Tamara V. Basova

Mesomorphic phthalocyanine as chemically sensitive coatings for chemical sensors

Abstract Octa(13,17-dioxanonacosane-15-sulfanyl)-substituted mesomorphic nickel(II) phthalocyanine (Pc) at room temperature is investigated for the detection of organic solvent vapors by utilizing quartz crystal microbalance (QCM). Determined by polarized Raman spectroscopy, the Ni(II) Pc layers as coated were disordered and the Ni(II) Pc layers thermally treated were ordered. The ordered films on QCM-devices show higher sensitivity and partition coefficient for all solvent molecules investigated such as ethanol, dichloromethane, acetone, n -hexane. The Raman Spectroscopy investigation results show that the molecules with saturated CC bonds such as ethanol interact with phthalocyanine films predominantly by formation of hydrogen bonds and the sensor response to π bond containing compounds such as acetone is the result of their π–π interaction with conjugated phthalocyanine ring.

Determination of the orientation of CuPc film by raman spectroscopy

Abstract In this work, Raman spectroscopy is used to define a molecular orientation in copper phthalocyanine (CuPc) films. The suggested approach is based on the analysis of the lattice vibrations coupled directly with the crystal structure of the compound. It is shown that the CuPc film deposited on heated silicon substrate is oriented so that the YZ crystallographic plane is oriented parallel to the substrate surface.

Raman polarization study of the film orientation of liquid crystalline NiPc

Abstract In this work, we determine, using Raman spectroscopy, the orientation of molecules relative to the substrate surface in films of octa(13,17-dioxanonacosane-15-sulfanyl)-substituted nickel(II) phthalocyanine, showing a liquid crystalline phase at room temperature. It was stated that the phthalocyanine molecules in the film are disordered relative to z -axis and rotated around x and y- axis on fixed α and β angles, respectively. We study the dependence of film orientation on temperature in the range from 0 to 30°C. The α angle is decreased from 30 to 10° with increasing temperature, whereas, the β angle is held constant (65°). The phase transition from liquid crystalline to isotropic phase in the NiPc film is observed at approximately 10°C.

Investigation of liquid-crystalline behavior of nickel octakisalkylthiophthalocyanines and orientation of their films

In this work, the mesogenic properties of octa-alkyl-substituted Ni(II) phthalocyanine derivatives are reported. These phthalocyanines (Pc) demonstrate thermotropic phase behavior and give rise to discotic liquid crystals. The dependence of film orientation on temperature in the temperature range from 0 to 300 °C was studied by the method of Raman spectroscopy. It was shown that the films are disordered in the temperature range where the samples of NiPc are solid. Oriented films may be obtained by annealing at the temperatures at which the materials are mesogenic. According to results from a Raman polarization study, the phthalocyanine molecules in this ordered films are oriented virtually perpendicular to the substrate surface.

Amphiphilic carbohydrate–phthalocyanine conjugates obtained by glycosylation or by azide–alkyne click reaction

Two series of amphiphilic carbohydrate–phthalocyanine conjugates have been prepared either by glycosylation or by copper-catalyzed click coupling. A common precursor, a hydroxylated phthalocyanine, was directly glycosylated or converted into an azido derivative before undergoing grafting of propargyl–carbohydrates by click reaction.

Use of the electrochromic behaviour of lanthanide phthalocyanine films for nicotinamide adenine dinucleotide detection

Electrochromic properties of spun films of bis[octakis(hexylthio)phthalocyaninato] dysprosium(III) were investigated for determining nicotinamide adenine dinucleotide hydride (NADH) in water solutions. A spin-coated film deposited on indium tin oxide electrode displays only one redox couple (at E1/2=0.78 V). The films of [(C6H13S)8Pc]2Dy were modified chemically or electrochemically for the detection of reduced NADH in water solution. The modified film in the oxidized ([(C6H13S)8Pc]2Dy)+ form is believed to be reduced to its neutral form on interaction with NADH.

Vapour pressure of some phthalocyanines

Mass spectrometric studies of the composition of the gaseous phase under solid compounds of free phthalocyanine (H2Pc) and its complexes with aluminium (AlClPc, AlFPc, (AlPc)2O) and copper (CuPc) were performed in the temperature range up to 700 °C. It has been shown that the phthalocyanines sublime in the form of monomers, excluding one aluminium complex. All phthalocyanines under investigation sublime without thermal decomposition until 700 °C. The vapour pressure of these phthalocyanines was determined as a function of temperature by the Knudsen effusion method, in which the rate of effusion of the equilibrium vapour through a small orifice was measured. The thermodynamic parameters of the sublimation process for phthalocyanies were calculated.

Investigations and application in piezoelectric phenol sensor of Langmuir–Schäfer films of a copper phthalocyanine derivative functionalized with bulky substituents

An octa-substituted copper phthalocyanine was dissolved in chloroform and spread on ultrapure water subphase in a Langmuir trough. The floating films were characterized at the air-water interface by the Langmuir isotherm, Brewster angle microscopy, and UV-Vis reflection spectroscopy and transferred by Langmuir-Schäfer technique on a silicon substrate, and thickness, refractive index, and extinction coefficient of the phthalocyanine derivative thin film were calculated by means of spectroscopic ellipsometry. A different number of layers were deposited using Langmuir-Schäfer method onto QCM crystals, and the active layers were tested as sensors for the detection of phenols in aqueous solution. The piezoelectric sensor response, totally reversible, is influenced by the number of transferred layers and by the nature of the substituent; on the contrary, the pK(a) value of the injected analytes slightly affects the device performances. Repeatability of the sensor responses was tested, and the frequency variation appears unchanged at least for 100 days.

Electric field assisted effects on molecular orientation and surface morphology of thin titanyl(IV)phthalocyanine films.

Herein we present electric field assisted effects on the molecular orientation, the polymorphism, and the surface morphology of thin titanyl(IV)phthalocyanine (TiOPc) films. The ability of electric fields to affect the thin film structure of polar molecules is demonstrated using titanyl(IV)phthalocyanine as a model compound exhibiting both a permanent and an induced electric dipole moment. Thin films of TiOPc prepared by organic molecular beam deposition (OMBD) in the absence and in the presence of an electric field during the thin film growth are characterized using polarization dependent Raman spectroscopy and atomic force microscopy (AFM). The distinctive pattern of vibrational modes of the phthalocyanine skeleton indicates different molecular orientations in these thin films: Raman spectra of regions where an electric field is present during thin film growth reveal a preferential molecular orientation with an inclination angle of the molecular plane (pseudoplanar macrocycle) with respect to the substrate plane of nearly 90 degrees. Contrary to that, in regions where the electric field was absent, the molecules adopt predominantly a configuration with a smaller tilt angle (approximately 60 degrees). In addition, an electric field assisted change is apparent in AFM images: A large amount of well-formed steplike crystallites lying parallel to the substrate is observed when no electric field was present, whereas in the case when an electric field was applied during thin film growth the crystallites exhibit a tilt with respect to the substrate plane.

Hybrid materials of pyrene substituted phthalocyanines with single-walled carbon nanotubes: structure and sensing properties

Hybrid materials of single walled carbon nanotubes (SWCNT) were obtained by their non-covalent functionalization with asymmetrically polyoxyethylene substituted phthalocyanines (MPc-py (M = Cu, Co, 2H)) bearing one pyrene group as a substituent. The attachment of MPc-py molecules onto the SWCNT surface have been confirmed using Raman spectroscopy, SEM, TEM and thermogravimetric analysis. The pyrene substituents were introduced to the phthalocyanine macrocycle in order to improve π–π interaction between the MPc-py and SWCNT. The effect of the central metal on the formation and sensor properties of the MPc-py within the hybrids has been verified. It has been shown that the electrical response of the hybrid films to ammonia vapor in the concentration range of 10–50 ppm changes in the following order CuPc-py > CoPc-py > H2Pc-py, which was found to be in good correlation with the amount of phthalocyanine molecules adsorbed onto the SWCNT walls, as estimated by thermogravimetric analysis (TGA).