This paper presents the results of quantum-chemical modeling performed by the Density Functional-Based Tight Binding (DFTB) method to investigate the change in the band structure of hybrid materials based on carbon nanotubes and unsubstituted, tetra-, or octa-halogen-substituted zinc phthalocyanines upon the adsorption of ammonia molecules. The study showed that the electrical conductivity of these materials and its changes in the case of interaction with ammonia molecules depend on the position of the impurity band formed by the orbitals of macrocycle atoms relative to the forbidden energy gap of the hybrids. The sensor response of the hybrids containing halogenated phthalocyanines was lower by one or two orders of magnitude, depending on the number of substituents, compared to the hybrid with unsubstituted zinc phthalocyanine. This result was obtained by calculations performed using the nonequilibrium Green’s functions (NEGF) method, which demonstrated a change in the electrical conductivity of the hybrids upon the adsorption of ammonia molecules. The analysis showed that in order to improve the sensor characteristics of CNT-based hybrid materials, preference should be given to those phthalocyanines in which substituents contribute to an increase in HOMO energy relative to the unsubstituted macrocycles.

In this paper, the temperature dependence of the saturated vapor pressure of fluorosubstituted phthalocyanines with substituents in non-peripheral positions of the macroring, viz. MPcF4-np, M=Cu, Fe, Co, VO, was investigated by the Knudsen effusion method with mass spectrometric registration of the gaseous phase composition. The standard thermodynamic parameters Delta H degrees T and Delta S degrees T of the sublimation process of these compounds were determined. The results were compared with the vapor pressure of the corresponding MPcF4-p analogs bearing F-substituents in the peripheral positions. It was shown that the volatility decreased in the order of VOPcF4-np > CoPcF4-np similar to CuPcF4-np similar to FePcF4-np > ZnPcF4-np, which correlated with the increase in their crystal lattice energy in the same order. The volatility of most MPcF4-np (M = Cu, Zn, Co, VO) was lower than that of MPcF4-p. The results were analyzed from the point of view of crystal packing and intermolecular interactions in the crystal.

Despite the large number of materials, e.g. semiconducting oxides, carbon nanomaterials, conducting polymers and others, that are used as active layers of chemiresistive sensors to ammonia and hydrogen sulfide, the search for new materials remains an urgent task. Special attention is paid to the search for environmentally friendly materials. Corrinoids are naturally occurring coordination complexes consisting of a central cobalt ion and a tetrapyrrole ligand called a corrin ring. Cobalamins and their derivatives are widely used as active layers of optical and electrochemical sensors. At the same time, vitamin B12 derivatives have not been studied as active layers of chemiresistive gas sensors. In this work, films of two vitamin B12 derivatives, viz. dicyanocobyrinic acid heptabutyl ester (DC) and its aquacyano form, aquacyanocobyrinic acid heptabutyl ester (AC), deposited by spin coating and drop casting techniques onto interdigitated electrodes, were tested for the first time as active layers of chemiresistive sensors for the detection of low concentrations of ammonia and hydrogen sulfide (1–50 ppm) in air. It was shown that films of both vitamin B12 derivatives demonstrated reversible sensor response to NH3 and H2S at room temperature. The limit of detection (LOD) of H2S was 0.1 ppm for both vitamin B12 derivatives, while LOD of ammonia was noticeably lower (0.06 ppm) in the case of AC films than in the case of DC films (0.4 ppm). Both sensors demonstrated a fairly low regeneration time, which did not exceed 180 s for 5 ppm of NH3 and 185 s for 5 ppm of H2S.

n this work, we demonstrate the effect of the synthesis technique on the structure of tetrafluorosubstituted tin phthalocyanines. Tetrafluorinated phthalocyanines of tin(II) and tin(IV) with substituents in peripheral and non-peripheral positions were synthesized by two different techniques, namely by fusing fluorinated phthalonitriles with SnCl2 and refluxing of the initial reagents in 1-chloronaphthalene, as a result of which their single crystals were grown and the crystal structure was determined. It was shown that during synthesis by the first technique, Sn(II)PcF4complexes were formed. At the same time, during the synthesis by the second technique, complexes of Sn(IV), namely Sn(IV)Cl2PcF4, were formed. Thin films of Sn(II)PcF4 deposited by vacuum sublimation were also investigated by an X-ray diffraction method.

In this work, tetrafluorinated titanyl phthalocyanines with F-substituents in both peripheral (TiOPcF4-p) and non-peripheral (TiOPcF4-np) positions were synthesized and characterized by the methods of elemental analysis, IR and electronic absorption spectroscopies. The influence of the position of F-substituents on the structure of TiOPcF4-p and TiOPcF4-np single crystals and thin films grown by vacuum sublimation was studied. TiOPcF4-p crystallizes in the I4/m space group and its molecules form uniform stacks along the tetragonal axis. Introduction of F-substituents to non-peripheral positions leads to the change of the crystal structure: TiOPcF4-np crystallizes in the P-1 space group and its molecules are packed into 2D layers. Both phthalocyanines form oriented polycrystalline films when deposited by thermal sublimation in vacuum, but their phase composition is different from that of single crystals. The effect of post-deposition annealing of TiOPcF4-p and TiOPcF4-np films on their phase composition, morphology, optical absorption and Raman spectra, as well as conductivity was revealed. It was shown that a phase transition, which led to the appearance of an additional band in the near-IR region in the optical absorption spectrum, was observed in TiOPcF4-p films when heated, whereas no phase transition was observed in TiOPcF4-np films.

Despite the large number of materials, e.g. semiconducting oxides, carbon nanomaterials, conducting polymers and others, that are used as active layers of chemiresistive sensors to ammonia and hydrogen sulfide, the search for new materials remains an urgent task. Special attention is paid to the search for environmentally friendly materials. Corrinoids are naturally occurring coordination complexes consisting of a central cobalt ion and a tetrapyrrole ligand called a corrin ring. Cobalamins and their derivatives are widely used as active layers of optical and electrochemical sensors. At the same time, vitamin B 12 derivatives have not been studied as active layers of chemiresistive gas sensors. In this work, films of two vitamin B 12 derivatives, viz. dicyanocobyrinic acid heptabutyl ester (DC) and its aquacyano form, aquacyanocobyrinic acid heptabutyl ester (AC), deposited by spin coating and drop casting techniques onto interdigitated electrodes, were tested for the first time as active layers of chemiresistive sensors for the detection of low concentrations of ammonia and hydrogen sulfide (1 -50 ppm) in air. It was shown that films of both vitamin B 12 derivatives demonstrated reversible sensor response to NH 3 and H 2 S at room temperature. The limit of detection (LOD) of H 2 S was 0.1 ppm for both vitamin B 12 derivatives, while LOD of ammonia was noticeably lower (0.06 ppm) in the case of AC films than in the case of DC films (0.4 ppm). Both sensors demonstrated a fairly low regeneration time, which did not exceed 180 s for 5 ppm of NH 3 and 185 s for 5 ppm of H 2 S.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Halogenated metal phthalocyanines are promising materials for the manufacture of active layers of chemiresistive sensors for the detection of various gases. Despite the high interest in such sensors, there are few systematic studies of the position of halogen substituents in phthalocyanine macroring on the chemiresistive response of their films to gases. In this work, we prepared and studied films of novel tetrachlorosubstituted vanadyl phthalocyanine derivatives with Cl substituents in the peripheral (VOPcCl4-p) and nonperipheral (VOPcCl4-np) positions of the phthalocyanine ring as active layers of chemiresistive sensors to reveal the effect of the position of substituents on their structure and sensor response to low concentrations of NH3. It was shown that the films of VOPcCl4-p exhibited a noticeably higher sensor response to NH3 than the VOPcCl4-np ones. The limit of detection of NH3 was 0.7 ppm. The sensing layers demonstrated a reversible sensor response at room temperature with fairly low response/recovery times. It was also demonstrated that NH3 can be detected in the presence of various interfering gases (CO2 and H2) and some volatile organic vapors, as well as in a mixture of gases with a composition close to exhaled air.

In this work, octafluoro-substituted phthalocyanines of zinc, vanadyl, and cobalt (MPcF8, M = Zn(II), Co(II), VO) were synthesized and studied. The structures of single crystals of the obtained phthalocyanines were determined. To visualize and compare intermolecular contacts in MPcF8, an analysis of Hirshfeld surfaces (HS) was performed. MPcF8 nanoscale thickness films were deposited by organic molecular beam deposition technique and their structure and orientation were studied using X-ray diffraction. Comparison of X-ray diffraction patterns of thin films with the calculated diffractograms showed that all three films consisted of a single crystal phase, which corresponded to a phase of single crystals. Only one strong diffraction peak corresponding to the plane (001) was observed on the diffraction pattern of each film, which indicated a strong preferred orientation with the vast majority of crystallites oriented with a (001) crystallographic plane parallel to the substrate surface. The effect of the central metals on the electronic absorption and vibrational spectra of the studied phthalocyanines as well as on the electrical conductivity of their films is also discussed.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In this work, the effect of the type of halogen substituents on the structure, morphology, and conductivity of thin films of zinc(II) phthalocyanines ZnPcHal4 (Hal = F, Cl, Br, I), deposited both by evaporations in vacuum and by a spin coating technique was studied. The influence of these different halogen substituents on the spectral properties of ZnPcHal4 derivatives was also investigated. For this purpose, the density-functional theory calculations of the vibrational spectra of ZnPcHal4 were carried out. It was shown that ZnPcHal4 (Hal = F, Cl) films obtained by physical vapor deposition (PVD) were polycrystalline and consisted of well-distinguishable rounded grains, whereas the introduction of the bulk bromine and iodine substituents led to the formation of amorphous films both in the PVD process and during spin coating deposition. The lateral d.c. conductivity of the films was shown to decrease in the order ZnPcCl4 > ZnPcF4 > ZnPcBr4 > ZnPcI4. The conductivity of PVD films, which were characterized by higher crystallinity and order, was higher than that of spun films.

A comparative analysis of the chemiresistive sensor response of thin films of a series of tetrasubstituted phthalocyanines of various metals with F-substituent in peripheral (MPcF4-p, M = Cu, Co, Zn, Pb, VO) and non-peripheral (MPcF4-np) positions in macroring to low concentrations of ammonia (1–50 ppm) was carried out. It was found that MPcF4-p films exhibit a higher sensor response than MPcF4-np ones. A CoPcF4-p film demonstrated a calculated LOD of 0.01 ppm with a recovery time of 215 s, while a VOPcF4-p film had LOD of 0.04 ppm and the recovery time of 270 s. The selectivity test showed that CO2, ethanol, acetone, benzene, and formaldehyde did not interfere with the determination of ammonia, while H2S at a concentration of more than 10 ppm could act as an interfering gas. It was shown that, as a result of quantum-chemical calculations, the observed regularities are best described by the interaction of NH3 with phthalocyanines through the formation of hydrogen bonds between NH3 and side atoms of the macroring. In the case of MPcF4-p, the NH3 molecule approaches the macrocycle more closely and binds more strongly than in the case of MPcF4-np. The stronger binding leads to a stronger effect of the ammonia molecule on the electronic structure of phthalocyanine and, as a consequence, on the chemiresistive sensor response of the films to ammonia.

In this work, we study crystal structures and thin films of tetrasubstituted metal phthalocyanines with fluorine substituents in non-peripheral positions, MPcF4-np (M = Cu(II), Co(II), Pd(II), Fe(II), Pb(II), VO). The effect of fluorosubstitution in non-peripheral positions of the phthalocyanine macmcycle on the structure of single crystals and thin films, and intermolecular interactions is elucidated and compared with that of other fluorinated phthalocyanine derivatives. MPcF4-np (M = Cu(II), Pd(II), Fe(II)) are isostructural and crystallize in the monoclinic P2(1)/c space group, while CoPcF4-np forms two polymorphs (P2(1) and P2(1)/c). Monoclinic PbPcF4-np (P2(1)/n) is packed in chains along the c axis, in which one PbPcF4-np molecule is oriented "up" and two neighboring molecules face "down". Two triclinic (P-1) phases were obtained for VOPcF4-np. For the better visualization and comparison of intermolecular contacts in different MPcF4-np, the analysis of Hirshfeld surfaces (HS) was carried out. All investigated MPcF4-np derivatives form thin films with a strong preferred orientation. The effect of the positions of F-substituents on the electronic absorption spectra of MPcF4 solutions and thin films is also discussed.

Metal phthalocyanines bearing electron-withdrawing fluorine substituents were synthesized a long time ago, but interest in the study of their films has emerged in recent decades. This is due to the fact that, unlike unsubstituted phthalocyanines, films of some fluorinated phthalocyanines exhibit the properties of n-type semiconductors, which makes them promising candidates for application in ambipolar transistors. Apart from this, it was shown that the introduction of fluorine substituents led to an increase in the sensitivity of phthalocyanine films to reducing gases. This review analyzes the state of research over the last fifteen years in the field of applications of fluoro-substituted metal phthalocyanines as active layers of gas sensors, with a primary focus on chemiresistive ones. The active layers on the basis of phthalocyanines with fluorine and fluorine-containing substituents of optical and quartz crystal microbalance sensors are also considered. Attention is paid to the analysis of the effect of molecular structure (central metal, number and type of fluorine substituent etc.) on sensor properties of fluorinated phthalocyanine films.

In this work, the effect of chloro-substitution in poly(oxyethylene)-substituted phthalocyaninato zinc(II) and oxotitanium(IV) complexes on the ordering and sensor response of their thin films to ammonia was studied. Thin films of thia-bridged tetrapoly(oxyethylene)- and tetrachlorotetrapoly(oxyethylene)-substituted zinc and titanyl Pcs forming mesophases in wide temperature range were spun onto glass slides with interdigitated electrodes to test their chemiresistive sensor response to ammonia in the concentration range from 1 to 50 ppm. It was shown by the methods of UV–Vis, polarized Raman spectroscopy and polarized optical microscopy that these phthalocyanines formed thin films with different orientation and ordering in dependence on their molecular structure. The introduction of chloride substituents into the phthalocyanine ring was found to lead to the increase of the chemiresistive sensor response of both zinc and oxotitanium phthalocyanine films toward low concentrations of ammonia in air.

In this work, the effect of the position of fluorine substituents in tetrafluorosubstituted metal phthalocyanines on their vibrational spectra is studied. For this purpose the assignments of the most intense bands in IR- and Raman spectra of tetrafluorosubstituted metal phthalocyanines with F-substituents in non-peripheral positions MPcF4-np (M = Zn, Co, Cu, Fe, Pd, VO, Pb) were carried out on the basis of the density functional theory (DFT) calculations. The vibrational spectra of MPcF4-np were compared with those of the corresponding derivatives bearing F-substituents in peripheral positions (MPcF4-p). It was shown that similarly to MPcF4-p, the bands in the IR and Raman spectra of MPcF4-np, which are dependent on central metals, are located in the spectral range from 1350 to 1550 cm(-1). The effect of the position of fluorine substituents in MPcF4 on the electronic absorption spectra of their solution and films is also discussed.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In this work, the effect of fluorine and chlorine substituents in tetrasubstituted zinc phthalocyanines, introduced into the non-peripheral (ZnPcR4-np, R = F, Cl) and peripheral (ZnPcR4-p, R = F, Cl) positions of macrocycle, on their structure and chemiresistive sensor response to low concentration of ammonia is studied. The structure and morphology of the zinc phthalocyanines films (ZnPcR4) were investigated by X-ray diffraction and atomic force microscopy methods. To understand different effects of chlorine and fluorine substituents, the strength and nature of the bonding of ammonia and ZnPcHal4 molecules were studied by quantum chemical simulation. It was shown on the basis of comparative analysis that the sensor response to ammonia was found to increase in the order ZnPcCl4-np < ZnPcF4-np < ZnPcF4-p < ZnPcCl4-p, which is in good agreement with the values of bonding energy between hydrogen atoms of NH3 and halogen substituents in the phthalocyanine rings. ZnPcCl4-p films demonstrate the maximal sensor response to ammonia with the calculated detection limit of 0.01 ppm; however, they are more sensitive to humidity than ZnPcF4-p films. It was shown that both ZnPcF4-p and ZnPcCl4-p and can be used for the selective detection of NH3 in the presence of carbon dioxide, dichloromethane, acetone, toluene, and ethanol.