MALDI-TOF Mass Analysis Research Articles

Triphenylamine-Based Solid-State Emissive Fluorene Derivative with Aggregation-Induced Emission Enhancement Characteristics

Aggregation-induced emission (AIE) has garnered considerable attention in recent years. Understanding the mechanisms underlying AIE phenomena is crucial. Here, we present the design and synthesis of a novel fluorene derivative (4) based on triphenylamine, which exhibits typical AIE properties. The structure of it was totally characterized using FT-IR, MALDI-TOF mass analysis, elemental analysis, 1H, and 13C NMR spectroscopy. It displayed strong solid-state emission with diverse fluorescence characteristics. The AIE property of the compound was systematically studied using photoluminescence spectroscopy, revealing a distinct yellow light-emitting phenomenon. The solid-state luminescence showed a red shift of 148 nm compared to its luminescence in dilute dimethylformamide (DMF) solutions. Moreover, photophysical characteristics, including absorption and emission spectra, as well as fluorescence lifetime, were examined using UV–vis absorption and fluorescence emission spectroscopy. Compound (4) exhibited superior photosensitization abilities in both solid and solution states, with a notably enhanced effect observed in the solid state compared to the solution state.

Identification of coke species on Fe/USY catalysts used for recycling polyethylene into fuels.

The Fe/USY catalyst used for converting plastic waste into fuels faces coking problems. A comprehensive understanding of coke distribution and structure is crucial for catalyst design, enabling resistance to coke deposition and facilitating regeneration. In this study, we analyze the coke deposition on Fe/USY catalysts after catalytic pyrolysis of polyethylene for fuel oil, and present insights into the coke distribution over the metal and acid sites, as well as its specific molecular structure. The coke distributes over both the metal and acid sites, exhibiting distinct TPO peaks corresponding to metal-site coke (370 °C) and acid-site coke (520 °C). The total coke yields range from 2.0% to 2.4%, with distribution on metal and acid sites dependent on Fe loading and acidity. Structurally, the coke is highly-condensed, containing more than four aromatic rings with limited alkyl groups. The acid-site coke is more condensed than the metal-site coke, showing lower H/C ratios (0.5-0.75) relative to the acid-site coke (0.75-0.9). Identified by MALDI-TOF mass analysis, the predominant molecular structures of the coke located on metal and acid sites are illustrated. The metal-site cokes typically exhibit 4-7 aromatic rings, while the acid-site cokes display even greater condensation with 5-12 aromatic rings.

The new polycyclotriphosphazenes: Synthesis, characterization, thermal and photophysical properties

Polyamides are used as high-performance materials in industry and electronics. Researchers have recently been focusing on this area and trying to synthesize more stable and high-performance molecules by polymerizing various groups into the backbone skeleton. In this work, we report the design, synthesis, and characterization of paracetamol derivatives of cyclotriphosphazene (DSPCT and DSHY) and polycyclotriphosphazenes (DSTPC and DSAC) for the first time. The structures of new products were fully characterized by MALDI-TOF Mass analysis, FT-IR, 1H and 31P NMR spectroscopies and single crystal X-ray (for DSPCT and DSHY) crystallography. The crystallization behaviours of the polyamides were studied by X-ray diffraction, and a scanning electron microscope was used to observe the morphology of the DSTPC and DSAC. Thermal degradation properties for DSHY, DSTPC and DSAC were determined by DSC and TGA techniques. Polyamides and the DSHY compound exhibited superior thermal stability with an initial decomposition temperature range of ca. 251–302 °C. Additionally, spectral characterization and photophysical behaviours (fluorescence quantum yields and lifetimes) of the all new compounds were also comprehensively investigated using UV–Vis and fluorescence spectroscopies (steady-state and time-resolved fluorescence).

Tetra-bodipy linked mono-spiro cyclotriphosphazene conjugates: Synthesis, characterization and photophysical properties

In this work, we report the design, synthesis, and characterization of two novel mono-spiro cyclotriphosphazene conjugates bearing four BODIPY units for the first time. The structures of new compounds were fully characterized by FT-IR, MALDI-TOF Mass analysis, 1H, and 31P NMR spectroscopies, and elemental analysis. On the other hand, precursor BODIPYs and mono-spiro compound were characterized by single-crystal X-ray diffraction technique. Photophysical properties including absorption and emission profiles and fluorescence lifetimes were investigated via UV–vis absorption and fluorescence emission spectroscopy techniques. The novel mono-spiro conjugates retain the unique photophysical properties of their precursor BODIPYs showing their promise as photosensitizers with remarkable ability like many other photosensitizers.

The bioactive new type paraben decorated dispiro-cyclotriphosphaze compounds: synthesis, characterization and cytotoxic activity studies

Cancer is a leading cause of death worldwide and hence studies to find anti-cancer agents for its treatment continue to grow in importance. Generally, cytotoxic drugs have been used for cancer treatment in susceptible cells. Parabens that is known for their anti-microbial and antifungal properties are widely used in the pharmaceutical industry. For this purpose, new type paraben decorated dispiro-cyclotriphosphazene compounds (2–6) were synthesized for the first time. After purification of all compounds (1–6), their structures were characterized by MALDI-TOF Mass analysis, FT-IR, 1H, 13C and 31P NMR spectra. In vitro cytotoxic activity of the cell lines were examined by MTT assay after treating MCF-7 (human breast adenocarcinoma) and DLD-1 (Dukes' Type C, Colorectal Adenocarcinoma) cells with varying concentrations of all compounds (12,5–200 µM) for 24 h. The obtained data were evaluated using Anova analysis and described as IC50 values. Particularly, compounds 1 and 3 for MCF-7 cells and compound 1 for DLD-1 cells takes attention as cytotoxic agents.

Simultaneous Production of Antibacterial Protein and Lipopeptides in Bacillus tequilensis, Detected by MALDI-TOF and GC Mass Analyses.

As antibiotic resistance is nowadays one of the important challenges, efforts are crucial for the discovery of novel antibacterial drugs. This study aimed to evaluate antimicrobial/anticancerous activities of halophilic bacilli from the human microbiota. A spore-forming halotolerant bacterium with antibacterial effect against Staphylococcus aureus was isolated from healthy human feces. The antibacterial protein components of the extracted supernatant were identified by SDS-PAGE and zymography. The MALDI-TOF, GC mass, and FTIR analyses were used for peptide and lipopeptide identification, respectively. The stability, toxicity, and anticancerous effects were investigated using MTT and Flow cytometry methods. According to the molecular analysis, the strain was identified as Bacillus tequilensis and showed potential probiotic properties, such as bile and acid resistance, as well as eukaryotic cell uptake. SDS-PAGE and zymography showed that 15 and 10-kDa fragments had antibacterial effects. The MALDI-TOF mass analysis indicated that the 15-kDa fragment was L1 ribosomal protein, which was the first report of the RpL1 in bacilli. GC-mass and FTIR analyses confirmed the lipopeptide nature of the 10-kDa fragment. Both the extracted fractions (precipitation or "P" and chloroform or "C" fractions) were stable at < 100°C for 10min, and their antibacterial effects were preserved for more than 6months. Despite its non-toxicity, the P fraction had anticancer activities against MCF7 cells. The anticancer and antibacterial properties of B. tequilensis, along with its non-toxicity and stability, have made it a potential candidate for studying the beneficial probiotic properties for humans and drug production.

Polyethylene glycol-based RAFT agent cum ATRP macroinitiator initiated block copolymerization of methyl methacrylate

PMMA-b-PEG-b-PMMA block copolymer has been synthesized by the activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) of methyl methacrylate (MMA) using modified polyethylene glycol (PEG) as initiator. PEG is chemically modified by CS2 followed by an esterification to incorporate initiating sites for ATRP as well as for RAFT polymerization. The prepared macroinitiator has been characterized by FT-IR and NMR analyses for its structural validation. FT-IR and NMR analyses confirmed the successful synthesis of the macro initiator. This macro initiator has been used to prepare ABA type triblock copolymer with MMA via ARGET-ATRP. The polymerization reaction is carried out using cupric bromide (CuBr2) as catalyst in combination with N,N,N′,N″,N″-pentamethyl diethylenetriamine (PMDETA) as ligand in N, N dimethyl formamide (DMF) at 70C. Ascorbic acid is used as reducing agent. The conversion of the monomer was calculated gravimetrically. The successful preparation of the block copolymer is confirmed by FT-IR, 1H NMR and 13C NMR analyses. The MALDI-TOF mass analysis of the block copolymers also confirm the presence of monomer MMA, dithionate and PEG parts in the block copolymer. The purified block copolymer is analyzed by TGA, and SEM analyses. TGA analysis shows that the prepared block copolymer has better (Tmax = 366C) thermal stability than the PMMA (Tmax = 349C) homopolymer.

Chemoselective radical polymerization of N-allylmethacrylamide with an aid of complexation with Li+ cation

Radical polymerization of N-allylmethacrylamide (NAlMAAm) was conducted in CH3CN in the presence or absence of lithium bis(trifluoromethanesulfonyl)imide (LiNTf2). The addition of LiNTf2 accelerated the polymerization and affected the molecular weight distribution of the polymers obtained. Polymers with unimodal molecular weight distributions were obtained in the presence of LiNTf2, whereas those with multimodal distributions were obtained in the absence of LiNTf2. This suggested that LiNTf2 suppressed side reactions such as cross-linking reaction, commonly observed in polymerization of divinyl monomers, and allylic hydrogen abstraction reaction. The 1H NMR, IR and MALDI-TOF mass analyses of the polymers obtained suggested that the radical polymerization proceeded in a chemoselective manner, leading to preferential formation of linear polymers having pendant allyl groups.

Selective electrochemiluminescent detection of sulfide based on a dual-quenching cyclometalated Ir(III) complex

Hydrogen sulfide (H2S) is known to be an important mediator of diverse cellular functions in health and in disease. It is of great importance to develop a selective and efficient detection method for H2S. Herein, we report an iridium-based electrochemiluminescent (ECL) sulfide probe (1) composed of the acrylate and dinitrobenzenesulfonyl (DNBS) units as both reactive and quenching groups. While control probes (2 and 3) having either acrylate or a DNBS group exhibited moderate selectivity for sulfide and other biothiols, the dual-quenching chemodosimetric ECL probe 1 installed with both acrylate and DNBS units enabled selective sensing of sulfide anions over various anions and biothiols with high turn-on ratio. The sensing mechanism of probe 1 was elucidated using MALDI-TOF mass and 1H NMR analyses. Probe 1 was successfully applied to the detection of H2S in human serum by the ECL method. This ECL-based detection method can be developed into a point-of-care testing method for selective sensing of sulfide.

Optimized MALDI‐TOF Mass Analysis Conditions for Natural Small Molecules

MALDI-TOF mass analysis conditions were optimized for natural small molecules using various organic and inorganic matrices.

N,N-Spiro bridged bis(cyclotriphosphazene) derivatives with four equivalent chiral centres: Synthesis, characterization and stereogenic properties

N,N-Spiro bridged bis(cyclotriphosphazene) derivatives having four equivalent centres of chirality were prepared and their stereogenic properties were investigated. Bis non-geminal trans-dibenzylaminocyclotriphosphazene {trans-P3N3Cl4[N(CH2Ph)2]2}, (1) and cis-mono ansa 2,2,3,3-tetrafluoro-1′,4′-butanedioxycyclotriphosphazene, {P3N3Cl4[OCH2(CF2)2CH2O]} (2), which have two chiral centres, were used as starting compounds and their de-protonation reactions resulted in the formation of the N,N-spiro bridged bis(cyclotriphosphazene) derivatives (3a,b and 6a,b). All new isolated compounds were analysed by elemental analysis, MALDI TOF mass analysis and NMR spectroscopy. In addition, the molecular structure of 3a was determined by X-ray crystallography. This new heterocyclic compound with four equivalent chiral centres (3a) exists as trans-cis geometric isomer and is meso due to centre and plane of symmetry. The chiral properties of the compounds (3a and 6a) were determined by X-ray crystallography and were supported by 31P NMR spectroscopy on addition of the chiral solvating agent (CSA) (R)-(+)-2,2,2-trifluoro-1-(90-anthryl)ethanol.

Synthesis, characterization and ethanol sensing properties of peripheral and non-peripheral tetrakis-(3,6-dihexyl-7-oxy-4-methylcoumarin)substituted zinc(II), cobalt(II), and copper(II) phthalocyanines

Phthalocyanines bearing coumarin moiety may exhibit interesting properties and also can soluble in organic solvents, easily. In this work, the phthalocyanine compounds bearing tetra-(3,6-dihexyl-7-oxy-4-methylcoumarin) units were synthesized and characterized. Firstly, the starting coumarin compound was synthesized by Pechmann condensation and then phthalonitrile compounds were synthesized by nucleofilic aromatic substitution. Phthalocyanine compounds were synthesized by cyclotetramerization of phthalonitriles. These compounds were characterized by spectroscopic methods such as FT-IR, 1H NMR, 13C NMR, electronic absorption spectra, MALDI-TOF mass and elemental analyses as well. The effect of the structure (position of substitution, central metal atom, etc.) of phthalocyanines on electronic absorption spectra and aggregation behavior was also investigated in this paper. In another set of experiments, the effects of the position of methylcoumarin substituent on ethanol vapor sensing performance of the synthesized compounds were investigated and discussed. The observed sensitivities of peripheral and non-peripheral substituted phthalcyanine films are different in spite of their similar bond numbers, indicating significant role of position of the substituent in interaction mechanism. According to the results, the peripheral substituted Pc based sensor not only had high sensitivity towards ethanol vapor, but exhibited very short response time and recovery times. When the concentration of ethanol reached 250 ppm, sensitivity and the response time of peripheral substituted CoPc reached 1.1 × 10−2 ppm−1 which was two-fold that than of non-peripheral substitueted CoPc. While peripheral substituted CoPc based sensor shows a response time of 70 s towards 250 ppm concentration of ethanol vapor, the response time of the non-peripheral substitueted CoPc based sensor was about 270 s. As a result, the presented peripheral methyl coumarin substituted compounds are good candidates for ethanol sensing applications.

Imidazole octasubstituted novel mono and double-decker phthalocyanines: Synthesis, characterization, electrical and gas sensing properties

Imidazole disubstituted phthalonitrile (1) was prepared by the reaction of 4,5-dichlorophthalonitrile with 4,5-diphenyl-1H-imidazolethiole. Imidazole octasubstituted metal free (2), zinc(II) (3), cobalt(II) (4) monophthalocyanines and lutetium(III) (5) and europium(III) (6) double-decker phthalocyanines were prepared by cyclotetramerization of compound 1. The new compounds were characterized by 1H NMR, 13C NMR, UV–vis, IR, MALDI-TOF mass, ESR spectra and elemental analysis. Dc and ac conductivity and gas sensing properties (at room temperature) of the compounds of 2–6 were studied between the temperatures of 295–523 K. Ac conductivity values of the films were measured in the frequency region of 40 Hz–100 kHz. The films were tested for the vapors of toluene, ethanol, THF, n-hexane, chloroform and xylene. DC conductivity results revealed that the compounds 2–6 show a semiconductor behavior. Results of ac measurements show dominant conduction mechanism can be modeled depending on temperature and frequency. The best sensitivity values were obtained for the xylene vapors. The sensor 3 showed best sensitivity among the other sensors for xylene vapor. Response times of the sensors were also determined.

Hydrogen and lactic acid synthesis by the wild-type and a laboratory strain of the hyperthermophilic bacterium Thermotoga neapolitana DSMZ 4359T under capnophilic lactic fermentation conditions

Thermotoga neapolitana is a hyperthermophilic eubacterium that produces hydrogen by sugar fermentation. A lab strain of T. neapolitana DSMZ 4359T maintained in a CO2-enriched atmosphere showed a stable increase of lactic acid production under capnophilic lactic fermentation (CLF) conditions. The genotypic comparison between the putative mutant (TN-CMut) and the original strain DSMZ 4359T (WT4359) revealed 88.1 (±2.4)% DNA homology. RiboPrint® and MALDI-TOF mass analyses support a genetic differentiation beyond subspecies level. The phenotypic characterization indicated a high correlation between the two strains, except for the lactic acid production. Under identical operating conditions, the lab mutant produced significantly more lactic acid than the parent strain without impairing the hydrogen yield. The highest divergence between TN-CMut and WT4359 was observed for fermentation of glucose or lactose at 80 °C. Based on these results, we propose that the lab strain is a new subspecies of the genus Thermotoga that is named T. neapolitana subsp. capnolactica with regards to its improved feature to produce lactic acid under capnophilic conditions.

Pendant structure governed the selectivity of Pd2+ using disubstituted polyacetylenes with sulfur functions and the application of thiophanate-methyl detection

A series of disubstituted polyacetylenes-based fluorescent chemosensors for Pd2+ has been designed and synthesized. The optimization of sensing performance for Pd2+ ions is realized through modulating the coordination mode, type and number of coordination atoms in pendant groups. The receptor groups containing both N and S atoms (Poly [1-phenyl-2-[3-(2-pyridylmercapto)propyl]acetylene] (P2) and Poly [1-phenyl-2-[3-(5-methyl-1,3,4-thiadiazole-2-mercapto)propyl]acetylene] (P4)) can respond simultaneously for Pd2+ and Pt4+/2+ ions, and the only introduction of sulfur as the ligand atoms (Poly [1-phenyl-2-[3-(p-methylphenylthio)propyl]acetylene] (P1) and Poly [1-phenyl-2-[3-(2-Thienylthio)propyl]acetylene] (P3)) can exhibit high selectivity for Pd2+. P3 containing double sulfur atoms in pendants exhibits more high selectivity and sensitivity toward Pd2+ than that of P1 containing single sulfur atom. Aforementioned results were illustrated by fluorescence titration, Ksv fitting and cyclic voltammetry (CV) analysis. The emission of P3–Pd2+ complex can be turned on by the addition of thiophanate-methyl (TM) without the interference from other anions and pesticides. Thus, P3–Pd2+ complex can work as the novel Pd2+−mediated conjugated polymer-based fluorescent (CPF) chemosensors platform for thiophanate-methyl detection. The “on-off-on” sensing mechanism was supported by MALDI-TOF mass analysis, density functional theory (DFT) calculations and the association constants Ka fitting.

Selective detection of Cu2 + and Co2 + in aqueous media: Asymmetric chemosensors, crystal structure and spectroscopic studies

Two new azo-azomethine receptors, H2L1 and H2L2, containing hydrazine, naphthalene and different electron withdrawing groups, Cl and NO2, have been designed and synthesized for qualitative and quantitative detection of Cu2+ and Co2+ in aqueous media. The crystal structure of H2L1is reported. The H2L1was used as a chemosensor for selective detection of trace amount of Cu2+ in aqueous media. H2L2 was also applied to naked-eye distinction of Cu2+ and Co2+ from other transition metal ions in aqueous media. Detection limit of Cu2+ is 1.13μM and 1.26μM, in water, for H2L1 and H2L2, respectively, which are lower than the World Health Organization (WHO) recommended level. The binuclear Cu2+ and Co2+ complexes of the receptors have been also prepared and characterized using spectroscopic methods and MALDI-TOF mass analysis. Furthermore, the binding stoichiometry between the receptors upon the addition Cu2+ and Co2+ has been investigated using Job's plot. Moreover, the fluorescence emission spectra of the receptors and their metal complexes are also reported.

UV-induced coloration of cotton fabrics by photografting of acrylamido dyes using acrylamide as a comonomer

Formulations of acrylamido dyes containing comonomers can be photografted onto cotton fabric upon UV irradiation at room temperature without neutral salts, which makes it a novel coloration process of excellent environmental friendliness. The photografting of the dyes can be assisted by the copolymerization of the acrylamide comonomer which may reduce the steric hindrance of the bulky dyes. About 90 % of the dyes and 94 % of the acrylamide are photopolymerized in the solution and the degree of polymerization is estimated to be 13.2 according to 1H-NMR and MALDI-TOF mass analyses. The optimal K/S values of the grafted cotton fabrics showed 13.3 and 12.3 for red and yellow dyes, respectively. The optimal UV-grafting coloration can be achieved when a UV energy of 25 J/cm2 was irradiated on the padded fabrics with a formulation of 0.65 mole ratio of acrylamide to the dyes, 7 wt% acetophenone photoinitiator (Irgacure 2959) based on the dye weight under pH 6. Furthermore, the color fastness properties of the grafted fabric were superior to those of conventional reactive dyeing of the dyes due to higher molecular weight of the polymerized dyes.

Oligoetherols based on melamine\u2013formaldehyde\u2013butanone resins

New oligoetherols with 1,3,5-triazine ring were obtained from melamine–formaldehyde–butanone resins using 12 molar excess propylene oxide (with respect to the amount of introduced melamine). The resins were obtained from melamine solutions in reactive solvent obtained from simple chemical compound—methyl ethyl ketone (butan-2-one) in its reaction with 3 molar excess formaldehyde. Physical and chemical properties of obtained oligoetherols were determined and their structure was confirmed on the basis of proton magnetic resonance, infrared spectral data and MALDI-ToF mass analysis. The amount of by-products was specified on the basis of chromatographic analysis. Initial tests proved that obtained oligoetherols can constitute a potential substrate for obtaining polyurethane foams of increased thermal resistance.

Erwinia gerundensis sp. nov., a cosmopolitan epiphyte originally isolated from pome fruit trees.

A survey to obtain potential antagonists of pome fruit tree diseases yielded two yellow epiphytic bacterial isolates morphologically similar to Pantoea agglomerans, but showing no biocontrol activity. Whole-cell MALDI-TOF mass spectrometry and analysis of 16S rRNA gene and gyrB sequences suggested the possibility of a novel species with a phylogenetic position in either the genus Pantoea or the genus Erwinia. Multi-locus sequence analysis (MLSA) placed the two strains in the genus Erwinia and supported their classification as a novel species. The strains showed general phenotypic characteristics typical of this genus and results of DNA-DNA hybridizations confirmed that they represent a single novel species. Both strains showed a DNA G+C content, as determined by HPLC, of 54.5 mol% and could be discriminated from phylogenetically related species of the genus Erwinia by their ability to utilize potassium gluconate, potassium 2-ketogluconate, maltose, melibiose and raffinose. Whole-genome sequencing of strain EM595T revealed the presence of a chromosomal carotenoid biosynthesis gene cluster similar to those found in species of the genera Cronobacter and Pantoea that explains the pigmentation of the strain, which is atypical for the genus Erwinia. Additional strains belonging to the same species were recovered from different plant hosts in three different continents, revealing the cosmopolitan nature of this epiphyte. The name Erwinia gerundensis sp. nov. is proposed, with EM595T ( = LMG 28990T = CCOS 903T) as the designated type strain.

A carbazole-based mitochondria-targeted two-photon fluorescent probe for gold ions and its application in living cell imaging

A carbazole-based two-photon fluorescent probe (PyCM) showed a remarkable fluorescence “turn-on” response to Au3+/Au+ in aqueous solution with a large Stokes shift (119nm). A good linear relationship of emission intensity at 539nm against Au3+/Au+ from 0 to 20 equiv. was observed, and the detection limits (3σ/k) were as low as 47nM for Au3+ and 73nM for Au+, respectively. The fluorescence enhancement was attributed to the gold ions-induced CN bond hydrolysis sensing mechanism, which is fully confirmed by the UV–vis absorption, fluorescence, IR, 1H NMR titration and MALDI-TOF mass analysis. Bio-imaging study established that PyCM could be used to detect Au3+ in living cells under two-photon excitation with large two-photon absorption cross sections (1321 GM at 860nm), little cytotoxicity and good biocompatibility. Meanwhile, standard co-staining experiments of PyCM and MitoTracker Red FM (co-localization coefficient: 0.85) revealed that PyCM was predominantly present in mitochondria.