Fullerene‐Crown Ether Coated Piezoelectric Crystal Liquid Chromatographic Detector for Metal Ions and Polar/Nonpolar Organic Molecules

Fullerene(C60)‐dibenzo‐16‐crown‐5‐oxyacetic acid (DBI6C5‐OCH₂‐COOC₆₀) was prepared and applied as the coating material on piezoelectric quartz crystals for detection of various metal ions and polar/nonpolar organic molecules. The C60‐crown ether‐coated piezoelectric crystal sensor with a home‐made computer interface for signal acquisition and data processing was applied as an ion chromatographic (IC) detector for various metal ions, e.g., alkali metal, alkaline earth metal and transition‐metal ions. The piezoelectric detector exhibited quite good sensitivity of 10⁴ ～ 10⁶ Hz/M and good detection limit of 10^?3 ～ 10^?4 M for these metal ions. The C60‐crown ether piezoelectric detector compared well with the commercial conductivity detector conventionally used for metal ions. The ionic size and ionic charge seemed to have significant effect on the frequency response of the piezoelectric detector. The C60‐crown ether coated piezoelectric crystal sensor was also employed as a high performance liquid chromatographic (HPLC) detector for various polar organic molecules with frequency responses in the order: amines > carboxylic acids > alcohols > ketones. Furthermore, nonpolar organic molecules, e.g., n‐hexane, 1‐hexene and 1‐hexyne, were also detected with this piezoelectric crystal detector. The frequency responses of the piezoelectric crystal detector for these nonpolar organic molecules were in the following order: alkynes > alkenes > alkanes. The effects of solvents and flow rate on the frequency responses of the piezoelectric crystal detector were investigated. The C60‐crown ether coated piezoelectric crystal detector also showed short response time (< 1 min.) and good reproducibility.     

Preparation and Application of Fullerene C60‐Polymers in Piezoelectric Quartz Crystal Sensors for Hemoglobin and Olefins

The C60—polycinnamaldehyde (C₆₀—PCA) and C60—polyphenylacetylene (C60—PPA) polymers were synthesized by the Friedel—Craft reaction and applied as piezoelectric (PZ) quartz crystal coating materials. A C60—polycinnamaldehyde (PCA) coated piezoelectric quartz crystal liquid sensor with a homemade computer interface was prepared and applied as a PZ hemoglobin sensor. The adsorption of hemoglobin onto the C60—PCA coated crystal resulted in a decreased oscillating frequency. The variations in crystal frequency were converted to voltage with a frequency to voltage converter, followed by amplification with OPA and data acquisition with an analog to digital converter. The PZ hemoglobin sensor exhibited good sensitivity of 6530 Hz/(mg/mL) with a detection limit at the ppm level for hemoglobin. Further, a C60—polyphenylacetylene (C60—PPA) coated piezoelectric quartz crystal gas sensor with an Intell‐8255 data processing system for various olefin vapors was also made. The aromatic hydrocarbons such as toluene seem to have greater adsorption onto C60—PPA membrane than alkynes, alkenes, and alkanes. The adsorption of polycyclic aromatic hydrocarbons (PAHs) onto the C60—PPA membrane was also examined. The C₆₀—PPA coated PZ crystal gas sensor showed much better sensitivity for PAHs than for other olefins such as toluene, 1‐hexyne and 1‐hexene, and a much larger frequency shift for naphthalene than other PAHs was also found.     

Piezoelectric Crystal Liquid Flow Detection Systems Based on Alkyl (C18)‐Benzo‐15‐Crown 5 for Organic Compounds and Metal Ions

A water in soluble long‐chain crown ether alkyl (C18)‐benzo‐15‐crown‐5 was synthesized and applied as a coating material on quartz crystal membranes of a liquid flow piezo electric crystal sensor. The oscillating crown ether‐coated piezo electric (PZ) crystal with a home‐made computer inter face was prepared as a liquid chromato graphic (LC) detector for organic species and metal ions in aqueous solutions. The oscillating frequency of the quartz crystal decreased due to the adsorption of organic molecules or metal ions on crown ether molecules. Effects of functional group, molar mass, steric hindrance, and polarity of organic molecules on frequency responses of the crown ether coated PZ crystal detector were investigated. The frequency responses of the crown ether coated PZ crystal detector for various molecules were in the order: amines > carboxylic acids > alcohols > ketones. The crown ether PZ detector also exhibited good sensitivity for some heavy metal ions and the frequency shifts were in the order: Cr³⁺ » Pb²⁺ > Co²⁺ > Cd²⁺ > Ni²⁺ > Cu²⁺. The crown ether coated piezo electric crystal LC detector demonstrated low detection limits for various polar organic molecules, e.g., 6.0 × 10^?5 M for propylamine, and metal ions, e.g., 2.9 × 10^?5 M (1.8 ppm) for Cu²⁺; the crown ether PZ detector also gave good reproducibility when re used. A quite sensitive electrochemical quartz crystal microbalance (EQCM) detection system was also set‐up for detecting trace heavy metal ions in solutions. The variation in frequency of the PZ crystal and the diffusion current were observed simultaneously after the reduction in heavy metal ions such as Cu²⁺ and Ni²⁺. The EQCM detection system exhibited fairly good sensitivity, e.g., 112 Hz/ppm for Cu²⁺ and a good detection limit, e.g., 0.13 ppm for Cu²⁺ ions. Comparison between EQCM and PZ detection systems was made and discussed.     

Preparation and Application of Cholesteryl‐Macrocyclic Polyether Liquid Crystals and Surfactants

Macrocyclic polyethers containing a cholesteryl moiety, e.g., cholesteryl benzo‐15‐crown‐5 (C₂₇H₄₅OOC‐B15C5) and cholesteryl cryptand22 (C₂₇H₄₅OOC‐Cryptand22), were synthesized. The cholesteryl crown ether C₂₇H₄₅OOC‐B15C5 showed liquid crystal characteristics which were observed by polarizing microscopy. In contrast, the cholesteryl cryptand C₂₇H₄₅OOC‐Cryptand22 showed no liquid crystal characteristics. The doping effect of inorganic salts on the liquid crystal formation of cholesteryl benzo‐15‐crown‐5 was also investigated, revealing that the addition of salts resulted in narrower liquid crystal temperature ranges. Both cholesteryl cryptand C₂₇H₄₅OOC‐Cryptand22 and cholesteryl crown ether C₂₇H₄₅OOC‐B15C5 also exhibited the distinctive characteristics of surfactants in solutions. Fluorescence probe of pyrene and surface tension measurement were applied as sensitive tools to study the formation of the micelles and determine the critical micellar concentration (CMC) of the cholesteryl cryptand and crown ether surfactants. The salt effect on the CMC of the cholesteryl cryptand surfactant was also investigated and is discussed. Furthermore, the cholesteryl benzo‐15‐crown‐5 was successfully employed as a quite good phase transfer catalyst for the oxidation of alcohols, e.g., benzhydrol, with NaMnO₄ as an oxidant. Effects of temperature, solvent and concentration of the crown ether catalyst on the oxidation of benzhydrol were also investigated.     

Piezoelectric Quartz Crystal Anti‐Protein Immunosensors Based on Immobilized Fullerene C60‐Proteins

Various fullerene C60‐proteins such as C60‐myoglobin (C60‐Mb), C60‐hemoglobin (C60‐Hb) and C60‐gliadin, coated piezoelectric quartz crystals were prepared and applied in piezoelectric quartz crystal immunosensors for protein‐antibodies such as anti‐myoglobin (Anti‐Mb), anti‐hemoglobin (Anti‐Hb) and anti‐gliadin respectively. The immobilizations of myoglobin, hemoglobin and gliadin onto Fullerene C60 were studied with a C60‐coated piezoelectric crystal detection system, respectively. The partially irreversible frequency responses for theses proteins were observed by a desorption study, implying that C60 can strongly adsorb these proteins. Thus, immobilized C60‐Mb, C60‐Hb and C60‐gliadin coating materials were successfully prepared and identified with FTIR spectrometry. The C60‐Mb, C60‐Hb and C60‐gliadin coated piezoelectric (PZ) quartz crystal immunosensors with homemade computer interfaces for signal acquisition and data processing were developed and applied for detection of Anti‐Mb, Anti‐Hb and anti‐gliadin respectively. The C60‐protein coated PZ immunosensors for Anti‐Mb, Anti‐Hb and antigliadin exhibited linear frequency responses to the concentrations of theses anti‐proteins with sensitivities of 1.43 × 10³, 2.59 × 10³ and 8.05 × 10³ Hz/(mg/mL) respectively. The detection limits of these PZ‐immunosensors were 4.36 × 10^?3, 3.23 × 10^?3 and 1.98 × 10^?3 mg/mL for Anti‐Mb, Anti‐Hb and anti‐gliadin respectively. Effects of pH and temperature on the frequency responses of the anti‐protein PZ‐immunosensors were also investigated. The optimum pH of these anti‐proteins and the optimum temperature for the PZ‐immunosensors were observed at pH = 7 and around 30 °C respectively. The interferences of various common species in human blood, e.g., cysteine, tyrosine, urea, glucose, ascorbic acid and metal ions, to these anti‐protein PZ‐immunosensors were also investigated respectively. These species showed nearly no interference or quite small interference with the anti‐protein PZ‐immunosensors. The reproducibility and lifetime of these immobilized C60‐protein coated PZ crystal immunosensors were also investigated and discussed.     

Detection of Hydrogen Peroxide and Glucose Based on Immobilized C60‐Catalase Enzyme

The interaction between fullerene C60 and catalase enzyme was studied with a fullerene C60‐coated piezoelectric (PZ) quartz crystal sensor. The partially irreversible response of the C60‐coated PZ crystal sensor for catalase was observed by the desorption study, which implied that C60 could chemically react with catalase. Thus, immobilized fullerene C60‐catalase enzyme was synthesized and applied in determining hydrogen peroxide in aqueous solutions. An oxygen electrode detector with the immobilized C60‐catalase was also employed to detect oxygen, a product of the hydrolysis of hydrogen peroxide which was catalyzed by the C60‐catalase. The oxygen electrode/C60‐catalase detection system exhibited linear responses to the concentration of hydrogen peroxide and amount of immobilized C60‐catalase enzyme that was used. The effects of pH and temperature on the activity of the immobilized C60‐catalase enzyme were also investigated. Optimum pH at 7.0 and optimum temperature at 25 °C for activity of the insoluble immobilized C60‐catalase enzyme were found. The immobilized C60‐catalase enzyme could be reused with good repeatability of the activity. The lifetime of the immobilized C60‐catalase enzyme was long enough with an activity of 93% after 95 days. The immobilized C60‐catalase enzyme was also applied in determining glucose which was oxidized with glucose oxidase resulting in producing hydrogen peroxide, followed by detecting hydrogen peroxide with the oxygen electrode/C60‐catalase detection system.     

Piezoelectric crystal/surface acoustic wave biosensors based on fullerene C60 and enzymes/antibodies/proteins

The development of piezoelectric (PZ) quartz crystal and surface acoustic wave (SAW) biosensors based on fullerene C60 and immobilized C60-enzymes/antibodies/proteins for the detection of various biological species are reported. The C60 coated piezoelectric crystal sensors can be applied to the study of interactions between fullerene C60 and some biological species, such as enzymes, antibodies, proteins and heparin. The partial irreversible responses for some biospecies from C60 molecules were observed by the desorption study which implied that C60 could chemically react with these biological species. Thus, immobilized biological species, e.g. C60-GOD, C60-catalase, C60-urease, C60-lipase, C60-anti IgG, C60-heparin, C60-Hb, C60-Mb and C60-anti-Hb were successfully prepared. The immobilized C60-GOD, C60-catalase, C60-urease, C60-anti-IgG and C60-anti-Hb were employed as adsorbents onto quartz crystal of various piezoelectric biosensors to detect glucose, H₂O₂, urea, IgG, and hemoglobin respectively. The immobilized C60-lipase was applied to distinguishably catalyze the hydrolysis of some optical isomers such as L- and D-phenyalanine methyl ester and to determine these optical isomers. The immobilized C60-heparin was employed as a good inhibitor for blood clotting like solvated heparin. The H₂O₂ bio-sensor was set up with the immobilized C60-catalase to detect oxygen, the product of the hydrolysis of H₂O₂ by C60-catalase. The immobilized C60-GOD enzyme piezoelectric glucose sensor exhibited a good sensitivity and a good lower limit for glucose. A piezoelectric crystal urea biosensor based on immobilized C60-urease was also prepared to detect urea. Comparison between solvated and immobilized enzymes used for biosensors was also made. The C60-anti IgG or C60-anti-Hb coated IgG piezoelectric crystal sensors exhibited good sensitivity, selectivity and repeatability for IgG or hemoglobin. Fullerene C60-Hb and C60-myoglobin (C60-Mb) coated surface acoustic wave (SAW) immunosensors were prepared to detect the anti-hemoglobin (anti-Hb) and anti-myoglobin (anti-Mb) antibody, respectively. An electrochemical SAW (ESAW) detection system was also developed to detect glucose in aqueous solutions.     

Multi‐Channel Piezoelectric Quartz Crystal Sensor with Principal Component Analysis and Back‐Propagation Neural Network for Organic Pollutants from Petrochemical Plants

A multi‐channel piezoelectric quartz crystal gas sensor comprising arrays coated with various organic materials and a home‐made computer interface for data processing were prepared and employed to detect six kinds of common organic pollutants from petrochemical plants including benzene, styrene, chloroform, octane, hexene and hexyne. The principal component analysis (PCA) method was employed to select six kinds of appropriate coating materials for these organic pollutants from 22 adsorbents onto piezoelectric crystals. After performing a PCA assay, six representative coating materials, namely Polyisobutylene, Poly(dimethylsiloxane) (SE30), 4‐tert‐Butylcalix[6]arene, Cholesteryl chloroformate, C60‐Polyphenyl acetylene (C60‐PPA) and Ag(I)/cryptand‐2,2/Ethylene diamine/NH₃/Polyvinyl chloride were selected. Moreover, effects of coating load of adsorbents and concentration of pollutants were also investigated. Three kinds of recognition techniques including 2D PCA score map, radar plot and back‐propagation neural network (BPN) were employed for qualitative analysis of these organic pollutants, and a quantitative analysis method could be established by creating calibration curves for each organic pollutant. This homemade multi‐channel piezoelectric quartz crystal gas sensor showed a good detection limit of 0.068‐1.127 mg/L for these organic pollutants. The multi‐channel piezoelectric gas sensor exhibited good reproducibility with a relative standard deviation (RSD) of 1.1‐9.6%. Furthermore, this multi‐channel piezoelectric crystal detection system with BPN recognition technique was also utilized to successfully distinguish and identify each component of the mixture of organic gas samples. Multivariate linear regression (MLR) analysis was employed to quantitatively compute the concentration of species in the organic mixtures.     

Multi‐Channel Surface Acoustic Wave (SAW) Sensor Based on Artificial Back Propagation Neural (BPN) Network and Multivariate Linear Regression Analysis (MLR) for Organic Vapors

A six‐channel surface acoustic wave (SAW) detection system with a 315 MHz one‐port quartz resonator and a homemade computer interface for signal acquisition and data processing was developed to detect various organic vapors. The oscillating frequency of the SAW quartz crystal decreased due to the adsorption of organic molecules on the coating materials. Polyethylene glycol, 18 crown 6 (18C6), Cr³⁺/cryptand‐22, stearic acid, polyvinylpyrrolidene and triphenyl phosphine coated quartz crystals were used as sensors. An artificial back propagation neural (BPN) network was used to recognize various organic gases such as hexane, 1‐hexene, 1‐hexyne, 1‐propanol, propionaldehyde, propionic acid and 1‐propylamine. It showed not only the distinction of unity of organic vapors but also mixtures of gases. The learning rate and the hidden unit of a neural network system for BPN analysis were investigated. Furthermore, the concentrations of these organic vapors were computed with about 10% error by multivariate linear regression analysis (MLR). MLR analysis with a multichannel SAW sensor was applied to determine the concentration of each component in a mixture of 1‐hexene, 1‐hexyne and propionaldehyde.     

Properties and Applications of Cryptand‐22 Surfactant for Ion Transport and Ion Extraction

A non‐ionic cryptand‐22 surfactant consisting of a macrocyclic cryptand‐22 polar head and a long paraffinic chain (C₁₀H₂₁‐Cryptand‐22) was synthesized and characterized. The critical micellar concentration (CMC) of the cryptand surfactant in ROH/H₂O mixed solvent was determined by the pyrene fluorescence probe method. In general, the cmc of the cryptand surfactant increased upon decreasing the polarity of the surfactant solution. The cryptand surfactant also can behave as a pseudo cationic surfactant by protonation of cryptand‐22 or complexation with metal ions. Effects of protonation and metal ions on the cmc of the cryptand surfactant were investigated. A preliminary application of the cryptand surfactant as an ion‐transport carrier for metal ions, e.g., Li⁺, Na⁺, K⁺ and Sr²⁺, through an organic liquid‐membrane was studied. The transport ability of the cryptand surfactant for these metal ions was in the order: K⁺ ≥ Na⁺ < Li⁺ < Sr²⁺. A comparison of the ion‐transport ability of the cryptand surfactant with other macrocyclic polyethers, e.g., dibenzo‐18‐crown‐6, 18‐crown‐6 and benzo‐15‐crown‐5, was studied and discussed. Among these macrocyclic polyethers, the cryptand surfactant was the best ion‐transport carrier for Na⁺, Li⁺ and Sr²⁺ ions. Furthermore, a foam extraction system using the cryptand surfactant to extract the cupric ion was also investigated.     

Preparation and Application of Immobilized Fullerene C60‐Heparin for Anticoagulation of Blood

The interaction between fullerene C60 and heparin was studied using a fullerene C60‐coated piezoelectric quartz crystal sensor. The irreversible response of the piezoelectric quartz crystal was found which could be attributed to the quite strong adsorption of heparin onto the C60 molecule. Immobilized fullerene C60‐Heparin was prepared and successfully applied as a good inhibitor for blood clotting. Like solvated heparin, both wet and dry C60‐heparin solid all demonstrated excellent ability of anticoagulation of blood. The blood clotting time with C60‐heparin solid was found to be > 7 days, while only 17.9 min required for blood clotting time in the absence of C60‐heparin solid. Furthermore, the C60‐heparin coated artificial PVC blood vessels were prepared by coating fullerene C60 onto the surface of artificial PVC blood vessels, followed by the adsorption of water solvated heparin onto the fullerene C60 molecule to form C60‐heparin coating. The blood clotting time of blood in artificial PVC blood vessels with C60‐heparin coating was found to be > 30 days, while only ≤ 30 min. of blood clotting time without the C60‐Heparin coating was observed. The C60‐heparin coated artificial PVC blood vessels can be expected to be employed in human body for the anticoagulation of blood.     

Polymer Coated Piezoelectric Quartz Crystal Protein Bio‐Sensors

A polymer coated piezoelectric crystal detection system with a home‐made computer interface for signal acquisition and data processing was prepared as a liquid chromatographic detector for various proteins. Various polymers, e.g., polyvinyl aldehhyde (polyacrolein) (PVA), polyacrylamide/glutaldehyde (PAA/GA) and bio‐gel A, were used as coating materials on quartz crystals for adsorption of various protein molecules, e.g., catalase (CA), hemoglobin (Hb), α‐chymotrypsin (Ch), albumin (Ab). The frequency responses of the polyacrlein coated piezoelectric detector for various proteins were in the order: catalase> hemoglobin> α‐chymotrypsin > albumin. In contrast, the order of the frequency responses of bio‐gel A and polyacrylamide/glutaldehyde coated piezoelectric crystals for these proteins were: hemoglobin> catalase > α‐chymotrypsin ≥ albumin and hemoglobin > albumin > catalase. The polyacrolein coated piezoelectric crystal protein detector exhibited a good linear frequency response with a high sensitivity of about 2.5×10³ Hz/(mg/mL) for catalase. In addition, bio‐gel A and polyacrylamide/glutaraldehyde coated crystals were sensitive to hemoglobin with sensitivities of about 4.5×10³ Hz/(mg/mL) and 3.0×10³ Hz/(mg/mL), respectively. Study of the interference of various organic molecules, e.g., alcohols, amines, ketones and carboxylic acids, in the detection of proteins with theses polymer coated crystals was also made. The polyacrolein coated crystal for proteins under went less interference from various organic molecules than bio‐gel A or polyacrylamide/glutaraldehyde coated crystals. Effects of coating load, concentration of proteins and flow rate of liquid chromatographic eluent were also investigated and discussed.     

Combining Fullerenes and Zwitterions in Non‐Conjugated Polymer Interlayers to Raise Solar Cell Efficiency

Polymer zwitterions were synthesized by nucleophilic ring‐opening of 3,3′‐(but‐2‐ene‐1,4‐diyl)bis(1,2‐oxathiolane 2,2‐dioxide) (a bis‐sultone) with functional perylene diimide (PDI) or fullerene monomers. Integration of these polymers into solar cell devices as cathode interlayers boosted efficiencies of fullerene‐based organic photovoltaics (OPVs) from 2.75 % to 10.74 %, and of non‐fullerene‐based OPVs from 4.25 % to 10.10 %, demonstrating the versatility of these interlayer materials in OPVs. The fullerene‐containing polymer zwitterion ( C₆₀‐PZ ) showed a higher interfacial dipole (Δ) value and electron mobility than its PDI counterpart ( PDI‐PZ ), affording solar cells with high efficiency. The power of PDI‐PZ and C₆₀‐PZ to improve electron injection and extraction processes when positioned between metal electrodes and organic semiconductors highlights their promise to overcome energy barriers at the hard‐soft materials interface of organic electronics.     

Bifunctional Ion‐Selective Electrode Based on C60‐Cryptand 22 for Silver and Iodine Ions

Fullerence C60‐cryptand 22 was prepared and successfully applied as the electric carrier in the PVC electrode membrane of a bifunctional ion‐selective electrode for cations, e.g., Ag⁺ ions as well as anions, e.g., I^? ions. The bifunctional ion‐selective electrode based on C60‐cryptand 22 can be applied as a Silver (Ag⁺) ion selective electrode with an internal electrode solution of 10^?3 M AgNO₃ in water (pH = 6.3), or as an Iodide (I^?) ion selective electrode with an acidic internal electrode solution of 10^?4 M KI_(aq) (pH = 2) in which the cryptand 22 is protonated, and the C60‐cryptand 22 is changed to C60‐Cryptand22–H⁺ and becomes an anionic electro‐carrier to absorb the I^? ion. The Ag⁺ ion selective electrode based on C60‐cryptand 22 gave a linear response with a near‐Nernstian slope (59.5 mV decade^?1) within the concentration range 10^?1‐10^?3 M Ag⁺_(aq). The Ag⁺ ion electrode exhibited comparatively good selectivity for silver ions, over other transition‐metal ions, alkali and alkaline earth metal ions. The Ag⁺ ion selective electrode with good stability and reproducibility was successfully used for the titration of Ag⁺_(aq) with Cl^? ions. The Iodide (I^?) Ion selective electrode based on protonated C60–cryptand22‐H⁺ also showed a linear response with a nearly Nernstian slope (58.5 mV decade^?1) within 10^?1 ‐ 10^?3 M I^? _(aq) and exhibited good selectivity for I^? ions and had small selectivity coefficients (10^?2–10^?3) for most of other anions, e.g., F^? , OH^?, CH₃COO^?, SO₄^2?, CO₃^2?, CrO₄^2?, Cr₂O₇^2? and PO₄^3? ions.     

A Three‐Dimensional Dynamic Supramolecular “Sticky Fingers” Organic Framework

Engineering high‐recognition host–guest materials is a burgeoning area in basic and applied research. The challenge of exploring novel porous materials with advanced functionalities prompted us to develop dynamic crystalline structures promoted by soft interactions. The first example of a pure molecular dynamic crystalline framework is demonstrated, which is held together by means of weak “sticky fingers” van der Waals interactions. The presented organic‐fullerene‐based material exhibits a non‐porous dynamic crystalline structure capable of undergoing single‐crystal‐to‐single‐crystal reactions. Exposure to hydrazine vapors induces structural and chemical changes that manifest as toposelective hydrogenation of alternating rings on the surface of the [60]fullerene. Control experiments confirm that the same reaction does not occur when performed in solution. Easy‐to‐detect changes in the macroscopic properties of the sample suggest utility as molecular sensors or energy‐storage materials.     

Bi‐channel Surface Acoustic Wave Gas Sensor for Carbon Disulfide and Methanol Vapors in Polymer Plants

A C₆₀‐polyphenylacetylene (C₆₀‐PPA) and polyvinylpyrrolidone (PVP) coated two‐channel surface acoustic wave (SAW) crystal gas sensor with a homemade computer interface for data acquisition and data processing was developed and employed to detect carbon disulfide (CS₂) and methanol (CH₃OH) vapors in polymer plants. The frequency of surface acoustic wave oscillator decreases due to the adsorption of gas molecules on the coated materials of the SAW sensor. Six coating materials (C₆₀‐PPA, nafion, PPA, crytand [2,2], polyethene glycol and PVP) were used to adsorb and detect carbon disulfide and methanol gases. Adsorption of all the six coating materials to CS₂ and CH₃OH was found to be physical adsorption. The C₆₀‐PPA coated SAW detector exhibited more sensitive to CS₂ than the other coating materials. In contrast, the PVP coated SAW detector was more sensitive to CH₃OH than the other coating materials. With the two‐channel SAW sensor, the C₆₀‐PPA coated SAW showed a good detection limit of 0.4 ppm and good reproducibility with RSD of 3.37 % (n=10) for CS₂. Similarly, the PVP coated SAW also showed a good detection limit of 0.05 ppm and good reproducibility, with RSD of 0.86 % (n=10) for CH₃OH. The interference effect of other organic molecules on the SAW detection system was negligible, except for the irreversible adsorption of C₆₀‐PPA to propylamine. The frequency signals from the two‐channel SAW sensor array C₆₀‐PPA and PVP coatings were processed by a back‐propagation artificial neural network (BPN) and multiple regression analysis (MRA). Thus a two‐channel SAW sensor array with BPN and MRA has been successfully applied for the qualitative and quantitative analyses of CS₂ and CH₃OH in mixtures.     

Ionic liquid high temperature gas sensors

An ionic liquid piezoelectric gas sensor was demonstrated for detection of polar and nonpolar organic vapors at high temperature with fast linear and reversible response.     

Selection of a piezoelectric sensor array for detecting volatile organic substances in water

Sensitive coatings for piezoelectric sensors used to assess the presence of anthropogenic volatile organic substances in the equilibrium gas phase over natural water have been selected using an array of measuring elements, and the data have been processed using principal component analysis. Groups of piezoelectric sensors with similar characteristics for substance identification have been determined based on the correlation between piezoelectric sensor responses when vapors of organic substances were detected. The stepby-step optimization of the piezoelectric sensor array has been carried out in order to identify the greatest number of organic compounds (vapors) in the sample. Volatile organic compounds can be identified in their aqueous solutions and natural water using the optimized piezoelectric sensor array.     

Application of Cryptand/Polystyrene Drift-Type Phase Transfer Catalysts for Reduction of Ketones

A drift-type phase transfer catalyst, cryptand-22, adsorbed on poly(styrene/diviny benzene)-sulfonic resin was prepared and applied to catalyze the reduction of ketones, e.g., acetophenone, benzophenone and benzaldehyde with NaBH₄ as a reducing agent. Before the reaction, cryptand-22 was adsorbed on the sulfonic resin with ion-pairing, resin-SO₃^{? +}NH-cryptand-22. The ion-pairs can be destroyed by adjusting the basicity of the reaction solution with NaOH and the cryptand can be released from the resin into the reaction solution as a homogeneous catalyst during the reaction period. After the reaction, the cryptand catalyst can be readsorbed on the resin by adjusting the acidity of the solution with HCl and can be readily recovered by filtration like a heterogeneous catalyst. The draft-type cryptand catalyst exhibited better catalytic ability than some common crown ethers, e.g., 15-crown-5, benzo-15-crown-5, 12-crown-4 and dibenzo-18-crown-6 for the reduction of acetophenone with NaBH₄. Effects of solvents, pH of solutions, concentration of the catalyst, reducing agents and resin property on the reduction of ketones were investigated and discussed. The reaction mechanism of the cryptand catalyzed reduction was also studied.     

Transforming Ionene Polymers into Efficient Cathode Interlayers with Pendent Fullerenes

A new and highly efficient cathode interlayer material for organic photovoltaics (OPVs) was produced by integrating C₆₀ fullerene monomers into ionene polymers. The power of these novel “C₆₀‐ionenes” for interface modification enables the use of numerous high work‐function metals (e.g., silver, copper, and gold) as the cathode in efficient OPV devices. C₆₀‐ionene boosted power conversion efficiencies (PCEs) of solar cells, fabricated with silver cathodes, from 2.79 % to 10.51 % for devices with a fullerene acceptor in the active layer, and from 3.89 % to 11.04 % for devices with a non‐fullerene acceptor in the active layer, demonstrating the versatility of this interfacial layer. The introduction of fullerene moieties dramatically improved the conductivity of ionene polymers, affording devices with high efficiency by reducing charge accumulation at the cathode/active layer interface. The power of C₆₀‐ionene to improve electron injection and extraction between metal electrodes and organic semiconductors highlights its promise to overcome energy barriers at the hard‐soft materials interface to the benefit of organic electronics.