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Synthetic chemistry plays an indispensable role in drug discovery, contributing to hit compounds identification, lead compounds optimization, candidate drugs preparation, and so on. As Nobel Prize laureate James Black emphasized, "the most fruitful basis for the discovery of a new drug is to start with an old drug"1. Late-stage modification or functionalization of drugs, natural products and bioactive compounds have garnered significant interest due to its ability to introduce diverse elements into bioactive compounds promptly. Such modifications alter the chemical space and physiochemical properties of these compounds, ultimately influencing their potency and druggability. To enrich a toolbox of chemical modification methods for drug discovery, this review focuses on the incorporation of halogen, oxygen, and nitrogen—the ubiquitous elements in pharmacophore components of the marketed drugs—through late-stage modification in recent two decades, and discusses the state and challenges faced in these fields. We also emphasize that increasing cooperation between chemists and pharmacists may be conducive to the rapid discovery of new activities of the functionalized molecules. Ultimately, we hope this review would serve as a valuable resource, facilitating the application of late-stage modification in the construction of novel molecules and inspiring innovative concepts for designing and building new drugs. This article reviews the recent strategies applied to late-stage modification of bioactive compounds and tries to provide a toolbox for efficient molecule generation in drug discovery. [Display omitted] [ABSTRACT FROM AUTHOR]

Flavin-dependent monooxygenases (FDMOs) are known for their remarkable versatility and for their crucial roles in various biological processes and applications. Extensive research has been conducted to explore the structural and functional relationships of FDMOs. The majority of reported FDMOs utilize C4a-(hydro)peroxyflavin as a reactive intermediate to incorporate an oxygen atom into a wide range of compounds. This review discusses and analyzes recent advancements in our understanding of the structural and mechanistic features governing the enzyme functions. State-of-the-art discoveries related to common and distinct structural properties governing the catalytic versatility of the C4a-(hydro)peroxyflavin intermediate in selected FDMOs are discussed. Specifically, mechanisms of hydroxylation, dehalogenation, halogenation, and light-emitting reactions by FDMOs are highlighted. We also provide new analysis based on the structural and mechanistic features of these enzymes to gain insights into how the same intermediate can be harnessed to perform a wide variety of reactions. Challenging questions to obtain further breakthroughs in the understanding of FDMOs are also proposed. [ABSTRACT FROM AUTHOR]

Oxyhalide glasses are utilized in the process of immobilizing nuclear waste and function as scintillating agents for the purpose of radiation detection. The objective of this study is to examine the enhanced mechanical and radiation attenuation characteristics of newly developed oxyhalide glasses by incorporating zinc-iodide. This study investigates the synthesis process, mechanical properties, and experimental gamma-neutron radiation transmission properties. A halogen-free base glass, consisting of an oxide mixture of P 2 O 5 , TeO 2 , and ZnO, was synthesized. Following that, the initial glass composition was further strengthened by the addition of zinc bromide (ZnBr 2), zinc chloride (ZnCl 2), zinc fluoride (ZnF 2), and zinc iodide (ZnI 2) in a successive manner. The experimental configuration entailed positioning circular glass samples between a 133Ba radioisotope and a Canberra High Purity Germanium (HPGe) detector. The determination of attenuation coefficients is achieved through the measurement of individual attenuation properties. Afterwards, theoretical approaches are utilized to determine the mechanical characteristics of halogenated glasses, including Young's modulus (Y), Bulk modulus (K), Shear modulus (G), Longitudinal modulus (L), and Poisson's modulus (v). The results of the study suggest that the implementation of the halogenation process on the P 2 O 5 –TeO 2 –ZnO base composition led to a significant enhancement in the examined properties. The incorporation of zinc-iodide in the halogenation process resulted in a significant improvement in the gamma absorption properties. The utilization of zinc in the halogenation process demonstrates multifunctional capabilities, which involve the potential to enhance various glass properties, including durability and gamma-ray absorption properties. It can be concluded that zinc-iodide demonstrates enhanced halogenation capabilities in comparison to zinc bromide, zinc chloride, and zinc fluoride. [ABSTRACT FROM AUTHOR]

[Display omitted] The present study explores the synthesis of new potential Cereblon ligands, 2-amino derivatives of (thio)morpholine-3,5-diones. The resulting compounds demonstrate notable cytotoxic effects in tests conducted in vitro on myeloma cell lines, highlighting the potential of these compounds as molecular glues. [ABSTRACT FROM AUTHOR]

Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity. Previous structure‒activity relationships indicated that triple halogenated depsidones display the best anti-pathogenic activity. However, the gene cluster and the tailoring steps responsible for halogenated depsidone nornidulin (3) remain enigmatic. In this study, we disclosed the complete biosynthetic pathway of the halogenated depsidone through in vivo gene disruption, heterologous expression and in vitro biochemical experiments. We demonstrated an unusual depside skeleton biosynthesis process mediated by both highly-reducing polyketide synthase and non-reducing polyketide synthase, which is distinct from the common depside skeleton biosynthesis. This skeleton was subsequently modified by two in-cluster enzymes DepG and DepF for the ether bond formation and decarboxylation, respectively. In addition, the decarboxylase DepF exhibited substrate promiscuity for different scaffold substrates. Finally, and interestingly, we discovered a halogenase encoded remotely from the biosynthetic gene cluster, which catalyzes triple-halogenation to produce the active end product nornidulin (3). These discoveries provide new insights for further understanding the biosynthesis of depsidones and their derivatives. A new and concise biosynthetic pathway of nornidulin (3) was elucidated. The depside skeleton 2 is synthesized by a collaborating hrPKS and nrPKS pair, followed by etherification, decarboxylation and halogenation. [Display omitted] [ABSTRACT FROM AUTHOR]

The worldwide detection of emerging transformation products of organic micropollutants has raised accumulating concerns owing to their unknown environmental fate and undesired toxicity. This work first explored the reaction kinetics and mechanisms of the prevalent N-acetylated sulfonamides (N4-AcSAs, the typical sulfonamide metabolites) from wastewater disinfection to solar-irradiated receiving waters. The transformation scenarios included chlorination/bromination, photodegradation, and solar/chlorine treatment. The halogenations of two N4-AcSAs (N4-acetylated sulfadiazine, N4-AcSDZ; N4-acetylated sulfamethoxazole, N4-AcSMX) were pH-dependent at pH 5.0–8.0, and the reactions between the neutral forms of oxidants and anionic N4-AcSAs dominated the process. Furthermore, solar-based photolysis significantly eliminated N4-AcSAs in small water bodies with low dissolved organic carbon levels, while the indirect photolysis mediated by hydroxyl radicals and carbonate radicals contributed the most. The presence of chlorine residues in solar-irradiated wastewater effluents promoted the decay of N4-AcSAs, in which the generated hydroxyl radicals and ozone played a major role. Product analysis suggested the main transformation patterns of N4-AcSAs during the above scenarios included electrophilic attack, bond cleavage, SO 2 extrusion, hydroxylation, and rearrangement. Multiple secondary products maintained higher persistence, mobility, and toxicity to aquatic organisms than N4-AcSAs. Overall, the natural and engineered transformations of such micropollutants underlined the necessity of including their degradation products in future chemical management and risk assessment. [Display omitted] ● Chlorination and bromination kinetics of N4-AcSAs were determined. ● Indirect photolysis mediated by •OH/CO 3 •- exhibited high environmental importance. ● Modeling indicated the photostability of N4-AcSAs in natural waters (up to 160 days). ● Contributions of •OH/O 3 were dominant during solar/chlorine treatment. ● Transformation products possessed similar or higher PMT properties. [ABSTRACT FROM AUTHOR]

The electrochemical CO 2 reduction reaction (CO 2 RR) has attracted significant attention as strategy for achieving carbon neutrality. Among the candidate materials for the CO 2 RR, Cu-based electrocatalysts can potentially produce various high-value carbon products. However, the diversity of their products obtained via CO 2 RR induces low selectivity and hinders the acquisition of a specific product with a high yield. Herein, we suggest the strategies for enhancing ethylene production via CO 2 RR by reconstructing the oxidation states of the Cu-based catalysts. The introduced chemical oxidation and following halogenation contributes to modulate the electron structures and oxidation states of the electrodeposited polygonal Cu catalyst surface. In particular, the chemical oxidation step induces the coexistence of Cu0 and Cu+ on the catalyst surface which stabilize the CO 2 adsorption onto the catalyst surface, and the halogenation maintains the Cu0/Cu+ ratio of the catalyst surface during the CO 2 RR. As a result, controlling the oxidation states of Cu-based catalyst improves the ethylene production selectivity up to 47.0 % of Faradaic efficiency. Furthermore, we employ a membrane electrode assembly-based electrolyzer for CO 2 RR which is used for commercialization, and achieve high ethylene production with a partial current density of 124.7 mA cm–2. [Display omitted] • Hexagonal Cu catalyst was fabricated by simple electrodeposition. • Chemical oxidation and halogenation modulated the oxidation states of Cu catalyst. • Cu0/Cu+ ratio of Cu catalyst was well maintained during the CO 2 electrolysis. • Optimized Cu catalyst exhibited 47 % of ethylene production selectivity. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a global public health crisis that undermines the efficacy of treatments for infectious diseases, contributing to higher healthcare costs. Among Gram-positive bacteria, Staphylococcus aureus poses significant challenges due to its ability to develop resistance to multiple antibiotics, particularly in food and healthcare settings. Biofilm formation by S. aureus further enhances its resistance and pathogenicity. This study investigated the effects of 126 halogenated compounds on S. aureus biofilms, identifying five potent halogenated phenols. Among these, 2,4,6-triiodophenol (2,4,6-TIP) emerged as the most effective, exhibiting strong biofilm inhibition at a minimum inhibitory concentration (MIC) of 5 μg mL−1. Additionally, 2,4,6-TIP demonstrated efficacy against biofilms formed by methicillin-resistant S. aureus MW2 and various Gram-negative bacteria, including Vibrio parahaemolyticus and uropathogenic Escherichia coli (UPEC), as well as the fungal species Candida albicans. It also prevented the formation of polymicrobial biofilms involving S. aureus and C. albicans. Beyond its antibiofilm properties, 2,4,6-TIP was effective in controlling key virulence factors in S. aureus , such as metabolic, hemolysis and protease activities. It also reduced swimming motility in V. parahaemolyticus and UPEC, and impaired hyphal formation in C. albicans. Transcriptomic analysis further revealed that 2,4,6-TIP significantly repressed the gene expression of RNAIII , a key regulator of biofilm and virulence production in S. aureus. Furthermore, in silico analysis, plant and nematode models showed that 2,4,6-TIP exhibited reduced toxicity compared to phenol. These findings unveiled the strong antimicrobial potential of 2,4,6-TIP and suggest a broad-spectrum capacity to target the virulent characteristics of medically important pathogens. It also highlights that strategic halogenation may play a critical role in enhancing the activity of phenolic compounds while alleviating their toxicity profiles. t [Display omitted] • Hundreds of halogenated phenols were investigated for antibiofilm activity. • The most active 2,4,6-triiodophenol (2,4,6-TIP) at 5 μg mL−1 MIC inhibits S. aureus. • 2,4,6-TIP also inhibited biofilm formation of Candida , Vibrio , and E. coli spp. • 2,4,6-TIP reduced virulence factors and showed low toxicity in in vivo models. • It highlights broad antimicrobial potential of halogenated phenols. [ABSTRACT FROM AUTHOR]

Non-fused ring electron acceptors (NFREAs) have displayed promising candidates for practical application of organic solar cells (OSCs) owing to their short synthesis routes and cost effectiveness. The terminal groups halogenation have facilitated the optimization the physicochemical properties of NFREAs. In this work, we developed two NFREAs using a phenyl-substituted benzodithiophenedione unit as central core and electron-withdrawing groups 2-(3-oxo-2,3-dihydro-1 H-inden-1-ylidene) malononitrile (IC) or chlorinated IC (IC-2Cl) as the terminal groups. These NFREAs were designated as BDDPh-H and BDDPh-Cl, respectively. DFT calculations revealing that both NFREAs exhibited good backbone coplanarity due to S...O noncovalent interactions, and BDDPh-Cl exhibited red-shifted absorption compared with BDDPh-H owing to the stronger molecular stacking caused by chlorinated terminal groups. Moreover, BDDPh-Cl-based blended film demonstrated better nano-scale morphology, facilitating exciton dissociation and charge transport. Thus, PM6: BDDPh-Cl-based OSCs achieved a higher power conversion efficiency (PCE) of 12.69 %, outperforming BDDPh-H-based device (3.20 %) due to the enhanced short-circuit current and fill factor. Our findings indicate that combining phenyl-substituted benzodithiophenedione as central unit with chlorinated terminal groups showed great potential to construct highly efficient NFREAs. [Display omitted] • Two NFREAs, BDDPh-H and BDDPh-Cl, based on phenyl-substituted benzodithiophenedione were developed. • Both NFREAs exhibited good backbone coplanarity, and BDDPh-Cl exhibited red-shifted absorption compared with BDDPh-H. • BDDPh-Cl-based OSCs yielded a power conversion efficiency of 12.69 %, outperforming BDDPh-H-based device (3.20 %). [ABSTRACT FROM AUTHOR]

Iodine(III) reagents have gained importance in organic synthesis due to their strong oxidative properties in addition to several advantages over other related such as, non-toxic, green, easy to handle and in general safe for using. These characteristics become them useful tools and represent relevant alternatives to procedures which involves harsh and/or hazardous reaction conditions. They are versatile oxidants that has been largely used in the functionalization of a broad variety of aromatic nucleus, resulting in the introduction of several groups, including in the most general classification, organic and inorganics. In this sense, the metal-free arylation mediated by iodine(III) reagents is the most reported issue in the literature. Nevertheless, other relevant inorganic functionalities were also introduced. Herein, we review the most important procedures described to date for the aromatic functionalization with inorganic groups such as halogens, as well as the nitro-, azido, cyano-, sulfur- and selenium groups, under the iodine(III) chemistry. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Parabens in WWTP lead to the formation of DBP during water disinfection. • DBP from parabens can include chlorinated, brominated, and hydroxylated parabens. • Parabens transformation products are found in WWTP, rivers, swimming pools, and DW. • Biofilms in DWDS and the type of water disinfection affect DBP production. • Parabens transformation products are more toxic than the parent parabens. Parabens are used as preservatives in personal care products and many other products of daily use. Their removal in wastewater treatment plants (WWTP) is inefficient, allowing their spread into the environment. A great diversity of biological and chemical transformations occurs in these water systems leading to the formation of parabens transformation products (PTP). The presence and persistence of PTP in water sources are primarily affected by the type of tertiary wastewater treatment employed and the extent to which paraben-containing products are used. Despite laboratory evidence of PTP formation, their detection in real-world water systems remains limited. Few reports described their presence in real WWTP, rivers, swimming pools, and even drinking water (DW), occasionally at concentrations surpassing their parent counterparts. Among them, para -hydroxybenzoic acid (PHBA) is the most frequently detected, reaching concentrations up to 200 μg/L in WWTP influents, followed by hydroxylated parabens (1 μg/L), as well as chlorinated and brominated parabens (<0.1 μg/L). The toxicological implications of these PTP raise concerns, considering the health risks associated with parabens such as their potential endocrine disruption and toxicity. This study provides a comprehensive analysis of PTP formation during water treatment processes and its prevalence in water sources in real and laboratory conditions. Their environmental and public health impacts are also addressed, highlighting the need to invest in the monitoring of PTP in water systems using integrated water management approaches and promote community education to reduce the use of these compounds, safeguarding environmental and human health. [ABSTRACT FROM AUTHOR]

Halogenation of aliphatic C–H bonds is a chemical transformation performed in nature by mononuclear nonheme iron dependent halogenases. The mechanism involves the formation of an iron(IV)-oxo-chloride species that abstracts the hydrogen atom from the reactive C–H bond to form a carbon-centered radical that selectively reacts with the bound chloride ligand, a process commonly referred to as halide rebound. The factors that determine the halide rebound, as opposed to the reaction with the incipient hydroxide ligand, are not clearly understood and examples of well-defined iron(IV)-oxo-halide compounds competent in C–H halogenation are scarce. In this work we have studied the reactivity of three well-defined iron(IV)-oxo complexes containing variants of the tetradentate 1-(2-pyridylmethyl)-1,4,7-triazacyclononane ligand (Pytacn). Interestingly, these compounds exhibit a change in their chemoselectivity towards the functionalization of C–H bonds under certain conditions: their reaction towards C–H bonds in the presence of a halide anionleads to exclusive oxygenation, while the addition of a superacid results in halogenation. Almost quantitative halogenation of ethylbenzene is observed when using the two systems with more sterically congested ligands and even the chlorination of strong C–H bonds such as those of cyclohexane is performed when a methyl group is present in the sixth position of the pyridine ring of the ligand. Mechanistic studies suggest that both reactions, oxygenation and halogenation, proceed through a common rate determining hydrogen atom transfer step and the presence of the acid dictates the fate of the resulting alkyl radical towards preferential halogenation over oxygenation. Synopsis. The prepared iron(IV)-oxo complexes are competent to perform the activation of aliphatic CH bonds. When chloride anions are present in the reaction media, the addition of a superacid completely diverts the reaction chemoselectivity affording preferential chlorination over oxygenation. [Display omitted] • Iron(IV)-oxo complexes halogenate CH bonds in the presence of a strong acid. • The presence of the acid favors halogenation over oxygenation. • Weak-field ligands increase the halogenation efficiency and the reactivity. • The chemoselectivity is dictated after the hydrogen atom transfer step. [ABSTRACT FROM AUTHOR]

Halogenation reaction is often used for structural modification of natural products in drug research. However, no literature was reported for the bromination of acid-sensitive β-anhydroicaritin. We found that DBDMH might act as a mild and effective brominating agent on C-6 of β-anhydroicaritin, and give the desired product in a good yield. This reaction has a wide substrate scope. [Display omitted] • A convenient bromination of β-anhydroicaritin has been successfully developed, which was mediated by DBDMH in good yields. • The mechanism was also investigated and the structure was identified by X-ray spectra. • This protocol provides a feasible method for the bromination on the other phenols natural products. [ABSTRACT FROM AUTHOR]

[Display omitted] Haloalkynes that could be accessed from diverse precursors, are versatile in synthetic chemistry as alkynylation and/or halogenation reagents, enabling concise and divergent delivery of functional molecules in selective manners. Recently, additional reactivity and substrate scope of haloalkynes, was also developed, facilitating expedient delivery of fused heterocycles. [ABSTRACT FROM AUTHOR]

The vicinal effect on chlorination reactions of diols was investigated by computational methods. Applying density functional theory (DFT) combined with polarizable continuum model (PCM) and explicit solvent molecules, we demonstrated the effect of hydration on the leaving and vicinal hydroxyl group in S N 2 reactions of selected alcohols. Our results point out to the importance of intermolecular hydrogen bonds as a stabilizing factor in reaction pre-complexes and alcohols with vicinal hydroxyl groups, highlighting the importance of solute-solvent network formation. This indicates the significance of adequately describing the solvent in the study of reaction mechanisms, in special when the interaction with solute molecules and ions are strong. Also, we found a "vinical effect" on the reactivity, in other words, alcohols with vicinal hydroxyl groups exhibit higher activation energies when compared to related monoalcohols. Moreover, 1,3-propanediol and 1,3-butanediol present the highest activation energies. [Display omitted] • The microsolvation allows capturing important effects for halogenation reactions. • Adjacent hydroxyls contribute to the solvation network formation. • The activation energy increases in respect to the number of water molecules. • The formation of a solvation network stabilizes the pre-complex. [ABSTRACT FROM AUTHOR]

• A novel one-pot strategy for self-photocatalytic synthesis of multifunctional 3,3-disubstituted oxindoles. • The protocol involves Friedel–Crafts type, halogenation, and oxidation reactions. • The catalytic system exhibited mild reaction conditions and good compatibility of functional groups. A visible-light-induced, self-catalyzed multi-component reaction has been established, delivering a facile and atom-economic method to 3,3-disubstituted oxindoles with wild functional group tolerance and good to excellent yields under photocatalyst-, oxidant- and base-free conditions. The process involves photocatalytic Friedel–Crafts type coupling, halogenation, and oxidation reactions, which makes it practical and attractive. Moreover, this strategy contributes to the development of an efficient protocol for accessing electrochemically active 3,3-disubstituted oxindoles, which have potential applications in flow batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The halogenation of imidazoheterocycles including iodine, bromine and chlorine imidazoheterocycles could perform in very simple and mild conditions. • This transformation features with short reaction time, ambient temperature, facile operation, good functional group tolerance and good yeilds. An efficient and environment-friendly method for the synthesis of 3-haloimidazopyridine derivatives has developed by the halogenation of imidazoheterocycles with Bu 4 NX (X = Cl, Br, and I) using iodobenzene diacetate as oxidant in ethanol. This protocol features with short reaction time for bromination and iodination, ambient temperature, facile operation, good functional group tolerance and good yeilds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halogenation is a powerful strategy to tune physicochemical features of organic molecules. • Synthetic metabolism can be tailored for the incorporation of halogen atoms. • Growth-coupled schemes can be harnessed to establish biohalogenation. • Cell factories programmed for halometabolite synthesis expand bioproduction. The pressing need for novel bioproduction approaches faces a limitation in the number and type of molecules accessed through synthetic biology. Halogenation is widely used for tuning physicochemical properties of molecules and polymers, but traditional halogenation chemistry often lacks specificity and generates harmful by-products. Here, we pose that deploying synthetic metabolism tailored for biohalogenation represents an unique opportunity towards economically attractive and environmentally friendly organohalide production. On this background, we discuss growth-coupled selection of functional metabolic modules that harness the rich repertoire of biosynthetic and biodegradation capabilities of environmental bacteria for in vivo biohalogenation. By rationally combining these approaches, the chemical landscape of living cells can accommodate bioproduction of added-value organohalides which, as of today, are obtained by traditional chemistry. [ABSTRACT FROM AUTHOR]

The investigation of electromechanical properties for the newly added two-dimensional materials is challenging and enthralling. In this work, we consider studying the piezoelectric and flexoelectric properties of diamane monolayers, firstly proposed by density functional simulations and later synthesized in experiments. For this aim, we develop machine learning-based inter-atomic moment-tensor potentials along with the charge-dipole model to calculate the electrical polarization under mechanical deformations in AB stacked Janus diamane monolayers with hetero halogenation. The developed potential parameters efficiently predict the AB stacked non-Janus diamane lattices and their AA stacked counterpart lattices. Tensile stretching of Janus diamanes produces the in-plane piezoelectricity along with the generation of significant out-of-plane polarization. The piezoelectricity is absent in AB stacked non-Janus diamanes. The increase in structural asymmetry in C 4 ClH monolayer under bending deformation increase the total polarization by the local electric fields originated from the π − σ and the σ − σ electron interactions. The flexoelectricity of C 4 ClH is lower than C 4 FH due to the removal of its high out-of-plane piezoelectric contribution. The Janus diamane monolayer has promising electromechanical energy applications due to its high out-of-plane piezoelectric coefficient, which is nearly 15 times higher than Janus transitional metal dichalcogenide monolayer. [Display omitted] [ABSTRACT FROM AUTHOR]

The Enolates of hexahydro-3,4-dioxa-8a-aza- as -indacen-2-ones can react with electrophiles in a substrate-controlled fashion to create a new stereogenic center positioned beta to the N-pyrrolidinyl moiety. Preferential diastereoselective reactions predominantly proceeded from the convex face of the enolates, yielding stereospecific alkylated or halo-substituted products with high yields and exceptional diastereoselectivities. Di-substituted compounds were obtained by the alkylation or halogenation of the enolates of the corresponding mono-substituted compounds. Total synthesis of (−)-indolizidine 195G was also accomplished. © 2024 Elsevier Science. All rights reserved. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present work, using a systematic approach with DFT and TD-DFT techniques, we investigate the isomerization impact on Y18 and Y18-ID, two electron acceptors belonging to the Y family. Furthermore, the effect of the halogen atom was assessed by changing the original fluorine atoms with chlorine, bromine, and iodine. Two structural isomers were proposed for each acceptor, and a configurational (rotamer) for each structural isomer. A benchmarking was performed for relative energies, molecular planarity, light-harvesting features, frontier molecular orbitals alignment, electron-accepting indexes, reorganization energies, and average electrostatic potential. Mainly, structural isomerization yields the most significant modification to the studied properties and, to a lower extent, rotamerization. Nonetheless, the impact of rotamers might not be ignored, mainly in electron-accepting character and intermolecular electric field. Indeed, the modification that rotamers induce in some properties is comparable to that induced by the modification of halogen atoms. [Display omitted] • Y18, Y18-ID, and proposed acceptors have isomers close in energy. • Structural isomerization induces considerable changes in electronic structure. • The changes by structural isomerization could imply substantial alterations of PCE. • Rotational isomerization induces less significant changes. • Changes caused by rotamers are comparable to those by halogen modification. [ABSTRACT FROM AUTHOR]

3,3′-Dimethyl-9,9′-bianthracene (MBAn) is a non-donor-acceptor type bipolar deep blue fluorophore with a twisted conformation that can effectively prevent π-π stacking quenching, thereby enhancing the luminescence efficiency. And the introduction of halogen elements can increase the electron affinity of the material, thus effectively improving the electron mobility of the material, which contributes to the better optoelectronic performance of organic light-emitting diodes (OLEDs). Five MBAn derivatives were synthesized by altering the positions and numbers of halogen substituents on the two phenyl rings attached to the MBAn core at positions 9 and 9'. The photophysical, electrochemical, thermal stability and theoretical studies of these five derivatives were carried out. The OLED using 10,10′-bis(4-chlorophenyl)-3,3′-dimethyl-9,9′-bianthracene (MBAn-4-Cl) as the emitter shows a comparable electroluminescence spectrum peaked at 440 nm (FWHM = 52 nm) and a maximum external quantum efficiency (EQE max) of 5.25% at Commission Internationale de l'Éclairage (CIE) coordinates of (0.143, 0.067), which matches the National Television Standards Committee (NTSC) standard (0.14, 0.08) very well. [Display omitted] • Five fluorescent emitters based 3,3′-dimethyl-9,9′-bianthracene were synthesized. • The deep-blue OLED using MBAn-4-Cl as dopant achieves an EQE of 5.25% with the CIE (0.143, 0.067). • The TICT and bipolar characteristics of MBAn core combined with halogen elements can improve EL performance. [ABSTRACT FROM AUTHOR]

UV/chlorine process, as an emerging advanced oxidation process (AOP), was effective for removing micro-pollutants via various reactive radicals, but it also led to the changes of natural organic matter (NOM) and formation of disinfection byproducts (DBPs). By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), the transformation of Suwannee River NOM (SRNOM) and the formation of chlorinated DBPs (Cl-DBPs) in the UV/chlorine AOP and subsequent post-chlorination were tracked and compared with dark chlorination. In comparison to dark chlorination, the involvement of ClO•, Cl•, and HO• in the UV/chlorine AOP promoted the transformation of NOM by removing the compounds owning higher aromaticity (AI mod) value and DBE (double-bond equivalence)/C ratio and causing the decrease in the proportion of aromatic compounds. Meanwhile, more compounds which contained only C, H, O, N atoms (CHON) were observed after the UV/chlorine AOP compared with dark chlorination via photolysis of organic chloramines or radical reactions. A total of 833 compounds contained C, H, O, Cl atoms (CHOCl) were observed after the UV/chlorine AOP, higher than 789 CHOCl compounds in dark chlorination, and one-chlorine-containing components were the dominant species. The different products from chlorine substitution reactions (SR) and addition reactions (AR) suggested that SR often occurred in the precursors owning higher H/C ratio and AR often occurred in the precursors owning higher aromaticity. Post-chlorination further caused the cleavages of NOM structures into small molecular weight compounds, removed CHON compounds and enhanced the formation of Cl-DBPs. The results provide information about NOM transformation and Cl-DBPs formation at molecular levels in the UV/chlorine AOP. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Halogenases: diverse structures mediating distinctive chemistries. Over 5000 halogenated natural products have been reported so far, many of these arising from the marine environment. The introduction of a halogen into a molecule can significantly impact its bioavailability and bioactivity. More recently enzymatic halogenation has been used to enable late stage functionalisation through site-selective halogenation and cross-coupling. Halogenases are becoming increasingly valued tools. This review outlines the various classes of halogenases that have been discovered, and examines these from both a structural and a mechanistic perspective, reflecting upon the many recent advances in halogenase discovery. [ABSTRACT FROM AUTHOR]

• 10–12% High power conversion efficiency is achieved by halogenated ITIC and BDT polymer. • Fluorinated, chlorinated and brominated ITIC acceptor all fit BDT-BDD backboned donor. • 70% FF are achieved by all halogenated ITIC based devices. Acceptor halogenation is an excellent modification method for modulating molecular energy levels, improving optical absorption, shortening the intermolecular packing distance thus ameliorating morphologies and achieving effective exciton dissociation and charge transfer of organic photovoltaic device. In this work, F, Cl and Br terminated ITIC small molecule acceptor (SMA) derivatives (IT-2F, IT-2Cl and IT-2Br) are designed and synthesized to compare the halogen substitution effect. Among these three acceptors, IT-2F based PSCs devices show the highest power conversion efficiencies (PCEs) around 12.08%, but Br terminated ITIC show downshifted LUMO energy level. Brominated ITIC show comparable PCEs with Cl and F terminated compound, and moreover chlorinated and brominated ITIC show low synthesis cost and easy purification than fluorinated materials, which may be favorable for future commercialization. [ABSTRACT FROM AUTHOR]

Halogenated Organic Compounds (HOCs) are a class of refractory organic compounds produced in large quantities in the ocean, and some compounds can even persist over millions of years. The processes of production, transportation, and burial of HOCs, as well as the transformation and degradation of these compounds by microorganisms, are important parts of the biogeochemical cycling of carbon and halogen in the ocean. Dehalogenation microorganisms and dehalogenation pathways are prevalent in the deep-sea and the subseafloor biosphere, indicating the significance of HOCs metabolism in the ocean and interior of the earth. This paper reviews the current understanding on the generation, distribution, and transport of HOCs, as well as microbial mediated HOC degradation processes in the ocean. The preliminarily model for biogeochemical cycle of marine HOCs is summarized based on the existing knowledge. The research gaps and limitations are identified and future directions are also discussed. • Diverse and abundant Halogenated Organic Compounds (HOCs) are produced in the ocean. • HOCs support the survival and metabolic activities of deep-sea microorganisms. • HOCs are linked to the processes of the biological pump/microbial carbon pump. • Microbial metabolism of HOCs drives a coupled carbon and halogen cycling. [ABSTRACT FROM AUTHOR]

Flavin-dependent halogenases (FDHs) have tremendous applications in synthetic chemistry. A single-component FDH, AetF, exhibits both halogenase and reductase activities in a continuous polypeptide chain. AetF exhibits broad substrate promiscuity and catalyzes the two-step bromination of l -tryptophan (l -Trp) to produce 5-bromotryptophan (5-Br-Trp) and 5,7-dibromo- l -tryptophan (5,7-di-Br-Trp). To elucidate the mechanism of action of AetF, we solved its crystal structure in complex with FAD, FAD/NADP+, FAD/ l -Trp, and FAD/5-Br-Trp at resolutions of 1.92–2.23 Å. The obtained crystal structures depict the unprecedented topology of single-component FDH. Structural analysis revealed that the substrate flexibility and dibromination capability of AetF could be attributed to its spacious substrate-binding pocket. In addition, highly-regulated interaction networks between the substrate-recognizing residues and 5-Br-Trp are crucial for the dibromination activity of AetF. Several Ala variants underwent monobromination with >98 % C5-regioselectivity toward l -Trp. These results reveal the catalytic mechanism of single-component FDH for the first time and contribute to efficient FDH protein engineering for biocatalytic halogenation. • Structure of the self-sufficient flavin-dependent halogenase AetF was solved. • The mechanism of action of AetF was revealed by structural and biochemical analyses. • Substrate flexibility and dibromination capability of AetF were elucidated. • Switching the function of AetF from di- to monobromination was achieved. [ABSTRACT FROM AUTHOR]

The Aryl Hydrocarbon Receptor (AhR), a ligand-activated transcription factor, orchestrates responses to numerous structurally diverse endogenous and exogenous ligands. In addition to binding various xenobiotics, AhR also recognizes endocrine disruptors, particularly those featuring chlorinated or brominated aromatic structures. There is limited data available on the impact of common household and personal care product ingredients let alone their halogenated transformation products. Herein we bridge this knowledge gap by preparing a library of chlorinated and brominated parabens, bisphenols, UV filters, and nonylphenols. An evaluation of total of 125 compounds for agonistic and antagonistic activity on AhR unveiled a low micromolar agonist, Cl 2 BPAF with an EC 50 of 13 μM. Moreover, our study identified several AhR antagonists, with BrBzP emerging as the most potent with an IC 50 of 8.9 μM. To further investigate the functional implications of these compounds, we subjected the most potent agonist and antagonist to a functional assay involving cytokine secretion from peripheral blood mononuclear cells and compared their activity with the commercially available AhR agonist and antagonist. Cl 2 BPAF exhibited an overall immunosuppressive effect by reducing the secretion of proinflammatory cytokines, including IL-6, IFN-γ, and TNF-α, while BrBzP displayed opposite effects, leading to an increase of those cytokines. Notably, the immunomodulatory effects of Cl 2 BPAF surpassed those of ITE, a bona fide AhR agonist, while the impact of BrBzP exceeded that of CH223191, a bona fide AhR antagonist. In summary, our study underscores the potential influence of halogenated transformation products on the AhR pathway and, consequently, their role in shaping the immune responses. [Display omitted] • A comprehensive library of halogenated transformation products was prepared. • Halogenated derivatives can exhibit more pronounced AhR activity than parent compounds. • Cl 2 BPAF was the most potent agonist and BrBzP most potent antagonist of the series. • Cl 2 BPAF decreased LPS-induced inflammatory cytokine secretion from PBMCs. • BrBzP increased LPS-induced inflammatory cytokine secretion from PBMCs. [ABSTRACT FROM AUTHOR]

Porous organic polymers have been considered potential materials for synthesizing molecules by selective activation of bonds of visible light photocatalytic catalysis. However, the low charge mobility and weak interface conductivity prohibited further application. Herein, three new polymers with fluorene as donor and benzothiadiazole by halogen substitution (F or Cl) as acceptor unit were successfully synthesized and further constructed heterostructure with g-C 3 N 4. DClB-BTDF/g-C 3 N 4 heterojunctions exhibited superior photocatalytic activity for the selective oxidation of sulfides to sulfoxides under visible-light illumination, the highest activity reached > 98 % of conversion in a short time, which was more than two times higher than that of pristine DClB-BTDF. This is mainly attributed to the enhanced carrier separation efficiency of DClB-BTDF/g-C 3 N 4. Our finding could provide further insights into the design and synthesis of the halogenation strategy of polymer/g-C 3 N 4 heterojunctions. [Display omitted] • Three benzothiadiazole-conjugated polymers were synthesized and finely tuned through halogen substitution. • Three polymers/g-C 3 N 4 heterojunctions were assembled for the selective oxidation of sulfides. • Excellent photocatalytic product selectivities (up to 99 %) were displayed for the selective oxidation of sulfides. [ABSTRACT FROM AUTHOR]

[Display omitted] Enaminone 1 was treated with an equivalent of a halogenating agent, specifically N -bromo- or N -chlorosuccinimide (NBS or NCS, respectively), forming the corresponding α-haloenaminone 3 , and its reaction with an equivalent of NBS or NCS gave the corresponding α,α-dihaloketone 2 with high yield under mild reaction conditions (no additive, at room temperature). Furthermore, we investigated the direct transformation of enaminone 1 into the corresponding α,α-dihaloketone 2 treated with two equivalents of the halogenating agent. Concerning the probable reaction mechanism, we initially expected the isolation of only α-bromo-α-chloroketone 2-BrCl when treating α-chloroenaminone 3-Cl with NBS or α-bromoenaminone 3-Br with NCS. However, the resulting mixture containedα-bromo-α-chloro-,α,α-dichloro-, and α,α-dibromoketones 2. Through experimentation with the 1H NMR spectrum, it was discovered that the formation of α,α-dichloro- and α,α-dibromoketone 2 and the existence of other compounds as an intermediate. [ABSTRACT FROM AUTHOR]

Regioselective C3-halogenations of N -(pyrazolo [1,5- a ]pyrimidin-7-yl)acetamide with N -halosuccinimides (NBS or NCS) have been achieved. A diverse array of C3-halogenated products are provided in high yields with excellent regioselectivity. The practicability of this approach is highlighted by simple condition reactions, broad substrate scope, gram-scale reaction. Moreover, further derivatization reactions demonstrated the versatility of the products. [Display omitted] • Regioselective C3-halogenation of N -(pyrazolo [1,5-a]pyrimidin-7-yl)acetamide with N -halosuccinimides has been achieved. • A wide diversity of C3-halogenated products are obtained in excellent yields with high regioselectivity. [ABSTRACT FROM AUTHOR]

• A highly regioselective halogenation of alkyl aromatics through nitromethane-assisted Brønsted acid catalysis is disclosed. • A wide diversity of halogenated alkyl aromatics is obtained in high yields (up to 95%) with excellent regioselectivity (up to p / o 43/1) under the mild reaction conditions. • MeNO 2 played multiple vital parts in as the assister of catalyst, an efficient regulator of X + (Br+ and I +) activity and reaction selectivity, an excellent stabilizer of the carbocation, and the solvent. The most prevalent strategies for preparing halogenated alkyl aromatics face one remarkable challenge: low regioselectivity. Therefore, the highly regioselective halogenation of alkyl arenes is still an unsolved problem. Herein, a highly regioselective halogenation of alkyl aromatics through nitromethane-assisted Brønsted acid catalysis is disclosed. Under the mild reaction conditions, a wide diversity of halogenated alkyl aromatics is obtained in high yields with excellent regioselectivity. The hydrogen bonding of protonic acid with the solvent nitromethane promotes this transformation. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel sterically congested bismuthine, Dipp 3 Bi (Dipp = diisopropylphenyl), was isolated. Dipp 3 Bi was treated with oxidative halogenating reagents. The reactivity of Dipp 3 Bi was compared with that of the less sterically congested bismuthine, Mes 3 Bi, as well as antimony-containing analogues. [Display omitted] • Sterically congested stibines and bismuthines were synthesized and characterized. • Oxidative halogenation reactions were explored and outcome differences as a function of substituent steric bulk were observed. • Dipp 3 SbCl 2 assumed an unexpected square pyramidal geometry. Dihalotriorganopnictoranes serve as important synthetic precursors in Group 15 chemistry, but the influence of the organic substituents on the synthesis and reactivity of these compounds remains underexplored for the heavy pnictogens. We recently reported the isolation of Dipp 3 Sb (Dipp = 2,6-diisopropylphenyl). The bulky Dipp substituents permit the isolation of monomeric tetrahedral stibine oxide Dipp 3 SbO, yet also allow for the formation of the trigonal bipyramidal Dipp 3 SbF 2. We now report the isolation of a sterically crowded bismuthine, Dipp 3 Bi. Reaction between Dipp 3 Bi and XeF 2 afforded Dipp 3 BiF 2 , which features a distorted trigonal bipyramidal geometry in the solid state. Reaction between Dipp 3 Bi and PhICl 2 resulted in the generation of 1-chloro-2,6-diisopropylbenzene. Reaction between Dipp 3 Sb and PhICl 2 resulted in the formation of Dipp 3 SbCl 2 , which features a square pyramidal geometry in the solid state. Mes 3 SbCl 2 , Mes 3 SbBr 2 , Mes 3 BiCl 2 , and Mes 3 BiBr 2 (Mes = mesityl) were structurally characterized and all exhibit trigonal bipyramidal geometries in the solid state. Solution-phase spectroscopic measurements reflect the fluxionality of all of these molecules, but theoretical analyses in the gas phase suggest that the square pyramidal geometry of Dipp 3 SbCl 2 is more thermodynamically favorable than the trigonal bipyramidal geometry, possibly due to the presence of intramolecular secondary interactions between the Dipp and Cl substituents. These results highlight the ability of Dipp substituents to alter reactivity pathways of heavy pnictines. [ABSTRACT FROM AUTHOR]

XtalFluor-E, [Et 2 NSF 2 ]BF 4 , is best known as a useful, versatile and inexpensive commercially available reagent for the deoxyfluorination of carbonyl compounds and alcohols. Although XtalFluor-E is commonly used in combination with an exogenous fluoride source as a deoxofluorinating reagent, it has also been widely employed in other chemical transformations such as dehydration, cyclodehydration, ring expansion, formylation, and proto-functionalization, etc. This Review aims to provide an overview for the applications of XtalFluor-E as a reagent in organic synthesis, including its physical properties, futures, and its unique roles beyond than being just as a deoxofluorinating reagent in organic transformation. [ABSTRACT FROM AUTHOR]

In this paper, we will describe the chlorogenation of pyrrole-based on di(pyridyl)pyrrolide ligand and the synthesis of their ruthenium carbonyl complexes. The ligand L3− is capable of bonding flexibility and displays versatile coordination modes. The treatment of 2-(5-(pyridin-2-yl)-1H-pyrrol-2-yl)pyridine (HL1) and PhICl 2 as halogenation reagent generated monochloro-pyrrole HL2, dichloro-pyrrole HL3 and penta-chloro L4. The reaction of HL3 with [Ru(CO) 2 Cl 2 ] n gave diruthenium(I) complex [Ru 2 (μ-κ 2 N,N′:κ 1 N″-L3) 2 (CO) 4 ] (1) and monoruthenium(II) complex [Ru(κ 3 N,N′,N‴-L3)(κ 2 N,N′-L3)(CO)] (2). All these newly synthesized compounds were fully characterized by 1H NMR, IR, UV–Vis spectra, elemental analyses and X-ray diffraction study. The structural analysis shows that dichloro-pyrrole L3− acts as chelating and bridging ligand to coordinate two ruthenium atoms in 1 , and acts as bidentated and tridentated ligand in 2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • K-PHI photooxidizes halide anions (Cl―, Br―) in aqueous media with oxygen as an acceptor of electrons. • Chlorination as well as bromination of electron rich aromatic hydrocarbons is carried out by K-PHI photocatalyst. • Halogenation of aromatic hydrocarbons proceeds via in situ formation of "HOHal" species by two different pathways. • Solution of NaCl (seawater mimic) is a suitable reagent for photochlorination. Abstract Halocarbons have tremendous significance for the chemical industry. Arylchlorides and arylbromides are typically prepared via Friedel-Crafts reaction, using oxidative halogenation or employing halogen transfer agents, such as N -chloro- and N -bromosuccineimide. Herein, we show that K-PHI, a photocatalyst of the carbon nitride family, can easily photooxidize halide anions (Cl−, Br−) in aqueous media to promote oxidative halogenation of electron rich aromatic compounds. The technique is convenient, safe and gives the haloaromatic products with excellent yields from non-harmful starting reagents in the most sustainable fashion. We show that a solution of NaCl, mimicking seawater, can be used as a reagent for photochlorination. [ABSTRACT FROM AUTHOR]

• 7-Halogenated derivatives of 6-dimethylamino-2-phenylbenzothiazoles were prepared. • The halogenated derivatives have the deformed dimethylamino group by steric repulsion. • The halogenated derivatives showed blue-shifted electronic absorption and fluorescence. • Intersystem crossing from the fluorescence state suffers from heavy atom effect. 6-Dimethylamino-2-phenylbenzothiazole (1 -H) is a push-pull benzothiazole fluorophore mimicking the firefly oxyluciferin structure. We newly prepared 7-chloro and 7-bromo derivatives of 1 -H and its 4-acetyl derivative (2 -H), and their spectroscopic and photophysical properties were investigated. The halogenated derivatives showed the blue-shifted electronic absorption maxima and fluorescence emission maxima compared to 1 -H and 2 -H, resulted from the deformations of the NMe 2 groups and the electron withdrawing properties of the halogen groups. In addition, the halogen substitutions accelerate intersystem crossing by heavy atom effect, resulting in a decrease in fluorescence quantum yields. Interestingly, however, the halogenated derivatives of 2 -H still showed moderate fluorescence quantum yields. The halogenation effect is one of the guides to design push-pull benzothiazole fluorophores for tuning fluorescence properties. [ABSTRACT FROM AUTHOR]

• Palladium(0)-catalyzed direct C(sp2) H halogenation of aromatic azo compounds. • The method exhibited a broad substrate scope of azobenzenes. • A convenient method syntheses of various ortho -tetrabromo(chloro) azoarenes. A palladium-catalyzed direct C X bond formation of azobenzenes with 1,3-dibromo-5,5-dimethylhydantoin or trichloro isocyanuric acid via C H activation has been developed. The reaction could proceed smoothly under an air atmosphere at 110 °C in the presence of Pd(Ph 3 P) 4 in DCE and 13 examples of products were obtained. [ABSTRACT FROM AUTHOR]

An efficient and convenient method for remote C5 halogenation of 8-aminoquinoline derivatives was developed in continuous flow at room temperature. This method employed inexpensive 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) and 1,3-dichlro-5,5-dimethylhydantoin (DCDMH) as halogenation reagents and visible light to catalyze the reaction. The reaction is scalable to gram-scale and proceeded with air and moisture tolerance, good functional group compatibility, and outstanding site selectivity, providing a new pathway for C5 halogenation of 8-aminoquinolines. Image 1 [ABSTRACT FROM AUTHOR]

Highlights • CuO nanoparticles act as haloperoxidase mimics. • CuO nanoparticle haloperoxidase mimics can be used to quantify H 2 O 2 and glucose. • CuO nanoparticles halogenate bacterial quorum sensing molecules in biofilms. Abstract CuO nanoparticles (CuO NPs) were demonstrated as a novel nanoenzyme, i.e. , haloperoxidase mimic, which catalyzes the oxidation of halide ions to form reactive halogen species (RHS). Two functions of CuO NPs have been demonstrated in the work. First, RHS halogenate bacterial signaling molecules, thus preventing biofilm formation. Second, CuO is used in sensitive colorimetric assays for H 2 O 2 and glucose. [ABSTRACT FROM AUTHOR]

Abstract Halogenated olefins can be an attractive alternative to working fluids that are under consideration for phase-out. In order to evaluate the potential of halogenated olefins as working fluids for organic Rankine cycle units with a realistic perspective it is necessary to predict both their primary thermophysical properties and their associated uncertainties. In this work we evaluated the uncertainty of two predictive models, based on the classical group contribution approach and on neural networks, for the critical temperature, critical pressure, acentric factor, and ideal gas heat capacity of halogenated substances. Based on this, guidelines for the most convenient model depending on the property and the fluid molecular structure were provided. The non-linear propagation of the uncertainty through the Peng-Robinson equation of state for the simulation of an organic Rankine cycle unit were also studied. The results suggest that the uncertainty of the predicted properties is highly dependent on the molecular structure for the classical model. The propagation of uncertainties in the simulation of an organic Rankine cycle unit also depends on the saturation properties of the fluid. Highlights • The uncertainty of predicted properties of halogenated substances is investigated. • A comparison between the estimated uncertainties for two different models is made. • Uncertainties of group contribution models are more sensitive to molecular structure. • Uncertainties of the neural network model are in most of the cases greater. • The propagation of the uncertainties in equations of state depend on the fluid nature. [ABSTRACT FROM AUTHOR]

Abstract More than 40 years after their publication, updated versions of the generalized Soave α-function (α ( T r , ω) = [ 1 + m (ω) (1 − T r 0.5 ) ] 2 ) suitable for the Redlich-Kwong (RK) and Peng-Robinson (PR) equations of state (EoS) are proposed in this work. The new mathematical expressions of m R K (ω) and m P R (ω) have been determined by correlating the optimal m values, fitted on vapor pressures ( P s a t ) and/or enthalpies of vaporization ( Δ v a p H) and/or saturated-liquid heat capacities ( c P , l i q s a t ) against the acentric factor ω. The correlations determined in this study can be considered as broad-based and sound since they were established for 1721 pure compounds belonging to many different chemical families (hydrocarbons, halogenated, oxygenated, sulfur, nitrogen compounds ...) for which experimental data were available. Significant improvements on the reproduction of vapor pressures were obtained for the PR EoS with respect to the original version. The updated SRK EoS achieved similar average deviations for the three properties of interest ( P s a t , Δ v a p H and c P , l i q s a t ), in comparison with the original SRK equation. A substantial improvement is however noticeable for heavy molecules with an acentric factor larger than 0.9. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A simple and convenient procedure for halogenation of 2-arylimidazo[1,2- a ]pyridines. • A method allows rapid preparation of 3-halo-2-arylimidazo[1,2- a ]pyridines in a short reaction time. • A procedure employ K 2 S 2 O 8 as an easy-to-handle oxidizing agent under convenient reaction conditions. Abstract A convenient halogenation of 2-arylimidazo[1,2- a ]pyridines using sodium chloride/bromide/iodide as the halogen sources in the presence of K 2 S 2 O 8 as an easy-to-handle oxidizing agent was developed. The present work offers an efficient and rapid access to 3-chloro-, 3-bromo- and 3-iodo-2-arylimidazo[1,2- a ]pyridines which can be readily converted to C 3-substituted imidazo[1,2- a ]pyridines by cross-coupling reactions. [ABSTRACT FROM AUTHOR]

Graphical abstract Synthesis of difluorinated phosphonium salts by interaction of the phosphobetaine reagent with halogen and chalcogen electrophiles is described. Highlights • Reactions of difluoromethylene phosphobetaine. • Halogenation of fluorinated ylides. • Synthesis of fluorinated phosphonium salts. Abstract A series of difluorinated phosphonium salts were obtained by reaction of difluoromethylene phosphobetaine with halogenating reagents, as well as arylsulfenyl and arylselenyl chlorides. The reaction proceeds via decarboxylation of the phosphobetaine followed by trapping of the difluorinated phosphorus ylide by heteroatom-centered electrophiles. The crystal structures of the phosphonium salts were studied by X-ray diffraction analysis. For the salt containing the CF 2 I group and iodide counterion, the I⋯I interaction was identified in the solid state. The nature of this halogen bond was evaluated by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Abstract Described in this review is the chemistry of 3 d metal alkynyls based on tetraaza macrocyclic ligands. Both the abundance of 3 d metals and easy access to the tetraazacyclotetradecane type ligands make these compounds more affordable and sustainable alternatives to metal alkynyls based on precious metals. Taking advantage of a rich variety of starting materials available in literature, the trans- [M(cyclam)(C 2 R) 2 ]X type (cyclam = 1,4,8,11-tetraazacyclotetradecane) compounds have been prepared from the reactions between [M(cyclam)X 2 ]X (M = Cr, Fe and Co; X = Cl or OTf) and LiC 2 R. With [Co(cyclam)Cl 2 ]+, both the { trans- [Co(cyclam)Cl] 2 (μ-(C≡C) n)}2+ and trans- [Co(cyclam)(C 2 R)Cl]+ type compounds can be prepared through a dehydrohalogenation reaction. The latter type compounds can undergo a second alkynylation reaction with LiC 2 R' to afford the dissymmetric trans- [Co(cyclam)(C 2 R)(C 2 R')]+ type compounds, including the trans- [Co(cyclam)(C 2 A)(C 2 D)]+ dyads with A and D as acceptor and donor chromophores respectively. These compounds are being studied to probe photo-induced electron transfer and related photophysical/photochemical processes. The trans- [Co(cyclam)(C 2 R)(NCMe)]2+ type complexes react with unactivated HC 2 R' in the presence of a weak base to provide trans- [Co(cyclam)(C 2 R)(C 2 R')]+ in high yields. Similar alkynylation chemistry with complexes of cyclam derivatives, like TMC (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), HMC (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) and DMC (5,12-dimethyl-1,4,8,11-tetraazacyclotetradecane), has been demonstrated with the studies of [Ni(TMC)(C 2 R)]+, trans-/cis- [Cr(HMC/DMC)(C 2 R) 2 ]+ and trans- [Co(DMC)(C 2 R) 2 ]+. Graphical abstract Image 1 Highlights • A brief overview on the history of metal alkynyl chemistry was provided. • Strategies for the synthesis of symmetric and dissymmetric M(cyclam) acetylides were analyzed. • Structure-property relationship based on spectroscopic and voltammetric studies was discussed. [ABSTRACT FROM AUTHOR]

Abstract We investigated the effects of both sulfuric acid (pH 0 to 2) and hydrogen halides (pH 0) on the physical, chemical, and performance properties of full aromatic nanofiltration (NF) polyamide (PA) NE90 membrane. Surface characterizations of the degraded membranes were conducted by Scanning Electron Microscopy (SEM), Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), goniometer, and zeta potential analyzer. No noticeable changes were observed in the surface properties of the membrane exposed to sulfuric acid; however, the permeable characteristics were changed due to the distortion of hydrogen bonding from additionally generated proton bridge for O-protonation and the formation of tetrahedral structure for N-protonation. On the other hand, the membrane's physico-chemical properties were much affected by hydrogen halides compared with sulfuric acid. Amide peaks N-H bending at 1541 cm−1 and C=O stretching at 1663 cm−1 in ATR-FTIR were reduced because of the reaction of the PA with halogens produced by oxidation of hydrogen halides. Molecular halogen gases (Cl 2 , Br 2 , I 2) generated in the reaction bottle were also analyzed by GC/MS during exposure of the membrane to various types of acids. The increment in halogenation on PA was in the order HCI, HBr, and HI, and it was the same as the order of temporary dipole moment from the effect of molecular size. Water flux after exposure to hydrogen halides was severely decreased due to broken hydrogen bonding by halogenation. Investigation of sulfuric acid and hydrogen halides on the change of the physico-chemical characteristics in the NE90 can be utilized when full aromatic NF membrane is applied to treat/recycle several industrial processes, which include sulfuric acid or hydrogen halides. Highlights • Degradation of full aromatic polyamide membrane by strong acids was investigated. • No noticeable changes of the membrane were observed after exposure to sulfuric acid. • But, permeability changed after exposure to sulfuric acid due to N/O-protonation. • Halogens are produced by oxidation of hydrogen halides, and caused halogenation. • Water flux was severely decreased due to halogenation of the polyamide membrane. [ABSTRACT FROM AUTHOR]

Abstract An efficient method for the preparation of 2,2 - diarylvinyl halides from the corresponding 1,1 - diarylethylenes has been developed. N- Halosuccinimides (N- bromosuccinimide or N- chlorosuccinimide) were used as the halogenation reagents. The practicability of this method is highlighted by its simple operation, broad substrate scope and capability for large - scale reaction. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract The stereochemistries of halogenated lumisantonin were rationalized by four distinct methods. In the first method the activation energies for the halonium ion intermediates and the reaction energies for all candidate structures were calculated. In the second approach the coupling constants were calculated and compared with the experimental values. The best matches for the calculated and experimental coupling constants were achieved by the modified procedure. In the third approach the computed 1H and 13C NMR chemical shifts were compared with the experimental values and the mean absolute errors (MAE) were measured. In the fourth method the adapted DP4 probabilities were evaluated and the determined stereochemistries for the sesquiterpene lactones (3a and 4a) were in agreement with the first three protocols. Graphical abstract Image 1 Highlights • Activation energies were determined for the halonium ion intermediates. • Reaction energies for the candidate structures were calculated. • Calculated coupling constants were compared with the experimental values. • Computed chemical shifts were compared with the experimental values. • The stereochemistries of the lactones were assigned by four distinct methods. [ABSTRACT FROM AUTHOR]

Abstract A detailed study on the vibrational spectra of monohalogenated acetylenes and their deuterated analogues has been reported in this work using the U(4) algebraic model. With detailed spectral analysis, it has been shown in this study that all the stable isotopes of monohalogenated acetylenes and their deuterated analogues can be approximated well using the U(4) algebraic model. Graphical Abstract Unlabelled Image Highlights • An economic set of parameters are needed to provide a good accuracy. • Complex potential energy surfaces and highly excited levels can be dealt well. • A general Hamiltonian can approximate all the molecules in a specific class. • Viable alternative to the traditional approaches [ABSTRACT FROM AUTHOR]