RESUMEN

A novel fluorenone-naphthyl pendant sensor (FTU) possessing thiourea functionality has been synthesized via a simple condensation method and utilized for the recognition of F- and Hg2+ ions in the solution of CH3CN. The addition of F- and Hg2+ ions to the FTU solution led to the appearance of red-shifted absorption bands at 340 and 315 nm, respectively. On the other hand, in the fluorescence spectrum, the two-fold decrease in fluorescence intensity of probe FTU was observed with F- ions; while complete quenching of the fluorescence intensity was noticed with Hg2+ ions at 423 nm. The limit of detection values of F- and Hg2+ ions were found to be 1.02 & 29.1 nM, respectively, measured by UV-vis studies and 0.0185 & 0.81 nM, respectively, measured by fluorescence studies, which are less than recommended by WHO. DFT computational assessments and 1H NMR titration experiments pointed to F- induced deprotonation of thiourea NH signals. However, the chelation-enhanced quenching effect (CHEQ) was held responsible for fluorescence quenching with Hg2+ addition. Moreover, the in-situ formed FTU + F- complex was utilized for secondary sensing of drug sobisis. Furthermore, the real-world applicability of sensor FTU has been successfully scrutinized for the recognition of F- ions in the toothpaste samples. In addition, molecular docking studies revealed that FTU exhibited excellent antibacterial potency towards different gram-positive as well as negative strains.

RESUMEN

The 2,7-fluorenone-linked bis(6-imidazo[1,5-a]pyridinium) salt H2-1(PF6)2 reacts with Ag2O in CH3CN to yield the [2]catenane [Ag4(1)4](PF6)4. The [2]catenane rearranges in DMF to yield two metallamacrocycles [Ag2(1)2](PF6)2. 2,7-Fluorenone-bridged bis-(imidazolium) salts H2-L(PF6)2 (L=2 a, 2 b) react with Ag2O in CH3CN to yield metallamacrocycles [Ag2(L)2](PF6)2 with interplanar distances between the fluorenone rings too small for [2]catenane formation. Intra- and intermolecular π⋅⋅⋅π interactions between the fluorenone groups were observed by X-ray crystallography. The strongly kinked 2,7-fluorenone bridged bis(5-imidazo[1,5-a]pyridinium) salt H2-4(PF6)2 reacts with Ag2O to yield [Ag2(4)(CN)](PF6), while the tetranuclear assembly [Ag4(4)2(CO3)](PF6)2 was obtained in the presence of K2CO3.

RESUMEN

Addressing critical challenges in enhancing the oxidative stability and proton conductivity of high-temperature proton exchange membranes (HT-PEMs) is pivotal for their commercial viability. This study uncovers the significant capacity of multiwalled carbon nanotubes (MWNTs) to absorb a substantial amount of phosphoric acid (PA). The investigation focuses on incorporating long-range ordered hollow MWNTs into self-cross-linked fluorenone-containing polybenzimidazole (FPBI) membranes. The absorbed PA within MWNTs and FPBI forms dense PA networks within the membrane, effectively enhancing the proton conductivity. Moreover, the exceptional inertness of MWNTs plays a vital role in reinforcing the oxidation resistance of the composite membranes. The proton conductivity of the 1.5% CNT-FPBI membrane is measured at 0.0817 S cm-1 at 160 °C. Under anhydrous conditions at the same temperature, the power density of the 1.5% CNT-FPBI membrane reaches 831.3 mW cm-2. Notably, the power density remains stable even after 200 h of oxidation testing and 250 h of operational stability in a single cell. The achieved power density and long-term stability of the 1.5% CNT-FPBI membrane surpass the recently reported results. This study introduces a straightforward approach for the systematic design of high-performance and robust composite HT-PEMs for fuel cells.

RESUMEN

The targeted compounds were prepared using both (9H-fluoren-9-ylidene)hydrazine (1) and 10H-phenothiazine (2) as starting materials. The treatment of 1 or 2 with different isocyanates afforded the title compounds 7a-d, 8a, and 8b in excellent yield. All compounds were characterized and ascertained by infrared, nuclear magnetic resonance, and elemental analyses as well as single-crystal X-ray diffraction. The antimicrobial efficiency of all was tested in vitro, and a noticeable inhibition activity against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans was obtained by compounds 7a, 7b, 8a, and 8b. Moreover, the biofilm mechanism activity was strongly inhibited by compounds 7b and 8b for all bacterial pathogens, with a percentage ratio of more than 55%. The findings from the molecular docking simulation revealed that compounds 7a, 7b, 8a, and 8b exhibited favorable binding energies and interacted effectively with the active sites of sterol 14-demethylase, dihydropteroate synthase, gyrase B, LasR (major transcriptional activator of P. aeruginosa), and carbapenemase for C. albicans, S. aureus, B. subtills, K. pneumoniae, and P. aeruginosa, respectively. These results suggest that the compounds have the potential to inhibit the activity of these enzymes and demonstrate promising antimicrobial properties. Moreover, the in silico evaluation of drug likeness and absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles for compounds 7a, 7b, 8a, and 8b demonstrated their compatibility with Lipinski's, Ghose's, Veber's, Muegge's, and Egan's rules. These findings suggest that these compounds possess favorable physicochemical properties, making them promising candidates for continued drug development efforts.

Asunto(s)

RESUMEN

The Sonogashira coupling reaction was used to synthesize a fluorenone derivative, with an extended conjugated structure to which fluorene is connected via acetylene linkage. This compound exhibited diverse fluorescence (FL) colors in the visible region depending on the polarity of the matrix solvents used. The solvatochromic FL presented as sky blue, green, and yellow in hexane, THF, and DMF, respectively. Fluorene moiety and fluorenone moiety acted as an electron donor (D) and as an electron acceptor (A), respectively, leading to an excited state intramolecular charge transfer based on the D-π-A electronic structure. In particular, this derivative showed a remarkable FL quenching in alcohol and chloroform, probably due to vibronic coupling through hydrogen bonding with these solvents. This idea was supported by the fact that the two solvents are characterized by very high hydrogen bond donor acidities compared to other solvents used in this study. This derivative also responded to the presence of very small amounts of water at several mg/mL levels in organic solvents, resulting in remarkable FL quenching.

RESUMEN

Human immunodeficiency virus-type 1 (HIV-1) remains one of the leading contributors to the global burden of disease, and novel antiretroviral agents with alternative mechanisms are needed to cure this infection. Here, we describe an exploratory attempt to optimize the antiretroviral properties of benfluron, a cytostatic agent previously reported to exhibit strong anti-HIV activity likely based on inhibitory actions on virus transcription and Rev-mediated viral RNA export. After obtaining six analogs designed to modify the benzo[c]fluorenone system of the parent molecule, we examined their antiretroviral and toxicity properties together with their capacity to recognize the Rev Recognition Element (RRE) of the virus RNA and inhibit the RRE-Rev interaction. The results indicated that both the benzo[c] and cyclopentanone components of benfluron are required for strong RRE-Rev target engagement and antiretroviral activity and revealed the relative impact of these moieties on RRE affinity, RRE-Rev inhibition, antiviral action and cellular toxicity. These data provide insights into the biological properties of the benzo[c]fluorenone scaffold and contribute to facilitating the design of new anti-HIV agents based on the inhibition of Rev function.

Asunto(s)

RESUMEN

A novel fluorenone appended Schiff base (L) has been synthesized and utilized for studying the binding interactions with Calf Thymus DNA (ct-DNA). The mechanism of binding with ct-DNA was explored by employing various spectroscopic techniques viz. UV-Vis absorption spectroscopy, fluorescence emission spectroscopy, gel-electrophoresis, circular dichroism (CD), melting studies, viscosity arrays and molecular modeling methodology. The interpretation of UV-vis absorbance spectra pointed to binding of L within minor groove of ct-DNA with the binding constant of Kb = 0.15 × 104 M-1. Dye-displacement studies with Rhodamine-B (RhB) and Ethylene Bromide (EB) in fluorescence spectroscopy verified the groove binding mode of interaction between L and ct-DNA. Melting studies, circular dichroism, and viscosity studies further elucidated the binding modes of L with ct-DNA. Thermodynamic variable measurements taken at various temperatures such as ΔG°, ΔH°, and ΔS° revealed that hydrophobic forces played a significant role in the binding process. The meticulous computational interaction demonstrated by molecular docking confirmed the minor groove binding of L with ct-DNA.

Asunto(s)

RESUMEN

The unprecedented increase in microbial resistance rates to all current drugs raises an acute need for the design of more effective antimicrobial strategies. Moreover, the importance of oxidative stress due to chronic inflammation in infections with resistant bacteria represents a key factor for the development of new antibacterial agents with potential antioxidant effects. Thus, the purpose of this study was to bioevaluate new O-aryl-carbamoyl-oxymino-fluorene derivatives for their potential use against infectious diseases. With this aim, their antimicrobial effect was evaluated using quantitative assays (minimum inhibitory/bactericidal/biofilms inhibitory concentrations) (MIC/MBC/MBIC), the obtained values being 0.156-10/0.312-10/0.009-1.25 mg/mL), while some of the involved mechanisms (i.e., membrane depolarization) were investigated by flow cytometry. The antioxidant activity was evaluated by studying the scavenger capacity of DPPH and ABTS•+ radicals and the toxicity was tested in vitro on three cell lines and in vivo on the crustacean Artemia franciscana Kellog. The four compounds derived from 9H-fluoren-9-one oxime proved to exhibit promising antimicrobial features and particularly, a significant antibiofilm activity. The presence of chlorine induced an electron-withdrawing effect, favoring the anti-Staphylococcus aureus and that of the methyl group exhibited a +I effect of enhancing the anti-Candida albicans activity. The IC50 values calculated in the two toxicity assays revealed similar values and the potential of these compounds to inhibit the proliferation of tumoral cells. Taken together, all these data demonstrate the potential of the tested compounds to be further used for the development of novel antimicrobial and anticancer agents.

Asunto(s)

RESUMEN

The development of high-performance n-type polymer semiconductors is powered by the design and synthesis of electron-deficient building blocks with optimized physicochemical properties. By meticulously installing an imide group onto fluorene and its cyanated derivative, we report here two very electron-deficient building blocks, imide-functionalized fluorenone (FOI) and its cyanated derivative (FCNI), both featuring a deep-lying lowest unoccupied molecular orbital energy level down to -4.05 eV and highly coplanar framework, endowing them ideal units for constructing n-type polymers. Thus, a series of polymers are built from them, exhibiting unipolar n-type transport character with a highest electron mobility of 0.11 cm2  V-1 s-1 . Hence, FOI and FCNI offer a remarkable platform for accessing high-performance n-type polymers and the imide functionalization of appropriate (hetero)arenes is a powerful strategy for developing polymers with deep-lying LUMOs for n-type organic electronics.

RESUMEN

Preparation of organic crystals mainly depends on solution-deposition, sublimation, and melt-deposition techniques. Solid-state growth methods are generally not suitable for organic crystal growth due to the unprocurable mass transfer. Herein, we report two pyridine-substituted fluorenone compounds with extraordinary crystal-growth capacity, and these compounds can directly and quickly form single crystals from their amorphous solid powder by heating under antisolvent-assistance conditions. The novel experimental phenomenon and crystal growth mechanism were investigated in depth. The results indicate that multiple intermolecular hydrogen-bonding sites and planar aromatic structure (prone to π-π interactions) of these molecules dominate the mass transfer during crystal growth by providing enough energy. This discovery enhances our knowledge of solid-state methods for single-crystal growth.

RESUMEN

Antimicrobial resistance is one of the major public health threats at the global level, urging the search for new antimicrobial molecules. The fluorene nucleus is a component of different bioactive compounds, exhibiting diverse pharmacological actions. The present work describes the synthesis, chemical structure elucidation, and bioactivity of new O-aryl-carbamoyl-oxymino-fluorene derivatives and the contribution of iron oxide nanoparticles to enhance the desired biological activity. The antimicrobial activity assessed against three bacterial and fungal strains, in suspension and biofilm growth state, using a quantitative assay, revealed that the nature of substituents on the aryl moiety are determinant for both the spectrum and intensity of the inhibitory effect. The electron-withdrawing inductive effect of chlorine atoms enhanced the activity against planktonic and adhered Staphylococcus aureus, while the +I effect of the methyl group enhanced the anti-fungal activity against Candida albicans strain. The magnetite nanoparticles have substantially improved the antimicrobial activity of the new compounds against planktonic microorganisms. The obtained compounds, as well as the magnetic core@shell nanostructures loaded with these compounds have a promising potential for the development of novel antimicrobial strategies.

Asunto(s)

RESUMEN

N-Acyloxy-N-alkoxyamides are direct-acting mutagens in S. typhimurium TA100 and TA98. A reliable QSAR for their activity in TA100 has been developed, which indicates reversible intercalation into the DNA helix through naphthalene substituents. In this paper, we show that fluorene as a substituent does not facilitate intercalation while fluorenone does, although the efficacy is determined by the position of substitution on the fluorenone as well as the N-acyloxy-N-alkoxyamide side chain. Where intercalation is evident, the increased binding to DNA is similar to that of naphthalene and is worth the equivalent of ca four LogP hydrophobicity units. 4-Substituted fluorenones, where the anomeric amide group is in the bay region do not intercalate, which is attributed to the requirement for a weaker edge-on, rather than an end-on intercalation. Mutagencity in S. typhimurium TA98, which detects frame shifts through intercalation, supports the findings. Fluorene appears not to intercalate, which points to the fact that the charge delocalised 2-fluorenylnitrenium ion, the ultimate metabolite from 2-aminofluorene (AF) and 2-acetylaminofluorene (AAF) is the itercalating agent responsible for frameshift mutations leading to their carcinogenicity.

Asunto(s)

RESUMEN

The development of fluorescent dyes capable of selective recognition of G-quadruplexes is essential for studying its localization and biological functions. However, considering the G-quadruplex topologies may vary significantly, the synthesis of compounds showing both selectivity and strong fluorescence properties still remains a great challenge. Recently we have developed fluorene/fluorenone derivatives with structure-specific binding towards dsRNA, indicating its potential for structure-selective ligands. Herein, we report the synthesis of novel fluorene/fluorenone derivatives and their selectivity towards various DNA structures, particularly G-quadruplexes, two of which showed strong affinity to the proto-oncogene c-myc promoter G-quadruplex.

Asunto(s)

RESUMEN

A new colorimetric and fluorescent chemosensor for fluoride anion based on calix [4]arene bearing four sulfonamide-fluorenone subunits on the upper rim was conveniently synthesized. It showed a remarkable color change as well as the fluorescence quenching upon addition of F- even in the presence of a wide range of anions in DMSO. The binding property of L with F- was studied by a combination of various spectroscopic techniques, such as absorption and emission titration, Job's plot and 1H NMR titration. It is anticipated that this design with functional group attached to upper rim of calix[4]arene platform can provide a new approach for the development of F- chemosensor.

RESUMEN

A metastable form of 9-fluorenone (MS9F) has been characterized using Raman spectroscopy, fluorimetry, and X-ray diffraction techniques. MS9F emits blue fluorescence (λmax =495 nm) upon 365 nm irradiation and undergoes a single-crystal-to-single-crystal (SCSC) transformation to reach the ground state form (GS9F) over approximately 30 minutes, whereupon it emits the expected green fluorescence. A structure-property relationship for this fluorescent behavior has been posited. MS9F and GS9F were applied as a means of visualizing latent fingermarks on a nonporous surface. This approach identified three different modes of fluorescent fingermark visualization using 9-fluorenone.

RESUMEN

The design of orange-light emitting, thermally activated, delayed fluorescence (TADF) materials is necessary and important for the development and application of organic light-emitting diodes (OLEDs). Herein, two donor-acceptor-donor (D-A-D)-type orange TADF materials based on fluorenone and acridine, namely 2,7-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (27DACRFT, 1) and 3,6-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (36DACRFT, 2), were successfully synthetized and characterized. The studies on their structure-property relationship show that the different configurations have a serious effect on the photoluminescence and electroluminescence performance according to the change in singlet-triplet splitting energy (ΔEST) and excited state geometry. This indicates that a better configuration design can reduce internal conversion and improve triplet exciton utilization of TADF materials. Importantly, OLEDs based on 2 exhibited a maximum external quantum efficiency of 8.9%, which is higher than the theoretical efficiency of the OLEDs based on conventional fluorescent materials.

RESUMEN

To sense biologically important entities with different size and dimensions, a fluorenone based fluorescent receptor was designed and synthesized. Probe 1 displayed a distinct fluorescence enhancement emission at 565nm for pyrophosphate and 530nm for alanine in polar solvent. The fluorescence titration experiments confirm 1:1 stoichiometric ratio with high-binding constant and very low limit of detection (LoD) values. Receptor 1 showed a highly selective and sensitive recognition to HP2O73- and to alanine over other competitive anions and amino acids. In addition, the fluorescence lifetime measurement and reversible binding study results support the practical importance of 1.

Asunto(s)

RESUMEN

We prepared fifty various 9H-fluorenone based 1,2,3-triazole analogues varied with NH, -S-, and -SO2 - groups using click chemistry. The target compounds were characterized by routine analytical techniques, 1 H, 13 CNMR, mass, elemental, single-crystal XRD (8a) and screened for in vitro antitubercular activity against Mycobacterium tuberculosis (MTB) H37Rv strain and two "wild" strains Spec. 210 and Spec. 192 and MIC50 was determined. Further, the compounds were evaluated for MTB InhA inhibition study as well. The final analogues exhibited minimum inhibitory concentration (MIC) ranging from 52.35 to >295 µm. Among the -NH- analogues, one compound 5p (MIC 58.34 µm), among -S- containing analogues four compounds 8e (MIC 66.94 µm), 8f (MIC 74.20 µm), 8g (MIC 57.55 µm), and 8q (MIC 56.11 µm), among -SO2 - containing compounds one compound 10p (MIC 52.35 µm) showed less than MTB MIC 74.20 µm: Compound 4-(((9H-fluoren-9-yl)sulfonyl)methyl)-1-(3,4,5-trimethoxyphenyl)-1H-1,2,3-triazole (10p) was found to be the most active compound with 73% InhA inhibition at 50 µm; it inhibited MTB with MIC 52.35 µm. Further, 10f and 10p were docked to crystal structure of InhA to know binding interaction pattern. Most active compounds were found to be non-cytotoxic against HEK 293 cell lines at 50 µm.

Asunto(s)

RESUMEN

We designed, synthesized, and characterized a series of novel electron deficient small molecule nonfullerene acceptors based on 1,8-naphthalimide (NAI) and 9-fluorenone (FN) with different branched alkyl chains using various techniques. These molecules are based on an acceptor-donor-acceptor-donor-acceptor (A1-D-A2-D-A1) molecular design configuration with NAI as the end-capping acceptor (A1), FN as electron-withdrawing central (A2) group, and thiophene ring as a donor (D) unit. These materials are named as NAI-FN-NAI (BO) and NAI-FN-NAI (HD) where BO and HD represent butyloctyl and hexyldecyl alkyl groups, respectively. To further modify energy levels of these materials, we converted the weak electron withdrawing ketonic group (C═O) attached to the FN moiety of NAI-FN-NAI (BO) to a stronger electron withdrawing cyano group (C≡N) to obtain the compound NAI-FCN-NAI (BO) by keeping the same alkyl chain. The optical, electrochemical, and thermal properties of the new acceptors were studied. The materials exhibited higher to medium band gaps, low lowest unoccupied molecular orbital (LUMO) energy levels, and highly thermally stable properties. Organic solar cell devices employing conventional poly(3-hexylthiophene) (P3HT) a donor polymer and the newly designed small molecules as the acceptor were investigated. Among all new materials, organic solar cell devices based on NAI-FN-NAI (BO) as an acceptor exhibit the highest performance with an open circuit voltage (VOC) of 0.88 V, a short-circuit current density (JSC) of 9.1 mAcm-2, a fill factor (FF) of 45%, and an overall power conversion efficiency (PCE) of 3.6%. This is the first report of 9-fluorenone based nonfullerene acceptor with P3HT donor in organic solar cell devices with such a promising performance.

RESUMEN

In this study, a gram-positive fluoranthene-degrading bacterial strain was isolated from crude oil in Dagang Oilfield and identified as Microbacterium paraoxydans JPM1 by the analysis of 16S rDNA sequence. After 25 days of incubation, the strain JPM1 could degrade 91.78 % of the initial amount of fluoranthene. Moreover, four metabolites 9-fluorenone-1-carboxylic acid, 9-fluorenone, phthalic acid, and benzoic acid were detected in the culture solution. The gene sequence encoding the aromatic-ring-hydroxylating dioxygenase was amplified in the strain JPM1 by PCR. Based on the translated protein sequence, a homology modeling method was applied to build the crystal structure of dioxygenase. Subsequently, the interaction mechanism between fluoranthene and the active site of dioxygenase was simulated and analyzed by molecular docking. Consequently, a feasible degrading pathway of fluoranthene in the strain JPM1 was proposed based on the metabolites and the interaction analyses. Additionally, the thermodynamic analysis showed that the strain JPM1 had high tolerance for fluoranthene, and the influence of fluoranthene for the bacterial growth activity was negligible under 100 to 400 mg L-1 concentrations. Taken together, this study indicates that the strain JPM1 has high potential for further study in bioremediation of polycyclic aromatic hydrocarbon (PAH)-contaminated sites.

Asunto(s)