Reconstruction and Solidification of Dion-Jacobson Perovskite Top and Buried Interfaces for Efficient and Stable Solar Cells.

Quasi-two-dimensional (Q-2D) perovskites show great potential in the field of photonic and optoelectronic device applications. However, defects and local lattice dislocation still limit performance and stability improvement by nonradiative recombination, unpreferred phase distribution, and unbonded amines. Here, a low-temperature synergistic strategy for both reconstructing and solidifying the perovskite top and buried interface is developed. By post-treating the 1,4-phenylenedimethanammonium (PDMA) based (PDMA)MA4Pb5I16 films with cesium acetate (CsAc) before thermal annealing, a condensation reaction between R-COO- and -NH2 and ion exchange between Cs+ and MA+ occur. It converts the unbonded amines to amides and passivates uncoordinated Pb2+. Meanwhile, it adjusts film composition and improves the phase distribution without changing the out-of-plane grain orientation. Consequently, performance of 18.1% and much-enhanced stability (e.g., stability for photo-oxygen increased over 10 times, light-thermal for T90 over 4 times, and reverse bias over 3 times) of (PDMA)MA4Pb5I16 perovskite solar cells are demonstrated.

Synthesis and antibacterial evaluation of (5Z)-5-[(2-piperidinequinoline-3-yl)methyl]-2-chloroquinoline derivatives: Docking study on substituted N-alkylation and binding mechanisms with E. Coli PDF enzyme.

A number of new substances were included into the (5Z)-5-[(2-piperidinequinoline-3-yl)methyl]-2-chloroquinoline structural framework. The condensation process 2-chloroquinoline, which served as a crucial reagent in the reaction with 3-carbaldehydes to produce 2,4-thiazolidinedione, allowed for the production of 1,3-thiazolidine-2,4-dione. The newly developed substances were described by means of their reactions with halide compounds, particularly those pertaining to substituted N-alkylation. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), and proton nuclear magnetic resonance spectroscopy (1H NMR) were used to identify the chemical. Furthermore, the antibacterial activity of the produced compounds was evaluated in vitro against a range of pathogens, including Bacillus subtilis, and Escherichia coli. Moreover, docking experiments were conducted using the PDF enzyme of E. coli to improve our understanding of the binding mechanism between the synthesized 5(A-N) compounds and the enzyme.

Targeted delivery of activatable 131I-radiopharmaceutical for sustained radiotherapy with improved pharmacokinetics.

Targeted radionuclide therapy (TRT) is an effective treatment for tumors. Self-condensation strategies can enhance the retention of radionuclides in tumors and enhance the anti-tumor effect. Considering legumain is overexpressed in multiple types of human cancers, a 131I-labeled radiopharmaceutical ([131I]MAAN) based on the self-condensation reaction between 2-cyanobenzothiazole (CBT) and cysteine (Cys) was developed by us recently for treating legumain-overexpressed tumors. However, liver enrichment limits its application. In this study, a new radiopharmaceutical [131I]IM(HE)3AAN was designed and synthesized by introducing a hydrophilic peptide sequence His-Glu-His-Glu-His-Glu ((HE)3) into [131I]MAAN to optimize the pharmacokinetics. Upon activation by legumain under a reducing environment, hydrophilic [131I]IM(HE)3AAN could react with its precursor to form heterologous dimer [131I]H-Dimer that is highly hydrophobic. Cerenkov imaging revealed that [131I]IM(HE)3AAN displayed superior tumor selectivity and longer tumor retention time as compared with [131I]MAAN, with a significant reduction in the liver uptake. After an 18-day treatment with [131I]IM(HE)3AAN, the tumor proliferation was obviously inhibited, while no obvious injury was observed in the normal organs. These findings suggest that [131I]IM(HE)3AAN could serve as a promising drug candidate for treating legumain-overexpressed tumors.

Molybdenum iron carbide-copper hybrid as efficient electrooxidation catalyst for oxygen evolution reaction and synthesis of cinnamaldehyde/benzalacetone.

Oxygen evolution reaction (OER) is the efficiency limiting half-reaction in water electrolysis for green hydrogen production due to the 4-electron multistep process with sluggish kinetics. The electrooxidation of thermodynamically more favorable organics accompanied by CC coupling is a promising way to synthesize value-added chemicals instead of OER. Efficient catalyst is of paramount importance to fulfill such a goal. Herein, a molybdenum iron carbide-copper hybrid (Mo2C-FeCu) was designed as anodic catalyst, which demonstrated decent OER catalytic capability with low overpotential of 238 mV at response current density of 10 mA cm-2 and fine stability. More importantly, the Mo2C-FeCu enabled electrooxidation assisted aldol condensation of phenylcarbinol with α-H containing alcohol/ketone in weak alkali electrolyte to selective synthesize cinnamaldehyde/benzalacetone at reduced potential. The hydroxyl and superoxide intermediate radicals generated at high potential are deemed to be responsible for the electrooxidation of phenylcarbinol and aldol condensation reactions to afford cinnamaldehyde/benzalacetone. The current work showcases an electrochemical-chemical combined CC coupling reaction to prepare organic chemicals, we believe more widespread organics can be synthesized by tailored electrochemical reactions.

Eu3+ doped ethylenediamine functionalized UiO-66 probe for fluorescence sensing of formaldehyde.

The development of probes with selectivity and prompt detection of aldehydes molecules is of great importance for protecting human health and public security. Herein, a system based on ethylenediamine (EDA) functionalized and Eu3+-doped UiO-66, namely EDA-Eu3+@UiO-66, was designed to detect formaldehyde molecules. Based on the "antenna effect" of lanthanide elements, UiO-66 transfers the absorbed energy to Eu3+ ions and emits characteristic fluorescence belonging to Eu3+. By using the fluorescence peaks of UiO-66 and Eu3+ respectively, a ratiometric fluorescence sensing probe can be constructed. Formaldehyde molecules react with the -NH2 on the surface of EDA-Eu3+@UiO-66 through an aldehyde-amine condensation reaction and connect to the functionalized surface of UiO-66. Due to the absorption of excitation light energy by formaldehyde molecules, the energy transfer efficiency from UiO-66 to Eu3+ ions is reduced, resulting in the fluorescence quenching of EDA-Eu3+@UiO-66, thus achieving selective detection of formaldehyde. The fabricated sensing platform successfully detected residual formaldehyde in frozen shrimp tail samples. The system was also used to respond to formaldehyde vapor, and a significant fluorescence quenching effect was observed. This strategy provides a sensitive, selective, and reliable method for the visual sensing of formaldehyde.

Titanium Tetrachloride-Assisted Direct Esterification of Carboxylic Acids.

Ester compounds, widely found in pharmaceutical and natural products, play a crucial role in organic synthesis, prompting the development of numerous methods for their synthesis. An important chemical approach in synthesizing esters from carboxylic acids involves the activation of the carboxyl function, requiring the conversion of the hydroxyl group into a suitable leaving group. This paper presents the findings of our investigations into an efficient method for producing esters from carboxylic acids and alcohols, using the Lewis acid titanium tetrachloride. Titanium tetrachloride has proven highly effective as a coupling reagent for the one-pot formation of esters from carboxylic acids and alcohols operating under mild and neutral conditions. Notably, the reaction eliminates the need for bases, yielding carboxylic esters in high purity and yields. The method is efficient, even with long-chain carboxylic acids, and operates well with primary alcohols in dichloromethane. Steric hindrance, potentially present in carboxylic acids, has a moderate effect on the reaction. Alcohol substrates that easily form stable carbocations require, instead, the use of non-polar solvents like hexane for the reaction.

Water-Tolerant Superbase Polyoxometalate [H2(Nb6O19)]6- for Homogeneous Catalysis.

Here, doubly protonated Lindqvist-type niobium oxide cluster [H2(Nb6O19)]6-, fabricated by microwave-assisted hydrothermal synthesis, exhibited superbase catalysis for Knoevenagel and crossed aldol condensation reactions accompanied by activating C-H bond with pKa >26 and proton abstraction from a base indicator with pKa=26.5. Surprisingly, [H2(Nb6O19)]6- exhibited water-tolerant superbase properties for Knoevenagel and crossed aldol condensation reactions in the presence of water, although it is well known that the strong basicity of metal oxides and organic superbase is typically lost by the adsorption of water. Density functional theory calculation revealed that the basic surface oxygens that share the corner of NbO6 units in [H2(Nb6O19)]8- maintained the negative charges even after proton adsorption. This proton capacity and the presence of un-protonated basic sites led to the water tolerance of the superbase catalysis.

Strategic Design and Synthesis of Ferrocene Linked Porous Organic Frameworks toward Tunable CO2 Capture and Energy Storage.

This work focuses on porous organic polymers (POPs), which have gained significant global attention for their potential in energy storage and carbon dioxide (CO2) capture. The study introduces the development of two novel porous organic polymers, namely FEC-Mel and FEC-PBDT POPs, constructed using a simple method based on the ferrocene unit (FEC) combined with melamine (Mel) and 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (PBDT). The synthesis involved the condensation reaction between ferrocenecarboxaldehyde monomer (FEC-CHO) and the respective aryl amines. Several analytical methods were employed to investigate the physical characteristics, chemical structure, morphology, and potential applications of these porous materials. Through thermogravimetric analysis (TGA), it was observed that both FEC-Mel and FEC-PBDT POPs exhibited exceptional thermal stability. FEC-Mel POP displayed a higher surface area and porosity, measuring 556 m2 g-1 and 1.26 cm3 g-1, respectively. These FEC-POPs possess large surface areas, making them promising materials for applications such as supercapacitor (SC) electrodes and gas adsorption. With 82 F g-1 of specific capacitance at 0.5 A g-1, the FEC-PBDT POP electrode has exceptional electrochemical characteristics. In addition, the FEC-Mel POP showed remarkable CO2 absorption capabilities, with 1.34 and 1.75 mmol g-1 (determined at 298 and 273 K; respectively). The potential of the FEC-POPs created in this work for CO2 capacity and electrical testing are highlighted by these results.

Carbonized Aminal-Linked Porous Organic Polymers Containing Pyrene and Triazine Units for Gas Uptake and Energy Storage.

Porous organic polymers (POPs) have plenteous exciting features due to their attractive combination of microporosity with π-conjugation. Nevertheless, electrodes based on their pristine forms suffer from severe poverty of electrical conductivity, precluding their employment within electrochemical appliances. The electrical conductivity of POPs may be significantly improved and their porosity properties could be further customized by direct carbonization. In this study, we successfully prepared a microporous carbon material (Py-PDT POP-600) by the carbonization of Py-PDT POP, which was designed using a condensation reaction between 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (PDA-4NH2) and 4,4',4'',4'''-(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde (Py-Ph-4CHO) in the presence of dimethyl sulfoxide (DMSO) as a solvent. The obtained Py-PDT POP-600 with a high nitrogen content had a high surface area (up to 314 m2 g-1), high pore volume, and good thermal stability based on N2 adsorption/desorption data and a thermogravimetric analysis (TGA). Owing to the good surface area, the as-prepared Py-PDT POP-600 showed excellent performance in CO2 uptake (2.7 mmol g-1 at 298 K) and a high specific capacitance of 550 F g-1 at 0.5 A g-1 compared with the pristine Py-PDT POP (0.24 mmol g-1 and 28 F g-1).

Efficient Synthesis of Imine-Carboxylic Acid Functionalized Compounds: Single Crystal, Hirshfeld Surface and Quantum Chemical Exploration.

Two aminobenzoic acid based crystalline imines (HMBA and DHBA) were synthesized through a condensation reaction of 4-aminobenzoic acid and substituted benzaldehydes. Single-crystal X-ray diffraction was employed for the determination of structures of prepared Schiff bases. The stability of super molecular structures of both molecules was achieved by intramolecular H-bonding accompanied by strong, as well as comparatively weak, intermolecular attractive forces. The comparative analysis of the non-covalent forces in HMBA and DHBA was performed by Hirshfeld surface analysis and an interaction energy study between the molecular pairs. Along with the synthesis, quantum chemical calculations were also accomplished at M06/6-311G (d, p) functional of density functional theory (DFT). The frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), natural bond orbitals (NBOs), global reactivity parameters (GRPs) and natural population (NPA) analyses were also carried out. The findings of FMOs found that Egap for HMBA was examined to be smaller (3.477 eV) than that of DHBA (3.7933 eV), which indicated a greater charge transference rate in HMBA. Further, the NBO analysis showed the efficient intramolecular charge transfer (ICT), as studied by Hirshfeld surface analysis.

A combined surface-enhanced Raman spectroscopy (SERS)/colorimetric approach for the sensitive detection of malondialdehyde in biological samples.

Variations of malondialdehyde (MDA) level in biological samples often induce pathological changes, which is associated with various diseases. Here, we developed a combined surface-enhanced Raman spectroscopy (SERS) and colorimetric strategy for MDA quantitation. The methodology is based on the condensation reaction between 4-aminothiophenol (4-ATP)-modified Au nanoflowers (Au NFs) with the aldehyde groups of MDA, which causes the aggregation of the Au NFs and a concomitant change in the solution color from purple to blue and shifts in the local surface plasmon resonance band to longer wavelengths compared with monodisperse NFs. Additionally, after the condensation reaction, a new Raman peak ascribable to the CN vibration appeared at 1630 cm-1. The intensity of this peak was directly related to the concentration of MDA in solution, which allowed establishing the quantitative measurement of MDA based on SERS. The developed SERS assay displayed satisfactory sensitivity and selectivity with a broad linear range from 1.0 × 10-12 to 1.0 × 10-7 M and a low detection limit (∼3.6 × 10-13 M), outperforming other reported optical and electrochemical methods. Furthermore, the use of 4-ATP-modified Au NF probes to monitor MDA in human serum demonstrates the applicability of this combined SERS/colorimetric approach in a real environment.

Low-Temperature Thermal Formation of the Cyclic Methylphosphonic Acid Trimer [c-(CH3 PO2 )3 ].

We report the formation of the cyclic methylphosphonic acid trimer [c-(CH3 PO2 )3 ] through condensation reactions during thermal processing of low-temperature methylphosphonic acid samples exploiting photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) along with electronic structure calculations. Cyclic methylphosphonic acid trimers are formed in the solid state and detected together with its protonated species in the gas phase upon single photon ionization. Our studies provide an understanding of the preparation of phosphorus-bearing potentially prebiotic molecules and the fundamental knowledge of low-temperature phosphorus chemistry in extraterrestrial environments.

Kinetics of anthocyanin condensation reaction in model wine solution under pulsed light treatment.

The effects of Pulsed Light (PL) technology on the anthocyanin condensation reaction in model wine solutions were investigated. Model wine solutions containing malvidin-3-O-glucoside, cyanidin-3-O-glucoside, and delphinidin-3-O-glucoside were separately prepared with the presence of (-)-epicatechin and acetaldehyde. The solutions were subjected to PL treatment with 2, 4, and 8 J/cm2 energy and stored in 10 °C. The loss of anthocyanin during the treatment and the aging period fitted the first-order reaction model (R2 > 98 %). Delphinidin-3-O-glucoside suffered the highest loss, only 46 % remaining after 60 s treatment; the malvidin-3-O-glucoside showed the lower loss, 72 % remaining after 60 s treatment. Furthermore, the PL treatment significantly influenced the kinetics of anthocyanin loss. The results from LC ESI TOF/Q-TOF MS/MS analysis revealed that in the PL treated samples, more peaks eluted in the chromatogram assigned to anthocyanin ethyl-linked (-)-epicatechin products, suggesting that PL treatment led to the formation of new isomers of anthocyanin ethyl-linked (-)-epicatechin. The color characteristics of the model solutions were affected by the PL treatment and the formation of ethyl-linked products. For example, the ΔE* value for samples treated with 8 J/cm2 increased by 42.52, 55.73, and 45.61 % for malvidin-3-O-glucoside, cyanidin-3-O-glucoside, and delphinidin-3-O-glucoside respectively after 110 days.

Scope and limitations of the preparation of xanthones using Eaton's reagent.

Xanthones comprise a large family of heterocycles displaying fascinating biological properties. Many synthetic protocols have been developed for the preparation of natural and nonnatural xanthone derivatives. Among them, condensation reactions between salicylic acid derivatives and phenol partners are highly desirable. Those reactions can be satisfactorily performed using Eaton's reagent (P2O5 in CH3SO3H). Despite being highly effective with a variety of substrates, this approach presents limitations that depend on the electronic nature of the reaction precursors. The scope and limitations of the Eaton's reagent-mediated preparation of xanthones are herein presented and discussed. In short, this approach is limited to the utilization of very electron-rich phenol substrates (like phloroglucinol compounds), or to electron-rich phenol precursors (like resorcinol derivatives) via the isolation of benzophenone intermediates in this latter case. Electron-poor phenols are not amenable to this transformation with Eaton's reagent.

Mechanism-based cross-linking probes capture the Escherichia coli ketosynthase FabB in conformationally distinct catalytic states.

Ketosynthases (KSs) catalyse essential carbon-carbon bond-forming reactions in fatty-acid biosynthesis using a two-step, ping-pong reaction mechanism. In Escherichia coli, there are two homodimeric elongating KSs, FabB and FabF, which possess overlapping substrate selectivity. However, FabB is essential for the biosynthesis of the unsaturated fatty acids (UFAs) required for cell survival in the absence of exogenous UFAs. Additionally, FabB has reduced activity towards substrates longer than 12 C atoms, whereas FabF efficiently catalyses the elongation of saturated C14 and unsaturated C16:1 acyl-acyl carrier protein (ACP) complexes. In this study, two cross-linked crystal structures of FabB in complex with ACPs functionalized with long-chain fatty-acid cross-linking probes that approximate catalytic steps were solved. Both homodimeric structures possess asymmetric substrate-binding pockets suggestive of cooperative relationships between the two FabB monomers when engaged with C14 and C16 acyl chains. In addition, these structures capture an unusual rotamer of the active-site gating residue, Phe392, which is potentially representative of the catalytic state prior to substrate release. These structures demonstrate the utility of mechanism-based cross-linking methods to capture and elucidate conformational transitions accompanying KS-mediated catalysis at near-atomic resolution.

Direct anabolic metabolism of three-carbon propionate to a six-carbon metabolite occurs in vivo across tissues and species.

Anabolic metabolism of carbon in mammals is mediated via the one- and two-carbon carriers S-adenosyl methionine and acetyl-coenzyme A. In contrast, anabolic metabolism of three-carbon units via propionate has not been shown to extensively occur. Mammals are primarily thought to oxidize the three-carbon short chain fatty acid propionate by shunting propionyl-CoA to succinyl-CoA for entry into the TCA cycle. Here, we found that this may not be absolute as, in mammals, one nonoxidative fate of propionyl-CoA is to condense to two three-carbon units into a six-carbon trans-2-methyl-2-pentenoyl-CoA (2M2PE-CoA). We confirmed this reaction pathway using purified protein extracts provided limited substrates and verified the product via LC-MS using a synthetic standard. In whole-body in vivo stable isotope tracing following infusion of 13C-labeled valine at steady state, 2M2PE-CoA was found to form via propionyl-CoA in multiple murine tissues, including heart, kidney, and to a lesser degree, in brown adipose tissue, liver, and tibialis anterior muscle. Using ex vivo isotope tracing, we found that 2M2PE-CoA also formed in human myocardial tissue incubated with propionate to a limited extent. While the complete enzymology of this pathway remains to be elucidated, these results confirm the in vivo existence of at least one anabolic three- to six-carbon reaction conserved in humans and mice that utilizes propionate.

Mycobacterium smegmatis acyltransferase: The big new player in biocatalysis.

After several decades during which proteases and after lipases took the biotransformation world scene as the predominant biocatalysts, a new, promising enzyme was discovered and characterized. The acyltransferase from Mycobacterium smegmatis (MsAcT) has in fact an extraordinary activity for a wide array of reactions, such as trans-esterification, amidation, trans-amidation and perhydrolysis, both in water and solvent media, giving rise to a series of interesting compounds including APIs (i.e., active pharmaceutical ingredients), natural flavors and fragrances, monomers for polymer synthesis, and peracids employed as disinfectants or antimicrobials. Although the most used acylating agent has been ethyl acetate (EtOAc), depending on the reaction type also acetamide, dimethyl carbonate and a variety of other esters, have been reported. The best yields were reached using very reactive donors such as vinyl or isopropenyl esters (almost complete conversion in rapid reaction times and water media for condensation reactions). In this review article the most innovative scientific advances on MsAcT, its mechanism and engineering are summarized, putting a particular focus on the different kind of processes (batch and flow) that it is possible to carry out using this enzyme as free or immobilized form. In conclusion, the author personal view on the unexplored reaction possibilities using MsAcT is reported as a window on the future of the topic.

Effective solid-phase extraction of chlorophenols with covalent organic framework material as adsorbent.

In this work, a porous extended network covalent organic framework designated as TP-NDA-COF was synthesized by the reaction of 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (TP) and 1,5-naphthalenediamine (NDA). The structure and morphology of the TP-NDA-COF was characterized by means of Fourier transform infrared spectra (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The TP-NDA-COF was applied as a solid-phase extraction adsorbent for the extraction of some chlorophenols from water and lemon black tea beverage samples prior to high performance liquid chromatography-UV detection. The main experimental parameters that affect the extraction efficiency including the type and volume of eluent, sample solution volume, sample loading rate and sample solution pH were investigated. Under the optimal conditions, the calibration curves were linear in the range of 0.30-60.0 ng mL-1 with the determination coefficients (R2) of 0.9996-0.9998 for water samples and in the range of 0.60-60.0 ng mL-1 with the R2 values from 0.9990 to 0.9996 for beverage samples. At the signal to noise ratio of 3 (S/N = 3), the method LODs for the analytes were 0.10-0.15 ng mL-1 for water samples and 0.20-0.50 ng mL-1 for lemon black tea beverage, respectively. Good repeatability was achieved with the relative standard deviations of less than 7%. The results showed that the SPE-HPLC method can be used for the determination of chlorophenols in environmental water and foodstuffs samples.

Claisen Condensation Reaction Mediated Pimelate Biosynthesis via the Reverse Adipate-Degradation Pathway and Its Isoenzymes.

Pimelic acid is an important seven-carbon dicarboxylic acid, which is broadly applied in various fields. The industrial production of pimelic acid is mainly through a chemical method, which is complicated and environmentally unfriendly. Herein, we found that pimelic acid could be biosynthesized by the reverse adipate-degradation pathway (RADP), a typical Claisen condensation reaction that could be applied to the arrangement of C-C bond. In order to strengthen the supply of glutaryl-CoA precursor, PA5530 protein was used to transport glutaric acid. Subsequently, we discovered that the enzymes in the BIOZ pathway are isoenzyme of the RADP pathway enzymes. By combining the isoenzymes of the two pathways, the titer of pimelic acid reached 36.7 mg ⋅ L-1 under the optimal combination, which was increased by 382.9 % compared with the control strain B-3. It was also the highest titer of pimelic acid biosynthesized by Claisen condensation reaction, laying the foundation for the production of pimelic acid and its derivatives.

Complex formation of lactic acid by atmospheric pressure chemical ionization.

Oligomers and polymers of lactic acid are generally synthesized through condensation reactions by dehydration at high emperature under catalysis. In the present work, ionization behaviors of lactic acid produced by atmospheric pressure chemical ionization were investigated. Influence of the sample concentration, the heating zone temperature, and the source fragmentor voltage on kinds and abundances of the product ions was examined. Complex formation of the product ions with neutral species was also investigated. Not only lactate, [M-H]- and its complexes but also ions of condended species, [nM-(n-1)H2 O-H]- with n = 2-5, and their complexes were observed. The condensation reactions occurred in an aerosol state generated in the heating zone for evaporation. By increasing the concentration of lactic acid, abundances of the product ions were increased and the increase of larger ones was noticeable. By increasing the heating zone temperature, abundances of the product ions were decreased and the decrease of larger ones was remarkable. By increasing the source fragmentor voltage, abundances of small product ions were increased and those of the complexes, [nM-(n-2)H2 O-H]- with n = 2-5, were significantly decreased. Complex formation of lactate with the neutral condensed species was more favorable than that of the condensed oligomer ions with a neutral lactic acid. The experimental results were explained by energies and structures of the product ions and neutral species obtained by theoretical calculations.