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This study includes the synthesis of 11 different calixarene derivatives, the preparation of thin film sensors on quartz crystal microbalance (QCM) crystals, and the specification of sensor-analyte pairs by examining the sensing properties of these sensors against different phenolic compounds such as p-nitrophenol (PNP), phenol (PHE), p-chlorophenol (PCP), and m-nitrophenol (MNP) in the aqueous medium. For this purpose, calixarene derivatives with different structures were first synthesized and characterized using spectroscopic methods such as Proton nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared spectroscopy (FTIR). Detection studies were carried out for proposed phenolic compounds with calixarene-based QCM sensors obtained by electrospinning. At the beginning of the experiments, sensor-analyte pairs were determined according to the values at which the highest sensor frequencies were observed. Therefore, according to the highest sensor responses towards 5 × 10–5 M analytes, the sensor-analyte pairs were determined as QCM-5 for PNP (17.8 Hz) and MNP (3.8 Hz). Also, for PHE and PCP, the highest responses were observed as 4.1 Hz and 4.0 Hz in the QCM-11 and QCM-1 sensors, respectively. In further experiments, determined sensor-analyte pairs were tested at different analyte concentrations. In addition, the limits of detection (LOD) of the sensors were calculated from different analyte concentration studies such as 0.580 (QCM-5), 0.659 (QCM-11), 0.490 (QCM-1), and 0.466 (QCM-5) mM against PNP, PHE, PCP, and MNP, respectively. Interactions between sensor-analyte pairs were evaluated in terms of adsorption kinetics. It was observed that the relationships between the sensor responses and the analyte concentration were highly consistent with the Freundlich isotherm. In addition, repeatability and stability tests of the sensors were performed, and it was observed that they exhibited good repeatability and stability properties. Finally, selectivity between analytes was assessed, and the highest selectivity was observed as with the QCM-4 sensor versus p-nitrophenol. It was found that the selectivity of the sensor to PNP was 21.1 times compared to PHE and PCP and 74 times compared to MNP.Graphical abstract: This study includes the synthesis of 11 different calixarene derivatives, the preparation of thin film sensors on quartz crystal microbalance (QCM) crystals, and the specification of sensor-analyte pairs by examining the sensing properties of these sensors against different phenolic compounds such as p-nitrophenol (PNP), phenol (PHE), p-chlorophenol (PCP), and m-nitrophenol (MNP) in the aqueous medium. For this purpose, calixarene derivatives with different structures were first synthesized and characterized using spectroscopic methods such as Proton nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared spectroscopy (FTIR). Detection studies were carried out for proposed phenolic compounds with calixarene-based QCM sensors obtained by electrospinning. At the beginning of the experiments, sensor-analyte pairs were determined according to the values at which the highest sensor frequencies were observed. Therefore, according to the highest sensor responses towards 5 × 10–5 M analytes, the sensor-analyte pairs were determined as QCM-5 for PNP (17.8 Hz) and MNP (3.8 Hz). Also, for PHE and PCP, the highest responses were observed as 4.1 Hz and 4.0 Hz in the QCM-11 and QCM-1 sensors, respectively. In further experiments, determined sensor-analyte pairs were tested at different analyte concentrations. In addition, the limits of detection (LOD) of the sensors were calculated from different analyte concentration studies such as 0.580 (QCM-5), 0.659 (QCM-11), 0.490 (QCM-1), and 0.466 (QCM-5) mM against PNP, PHE, PCP, and MNP, respectively. Interactions between sensor-analyte pairs were evaluated in terms of adsorption kinetics. It was observed that the relationships between the sensor responses and the analyte concentration were highly consistent with the Freundlich isotherm. In addition, repeatability and stability tests of the sensors were performed, and it was observed that they exhibited good repeatability and stability properties. Finally, selectivity between analytes was assessed, and the highest selectivity was observed as with the QCM-4 sensor versus p-nitrophenol. It was found that the selectivity of the sensor to PNP was 21.1 times compared to PHE and PCP and 74 times compared to MNP. [ABSTRACT FROM AUTHOR]

The polymeric calix[6]arene-tethered silica (C[6]TS) was prepared by the tethering of p-tert-butylcalix[6]arene onto 3-glycidoxypropyl-bonded stationary phase. The structural and composition analysis of the C[6]TS was performed by FTIR, XRD, TGA, and SEM techniques. C[6]TS was used as an adsorbent for the removal of 4-nitrophenol (4-NP) from aqueous solutions. Initial adsorption experiments demonstrated that C[6]TS showed outstanding performance for the removal of 4-NP. So it exhibited rapid and effective adsorption with a %83 yield within ten minutes. Subsequently, some adsorption criteria such as pH, initial concentration, contact time, sorbent dosage, and temperature were evaluated in detail. Thus, adsorption phenomena of 4-NP onto C[6]TS were clarified in this way. [ABSTRACT FROM AUTHOR]

The immobilization of a calix[4]arene derivative bearing methyl ester moieties onto mesoporous silica was successfully achieved to obtain calix[4]arene based organosilica (CBOS). IR spectroscopy, X-Ray powder diffraction, energy-dispersive spectroscopy, and scanning electron microscopy analysis were carried out for the characterization of the CBOS. After that, the proposed mesoporous silica-supported adsorbent was studied for the adsorption of benzene and toluene vapors, which are essential VOCs. The effects of operating parameters on the adsorption of these vapors with the CBOS adsorbent were analyzed and optimized by applying response surface methodology (RSM)-central composite design (CCD). According to initial experimental results, CBOS exhibited excellent performance for these vapors. The adsorption capacities of calix-3, GBS, and CBOS adsorbents were determined to be 203, 357, and 606 mg g−1 for benzene vapors, respectively, while they were found to be 258, 394 and 672 mg g−1 for toluene vapors, respectively. Thus, the proposed CBOS adsorbent showed better adsorption performance when compared to its precursors. In addition to the distinctive adsorptive behavior, the CBOS adsorbent exhibited a high reproducibility adsorption/desorption capacity after five consecutive cycles. After the fifth adsorption/desorption cycle, the CBOS retained 94.2% and 95.1% of its initial adsorption capacities for benzene and toluene, respectively. Finally, adsorption phenomena of benzene and toluene vapors onto CBOS were evaluated in terms of isotherm and kinetic parameters. [ABSTRACT FROM AUTHOR]

This paper describes the sensing studies of a chiral calix[4]arene receptor (5) having (R)-2-phenylglycinol moiety for arginine enantiomers (D- / L -arginine) by using Quartz Crystal Microbalance (QCM) technique. The initial experiments have revealed that the chiral calix[4]arene 5 coated QCM (CCC-QCM) sensor showed good sensing for arginine enantiomers, such that it has exhibited higher sensing towards D -arginine than that of L -arginine. It has been determined that the sensitivity, limit of detection values of CCC-QCM sensor for the D-/L -arginine solutions as 0.024/0.023 Hz/μM and 0.38/1.29 μM, respectively. On the other hand, the racemic mixture studies were optimized using the response surface methodology with central composite design. Consequently, it has been demonstrated that the QCM sensor modification with a calix[4]arene receptor bearing asymmetric centers provided rapid, real-time, sensitive and effective sensing of arginine enantiomers. Image 1 • Rapid, real-time, sensitive and effective arginine sensing was accomplished. • Chiral calix[4]arene based QCM sensors were firstly used for amino acid sensing. • It was produced a QCM sensor to be durable and easy recoverable with distilled water. • Calixarene coating onto QCM surface to sense amino acids became useful approach. [ABSTRACT FROM AUTHOR]

We describe the synthesis of new chiral calix[4]arene derivatives having (R)-1-phenylethylamine, (S)-1-phenylethylamine, (R)-2-phenylglycinol, and (S)-2-phenylglycinol moieties, and chiral recognition studies for enantiomers of some selected α-amino acid derivatives such as alanine, phenylalanine, serine, and tryptophan using a quartz crystal microbalance (QCM). Initial experiments indicated that the highest selective chiral recognition factor was 1.42 for alanine enantiomers. The sensitivity, limit of detection, and time constant for l-alanine were calculated as 0.028 Hz/μM, 60.9 μM, and 36.2 s, respectively. The results indicated that real-time, sensitive, selective, and effective chiral recognition of alanine enantiomers was achieved with a QCM sensor coated with a chiral calix[4]arene derivative having (R)-2-phenylglycinol moieties. [ABSTRACT FROM AUTHOR]

This article describes the preparation of calix[4]arene-bonded silica gels ( C[4]BS and DMC[4]BS ), and their application to the removal of some selected phenolic compounds such as phenol (PHE), p -chlorophenol (PCP), m -nitrophenol (MNP) and p -nitrophenol (PNP) from aqueous solutions by adsorption method. In initial adsorption experiments appeared that C[4]BS was much more effective in adsorption of PNP rather than PHE, PCP and MNP, whereas DMC[4]BS exhibited too little adsorption ability towards all phenols. Herein, it was concluded that the hydrogen bonding capacities of both phenols and calix[4]arene based adsorbents played a predominant role in the interactions between adsorbate and adsorbent within the adsorption mechanism. Thus, in subsequent studies, the C[4]BS was employed as an adsorbent in the adsorption of PNP, and adsorption conditions were optimized. Furthermore, isotherm and kinetic studies were performed to clarify the phenomena of PNP adsorption onto C[4]BS . [ABSTRACT FROM AUTHOR]

This study presents the sensing studies of QCM sensors which coated with calix[4]arene derivatives bearing different functional groups towards some selected Volatile Organic Compounds (VOCs). Initial experiments revealed that QCM sensor coated with calix -3 bearing bromopropyl functionalities was relatively more effective sensor for methylene chloride (MC) emissions than the other calix[4]arene coated QCM sensors, in aqueous media. In further experiments, this effective calix -3 coated QCM sensor were used in detailed sensing studies of selected VOCs. However, the results demonstrated that calix- 3 coated QCM sensor was most useful sensor for toluene (TOL) emissions among all. Moreover, the sensing of TOLs with calix- 3 coated QCM sensor was also evaluated in terms of sorption phenomena. Consequently, calix- 3 coated QCM sensor was good sensor for TOL emissions, and thus it demonstrated that the coating of QCM sensor surface with calixarenes was good approach for sensing of the VOCs. [ABSTRACT FROM AUTHOR]

This paper describes the sensing studies of QCM sensors with coated some calixarene derivatives bearing different functional groups for some selected Volatile Organic Compounds (VOCs) such as acetone, acetonitrile, carbon tetrachloride, chloroform, methylene chloride (MC), N,N-dimethylformamide, 1,4-dioxane, ethanol, ethyl acetate, xylene, methanol, n -hexane and toluene. The initial experiments have revealed that whole the calix[4]arene modified QCM sensors exhibited strongest sensing ability to MC emissions. Thus, the detailed studies were performed for only MC emissions after the determination of relatively more effective calix-coated QCM sensors for MC emissions in aqueous media. The results demonstrated that QCM sensor coated with calix- 7 bearing both amino and imidazole groups was most useful sensor for MC emissions with 54.1 ppm of detection limit. Moreover, it was understood that cyclic structures, H-bonding capabilities and also good preorganization properties of calixarene derivatives played an important role in VOC sensing processes. [ABSTRACT FROM AUTHOR]

This study describes the preparation of a new polymeric calix[4]arene derivative and its application as a sorbent material in adsorption of p-nitro phenol (PNP). Thus after the preparing of the precursor calixarene derivatives (1-5), compound 5 was immobilized onto aminopropyl silica gel supporting material to obtain polymeric calix[4]arene (6). All compounds were characterized by using some methods such as FTIR, ¹H NMR, elemental analysis, TGA and SEM. Aminopropyl silica gelimmobilized calix[4]arene (C[4]APS) 6 was used as a sorbent in the adsorption studies of PNP and it was examined some parameters such as pH, contact time, initial concentration, process temperature and sorbent dosage. The results showed that pH 6, contact time 1 hour, the concentration of 5.0x10-5 M PNP, 0.025 g of sorbent dosage and 25°C of temperature was found as optimum parameters of PNP adsorption by 6. Also Langmuir and Freundlich isotherms were evaluated to clarify the PNP adsorption mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrospinning of PBI/PVDF was performed to obtain PBINF onto the QCM sensor. • The sensor was tested towards some hydrocarbon vapors. • The sensor exhibited the higher responses towards toluene and ethylbenzene vapors. • The limit of detection was calculated as 0.41 and 0.45 ppm for toluene and ethylbenzene vapors, respectively. • The repeatability and durability performance of the sensor were analyzed. This paper describes the preparation of the polybenzimidazole nanofiber (PBINF) onto the QCM sensor by electrospinning of 2,2'-(p-phenylene)-5,5'-bis(benzoxazole) (PBI) and polyvinylidene fluoride (PVDF) as the hydrocarbon sensing material for the first time. The characterization of PBINF was conducted by FTIR, SEM, TGA, AFM, and contact angle analysis. Initial experiments revealed that the higher responses were observed towards toluene and ethylbenzene vapors. The proposed chemosensor performance was then tested towards toluene and ethylbenzene vapors in different concentrations ranging from 1−10 ppm-level. Hence, the chemosensor sensitivity (S, Hz ppm−1) and limit of detection (LOD, ppm) were determined as 6.7411 Hz ppm−1 (toluene), 7.0743 Hz ppm−1 (ethylbenzene) and 0.41 ppm (toluene), 0.45 ppm (ethylbenzene), respectively. Also, the adsorption phenomena were investigated by adapting the experimental results to some adsorption models. The Freundlich and Langmuir-Freundlich adsorption models were in good correlation with experimental data. Thus, it was thought that PBINF formed a heterogeneous surface, and the toluene sensing by the proposed chemosensor reached equilibria in high volatile organic compound (VOC) concentrations. In further experiments, the sensor performance was evaluated by five sequential adsorption/desorption cycles and every week for six weeks towards 10 ppm toluene vapors. Hence, the chemosensor exhibited good repeatability and durability feature. It was thought that the adsorption of toluene onto the sensor surface was weak physical adsorption, such as π-π interaction between the toluene and the benzene rings in the PBI. In conclusion, the PBINF platform onto the QCM sensor will be a useful, promising agent for hydrocarbon detection in many sensing applications. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, it is aimed to increase the wear and fatigue performance of aluminium‐based sliding bearing material by using silver nanoparticles (AgNPs) added lubricant and shot‐peening process. The main purpose is to minimise the wear of the bearing material by penetrating AgNPs added lubricants into the rough surfaces formed by shot peening. Almen intensity, coverage and shot size parameters in the shot‐peening process were analysed in terms of hardness, surface roughness and fatigue strength. The shot‐peened aluminium bronze was subjected to wear experiments under dry, pure water and AgNPs added lubricant conditions. The wear test results were analysed in terms of friction coefficient, wear volume and surface roughness parameters, and the interaction of lubricant and shot‐peening parameters was evaluated. According to the results of the shot‐peening experiments, the Almen intensity was the most effective parameter in terms of hardness and surface roughness (91.62%). It was concluded that the hardness value was 8% higher at high Almen (12–14A) intensity compared with low Almen intensities, and the shot‐peening process could increase the fatigue strength by ~21 times. According to the wear tests, the most effective parameters were 4–6 Almen intensity and AgNP‐added lubricant. [ABSTRACT FROM AUTHOR]

• The diacid calix[4]arene derivative tethered silica (DACTS) was successfully prepared and applied to remove VOCs. • The RSM and BBD optimization technique was applied to specify the maximum adsorption capacity. • The adsorption of xylene and toluene gases was investigated in terms of kinetics and isothermal conditions. • The maximum adsorption uptake of xylene and toluene gases was found to be 882.94 and 660.87 mg/g. • The DACTS exhibited a superior regeneration and repeatability performance towards VOCs. The diacid calix[4]arene tethered silica (DACTS) as an adsorbent was obtained by the tethering of calix[4]arene carboxylic acid derivative onto 3-glycidoxypropyl-bonded stationary phase (GBS). The characterizations were carried out by some analysis techniques such as FT-IR, XRD, EDS, SEM, and BET. The adsorption behavior of the prepared adsorbent was investigated towards the dynamic adsorption of volatile organic compounds (VOCs) such as xylene and toluene gases. For the optimization of process parameters, response surface methodology (RSM), and Box-Behnken design (BBD) were applied. The adsorption results were evaluated in terms of the kinetic and isothermal conditions. Hence, DACTS showed substantial adsorption performance towards xylene and toluene gases. It was observed that for xylene gas, the adsorption capacities of the precursor calixarene, GBS, and DACTS were 441.43, 542.98, and 882.94 mg/g, respectively. Additionally, their adsorption capacities towards toluene gas were found as 300.50, 398.14, and 660.87 mg/g, respectively. Hence, the tethering of calixarene units into GBS could considerably enhance the adsorption capacity of prepared adsorbent towards xylene and toluene gases. Additionally, as well as the excellent adsorption behavior towards xylene and toluene gases, DACTS adsorbent has a superior regeneration and repeatability performance towards VOCs. The possible adsorption mechanism can be explained by π-π and, van der Waals interactions between the VOCs and the benzene rings on calixarene moiety. The findings of this study indicated that the successfully synthetized DACTS adsorbent has excellent adsorption capacity and repeatability for VOCs, which means that it will be useful adsorbent for many areas. [ABSTRACT FROM AUTHOR]

This work designs the synthesis of a novel amino morpholine schiff base functionalized calix[4]arene cage (SCC), its deposition onto Quartz Crystal Microbalance (QCM) crystal surface, and usage for the selective detecting of formaldehyde (HCHO). The SCC modified QCM sensor has been characterized by contact angle measurements and microscopy images. Initial experiments revealed that the frequency response decreased significantly which means that there was a good interaction between the SCC molecules and HCHO. The proposed sensor exhibited a linear response towards HCHO in different concentrations ranging from 1.85 to 9.25 ppm, having the high sensitivity (S) and low limit of detection (LOD) being 18.324 Hz/ppm and 0.67 ppm, respectively. Furthermore, the adsorption behavior and mechanism of HCHO onto the QCM sensor were investigated for this sensing system and the adsorption data exhibited a good correlation with the Freundlich and Langmuir-Freundlich adsorption models in terms of the regression coefficient. The QCM sensor showed outstanding selective performance to HCHO among %97 RH and some a number of interfering volatile organic compounds (VOCs) such as chloroform, dichloromethane, acetone, n-hexane, methanol, xylene, and ammonia. Thus, real-time, sensitive, selective and effective recognition of HCHO by the sensor can be explained some adsorption mechanisms such as size-fit concept, three-dimensional structures of molecules and interaction between moieties of the sensible film layer and analyte molecules such as hydrogen bonding interactions. Image 1 • A novel amino morpholine schiff base calix[4]arene cage (SCC) was synthesized. • SCC was used as a sensor material for the detection of HCHO for the first time. • The sensor exhibited superior and remarkable performance towards HCHO. • The limit of detection was calculated as 0.67 ppm for HCHO. • The sensor was evaluated in terms of selectivity and durability towards HCHO. [ABSTRACT FROM AUTHOR]

• The silica gel supported dinitro calix[4]arene cage was successfully prepared, characterized, and used for methylene blue (MB) adsorption for the first time. • The applicability of DNCC for MB adsorption in real samples such as tap water and textile wastewater was investigated. • MB adsorption by DNCC was comprehensively evaluated in terms of thermodynamics, kinetic, and isotherm. • The MB uptake of DNCC was determined to be 212.770 mg g−1. The silica gel supported dinitro calix[4]arene cage (DNCC) was successfully prepared by immobilization of 3-glycidoxypropyl-bonded stationary phase (GBS) on p-tert- butylcalix[4]arene derivative having p -nitro benzyloxy moieties. The structural and composition analysis of the DNCC was performed by FT-IR, XRD, EDX, SEM, BET, and TGA techniques. After that, the proposed polymeric material as an adsorbent was used for the adsorption of methylene blue (MB) from aqueous solutions. Initial adsorption experiments demonstrated that DNCC showed outstanding performance for the removal of MB from aqueous solutions. Furthermore, many adsorption experiments were performed to evaluate the effects of some adsorption criteria on the MB adsorption. The MB adsorption capacity of DNCC was obtained approximately 212.770 mg g−1. Besides, thermodynamic parameters were evaluated and it was concluded that the MB adsorption came true in exothermically and spontaneously. Adsorption phenomena of MB on DNCC were clarified by the investigation of isotherm and kinetic criteria. Finally, the applicability of proposed adsorbent for MB adsorption was investigated in real samples such as tap water and textile wastewater. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of an amino morpholine-based the new schiff base calix[4]arene (compound 5), it's coating on Quartz Crystal Microbalance (QCM) crystal as a self-assembled monolayer (SAM), and real-time detection of erythromycin (ERY) in aqueous media. The characterization of the QCM sensor has been succeeded with atomic force microscopy and contact angle measurements. Initial experiments revealed that the frequency response decreased quickly as expected and reached equilibrium within 5 min which means that there was a good interaction between the compound 5 coated QCM sensor surface and ERY molecules. The QCM sensor showed a linear response towards ERY solutions in different concentrations ranging from 10 to 200 μM, with the sensitivity (S) and limit of detection (LOD) being 0.66 Hz/μM and 4.80 μM, respectively. Furthermore, the adsorption behavior and mechanism of ERY onto the QCM sensor were applied for this sensing system and the adsorption data exhibited a good correlation with the Langmuir adsorption isotherm in terms of R 2 and Δm max. The QCM sensor was shown outstanding selective performance to ERY among some biologic molecules such as amino acid, drug, hormone, vitamin. Thus, real-time, sensitive, selective and effective recognition of ERY was performed by a calixarene derivative coated QCM sensor. Image 1 • Calixarene based film was prepared onto the QCM surface by self-assembled monolayer to detect ERY. • Real time detection of ERY by calixarene-based QCM was accomplished for the first time. • Molecular recognition of ERY as sensitive, selective and effective was achieved. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of new chiral calix [4]arene derivative having (R)-2-phenylglycinol moiety (compound 6), and its chiral recognition studies for ascorbic acid (AA) enantiomers by using Quartz Crystal Microbalance (QCM). Initial experiments indicated that the outstanding selective chiral recognition (α) was observed as 2.61 for l -enantiomer of AA. The sensitivity (S) and the limit of detection (LOD) values for L -AA were calculated as 0.0226 Hz/μM and 0.63 μM, respectively. Furthermore, the sorption behavior and mechanism of AA onto compound 6 film were evaluated and the sorption data exhibited a good correlation with the Freundlich isotherm models. The maximum uptake of L -AA by the sensor was found as 5895.76 mg/g. In conclusion, chiral recognition of AA enantiomers as real-time, sensitive, selective and effective was performed by a calixarene derivative coated QCM sensor. Image 1 • Chiral detection of AA enantiomers by calixarene-based QCM was performed for the first time. • Enantiomeric detection of AA as real-time, sensitive, selective and effective was accomplished. • It was produced a QCM sensor to be durable and easily recoverable with distilled water. • Calixarene coating onto QCM surface was found to be a useful approach to detect AA. [ABSTRACT FROM AUTHOR]