereas the cyclohexane solvent had an LOD value of 2.660 mg/kg and the LOQ was 8.866 mg/kg. According to the required precision acceptance, the %RSD value of 2%, precision values for both standard iodine solutions with two modifications of solvents demonstrated good results. Recovery percentages of ethanol solvents are 96% and cyclohexane solvents are 86%, respectively, according to accuracy measurements. The combined uncertainty value for this test is 0.109 for the ethanol solvent and 0.019 for the cyclohexane solvent, respectively. This research provides a comprehensive understanding of the validity of the iodine analysis method, establishing a robust foundation for the sustainability and reliability of using UV-Vis spectrophotometer in the analysis

Construction of Ketoenamine-Based Covalent Organic Frameworks with Electron-Rich Sites for Efficient and Rapid Removal of Iodine from Solution.

Porous covalent organic frameworks (COFs) have been widely used for the efficient removal of iodine from solution due to their abundance of electron-rich sites. In this study, two kinds of ketoenamine-based COFs, TpBD-(OMe)2 and TpBD-Me2, are successfully synthesized via Schiff base reaction under solvothermal conditions using 1, 3, 5-triformylphoroglucinol as aldehyde monomer, o-tolidine and o-dianisidine as amino monomers. The ability of TpBD-(OMe)2 and TpBD-Me2 to adsorb iodine in cyclohexane or aqueous solutions has been quantitatively analyzed and interpreted in terms of adsorption sites. TpBD-Me2 possesses two adsorption sites, -NH- and -C=O, and exhibits an adsorption capacity of 681.67 mg/g in cyclohexane, with an initial adsorption rate of 0.6 g/mol/min with respect to COF unit cell. The adsorption capacity of TpBD-(OMe)2 can be as high as 728.77 mg/g, and the initial adsorption rate of TpBD-(OMe)2 can reach 1.2 g/mol/min in the presence of oxygen atoms between the methyl group and the benzene ring. Compared with TpBD-Me2, the higher adsorption capacity and adsorption rate of TpBD-(OMe)2 towards iodine are not only reflected in organic solvents, but also in aqueous solutions. It is proven through X-ray photoelectron spectroscopy and Raman spectroscopy that iodine exists in the form of I2, I3-, and I5- within TpBD-(OMe)2 and TpBD-Me2 after adsorption. This work not only expands the application of COFs in the field of iodine adsorption, but also provides research ideas and important an experimental basis for the optimization of iodine adsorption sites.

Polyamide film containing a molecularly imprinted polymer prepared on a paper surface by interfacial polymerization and its selective adsorption of benzalkonium chloride

AbstractIn this study, paper coated with a polyamide film containing a molecularly imprinted polymer (MIP) of benzalkonium chloride (BKC) is prepared. Its BKC adsorption ability and selectivity for BKC adsorption are investigated. The MIP is prepared by agitating an ethylenediamine solution containing an azo initiator, BKC as a template material, and methacrylic acid (MAA) as the functional monomer. First, filter paper soaked in this mixture is impregnated with a cyclohexane solution of terephthaloyl chloride and a BKC–MAA–MIP‐containing polyamide film is prepared on the surface of the paper. Paper containing BKC–MAA–MIP adsorbs BKC. The paper with the highest BKC removal efficiency is prepared under the following conditions: 4 mL MAA functional monomer, 2.5 w/v% ethylenediamine, and 10 min MIP synthesis time. The paper with BKC–MAA–MIP selectively adsorbs BKC from a solution containing BKC, tetracycline hydrochloride, and caffeine. Thus, a polyamide film containing BKC‐MAA‐MIP formed on paper can effectively and selectively remove BKC from aqueous environments.

Preparation of phenolic hydroxyl-modified hyper-crosslinked polymers and their adsorption performance towards small molecular aromatic amines

Herein, three phenolic hydroxyl-modified hyper-crosslinked polymers were synthesized according to two-step Friedel-Crafts alkylation, and they were applied to adsorb small aromatic amines in aqueous and organic solvents. The first low-temperature Friedel-Crafts at 313 K introduced massive phenolic –OH to the intermediates, then the second high-temperature Friedel-Crafts at 353 K, also known as post-crosslinking reaction, brought a hyper-crosslinked skeleton composed of plentiful rigid methylene bridges to the target products, greatly enhancing the Brunauer-Emmett-Teller (BET) surface area (SBET) and total pore volume (Vtotal) of the polymers. In aqueous solution, the HCPS-BNAP-FDA had great potential for efficient adsorption of aniline and p-nitroaniline (p-NANL), and the Langmuir model predicted that their maximum capacities (qmax) were 209.25 mg/g and 277.30 mg/g, respectively. In cyclohexane solution, the qmax of aniline on HCPS-BNAP-FDA was predicted to be 202.38 mg/g. The removal aniline in aqueous solution could exceed 95 % when the original concentration was less than 200 mg/L, and the final concentration was 0.12 mg/L, much lower than the emission limit of China (GB 4287–2012, China). The polymer with 1,4-bis(chloromethyl)benzene (DCX) as crosslinking agent had the highest SBET (1282 m2/g) and the best adsorption performance for aniline (qmax, 258.73 mg/g). The adsorption mechanism demonstrated that the grafting of phenolic –OH groups improved the adsorption performance, as the possible hydrogen bonds and acid-base interactions. The micropores added via post-crosslinking also achieved a significant increase in adsorption capacity, that is, the pore filling adsorption mechanism.

Synthesis of electron-rich benzbisimidazole-containing amorphous poly(Schiff-base) networks for efficient iodine capture

In this work, two benzbisimidazole-containing amorphous poly(Schiff-base) networks (namely ATA-BA and ATA-BZ) are synthesized by reacting benzbisimidazole-containing aromatic tetra-aldehyde building block (ATA) with benzene-1,4-diamine and benzidine, respectively, under solvothermal conditions. The resultant ATA-BA and ATA-BZ networks possess the specific surface areas of 113 and 87 m2/g, respectively. Owing to the presence of abundant imine bond, alkyl-substituted imidazole ring, and extended π-conjugated system, ATA-BA network can effectively capture iodine in both vapor and solution phases with the capture capacities up to 5.29 g g−1 and 2343 mg g−1, respectively, although its specific surface area is not high. The exceptional iodine capture performance of ATA-BA network can be attributed to the strong charge-transfer interactions between imine bond/imidazole ring/π-conjugated system and iodine molecules, as demonstrated by spectroscopic analysis and density functional theory (DFT) calculations. In addition, the iodine capture by ATA-BA network in cyclohexane solution is systematically investigated. The experimental results indicate that the iodine adsorption kinetics and capture behavior obey pseudo-second-order model and Freundlich isotherm model, respectively.

Solution Self‐Assembly of Branched Macromolecules Obtained via Iterative OPE Synthesis and the Passerini Three‐Component Reaction

AbstractIn the last decade, isocyanide‐based multicomponent reactions, like the Passerini three‐component reaction (P‐3CR), have gained significant interest in the synthesis of sequence‐defined macromolecules due to their high efficiency and straightforward one‐pot procedures. The P‐3CR results in unique product structures that are particularly interesting for the synthesis of uniform, branched macromolecules, as they enable the direct introduction of a new branching point into the molecule. In this work, the synthesis of uniform first‐generation dendrons is performed via the P‐3CR using a divergent approach, utilizing three uniform and poorly soluble oligo(phenylene ethynylene)s (OPEs) of varying lengths as a focal moiety. Self‐assembly of the dendrons in cyclohexane solution is confirmed by fluorescence spectroscopy and diffusion‐ordered NMR (DOSY NMR) spectroscopy, highlighting the utility of DOSY NMR spectroscopy for the investigation of solution self‐assembly. Diffusion coefficients for the dendrons and their aggregates are determined and compared for different lengths of the OPE focal moiety. The successful synthesis of the dendrons in good yields and the selective branching introduced on the OPEs by the P‐3CR emphasize the high efficiency and synthetic advantages of multicomponent reactions for the preparation of uniform, branched macromolecules.

Selectivity of Diphenylacetylene Semi-Hydrogenation on Pt1Pd99/C Using PEM Electrolyzer

Introduction For carbon neutralization, organic synthesis should be electrified with renewable electricity besides energy synthesis. The Lindlar catalyst has been a common means for stereoselective Z-alkene synthesis from alkynes, which need hydrogen as a reactant and lead as an additive on the catalyst and has substrate limitation. By contrast, a proton exchange membrane (PEM) reactor is one of the alternative ways of Z-alkene formation, enabling the synthesis under mild conditions without lead use and substrate restriction, using renewable electricity and water instead of hydrogen.The previous research figured Pt1Pd99/C (at%) catalyst had the highest selectivity among various compositions of Pt-Pd catalysts for semi-hydrogenation of diphenylacetylene (DPA) to cis-stilbene. Pd sites selectively adsorb the DPA, while even a small amount of Pt sites quickly reduces protons to Had, which hydrogenate the DPA. The Pt1Pd99 catalyst indicated the best synergy effect of Pt and Pd.1,2) For an optimal PEM electrolyzer on a larger scale, its flow field structure and dimension must be decided with the selected electrocatalyst property. Therefore, a better understanding of the electrocatalyst activity is essential.In this study, we have investigated the relationship among catalyst loading, reactant flow rate, overall current density, and selectivity to understand the nature of the Pt1Pd99 catalyst. Experimental DSE® (De Nora Permelec Ltd) was used for the oxygen evolution as the anode and Nafion® 117 (DuPont) as the PEM, respectively. Carbon paper (39BB, SGL Carbon), loaded with 0.2–1.6 mg cm-2-precious metal of Pt1Pd99 (ISHIFUKU Metal Industry Co., Ltd.) and cut into 3.3 cm × 3.5 cm, was employed as the cathode. The cathode was hot-pressed on the PEM at 120 ℃, 3 MPa, for 3 min to make a membrane cathode assembly. In the anode compartments, 1 M (= mol dm-3) sulfuric acid circulated, and 1 M cyclohexane solution of DPA in the cathode compartments.As electrochemical measurements, electrochemical impedance spectroscopy at 100 kHz–0.1 Hz with an amplitude of 10 mV, chronoamperometry at 1.3–2.0 V for catalyst loading dependency experiments, chronopotentiometry at 9–36 mA cm-2 for flow rate dependency were conducted. The concentrations of cis-Stilbene and dibenzyl in electrolytes were quantified with high-performance liquid chromatography (HPLC) after collection during the last 2 min out of 5 min of electrolysis at 60 ℃. Each partial current was derived by the multiplications of each concentration, the stoichiometric coefficient of electrons (2 for cis-stilbene and 4 for dibenzyl), the Faraday constant, and the flow rate. Results and Discussion Figure 1 shows anode and cathode potentials as functions of current density. The anode potential was stable around 1.6 V vs. RHE, while the cathode potential appeared to get higher with more catalyst loading, considering the variation of the anode potential.Figures 2 and 3 show the current efficiencies of cis-stilbene and dibenzyl as functions of cathode potential. The current efficiency of cis-stilbene decreased with the cathode potential increase, while that of dibenzyl increased and peaked at approximately -0.2 V vs. RHE, where cis-stilbene current efficiency steeply dropped.Figures 4 and 5 show both current efficiencies at various cathode potentials as functions of the catalyst loading. The current efficiency of cis-stilbene decreased with the catalyst loading increase, while that of dibenzyl increased. Both absolute values of the slopes of Figs. 4 and 5 are the highest at -0.2 V vs. RHE, where over-hydrogenation to dibenzyl overwhelmed cis-stilbene formation. Since at a more negative potential, reducing current was almost consumed by hydrogen evolution, the effect of the catalyst layer thickness on the selectivity was maximum here.The current efficiencies of cis-stilbene and dibenzyl and the selectivity at various flow rates are shown in Figure 6. As the flow rate rose, the current efficiency and selectivity of cis-stilbene increased.With a thin catalyst layer, the substrate quickly moved away from the reaction field, and the same happened at a high flow rate. Therefore, produced cis-stilbene is less over-hydrogenated, and the selectivity increased.According to these results, since the reaction of cis-stilbene formation is quick, speedy product elimination would be the key to further selectivity improvement. Acknowledgment This work was financially supported by CREST (JST Grant 18070940). The authors are grateful to ISHIFUKU Metal Industry Co., Ltd. for providing the cathode catalysts. References 1) S, Nogami, K. Nagasawa, A. Fukazawa, K. Tanaka, S. Mitsushima, M. Atobe, J. Electrochem. Soc., 167, 155506 (2020).2) S. Nogami, N. Shida, S. Iguchi, K. Nagasawa, H. Inoue, I. Yamanaka, S. Mitsushima, M. Atobe, ACS Catal., 12, 5430 (2022). Figure 1