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In this study, the primary objective is to synthesize a novel fluorescent Rh-PP-Rh compound and explore its extensive range of photochemical behaviors. Initially, the synthesis of the novel Rh-PP-Rh was carried out for this purpose. Subsequently, UV-Vis and fluorescence spectroscopy were employed to investigate the interactions between Rh-PP-Rh and a diverse array of ions in aqueous solvent systems. Through fluorescence and UV-Vis studies, it was observed that Rh-PP-Rh demonstrated turn-on sensor properties in the presence of Hg2+ ions. Furthermore, the limits of detection (LOD) and association constant (Ka) values for Rh-PP-Rh/Hg2+ were determined as 334 nM and 9.13×1011 M-2, respectively. Additionally, the reversible studies demonstrated a switchable on/off response upon alternate addition of HgCl2 and [Bu4N]F to Rh-PP-Rh. These findings suggest that the probe Rh-PP-Rh also possesses specific sensor properties for F- ions in the presence of mercury. In addition, the investigation encompassed an assessment of the visual analysis of the color alterations of Rh-PP-Rh both on filter paper and in an EtOH/H2O solution. The findings demonstrated that Rh-PP-Rh can be successfully utilized in solutions containing mercury, as it generates significant color transformations.

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Alkylated imidazopyridines are crucial structures for medicinal chemistry. Here, an efficient method for the C3-H alkylation of imidazopyridines was devised. Under Lewis acid-catalyzed conditions, reactions of imidazopyridines with different donor-acceptor cyclopropanes were carried out. Finally, 1,3-bisfunctionalizaton of donor-acceptor cyclopropanes was performed. In addition, synthesized C3-alkylated imidazopyridines are amenable for diverse synthetic applications.

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The main purpose of this study is the synthesis of novel fluorescent Bis-TPE and the investigation of its wide range of photochemical behaviors. For this purpose, initially, Bis-TPE was synthesized. Following this, the interactions of Bis-TPE with a wide range of ions were studied in EtOH using ultraviolet-visible (UV-vis) and fluorescence spectroscopy. As a result of all UV-vis and fluorescence studies, it was determined that Bis-TPE showed turn-on sensor features against Zn2+ ions. Moreover, the limit of detection (LOD) and Ka values of Bis-TPE/Zn2+ were calculated as 0.97 µM (970 nM) and 3.76 × 105 M-1, respectively. Moreover, all reversal studies resulted in switchable on/off variation of the alternative addition of ZnCl2 and [Bu4N]OH to Bis-TPE. This result also implies that the probe Bis-TPE also exhibits specific OH- sensor properties in the presence of zinc.

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In this study, a new tetraphenylethene derivative bearing triazole and pyridine moieties (TPE-TAP) was synthesized using click chemistry. The fluorescence sensing properties of TPE-TAP were investigated in almost 100% aqueous media. For this purpose, first of all, structural characterization of the newly synthesized compound TPE-TAP was performed by NMR and HRMS analyses. Then, the optical behavior of TPE-TAP was investigated in different ratios of a THF-water mixture (0-98%). The obtained results showed that the best fluorescence for TPE-TAP was observed in the presence of 98% water in the medium. Then, the ion selectivity of TPE-TAP was determined using 19 different cations in the THF-water medium (2 : 98 v/v%). It was observed that among the cations studied, only Fe3+ quenched the fluorescence of TPE-TAP. The detection limit and binding constant values of TPE-TAP for Fe3+ were calculated as 1.3 µM and 26.65 M-2, respectively, from the graph results of the decrease in the fluorescence intensity of TPE-TAP in the presence of Fe3+ at different concentrations. In addition, the study investigating the selectivity of TPE-TAP in the presence of 18 cations other than Fe3+ showed that none of the studied cations interfered with Fe3+. Practical application of TPE-TAP was also carried out using a commercial iron drug. All results showed that TPE-TAP is a fluorometric sensor highly selective, sensitive, and suitable for practical application for Fe3+ ions in aqueous medium.

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Aggregation-induced emission (AIE) is an extraordinary photochemical phenomenon described by Tang's group in 2001, where the aggregation of some organic molecules enhances their light emission by limiting intramolecular activity in the aggregate state. This phenomenon offers new opportunities for researchers due to its potential applications in optoelectronics, energy, and biophysics. Tetraphenylethylenes (TPEs) are reliable AIE luminogens with a wide range of successful applications in material chemistry. To expand the library of AIE-active TPEs, both a series of TPE analogues, in which the phenyl rotor has been replaced by the indole ring, and indole-substituted TPE derivatives were designed and synthesized through vinyl-aryl and aryl-aryl bond formations using the Suzuki coupling reaction. Efficient synthetic routes that delivered indole-modified and indole-substituted TPEs have been developed, and almost all heterocyclic TPE analogues have demonstrated AIE behavior. Furthermore, to test whether the indole ring can be diversified, two title compounds were converted to a series of bis(indolyl)methane (BIM), and these BIM-TPE materials showed typical AIE properties. Interestingly, two compounds indicated a solvent vapor fuming reversible switch between bright blue emission and greenish-yellow emission. Upon fuming with dichloromethane, their fluorescence spectra showed 8 and 32 nm red-shift and could return to the original state after fuming with hexane. Furthermore, we have explored the effects of replacing the phenyl ring in TPE with indole together with the substitution of TPE with indole ring(s) on the performance of organic light-emitting diode (OLED) device applications. In addition, density functional theory calculations; the optical, electrochemical, light emission, electroluminescence characteristics; and admittance spectroscopic analysis of OLED devices of four representative TPEs have been investigated in detail. As a result, the indole-TPEs are potential blue emitters with AIE features for conventional OLEDs, which is a significant color in displays and lighting.

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Solvent-promoted and -controlled regioselective bond alkylation reactions of para-quinone methides (p-QMs) with N-H free-indoline and 1,2,3,4-tetrahydroquinoline (THQ) under metal-free conditions have been developed. In the presence of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent, 1,6-addition alkylation reactions of p-QMs with NH-free indolines and THQs efficiently gave C5-alkylated indolines and C6-alkylated THQs. Using catalytic amounts of HFIP in DCM, the reaction of indolines and p-QMs resulted in the alkylation of indolines at the N1-position. HFIP plays two roles in the reactions: converting the indoline and THQ into bidentate nucleophiles and activating the p-QMs to achieve the 1,6-addition alkylation via hydrogen bond clusters. The indoline and THQ act as a C-nucleophile due to the H-bond clusters between HFIP and the nitrogen atom, whereas upon using catalytic amounts of HFIP, the compounds act as an N-nucleophile. All alkylation products were transformed into the corresponding indoles and quinolines via oxidation in the presence of diethyl azodicarboxylate (DEAD). Furthermore, the synthetic utilities have been showcased with both the removal of the tert-butyl groups from the C5-alkylated indole products and submission to their Suzuki coupling reactions.

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8-Aminoquinolines are the building blocks of many pharmaceutical compounds, which has motivated the scientific community to develop new ways to derivatize these compounds. In this work, we performed a site-selective C5-H and N-H alkylation of 8-aminoquinolines using para-quinone methides under extremely mild conditions. C5-H alkylation was performed using protecting group-free 8-aminoquinolines and in metal-free conditions. N-H alkylations were also carried out under mild conditions. All corresponding alkylation products were obtained in high to excellent yields.

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Novel magnetically recoverable nanocatalyst comprising nickel-palladium (NiPd) alloy nanoparticles (NPs) supported on reduced graphene oxide (rGO) modified with cobalt ferrite (CoFe2O4) NPs was fabricated for the direct C-H arylation of imidazopyridine, imidazole, indolizine and furan with aryl halides. To prepare the presented catalyst, rGO nanosheets were first modified with as-synthesized CoFe2O4 NPs and then the obtained CoFe2O4-rGO nanocomposites served as a support material for the synthesis of bimetallic NiPd alloy NPs at various compositions. The obtained CoFe2O4-rGO/NiPd nanocatalysts were characterized by many advanced analytical techniques including TEM, STEM-EDS, XRD, XPS, and ICP-MS. Next, to optimize the reaction conditions, CoFe2O4-rGO/NiPd nanocatalysts with different alloy compositions and their monometallic counterparts (CoFe2O4-rGO/Ni and CoFe2O4-rGO/Pd) were initially tested in the direct C-H arylation of imidazopyridine with bromobenzene. Among all tested nanocatalysts under the optimum reaction conditions, CoFe2O4-rGO/Ni20Pd80 showed the best catalytic activity in terms of the isolated product yields. The C-H arylation reactions were studied over a broad substrate scope (35 examples from 36 substrates) and gave the related biaryl products in good to excellent yields. Besides a broad substrate scope, the late-stage C-H arylation of zolimidine, a gastroprotective drug, was realized under the optimized reaction conditions. Moreover, the CoFe2O4-rGO/Ni20Pd80 nanocatalysts were recovered from the reaction medium using a simple magnet and reused in the C-H arylation reactions up to five consecutive runs without a significant drop in the product yield. This study shows that magnetically recoverable Pd nanoalloys are promising heterogeneous catalysts to be used in sustainable C-H functionalization reactions.

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The self-assembly of bolaamphiphiles comprised of a central photochromic dithienylethene (DTE) chromophore was investigated in aqueous media. Irradiation at 254 nm induced a conversion from the open to closed states of the DTE chromophores. Whereas, in water, irradiation produced a photostationary state of 20 : 80 (open/closed), in methanol the ratio improved to 10 : 90 (open/closed). The open → closed transition was accompanied by the formation of 1D nanofibers during incubation in darkness.

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Black phosphorus (BP) is for the first time employed as a metal-free, heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes with aryl diazonium salts. The arylated heteroarenes are obtained in moderate to good yields under visible-light illumination, and the protocol is shown to be applicable for the scale-up synthesis.

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The electrophilic substitution reaction of 4,7-dihydroindole with aryl-aldehydes as an electrophilic partner followed by an oxidation step to deliver 2,2'-bis(indolyl)arylmethanes was studied for the first time. The reaction afforded regioselectivity at the 2,2'-positions of indole in an operationally simple and inexpensive procedure with a variety of substrates. To the best of our knowledge, this is the first set of examples of 2,2'-bis(indolyl)arylmethanes obtained in a substituent-free manner. A facile method from dipyrromethanes to the corresponding 2-benzylindoles was also reported. In addition, 2,2'-bis(indolyl)arylmethanes were converted to 5,7-dihydroindolo[2,3-b]carbazoles.

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This review focuses on the chemistry of benzo-annulated tropones and tropolones reported since the beginning of the 20th century, which are currently used as tools by the synthetic and biological communities.

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A straightforward synthetic route toward C5-alkylated indolines/indoles has been developed. The strategy is composed of Zn(OTf)2-catalyzed Friedel-Crafts alkylation of N-benzylindolines with nitroolefins, and a series of diverse indolines was first obtained in up to 99% yield. This reaction provides a direct and practical route to a variety of the C5-alkylated indolines which were also utilized for accessing corresponding indoles. Indoline derivatives with free NH groups could be obtained through an N-deprotection reaction. Moreover, the primary alkyl nitro groups in both indolines and indoles are amenable to further synthetic elaborations, thereby broadening the diversity of the products.