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Quadruple azidation of 2,4,6,8-tetrachloropyrimido[5,4-d]pyrimidine gave tetraazidopyrimido[5,4-d]pyrimidine (C6N16) with 86% yield. The title compound undergoes azide–tetrazole tautomerism in neutral organic solvents, but exists as a protonated C2-symmetric tetraazide dication in trifluoroacetic acid. On the other hand, in the solid state it occurs as a monotetrazole tautomer as revealed by its single crystal X-ray analysis. The newly obtained binary compound C6N16 is very sensitive towards both impact (<1 J) and friction (1 N). A detonation velocity of 7477 m s−1 with a 20.8 GPa detonation pressure was calculated using the EXPLO5 code (version V7.01.01). [ABSTRACT FROM AUTHOR]

The biomolecular interactions of two previously reported cycloplatinated complexes, [Pt(C^N)(SMe2)(OCOCF3)] (C^N = deprotonated benzo[h]quinoline (bhq), 1, or deprotonated 2-phenylpyridine (ppy), 2), with bovine serum albumin (BSA) were investigated using various spectroscopic techniques. Structural characterization of 1 and 2 by NMR, UV-vis spectroscopies and conductivity measurements in aqueous media revealed that the TFAc functions as a leaving group ligand and is rapidly replaced by water molecules to form cationic cycloplatinated complexes having an aqua ligand, [Pt(C^N)(SMe2)(H2O)]+[CF3COO]−. Fluorescence titration of BSA indicated a strong binding interaction between Pt(II) compounds and protein with a static quenching mechanism. The thermodynamic parameters (ΔH°, ΔG° and ΔS°) showed that the binding was exothermic, involving main noncovalent hydrophobic forces and ionic interactions. As revealed by the displacement experiment, while 1 could bind to subdomain IIIA (site II) of albumin, the binding sites of 2 were mostly located at subdomain IIA (site I). The synchronous fluorescence spectra indicate that the cycloplatinated compounds induce structural changes in the protein structure. Moreover, far-UV CD spectroscopy is in agreement with a reduction of the α-helix content of albumin through binding. Further evidence for noncovalent association was obtained from inductively coupled plasma-optical emission spectroscopy (ICP-OES). In addition, the cytotoxicity investigation of 1 as a model complex against two human leukemic cancer cell lines (K562 and HL-60), MCF-7 (human breast adenocarcinoma), U-87MG (human glioblastoma cell line) and HT-29 (human colorectal adenocarcinoma cell line) suggested that 1 is more cytotoxic than cisplatin against HL-60 and generally toxic toward K562, MCF-7 and U-87MG. Finally, the quantitative structure–activity relationship (QSAR) was applied to correlate the structure of some cycloplatinated complexes including 1 and 2 with the SA albumin binding constant. [ABSTRACT FROM AUTHOR]

Maleimide derivatives are widely synthesized as luminescent materials due to their excellent structural advantages and good chemical stability. In this article, we have designed and synthesized two new dual-state emission (DSE) molecules that use maleimide as the skeleton and introduce different amounts of conjugation-induced rigidity biphenyl by Suzuki–Miyaura coupling. The obtained fluorophores show bright blue fluorescence emission both in solution and solid state, displaying DSE effects. Moreover, the fluorophores also display positive solvatochromic effects in solvent of different polarity, and they response to the addition of trifluoroacetic acid (TFA) and triethylamine (TEA), displaying reversible acidochromic behavior. [ABSTRACT FROM AUTHOR]

Other than triarylamines, which are protonated by strong acids both at their N‐atom and aromatic rings, pyrrole and its N‐substituted derivatives were exclusively protonated at the carbon atoms of their heteroaromatic rings. Whereas with the strong trifluoromethane sulfonic acid (TFS) stable pyrrolium salts were obtained, with the weaker trifluoroacetic acid (TFA) oligomers are formed. E.g. from the N‐(tert‐butyl)pyrrole a dimeric compound could be unambiguously identified and structural characterised by means of 1H NMR measurements. Treatment of N‐aryl substituted pyrroles with deuterated TFS revealed an H/D exchange not only at the pyrrole rings but also at their aryl moieties even. [ABSTRACT FROM AUTHOR]

(4-Cyanooxazol-5-ylamino)acetates and (4-cyanooxazol-5-ylamino)acetamides after treatment with trifluoroacetic acid undergo recyclization to the mixture of corresponding 5-aminooxazoles, 5-trifluoroacetylaminooxazoles, and oxazolopyrimidinones. The structures have been confirmed for certain products which have been isolated in pure form. [ABSTRACT FROM AUTHOR]

Simultaneous electrochemical ring contraction and expansion reactions remain unexplored to date. Herein, the reductive electrosynthesis of heterocycle‐fused fulleroids from fullerotetrahydropyridazines and electrophiles in the presence of a trace amount of oxygen has been achieved with concurrent ring contraction and ring expansion. When trifluoroacetic acid and alkyl bromides are employed as electrophiles, heterocycle‐fused fulleroids with a 1,1,2,6‐configuration are regioselectively formed. In contrast, heterocycle‐fused fulleroids with a 1,1,4,6‐configuration are regioselectively produced as two separable stereoisomers if phthaloyl chloride is used as the electrophile. The reaction proceeds through multiple steps of electroreduction, heterocycle ring‐opening, oxygen oxidation, heterocycle contraction, fullerene cage expansion, and nucleophilic addition. The structures of these fulleroids have been determined by spectroscopic data and single‐crystal X‐ray diffraction analyses. The observed high regioselectivities have been rationalized by theoretical calculations. Representative fulleroids have been applied in organic solar cells as the third component and exhibit good performance. [ABSTRACT FROM AUTHOR]

Novel boronyl borinic ester I was generated by quenching the B2pin2/secBuLi‐ate complex with trifluoroacetic acid anhydride (TFAA) via ring‐opening in the 1,3,2‐dioxaborolane moiety on ate‐boron. Detailed NMR studies of the B2pin2/secBuLi‐ate complex in solution and in solid state allowed us to assume its oligomeric nature in solids with only ate‐boron involved in the oligomerization process. The O‐trifluoroacetyl pinacolate residue on borinic ester I initially formed on quenching with TFAA undergoes an unusual intramolecular transesterification with the carbonyl group of trifluoroacetyl forming othroester moiety in a few hours at r. t. to give boronyl borinic ester II. A solution of these reagents I/II was proved to be efficient for borylation of (2‐fluoroallyl)pyridinium salts that are highly base sensitive. [ABSTRACT FROM AUTHOR]

A decarboxylative condensation of malonic acid half thioesters (MAHTs) with aldehydes catalyzed by benzylammonium trifluoroacetate has been developed for the synthesis of (E)‐α,β‐unsaturated thioesters. The reaction of aromatic aldehydes and sterically non‐demanding aliphatic aldehydes proceeded smoothly at room temperature in DMF in a stereo‐ and regioselective manner. Besides the unsubstituted malonate, 2‐fluoro‐ and 2‐methylmalonates could be employed as a nucleophile. Use of the present catalyst could avoid nonproductive protiodecarboxylation of MAHTs. [ABSTRACT FROM AUTHOR]

A family of trans‐porphyrins (A2B2, A2BC and A2C2), including fewer fused cyclic aromatics, was synthesized using 5‐mesityldipyrromethane under negligible scrambling reaction conditions in high yields (15–48 %) with BF3(OEt2)/EtOH relative to that in trifluoroacetic acid (12–22 %) in CHCl3. The push‐pull trans‐A2BC, Zn(II)‐carboxy porphyrins were prepared from their ester porphyrins and examined their fluorescence and electrochemical redox properties. In addition, the synthesis and single‐crystal X‐ray structure of a 5‐(pyren‐1‐yl)dipyrromethane are also reported. [ABSTRACT FROM AUTHOR]

An oxidative cyclization of electron‐rich α‐arylhydrazones promoted by phenyliodine bis(trifluoroacetate) (PIFA) has been accomplished. This metal‐free, chemoselective transformation allows to obtain synthetically and medicinally important N‐amino‐1H‐indoles, obviating the need for pre‐functionalization of substrates. [ABSTRACT FROM AUTHOR]

The first 8‐electron Pd/Ag superatomic alloys with an interstitial hydride [PdHAg19(dtp)12] (dtp=S2P(OiPr)2−) 1 and [PdHAg20(dtp)12]+2 are reported. The targeted addition of a single Ag atom to 1 is achieved by the reaction of one equivalent of trifluoroacetic acid, resulting in the formation of 2 in 55 % yield. Further modification of the shell results in the formation of [PdAg21(dtp)12]+3 via an internal redox reaction, with the system retaining an 8‐electron superatomic configuration. The interstitial hydride in 1 and 2 contributes its 1s1 electron to the superatomic electron count and occupies a PdAg3 tetrahedron. The distributions of isomers corresponding to different dispositions of the outer capping Ag atoms are investigated by multinuclear VT NMR spectroscopy. The emissive state of 3 has a lifetime of 200 μs (λex=448; λem=842), while 1 and 2 are non‐emissive. The catalytic reduction of 4‐nitrophenol is demonstrated with 1–3 at room temperature. [ABSTRACT FROM AUTHOR]

Organic–inorganic nanocomposite particles, possessing defined morphologies, represent the next frontier in advanced materials due to their superior collective performance. In this pursuit of efficient preparation of composite nanoparticles, a series of diblock polymers polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) were initially synthesized using the Living Anionic Polymerization-Induced Self-Assembly (LAP PISA) technique. Subsequently, the tert-butyl group on the tert-butyl acrylate (tBA) monomer unit in the diblock copolymer, yielded from the LAP PISA process, was subjected to hydrolysis using trifluoroacetic acid (CF3COOH), transforming it into carboxyl groups. This resulted in the formation of polystyrene-block-poly(acrylic acid) (PS-b-PAA) nano-self-assembled particles of various morphologies. The pre-hydrolysis diblock copolymer PS-b-PtBA produced nano-self-assembled particles of irregular shapes, whereas post-hydrolysis regular spherical and worm-like nano-self-assembled particles were generated. Utilizing PS-b-PAA nano-self-assembled particles that containing carboxyl groups as polymer templates, Fe3O4 was integrated into the core region of the nano-self-assembled particles. This was achieved based on the complexation between the carboxyl groups on the PAA segments and the metal precursors, facilitating the successful synthesis of organic–inorganic composite nanoparticles with Fe3O4 as the core and PS as the shell. These magnetic nanoparticles hold potential applications as functional fillers in the plastic and rubber sectors. [ABSTRACT FROM AUTHOR]

In the reaction of terbium trifluoroacetate Tb(tfa)3(H2O)3 with diethylenetriamine (deta) in air, tetranuclear terbium hydroxotrifluoroacetate [Tb4(OH)4(tfa)3(deta)4(detadcH)2](tfa)4(detaH)(H2O) (Tb4) is obtained and characterized by single crystal X-ray diffraction (XRD), powder XRD, IR spectroscopy, and TGA. The structure of the complex cation with the isolated metal-oxygen cubane core {Tb4(μ-OH)4} and the cation packing motif are analyzed. The thermal behavior of the Tb4 compound in air is studied and its decomposition product is found to be terbium oxide. Tb4 exhibits metal-centered luminescence and can be used as a platform for mixed-metal luminescent materials. [ABSTRACT FROM AUTHOR]

The design of an appropriate analytical method for assessing the quality of pharmaceuticals requires a deep understanding of science, and risk evaluation approaches are appreciated. The current study discusses how a related substance method was developed for Nintedanib esylate. The best possible separation between the critical peak pairs was achieved using an X‐Select charged surface hybrid Phenyl Hexyl (150 × 4.6) mm, 3.5 μm column. A mixture of water, acetonitrile, and methanol in mobile phase‐A (70:20:10) and mobile phase‐B (20:70:10), with 0.1% trifluoroacetic acid and 0.05% formic acid in both eluents. The set flow rate, wavelength, and injection volumes were 1.0 ml/min, 285 nm, and 5 μl, respectively, with gradient elution. The method conditions were validated as per regulatory requirements and United States Pharmacopeia general chapter < 1225 >. The correlation coefficient for all impurities from the linearity experiment was found to be > 0.999. The % relative standard deviation from the precision experiments ranged from 0.4 to 3.6. The mean %recovery from the accuracy study ranged from 92.5 to 106.5. Demonstrated the power of the stability‐indicating method through degradation studies; the active drug component is more vulnerable to oxidation than other conditions. Final method conditions were further evaluated using a full‐factorial design. The robust method conditions were identified using the graphical optimization from the design space. [ABSTRACT FROM AUTHOR]

Here, we first report the 2′-acyloxy-1,3-dicarbonyl compound construction in a three-component oxidative reaction of alkyl ketene dimer with cyclic diacyl peroxide and trimethyl orthoformate. The discovered synthesis allows us to form 2′-functionalized 1,3-dicarbonyl compounds instead of the common 2-functionalized moiety. The reaction between 4-butylidene-3-propyloxetan-2-one and cyclopropyl malonoyl peroxide proceeds in the presence of trifluoroacetic acid and trimethyl orthoformate at 120 °C for 1 h. The synthesized compound was characterized by NMR spectroscopy, mass spectrometry, and IR spectroscopy. [ABSTRACT FROM AUTHOR]

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A robust as well as precise technique aimed at determining the concentration of Cariprazine in bulk drugs along with formulations using RP-HPLC has been developed. The robustness study was optimized using Box Behnken statistical design. Separation was achieved using an Agilent 1260 Infinity II HPLC with an Agilent Zorbax Bonus RP column, as well as the mobile phase contained of methanol and 0.1% trifluoroacetic acid buffer (52.5:47.5) at a flow rate of 1 ml/min. The wavelength was set at 248 nm, and the method had an overall running period of 8 minutes, with the Cariprazine peak retention time at 3.83 min. The method exhibited linearity and accuracy for concentrations ranging from 80 to 120 μg/ml, with an R2 of 0.999 and accuracy RSD of 0.2%, 0.13%, and 0.05% for 80%, 100%, and 120%, respectively. Stress stability testing under basic conditions revealed 53.32% degradation. The technique's limit of detection (LOD) and limit of quantification (LOQ) were very low, at 44.80 ng/ml and 135.60 ng/ml, correspondingly. These findings suggest that this method may be helpful during regular quality control evaluation of Cariprazine Hydrochloride in a variety of pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Two-dimensional Ag(I) coordination polymers containing a sulfur coordination atom, [Ag(tzdt)]n (KGF-24), and [Ag(tzdt)(TFA)]n (KGF-25) (Htzdt = 1,3-thiazolidine-2-thione, TFA = trifluoroacetate), were synthesized and characterized. Time-resolved microwave conductivity measurements and first-principles calculations revealed that KGF-24 and KGF-25 exhibit charge mobility along their (–Ag–S–)n network. [ABSTRACT FROM AUTHOR]

The template cyclomerization of the iminoimide derivatives (obtained by the treatment of diarylfumarodinitriles with NH3 in methanol containing catalytic amounts of dissolved Na) in the presence of SiCl4 in pyridine leads to silicon(IV) octaarylporphyrazine complexes ((HO)2SiPzAr8, Ar = Ph, tBuPh) as a main reaction product. In the case of phenyl-substituted derivative, the formation of a distinctive Si(IV) complex as a byproduct was observed, which according to mass-spectroscopy measurement contains the macrocycle with five diphenylpyrrolic units. The treatment of bishydroxy complexes with tripropylchlorosilane in the presence of magnesium in pyridine leads to the formation of axially siloxylated porphyrazines (Pr3SiO)2SiPzAr8, followed by the reductive contraction of the macrocycle and formation of the corresponding corrolazine complexes (Pr3SiO)SiCzAr8. It is shown that the addition of acid (trifluoroacetic acid, TFA) facilitates the detachment of one siloxy group in (Pr3SiO)2SiPzAr8 and is essential for its Pz → Cz transformation. In the presence of TFA, only one meso-nitrogen is protonated in the porphyrazine complexes (Pr3SiO)2SiPzAr8 (stability constant of the protonated form pKs1 = −0.45 for Ar = Ph; pKs1 = 0.68 for Ar = tBuPh), while two consequent protonation stages are observed for the more basic corrolazine complex (Pr3SiO)SiCzPh8 (pKs1 = 0.93, pKs2 = 0.45). Both types of Si(IV) complexes are poorly fluorescent (ΦF < 0.07). The porphyrazine complexes have low ability to generate singlet oxygen (ΦΔ < 0.15), whereas the corrolazine derivative (Pr3SiO)SiCzPh8 is a very efficient photosensitizer (ΦΔ = 0.76). [ABSTRACT FROM AUTHOR]

High‐detectivity and stable photodetectors (PDs) have been intensively concerned in the field of wireless optical communication, among which perovskite material has become a prospective candidate owing to its outstanding photoelectric properties. However, the defects and mismatched energy levels of perovskite material can significantly reduce the detectivity and stability of PDs. Herein, the CsPbBr2I quantum dots (CQDs) with the surface modulation via potassium trifluoroacetate (KTFA) are utilized to deserve high‐detectivity and stable PDs. The surface modulation for CQDs not only passivates defects by inhibiting vacancies, but also enhances hole transport capacity by modulating energy level mismatch. As a result, the assembled CsPbBr2I PDs show a responsivity of 0.375 A W−1, a detectivity of 1.12 × 1013 Jones and an on/off ratio of 104. More importantly, the CsPbBr2I PDs exhibit excellent long‐term stability for 12 weeks and can withstand 1000 bending cycles. This work provides a guideline for the development of perovskite in wireless optical communication. [ABSTRACT FROM AUTHOR]

A previously developed high‐performance liquid chromatography method combined with pulsed amperometric detection allowed to separate many impurities of paromomycin. However, due to the presence of ion pairing agents and sodium hydroxide in the mobile phase, direct coupling to mass spectrometry for the identification of the chemical structures of the impurities was not an option. Indeed, ion suppression was encountered by trifluoroacetic acid and pentafluoroproponic acid in the mobile phase. A cation self‐regenerating suppressor, which was originally designed for increasing analyte conductivity of ammonia and amines analysis in ion chromatography, was coupled between the liquid chromatography and ion trap‐time of flight‐mass spectrometry and almost all trifluoroacetic acid and pentafluoroproponic acid in the mobile phase was removed. The limit of detection of paromomycin in this integrated system improved significantly to 20 ng/ml (0.4 ng). The chemical structures of 19 impurities were elucidated and seven impurities were reported for the first time. [ABSTRACT FROM AUTHOR]

We developed a method for the fabrication of in-situ reduced bacterial cellulose membrane (BCM) for the simple synthesis of three-dimensional (3D) flexible SERS substrate. Ag NPs with high density were in-situ grown and uniformly distributed on the 3D BCM nanofibers through a controlled "silver mirror reaction" and "volume shrinkage" treatment, which created highly stable and uniform hot spots in the networked SERS substrate. "Hydrogel" BCM was formed by soaking in ammonia solution to hydrolyze the hemiacetal structure of cellulose, followed by in-situ reduction in silver trifluoroacetate (CF3COOAg) solution, the BCM enriched with silver nanospheres (Ag NPs-BCM) substrate was prepared. The results showed that the optimized Ag NPs-BCM substrate exhibited high SERS activity, and displayed an average EF of 5.3 × 108 and RSD of 11.0%, especially when protected from light for 45 days, the SERS performance kept steady. The Ag NPs-BCM substrate was used to detect glutathione (GSH). Interestingly, adding Ellman's reagent (DTNB) to serum, we clearly distinguished the amount of GSH content in cancer and normal using Ag NPs-BCM substrate. This has provided the opportunity to use flexible substrate in rapid biomedical assays. [ABSTRACT FROM AUTHOR]

A 3Fe4S cluster related to M‐cluster of Mo‐nitrogenase is reported. [K(THF)5][Fe3(μ‐bdt)2(μ‐PPh2)(CO)5] (1) is synthesized from photo‐assisted structural rearrangement of [K(THF)2][(μ,κ2‐bdt)Fe2(μ‐PPh2)(CO)5] under visible light irradiation. The molecular structure of 1 consists of a Fe3 core bearing one dithiolate bridge and the second dithiolate group capping onto the metallic plane. The structural motif of 1 is analogous to that of Mo‐participated 3Fe4S unit in M‐cluster of Mo‐nitrogenase, with the similar Fe‐Fe and Fe‐S bond distances. Upon protonation in 193 K, a Fe‐hydride species (1H) is generated and characterized to possess the bridging hydride group (δ = −12.57 ppm) by 1H‐NMR spectroscopy and DFT calculation. In CH3CN solution, complex 1 exhibits a reversible reduction and oxidation process at E1/2red = −1.94 V and E1/2ox = −0.18 V, respectively, at 273 K. The reduction behavior of 1 in CH2Cl2 solution at 243 K displays a slight modification in the presence of trifluoroacetic acid, revealing a moderate anodic potential shift (~50 mV). The current amplitude of the reduction wave is linearly increased with the increasement of acid added, indicative of the catalytic event. [ABSTRACT FROM AUTHOR]

Novel 1,3,4-oxadiazole-functionalized pyrido[2,3-d]pyrimidine derivatives were prepared starting from 2-amino-6-(thiophen-2-yl)-4-(trifluoromethyl)nicotinonitrile, which was reacted with trifluoroacetic acid in the presence of conc. H2SO4 and further with bromoethyl acetate to obtain ethyl 2-{4-oxo-7-(thiophen-2-yl)-2,5-bis(trifluoromethyl)pyrido[2,3-d]pyrimidin-3(4H)-yl}acetate. The reaction of the latter products with hydrazine hydrate gave 2-{4-oxo-7-(thiophen-2-yl)-2,5-bis(trifluoromethyl)pyrido[2,3-d]pyrimidin-3(4H)-yl}acetohydrazide. The subsequent treatment of the products with a series of aromatic acids resulted in the synthesis of 3-[(5-aryl-1,3,4-oxadiazol-2-yl)methyl]-7-(thiophen-2-yl)-2,5-bis(trifluoromethyl)pyrido[2,3-d]pyrimidin-4(3H)-ones and 2-aryl-5-({[7-(thiophen-2-yl)-2,5-bis(trifluoromethyl)pyrido[2,3-d]pyrimidin-4-yl]oxy}methyl)-1,3,4-oxadiazoles. All the synthesized final products were tested for anticancer activity against 4 human cancer cell lines: such as A549-Lung cancer (CCL-185), MCF7-Breast cancer (HTB-22), DU145-Prostate cancer (HTB-81), and HeLa-Cervical cancer (CCL-2). Some of the tested compounds showed promising anticancer activity. [ABSTRACT FROM AUTHOR]

A rapid and efficient acid‐promoted strategy to access allylic thiocyanates using allylic alcohols as substrates and easily‐available NH4SCN as the thiocyanate source is presented under metal‐ and oxidant‐free conditions. Through screening of various kinds of acids, organic and strong trifluoroacetic acid (TFA) was found most effective. Testing of substrates showed that the strategy has remarkable functional group tolerance. A possible mechanism is provided, and the gram‐scale experiment demonstrate that this novel protocol has potential industrial application value. [ABSTRACT FROM AUTHOR]

An easy to handle high-efficient approach to 5-polyfluoroalkyl-1,2,4-triazole-3-thiones (11 examples, up to 91% yield) is reported. The tautomerism of thione and thiol forms for the obtained products is discussed. A one step procedure for 6,6-dimethyl-3-(trifluoromethyl)-5,6-dihydro[1,3]thiazolo[2,3- c ][1,2,4]triazole formation from trifluoroacetic acid and 4-methallylthiosemicarbazide has been developed. The structures of the products were unambiguously determined by complex NMR investigation and by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Polymyxin B (PB) is a dose-dependent drug used to treat multidrug-resistantgram-negative bacteria, for which a suitable method is needed to determine clinical samples. A simple, economical, and efficient high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method was developed and validated for polymyxin B1 (PB1), polymyxin B1-Ile (PB1-I), polymyxin B2 (PB2), and polymyxin B3 (PB3) in human plasma. Chromatographic column was Waters BEH C18 column (2.1 × 50 mm, 1.7 μm). Phase A was water with 0.2% formic acid (FA), and phase B was acetonitrile containing 0.2% FA. The elution method is gradient elutio. The total analysis time was 5 min. The pretreatment method involved protein precipitation using acetonitrile containing 0.2% trifluoroacetic acid and 0.1% FA as the precipitant. The recovery rate was 92–99%. The total quantity of PB1 and PB1-I was measured in the linear range of 100–8000 ng/mL. Simultaneously, the total amounts of PB2 and PB3 were measured in the linear range of 11.9–948.5 ng/mL. This validated method was successfully applied to the pharmacokinetics of PB in critically ill patients. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Regioselective electrochemical hydroalkylations of [60]fullerene‐fused furochromenone with alky halides under different acidic conditions unexpectedly afford three types of tetra‐functionalized [60]fullerene derivatives in high yields. When acetic acid is used as the proton source, two 1,2,3,4‐adducts with retained or rearranged five‐membered heterocycle are obtained as major and minor products, respectively. While trifluoroacetic acid is employed as the proton source, 1,2,3,16‐adducts and 1,2,3,4‐adducts, both with the five‐membered heterocycle rearranged from [6,6]‐junction to [5,6]‐junction, are generated. Intriguingly, the obtained 1,2,3,16‐adducts can be transformed into 1,2,3,4‐adducts accompanied by rearrangement of the fused five‐membered heterocycle from [5,6]‐junction to [6,6]‐junction. These products have been characterized by spectroscopic data and single‐crystal X‐ray analysis. Moreover, the two 1,2,3,4‐adducts with the heterocycle fused to [5,6]‐junction or [6,6]‐junction show diagnostic UV‐vis spectra, which may be useful for the identification of these two types of 1,2,3,4‐adducts in the future. A plausible reaction mechanism has been proposed to elucidate the formation of hydroalkylation products in the presence of different acids. [ABSTRACT FROM AUTHOR]

While trifluoroacetic acid has limited technical uses, the highly water-soluble trifluoroacetate (TFA) is reported to be present in water bodies at low concentrations. Most of the TFA in the environment is discussed to arise from natural processes, but also with the contribution from decomposition of environmental chemicals. The presence of TFA may result in human exposures. For hazard and risk assessment, the mammalian toxicity of TFA and human exposures are reviewed to assess the margin of exposures (MoE). The potential of TFA to induce acute toxicity is very low and oral repeated dose studies in rats have identified the liver as the target organ with mild liver hypertrophy as the lead effect. Biomarker analyses indicate that TFA is a weak peroxisome proliferator in rats. TFA administered to rats did not induce adverse effects in an extended one-generation study and in a developmental toxicity study or induce genotoxic responses. Based on recent levels of TFA in water and diet, MoEs for human exposures to TFA are well above 100 and do not indicate health risks. [ABSTRACT FROM AUTHOR]

The complex [Re(CO)3(Ph4TAP)(OCOCF3)] where Ph4TAP is 2,3,6,7-tetraphenyl-1,4,5,8-tetraazaphenanthrene was synthesized, characterized and fully studied by computational approaches. The structural aspects of the complex were compared with similar structures YIBRIL and PODWIR available in the Cambridge Structural database (CSD). The intra- and intermolecular interactions were theoretically determined by QTAIM, non-covalent interaction index-independent gradient model (NCI-IGM), and natural bond orbital (NBO) approaches and compared with similar structures. The complex showed interesting intermolecular n → π* and C–H⋯π interactions which were supported by non-classic C–H⋯O hydrogen bonding, mediating the supramolecular assembly of molecules into two concurrent chains along the b- and c-axes. The molecular structure shows an interesting intramolecular n → π* interaction between the carboxylate group and metal-bound carbonyl ligand and also intramolecular π⋯π* contacts of the equatorial metal-bound carbonyls and the peripheral phenyl rings. Additionally, energy decomposition analysis combined with natural orbital for chemical valence (EDA–NOCV) analysis has been performed to estimate the pairwise interaction energies in the title complex and its dimer associates. [ABSTRACT FROM AUTHOR]

A novel synthesis of degenerate [2]rotaxanes with two different amine stations is presented. Variable‐temperature 1H NMR and rotating‐frame nuclear Overhauser effect correlation spectroscopy experiments revealed that the addition of trifluoroacetic acid initiates molecular shuttling. The activation barrier for the motion remained constant even when the amine in the outer station was changed. Conversely, the addition of camphorsulfonic acid caused a rotational motion, which was demonstrated by synthesizing a new [2]rotaxane without an outer station and examining its molecular behavior in the presence of acid. [ABSTRACT FROM AUTHOR]

Background: Targeted radionuclide therapy with [177Lu]Lu-PSMA I&T (zadavotide guraxetan) has proven high efficacy and safety in treating patients with advanced prostate cancer worldwide. Several methods to determine the radiochemical purity have been reported but also limitations in the HPLC analysis due to retention of the sample and tailing effects when using standard gradients containing trifluoroacetic acid (TFA). We here report on the validation of a method for quality control of [177Lu]Lu-PSMA I&T including determination of radiochemical purity, identity testing and limit test for PSMA I&T by HPLC using a Phosphate buffer /Acetonitrile gradient system, complemented with a TLC system with 0.1N Citrate buffer pH 5 as mobile phase including validation of the methods, batch and stability data as well as identification of the main radiochemical impurity by mass spectrometry. Results: The described HPLC method met the defined acceptance criteria in terms of accuracy, specificity, robustness, linearity, range and LOQ. HPLC analysis revealed symmetrical peaks and quantitative recovery from the column. Batch data showed a radiochemical purity > 95% as determined by HPLC, stability data a pronounced degradation due to radiolysis, which could be limited by addition of ascorbic acid, dilution and storage at low temperatures. The main radiochemical impurity was found to be the de-iodinated form of [177Lu]Lu-PSMA I&T. TLC analysis allowed to determine the amount of free Lu-177 even in the presence of DTPA in the final formulation. Conclusion: Overall the described combination of HPLC and TLC provides a reliable tool for quality control of [177Lu]Lu-PSMA I&T. [ABSTRACT FROM AUTHOR]

Background: Per- and polyfluorinated alkyl substances (PFAS) have received increasing scientific and political attention in recent years. Several thousand commercially produced compounds are used in numerous products and technical processes. Due to their extreme persistence in the environment, humans and all other life forms are, therefore, increasingly exposed to these substances. In the following review, PFAS will be examined comprehensively. Results: The best studied PFAS are carboxylic and sulfonic acids with chain lengths of C4 to C14, particularly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These substances are harmful to aquatic fauna, insects, and amphibians at concentrations of a few µg/L or less, accumulate in organisms, and biomagnify in food webs. Humans, as the final link in numerous food chains, are subjected to PFAS uptake primarily through food and drinking water. Several PFAS have multiple toxic effects, particularly affecting liver, kidney, thyroid, and the immune system. The latter effect is the basis for the establishment of a tolerable weekly dose of only 4.4 ng/kg body weight for the sum of the four representatives PFOA, PFOS, perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) by the European Food Safety Authority (EFSA) in 2020. Exposure estimates and human biomonitoring show that this value is frequently reached, and in many cases exceeded. PFAS are a major challenge for analysis, especially of products and waste: single-substance analyses capture only a fragment of the large, diverse family of PFAS. As a consequence, sum parameters have gained increasing importance. The high mobility of per and polyfluorinated carboxylic and sulfonic acids makes soil and groundwater pollution at contaminated sites a problem. In general, short-chain PFAS are more mobile than long-chain ones. Processes for soil and groundwater purification and drinking water treatment are often ineffective and expensive. Recycling of PFAS-containing products such as paper and food packaging leads to carryover of the contaminants. Incineration requires high temperatures to completely destroy PFAS. After PFOA, PFOS and a few other perfluorinated carboxylic and sulfonic acids were regulated internationally, many manufacturers and users switched to other PFAS: short-chain representatives, per- and polyfluorinated oxo carboxylic acids, telomeric alcohols and acids. Analytical studies show an increase in environmental concentrations of these chemicals. Ultra-short PFAS (chain length C1–C3) have not been well studied. Among others, trifluoroacetic acid (TFA) is present globally in rapidly increasing concentrations. Conclusions: The substitution of individual PFAS recognized as hazardous by other possibly equally hazardous PFAS with virtually unknown chronic toxicity can, therefore, not be a solution. The only answer is a switch to fluorine-free alternatives for all applications in which PFAS are not essential. [ABSTRACT FROM AUTHOR]

A series of new substituted tetrahydropyrimidines was obtained by the reaction of sodium [1-(3,3-diethoxypropyl)ureido]methanesulfonates with various C-nucleophiles (4-chlororesorcinol, sesamol, 2,4-dihydroxybenzoic acid, 4-hydroxy-6-methyl-2H-pyran-2-one) in chloroform in the presence of trifluoroacetic acid. [ABSTRACT FROM AUTHOR]

Syntheses and X-ray crystal structures of four 4-(4-methoxyphenyl)piperazin-1-ium (MeOPP) salts, with 2,2,2-trifluoroacetate, C11H17N2O+πC2F3O2- (I), 2,3,4,5,6-pentafluorobenzoate, C11H17N2O+πC7F5O2-πH2O (II), 4-iodobenzoate C11H17N2O+πC7H4IO2-πH2O (III), and 4-methylbenzoate, C11H17N2O+π- C8H7O2-πH2O (IV) anions are presented. The salts form directly from equimolar quantities of N-(4-methoxyphenyl)piperazine and the corresponding organic acid in methanol and crystallize from 1:1 methanol/ethyl acetate. Salt I is anhydrous whereas II, III, and IVare all monohydrates. In all cases, the MeOPP cation conformation is determined by the torsion about the N--C bond between the piperazinium and 4-methoxybenzene rings. Crystal packing in each structure is largely dictated by N--Hπ π πO and (in II, III, and IV) O--Hπ π πO hydrogen bonds, although each also features weak C--Hπ π πO-type hydrogen bonds. Salt II also has π-π-stacking interactions between cation and anion arene rings, and III exhibits Iπ π πI close contacts. [ABSTRACT FROM AUTHOR]

Gambir (Uncaria gambir Roxb) has long been thought to provide various health benefits due to the main secondary metabolite, catechin. The high catechin content makes gambir a strong antioxidant. The present study was conducted to develop and validate the quantification of catechin in gambir leaves by high-performance liquid chromatography (HPLC). The method was performed using a 100 mL sample with dilution. The separation process employed a Sunfire C18 (150 mm x 4.6 mm) column, the mobile phase was composed of solvent A: 0.03% trifluoroacetic acid in acetonitrile-water (5:95) and solvent B: 0.1% trifluoroacetic acid in acetonitrile at a 0.45 mL/min flow rate. The validation was conducted by measuring the accuracy, precision, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The results showed that the percent recovery was 98.30-99.82% with a precision value of 0.28% RSD, good linearity with a 0.9996 R-value, 2.7 µg/mL of LOD, and 8.3 µg/mL of LOQ. There was no significant difference between changes in the mobile phase of 4% (comparison of area and retention time), and 6% (comparison of area). However, the results also demonstrated that the mobile phase was not resistant to changes in the mobile phase of 6% in the ratio of retention time because of the shift in retention time that was faster than the catechin standard. The findings of this study reveal that this method satisfies the validation requirements for accuracy, precision, linearity, and robustness tests, therefore, the HPLC-based method can be applied to analyze catechin in gambir leaves. [ABSTRACT FROM AUTHOR]

While reports of innovations in the production of cellulose nanocrystals (CNCs) are common, strategies for dispersing CNCs in various media, on which many practical applications depend, are limited. Although the suspension of surface-modified cellulose nanoparticles in water and other media has been described, dispersion of native CNCs in common solvents is challenging. Here, we show that trifluoroacetic acid, a volatile liquid which is miscible both with water and organic solvents, can be used to prepare metastable, turbid suspensions of native CNCs that clarify and stabilize over the course of several hours. These suspensions were characterized by imaging (TEM/AFM), thermal analysis (TGA), spectroscopic analysis (FT-IR and NMR), and evolution of crystallinity (XRD). Composite films could be made from these suspensions and waste poly(ethylene terephthalate) (PET) by simple evaporation of the TFA medium and subsequent washing with water. These films were observed to be hydrophilic and porous, and were characterized by SEM and porosimetry.

[Display omitted] The use of excess of trifluoroacetic acid in chloroform (1 : 1, v/v) in a one-pot acid-catalyzed cyclocondensation of functionalized benzaldehydes with 2-methylresorcinol significantly improves the yield of calix[4]resorcinol rccc diastereoisomers compared to rctt ones. The fraction and yield of the rccc isomers sometimes approach 100% along with shortening the reaction time. The structure of new rccc diastereoisomer of chlorine-containing calix[4]resorcinol has been established by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Developing silica membranes that are highly selective for CO2 has always been a challenge due to the small sizes of the pores and less amount of CO2 philic sites in a typical silica network structure. Herein, we describe the fabrication of silica (tetraethoxysilane) membranes functionalized with 3-aminopropyltriethoxysilyl (APTES) and trifluoroacetic acid (TFA). An interaction generated among primary (NH2) amines and TFA was identified, which was then also revealed by the reversible nature of CO2 adsorption/desorption — an opposite trend from observations when using another catalyst (HCl). The resultant TEOS-APTES (TFA) membranes demonstrated CO2 permeance of 3.8 × 10−7 mol m − 2 s − 1 Pa−1 and CO2/N2 selectivity of 35 at 50 ⁰C via the effect of surface diffusion. This is attributed to the increased microporosity and structural variations affected by TFA, which enhanced molecular sieving and controls the CO2-philic sites (-NHCOCF3) via interaction with amines. This novel approach would be effective for the energy-efficient fabrication of highly CO2-permeable membranes.

The complexation between tiara[5]arene (T[5]) and silver trifluoroacetate affords a binuclear metallo-pseudorotaxane on account of multiple endo-cavity AgI η2-arene interactions. Furthermore, two such enantiomeric [(CF3CO2Ag)2⊂T[5]] complexes are bridged by an extra (CF3CO2Ag)2 dimer through exo-wall AgI η2-arene coordination, resulting in a unique handcuff metallo-bis-pseudorotaxane structure in the solid state. [ABSTRACT FROM AUTHOR]

Significant progress has been made in the bioinorganic modeling of the paramagnetic states believed to be involved in the hydrogen redox chemistry catalyzed by [NiFe] hydrogenase. However, the characterization and isolation of intermediates involved in mononuclear Ni electrocatalysts which are reported to operate through a NiI/III cycle have largely remained elusive. Herein, we report a NiII complex (NCHS2)Ni(OTf)2, where NCHS2 is 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane, that is an efficient electrocatalyst for the hydrogen evolution reaction (HER) with turnover frequencies of ~3,000 s−1 and a overpotential of 670 mV in the presence of trifluoroacetic acid. This electrocatalyst follows a hitherto unobserved HER mechanism involving C-H activation, which manifests as an inverse kinetic isotope effect for the overall hydrogen evolution reaction, and NiI/NiIII intermediates, which have been characterized by EPR spectroscopy. We further validate the possibility of the involvement of NiIII intermediates by the independent synthesis and characterization of organometallic NiIII complexes. The characterization of nickel (Ni)‐centred paramagnetic states relevant to [NiFe] hydrogenases is rare in mononuclear Ni hydrogen evolution catalysts. Here, the authors report the spectroscopic and synthetic characterization of NiI and NiIII states in an organometallic Ni hydrogen evolution catalyst. [ABSTRACT FROM AUTHOR]

Amino-[1,1′]-biphenyl-containing 3-aryl-[1,2,4]triazolo[4,3-c]quinazoline derivatives with fluorescent properties have been designed and synthesized. The type of annelation of the triazole ring to the pyrimidine one has been unambiguously confirmed by means of an X-ray diffraction (XRD) method; the molecules are non-planar, and the aryl substituents form the pincer-like conformation. The UV/Vis and photoluminescent properties of target compounds were investigated in two solvents of different polarities and in a solid state. The samples emit a broad range of wavelengths and display fluorescent quantum yields of up to 94% in toluene solutions. 5-(4'-Diphenylamino-[1,1′]-biphenyl-4-yl)-3-(4-(trifluoromethyl)phenyl)-[1,2,4]triazolo[4,3-c]quinazoline exhibits the strongest emission in toluene and a solid state. Additionally, the solvatochromic properties were studied for the substituted [1,2,4]triazolo[4,3-c]quinazolines. Moreover, the changes in absorption and emission spectra have been demonstrated upon the addition of water to MeCN solutions, which confirms aggregate formation, and some samples were found to exhibit aggregation-induced emission enhancement. Further, the ability of triazoloquinazolines to detect trifluoroacetic acid has been analyzed; the presence of TFA induces changes in both absorption and emission spectra, and acidochromic behavvior was observed for some triazoloquinazoline compounds. Finally, electronic-structure calculations with the use of quantum-chemistry methods were performed for synthesized compounds. [ABSTRACT FROM AUTHOR]

A series of manganese corroles bearing different substituents had been prepared and characterized by UV–vis, 1H NMR, 19F NMR, HRMS and XPS. These manganese corrole complexes were applied to electrocatalytic hydrogen evolution reaction (HER) for the first time. The results showed that manganese corroles are effective catalysts for HER in DMF solvent by using acetic acid (AcOH), trifluoroacetic Acid (TFA) and p-toluenesulfonic acid (TsOH) proton sources, and strong acid leads to higher electrocatalytic activity. When using TsOH as proton source, protonation of corroles ligand may be involved in HER. The electrocatalytic HER activity can be improved by increasing the electron-withdrawing substituent of the corrole macrocycle in both organic and aqueous media. [Display omitted] • Manganese corrole was firstly used as HER electrocatalyst. • Manganese corrole exhibits good electrocatalytic HER activity in aqueous solution. • Electron-withdrawing substituent benefits the HER activity. [ABSTRACT FROM AUTHOR]

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It has been widely postulated that thermal degradation of polytetrafluoroethylene (PTFE; commercially known as Teflon) under the presence of moisture presents a likely source for the formation of the notorious perfluorocarboxylic acids (CF3(CF2)nCO(OH) PFCAs) and perfluorinated aldehydes (CF3(CF2)nCO(F/H). Thus, deployment of objects laden with Teflon at the peak of their thermal stability may contribute to the atmospheric budget of PFCAs. However, the underlying mechanism remains largely speculative. This study reports potential energy surfaces for reactions that govern oxidative transformation of n-C8F18 (as a model compound of PTFE) into tridecafluoroheptanoyl fluoride and perfluoroheptanoic acid. Central to computed pathways are dissociative addition reactions of water over the carbonyl group and elimination of hydroperoxyl radicals. Facile activation enthalpies are encountered in the involved steps. Our analysis discloses that formation of the building monomer C2F4 should be suppressed under thermolysis oxidation conditions at which synthesis of trifluoroacetic acids is preferred. Constructed kinetic model illustrates a near-complete conversion of the PTFE model compound into perfluorocarboxylic acids (CF3(CF2)nCO(OH) and perfluorinated aldehydes. Outcomes from this study should be instrumental in providing a better understanding of the likely contribution of fluoropolymers in the observed environmental loads of perfluorocarboxylic acids. [ABSTRACT FROM AUTHOR]

Linear polycyclic systems are promising candidates in the area of organic electronics. Herein, we present the syntheses of three azulene‐indole (AzIn) fused polycyclic heteroaromatics (PHAs), AzIn‐1, AzIn‐2 and DGAzIn, which have nitrogens and nonhexagonal rings simultaneously. The chemical structures, optical and electrochemical properties of three AzIn‐based PHAs have been investigated, as well as their protonation behaviors with trifluoroacetic acid (TFA). All three AzIn‐based PHAs exhibit narrow optical band gaps with moderate to good air stability, anti‐Kasha emission and reversible stimuli‐responsiveness. Furthermore, these straightforward and simple synthetic routes would provide a new entry for constructing novel azulene‐embedded π‐conjugates, especially for the seven‐membered ring of azulene unit, wherein the regioselective transformation is not well developed. [ABSTRACT FROM AUTHOR]

Tanacetum vulgare is an herbaceous plant widely used in folk medicine. It is rich in phenolic acids and flavonoids, which have pharmacological and medicinal properties, such as anthelmintic, antispasmodic, tonic, antidiabetic, diuretic, and antihypertensive. This study aimed to confirm the presence of biologically active substances in Tanacetum vulgare and to determine the pharmacological spectrum of biological activity of Tanacetum vulgare extract components. When preparing Tanacetum vulgare extracts, the highest yield was observed when using the maceration method with a mixture of solvents methanol + trifluoroacetic acid (22.65 ± 0.68%). The biologically active substances in Tanacetum vulgare extract samples were determined using high-performance liquid chromatography. Biologically active substances such as luteolin-7-glucoside (550.80 mg/kg), chlorogenic acid (5945.40 mg/kg), and rosmarinic acid (661.31 mg/kg) were identified. Their structures were determined. The experiments have confirmed the antioxidant and antibacterial activities. Secondary metabolites of Tanacetum vulgare extracts have been found to have previously unknown biological activity types; experimental confirmation of their existence will advance phytochemical research and lead to the development of new drugs. [ABSTRACT FROM AUTHOR]

The protonation of thioanisols by strong acids, such as trifluoroacetic acid or trifluoromethane sulfonic acid was investigated by 1H NMR spectroscopy, including experiments with deuterated acids. Contrary to reported literature and to general expectations, protonation of thioanisole does not occur exclusively at the methylmercapto group but also to a lower extent at the aromatic ring. In cases of methoxy-substituted thioanisols protonation can take place at both heteroatomic groups and at the aromatic ring. The sites of protonation depend on the substituent pattern as unambiguously indicated by deuteration. [ABSTRACT FROM AUTHOR]

The protonation of thioanisols by strong acids, such as trifluoroacetic acid or trifluoromethane sulfonic acid was investigated by 1H NMR spectroscopy, including experiments with deuterated acids. Contrary to reported literature and to general expectations, protonation of thioanisole does not occur exclusively at the methylmercapto group but also to a lower extent at the aromatic ring. In cases of methoxy-substituted thioanisols protonation can take place at both heteroatomic groups and at the aromatic ring. The sites of protonation depend on the substituent pattern as unambiguously indicated by deuteration. [ABSTRACT FROM AUTHOR]

Synthesis of new ionic liquid methacrylates and dimethacrylates is described comprising ammonium structures and various anions (bis(trifluoromethylsulfonyl)imide (NTf2), tris(pentafluoroethyl)trifluorophosphate (FAP), triflate (TFl), and trifluoroacetate (TFAc)). The structure of the anion has a stronger effect on both melting behavior and photopolymerization kinetics compared to the cation pattern. Photo‐differential scanning calorimetry investigation shows significant differences in the polymerization rate and final conversion depending on both the polymerization technique (bulk or solution polymerization using an ionic liquid as solvent) and the ionic liquid monomer under consideration. The results show that NTf2 or FAP should be preferred as anion over TFl and TFAc in the crosslinking photoinitiated polymerization because NTf2 and FAP result in both faster polymerization and higher final conversion. Interestingly, the presence of an ionic liquid methacrylate comprising the same anion as the ionic liquid dimethacrylate during the photoinitiated polymerization of the ionic liquid dimethacrylates results in an increase in final conversion that may be caused by lower crosslink density of the network formed, and therefore, higher mobility during the crosslinking process. [ABSTRACT FROM AUTHOR]