Supramolecular associates of double-decker lanthanide phthalocyanines with macromolecular structures and nanoparticles as the basis of biosensor devices

The electronic-spectroscopy technique is used to study the properties of solutions of double-decker diphthalocyanine complexes of lanthanides LnPc₂ (Ln = Ho, Er, Yb, Lu) in chloroform, dimethylformamide, water-micellar systems, solutions of proteins, and polymers, as well as on the surface of silica nanoparticles. In all the studied systems, a correlation is established between the positions of maxima of absorption bands of LnPc₂ and the ionic radius of the complexing metal. Redox processes determined by the nature of the solubilizer are detected in supramolecular associates of LnPc₂ with macrocompounds and nanoparticles. Finally, prototypes of sensor systems are suggested for determination of albumin and silica nanoparticles in solutions. Films of polyvinyl pyrrolidone and polyvinyl alcohol containing LuPc₂ and YbPc₂ are obtained, for which sensor response to albumin and nanosilica is also established. On the whole, the results show good prospects for development of sensor devices based on the studied systems.     

Synthesis,characterization and electrical and CO2 sensing properties of triazine containing three dendritic phthalocyanine

The metal-free phthalocyanine 1a was synthesised by statistically mixed condensation of 4-nitrophthalonitrile and 4-(2-dimethylaminoethylsulfanyl)phthalonitrile in dry 2-(dimethylamino)ethanol. The same route were applied to prepare metal-containing phthalocyanines using metal salts Zn(OAc)₃·2H₂O and CoCl₂, respectively, in dry DMF. The nitro compounds were reduced to amine with sodium sulfide and quarternized by reaction of MeI. These compounds were then reacted with cyanuric chloride in the presence of potassium carbonate as a base in mixture of THF and DMF gave s-triazine containing three amino phthalocyanines 4a–c. The reaction of three phthalocyanines with sodium salt of triethylmethanetricarboxylate in absolute ethanol were synthesised first generation of dendrimer 5a–c. The second generation of dendritic phthalocyanines 6a–c were prepared by the reaction of dentritic phthalocyanines with tris (H₂NC(CH₂OH)₃) using K₂CO₃ as a base in DMSO. The dendritic phthalocyanines containing tris are slightly soluble in water. The new compounds were characterized by elemental analysis and UV–vis, IR, NMR spectra. The temperature dependence of the dc and ac conductivity of these compounds and the adsorption of CO₂ gas on thin film of the compounds were investigated by dc conductivity and impedance spectroscopy technique using an interdigital transducer structure on glass substrate. While exposure to CO₂ have no influence on the electrical conductivity (ac and dc) of compound 6a and 6c, the conductivity of the film of 6b strongly depend on the presence of the CO₂ gas. Completely reversible sensor signals were obtained for compound 6b. The impedance spectra were obtained at frequencies between 40 and 10⁵ Hz, and in a wide range of CO₂ concentrations (from 500 to 8000 ppm) at room temperature. The temperature dependence of dc conductivity show typical Arrehenius behaviour for all compounds. The ac conductivity of the films is represented by the form ω^s. The dependency of frequency exponent s on temperature suggests a correlated barrier hopping (CBH).     

Synthesis,characterization and electrical properties of dihalogenated polyanilines

Poly(2.5-dichloroaniline), poly(2,3-dichloroaniline), poly(3,5-dichloroaniline), poly(2,5-dibromoaniline) and poly(2,6-dibromoaniline) have been synthesized from dihaloanilines in protic and aprotic media with different oxidizing agents, such as copper perchlorate, potassium dichromate and potassium permanganate. Each polymer is characterized by elemental analysis, IR and UV-Vis spectroscopy, scanning electron microscopy (SEM) and conductivity measurements. To obtain the doped polymers, they are treated with inorganic acids and then their electric properties determined. The use of different oxidants allows the obtention of polymers with different redox states which, in some cases, present semiconducting properties and are soluble in methanol and acetone. For the sake of comparison of the electrical and structural properties of the new polymers, polyaniline (PANI) has also been synthesized in a manner analogous to the poly(dihaloanilines).     

Polypyrrole coated carbon nanotubes: Synthesis,characterization, and enhanced electrical properties

We describe a simple approach to the synthesis of MWNT/polypyrrole nanotubes by the in situ chemical polymerization of pyrrole on the carbon nanotubes using ferric chloride as an oxidant. The effects of pyrrole concentration on the coating and properties of the resulting complex nanotubes were studied by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, and thermal gravimetric analysis. The coated PPy layers could be controlled easily by adjusting a feed ratio of pyrrole to MWNTs. FT-IR results suggested an existence of interaction between the –COOH groups of chemically modified MWNTs and NH groups of the PPy. SEM and TEM studies indicated that each individual MWNT could be coated with PPy. The resultant nanotubes enhanced electrical conductivity compared to PPy and MWNT which was strongly influenced by the feed ratio of pyrrole to MWNTs.     

Synthesis, characterization and electrical properties of soluble conjugated poly-Schiff bases

Four conjugated poly-Schiff bases with the same backbone but different side groups were prepared by polycondensation of 1,4-diaminobenzene with glyoxal, 2,3-butanedione, 3,4-hexanedione and 4,5-octanedione, respectively. The polymers were characterized by FT-IR, elemental analysis, etc. It was discovered that the conjugated poly-Schiff bases with alkyl side groups can be dissolved in common organic solvents. Electrical conductivities of the pristine polymers and their relationship with temperature were measured, showing that the polymers are typical semiconductors. When the polymers were doped with iodine, electrical conductivity increased by seven to nine orders of magnitude (up to 10⁻³-10⁻⁴ S/cm). The effect of side groups on the conductivity of the I₂-doped polymers is discussed.     

Synthesis and electrochemical,electrochromic and electrical properties of novel s-triazine bridged trinuclear Zn(II), Cu(II) and Lu(III) and a tris double-decker Lu(III) phthalocyanines

The new s-triazine-bridged trinuclear Zn(II) and Cu(II) phthalocyanines have been synthesized from the reaction of corresponding anhydrous metal salts, Zn(OAc)₂ and CuCl with 4,5-bis(hexylthio)-phthalonitrile and 2,4,6-tris(2-thiophthalonitrile)-s-triazine. The tris phthalonitrile derivative of s-triazine was prepared from the reaction of 4-nitrophthalonitrile and thiocyanuric acid in dry dimethylformamide as solvent using K₂CO₃ as the base. The same route was applied to prepare the trinuclear Lu(III) phthalocyanine analogue. The conversion of tris phthalonitrile into its isoindoline derivative was accomplished by bubbling ammonia gas through a solution in methanol in the presence of sodium methoxide. The cyclization of two different isoindoline derivatives and 4,5-bis(hexylhthio)-1,2-diiminoisoindoline, with lutetium (III) acetate in dimethylformamide gave trinuclear Lu(III) phthalocyanine. The reaction of this complex with octakis-hexylthio phthalocyanine led to the isolation of tris double-decker Lu(III) phthalocyanine. The structures of the target compounds were confirmed by elemental analysis, UV–vis, IR and MALDI-TOF mass spectroscopies. The d.c. and a.c. conductivities of the phthalocyanine compounds were measured as a function of temperature. The small value of pre-exponential factor suggested the conduction by localized states in the band tails and by localized states near the Fermi level. The temperature dependence of the frequency exponent showed that the conduction in these compounds is due to hopping of charge carriers. The tris double-decker phthalocyanine complex showed well-defined electrochromic behaviour with green-blue and blue-purple colour transitions.     

WO3纳米片的制备、表征及气敏性能研究

论文采用水热法合成WO₃纳米片,利用扫描电镜(SEM)和X射线衍射(XRD)对WO₃纳米片的形貌特征和结构性能进行表征,并进一步系统地考察了利用WO₃纳米片制备的传感器的气敏性能。实验结果表明,合成的WO₃纳米片尺寸规则,边长在200-300 nm,厚度在50 nm左右,结晶性好。以WO₃纳米片为材料制备的气体传感器的最佳工作温度为300 _oC,在此工作温度下,WO₃纳米片传感器对乙醇表现出超快的响应(2-4秒)和恢复时间(4-16 S)。与其他还原性气体如甲醇,苯、二氯甲烷和正己烷对比检测发现,WO₃纳米片传感器对乙醇表现出高的灵敏度和选择性,表明WO₃纳米片在乙醇检测气体传感器方面具有极大的应用潜力。     

Synthesis and characterization of graft copolymers of melamine: Thermal stability, electrical conductivity, and optical properties

In this study, novel three Schiff bases of melamine were synthesized via condensation reaction of melamine with salicylaldehyde, 3-hydroxybenzaldehyde, and 4-hydroxybenzaldehyde namely N,N′,N′′,-tris[(2-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (2-HPMTT), N,N′,N′′-tris[(3-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (3-HPMTT), N,N′,N′′-tris[(4-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (4-HPMTT), respectively. Then, oligo/polyphenol derivatives of these Schiff bases were obtained by grafting melamine onto oligosalicylaldehyde (OSA), oligo-3-hydroxybenzaldehyde, and oligo-4-hydroxybenzaldehyde that have generate names of poly-N,N′,N′′-tris[(2-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (P-2-HPMTT), poly-N, N′,N′′-tris[(3-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (P-3-HPMTT), and oligo-N,N′,N′′-tris[(4-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (O-4-HPMTT), respectively. The structures of the synthesized compounds were confirmed by FT-IR, UV–vis, ¹H NMR, and ¹³C NMR techniques. The characterization was made by TG-DTA, DSC, size exclusion chromatography (SEC), and solubility tests. Electrical conductivities of the synthesized materials were measured by four-point probe technique using a Keithley 2400 electrometer showing that the synthesized oligo/polyphenols have higher electrical conductivities than the monomeric Schiff bases. Also considerable increases in the conductivities were observed when they were doped with iodine as a doping agent. The order of increase rates of the conductivities were found as follows: 2-HPMTT > P-2-HPMTT > P-3-HPMTT > 3-HPMTT > 4-HPMTT > P-4-HPMTT. Additionally, the optical band gaps (E_g) were calculated by using the absorption spectra and found to be 2.78, 2.17, 3.58, 3.30, 4.03, and 2.82 eV for 2-HPMTT, P-2-HPMTT, 3-HPMTT, P-3-HPMTT, 4-HPMTT, and O-4-HPMTT, respectively.     

Synthesis,characterization, and electrical,electrochemical and gas sensing properties of a novel cyclic borazine derivative containing three phthalocyaninato zinc(II) macrocycles

A novel borazine derivative of trinuclear phthalocyanine has been prepared by following the multistep reactions of unsymmetrically substituted phthalocyanines. 4-(4-Amino-3-nitrophenoxy)phthalonitrile (3) which is one of the precursor molecules of the phthalocyanine was obtained from 4-nitrophthalonitrile (1) and 4-amino-3-nitrophenol (2) with K₂CO₃ in DMF at 50 °C. The zinc(II) phthalocyanine (5) containing an unsymmetrical substituted 4-amino-3-nitrophenoxy group was synthesized by statistical condensation of two different phthalonitriles. 4-(4-Amino-3-nitrophenoxy)phthalonitrile (3) and 4,5-bis(hexylthio)phthalonitrile (4) were cyclotetramerized with zinc acetate in DMF at 170–180 °C to yield 2-(4-amino-3-nitrophenoxy)-9,10,16,17,23,24-hexa(hexylthio)phthalocyanine zinc(II) complex (5), which was then separated by column chromatography on silica gel. The unsymmetrically substituted compound was reduced to the diamine form (6) using hydrazine hydrate in the presence of Pd/C catalyst, and the product was purified with chromatographic separation. Compound 6 was then reacted with triisopropoxyborane in refluxing xylene to give 5H,12H,19H-tris[2-(3,4-diaminophenoxy)-9,10,16,17,23,24-hexa(hexylthio)phthalocyaninato zinc(II) diazaborolo] borazine (7). The resulting product was purified by column chromatography on silica gel. All the target unsymmetrical phthalocyanines and borazine derivative were characterized by elemental analysis, IR, UV–vis, and ¹H NMR. Boron and zinc(II) percents in 7 were quantified with ICP-MS. Impedance spectroscopy and dc measurements were performed on spin coated 5–7 films as a function of temperature (293–400 K). The dc results showed an activated conductivity dependence on temperature. The ac results gave a temperature dependent frequency exponent s. The results were compared with the prediction of the Quantum Mechanical Tunelling and Correlated Barrier Hopping models. The ac conductivity of the films was well represented by the form Aω^s. Gas sensing properties of the films for the volatile organic compounds (VOCs) (chloroform, acetone, carbontetrachloride and ammonia) were also investigated in the temperature range from 293 to 400 K. The operating temperature had a considerable effect on sensing characteristics. Maximum sensitivity to VOCs were observed at room temperature for all films. Cyclic voltammetry of compounds 6 and 7 in solution indicated that these compounds have similar voltammetric behaviour.     

Synthesis, photophysical and photochemical properties of crown ether substituted zinc phthalocyanines

The photophysical and photochemical properties of the tetra- and octa-12-crown-4-substituted zinc (II) phthalocyanines are reported for the first time in the scope of this work. The new compounds have been characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in dimethylsulphoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for photodynamic therapy (PDT) applications. The effects of the substituents on the photophysical and photochemical parameters of the zinc (II) phthalocyanines (5, 6 and 7) are also reported. The singlet oxygen quantum yields (Φ_Δ) ranged from 0.48 to 0.78 are indicating the potential of the complexes as photosensitizers in applications of PDT. The fluorescences of the substituted ZnPc complexes are effectively quenched by benzoquinone (BQ).     

Synthesis,structure characterization,and ion exchange properties of a novel open—framework ecomaterial silicotitanate

A novel open-framework ecomaterial silicotitanate (Na4Ti4Si3O10) was synthesized by a combination of sol-gel and hydrothermal methods. The investigation on ion exchange properties shows that Na4Ti4Si3O10 exhibits high adsorption for cesium, i.e., Kd is as high as 60 000 mL/g in neutral solution. The crystal structure of Na4Ti3O10 was characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), transmission electron microscope (TEM), Raman spectrum, differential thermal and thermogravimetric analysis (DTA/TGA), inductively coupled plasma (1CP), and X fluorescence analysis. The compound is tetragonal, P42, a = b = 0.781 10 nm, c= 1.196 45 nm, α =β =γ = 90°, Z = 4, and Ra = 0.041; Na4Si3O10 has a three dimensional framework consisting of Ti-O octahedral clusters and Si-O tet-rahedra. The results show that Na4Ti4Si3O10 has good chemical stability, thermal stability, and high cesium ion exchange capacity in the whole pH range.     

Synthesis and spectroscopic properties of a series of octacationic water-soluble phthalocyanines

The synthesis, characterization of newly synthesized metal-free 2 and metallophthalocyanine complexes 3–5 (MPcs, M = Ni, Co, Cu) and quaternized metallophthalocyanine derivatives 3a, 5a (MPcs, M = Ni, Cu) containing 4,5-bis(quinolin-6-yloxy) substituents have been presented in this work. The new compounds have been characterized by using elemental analysis, UV–vis, IR, ¹H NMR, ¹³C NMR and MS spectroscopic data. Also, aggregation properties of Pcs were investigated at different concentrations in chloroform, dimethylformamide and water. The effect of the concentration on the aggregation properties of complexes 2–5 was studied in chloroform. No aggregation was demonstrated in chloroform from concentration between 1 × 10^?5 and 0.4 × 10^?5 M.     

Oxygen sensing nanofibers doped with red-emitting Eu(III) complex: Synthesis,characterization, mechanism,and sensing performance

In this paper, we synthesize a novel diamine ligand of PIP and its corresponding Eu(III) complex of Eu(DBM)₃PIP, where PIP = 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline, and DBM = 1,3-diphenyl-propane-1,3-dione. The UV–Vis absorption spectra, low temperature phosphorescence spectra, energy transfer mechanism, excited state lifetime of Eu(DBM)₃PIP, as well as its photoluminescence spectra, are investigated in detail. Data suggest that the emission of Eu(DBM)₃PIP is quenchable by molecular oxygen due to the back-energy transfer process. By doping Eu(DBM)₃PIP into a polymer matrix of poly(vinylpyrrolidone) (PVP), the oxygen sensing performance of the resulted nanofibrous membrane is investigated. Finally, the 0.6 wt% doped sample exhibits a linear response towards molecular oxygen, with a sensitivity of 3.5 and response/recovery time of 15 s/24 s.     

Synthesis and electrochemical,in situ spectroelectrochemical,electrical and gas sensing properties of ball-type homo- and hetero-dinuclear phthalocyanines with four [1a,8b-dihydronaphtho[b]naphthofuro[3,2-d]furan-7,10-diyl] bridges

The new mono-nuclear Fe^II 2 and ball-type homo-dinuclear Fe^II–Fe^II 3 phthalocyanines have been synthesized from the corresponding 4,4′-(1a,8b-dihydronaphtho[b]naphthofuro[3,2-d]-furan-7,10-diyl)bis(oxy)diphthalonitrile 1 while ball-type hetero-dinuclear Fe^II–Co^II phthalocyanine 4 was synthesized from 2. The compounds have been characterized by elemental analysis, UV–vis, IR and MALDI-TOF-mass spectroscopies. The redox behaviours of the complexes were identified by controlled-potential coulometry, cyclic voltammetry and differential pulse voltammetry measurements on Pt in dimethylsulfoxide containing tetrabutylammonium perchlorate. The assignments of the redox processes and the understanding of the interactions between the metal phthalocyanine units in 3 and 4 were achieved by the combined evaluation of the voltammetric and in situ spectroelectrochemical outcomes. Complex 3 showed ring-based mixed-valence behaviour as a result of the considerable interaction between the phthalocyanine rings. On the other hand, the interactions between the two metal phthalocyanine units of 4 were found to be much weaker than those in 3. The potential application of molecular organic semiconductors needs the control adjustment of conductivity. Ac and dc conductivity measurements were performed with the applied external electric filed. At high frequency, the conduction follows the universal power law and conduction mechanism can be explained by classical hopping barriers mechanism for the system.     

Synthesis,characterization, mesomorphic and electrical properties of tetrakis(alkylthio)-substituted lutetium(III) bisphthalocyanines

The synthesis of new lutetium(III) bisphthalocyanines substituted with alkylthio groups (1–5) is described. These compounds (Pc₂Lu) are soluble in most common organic solvents and have been fully characterized (elemental analysis, FT-IR, UV–Vis spectroscopy, mass spectrometry). The thermal stabilities of the Pc compounds were determined by thermogravimetric analysis (TGA). The mesogenic properties of these new materials forming columnar-hexagonal (Col_h) mesophases were studied by differential scanning calorimetry (DSC), optical microscopy and X-ray diffraction. The compounds 2–5 exhibit a double clearing point. DC electrical properties of these compounds in different phases were determined by measuring I–V characteristics and dark current of their thin films on interdigital electrodes. The measurements were carried out in ambient air, in vacuum and in high purity nitrogen (N₂) flow in the temperature range between 300 and 420 K. Dark current measurements obtained in the crystal, liquid crystal (LC) and isotropic liquid phases were in agreement with the phase transitions of these compounds obtained by DSC and optical microscopy results. The relation between the phase transition and conductivity of the Pc₂Lu derivatives were investigated. Also, the influence of the nature of the substituted group (alkylthia and alkoxy) upon the DC electrical properties of the Pc₂Lu derivatives was investigated. The DC conductivities and the thermal activation energies depending on alkyl chain lengths of these compounds were found to be in the range of 10^?8 to 10^?5 S/cm and 0.12–0.38 eV in solid phase.     

Synthesis,characterization and electrical conductivity of polyesters,polyamides and doped polymers

The synthesis and characterization of polyamides and polyesters containing azomethyne linkages are reported here. The electrical conductivity of the polymers is measured and the results explained with simple Pariser-Parr-Pople calculations. The polymers are doped with Ag and the electrical conductivity of each polymer is found to register a significant increase. Attempts are made to explain this increase.     

Synthesis and characterization of lanthanide trifluoroacetate complexes with 3-picoline-N-oxide

Complexes with composition Ln(F₃C-COO)₃·2(3-picNO)·ξH₂O were synthesized. According to X-ray powder patterns and IR data five series of isomorphous compounds were detected: La---Nd; Sm---Eu; Gd>Tm, Y; Ho, Er, Tb; Dy, Yb, Lu. They behave as nonelectrolytes in methanol. IR spectra show a shift of νNO to lower frequencies, as compared with the free ligand, as a result of coordination through the oxygen. The bands attributed to the anions indicate two modes of coordination. The neodymium spectrum at 77 K shows that the central ion is not involved in a cubic site. Electrostatic bonds between Nd³⁺ and ligands were evidenced by the nephelauxetic, Sinha's parameters and covalent factor from the room temperature spectrum. Using the electronic emission spectrum, at 77 K, it was possible to conclude that europium ions present two different symmetry sites, since a splitting of the ⁵D₀ → ⁷F₉ band was observed. The complex species are probably polymeric or at least dimeric, and europium ions are involved in two different sites, but with the same C_3ν symmetry.     

Synthesis and electrochemical,electrical and gas sensing properties of novel mononuclear metal-free,Zn(II), Ni(II), Co(II), Cu(II), Lu(III) and double-decker Lu(III) phthalocyanines substituted with 2-(2H-1,2,3-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl) phenoxy

A new mono substituted phthalonitrile derivative 3 was prepared by a nucleophilic displacement reaction of 4-nitrophthalonitrile with 2-(2H-1,2,3-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol. Novel metallophthalocyanines 4–8 (M = Zn, Ni, Co, Cu, Lu, respectively), metal free 9 and double decker Lu(III) phthalocyanine 10 with four peripheral 2-(2H-1,2,3-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenoxy groups were synthesized by cyclotetramerisation of the phthalonitrile and characterized by elemental analyses, FTIR, ¹H NMR, UV–vis and MALDI-TOF MS spectral data. Cyclic voltammetry, differential pulse voltammetry and in situ spectroelectrochemistry of the phthalocyanine compounds have been studied. This allowed us to identify and compare metal- and phthalocyanine ring-based redox processes of the complexes. Impedance spectroscopy (IS) and dc conductivity measurements were performed as a function of temperature (300–430 K) and frequency (40–10⁵ Hz.). The sensing properties of the films for toluene were also investigated. The dc results showed an activated conductivity dependence on temperature for all films. While room temperature impedance spectra consist of a curved line, a transformation into a full semicircle with increasing temperature was observed. The analysis of ac conductivity data showed that the CBH model is the dominant conduction mechanism for the electron transport in the films. While exposure to toluene has no effect on the conductivity of the film of 8–10 completely reversible sensor response to toluene only were obtained for compounds 4–7. It was also observed that the operating temperature had a considerable effect on sensing characteristics of the films.