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Papers by Andrii Buvailo
Absorption correction: multi-scan
T min = 0.720, T max = 0.888 = 1.53 mm 1 T = 120 (2) K 0.23 0.13 0.08 mm 11529 measured reflectio... more T min = 0.720, T max = 0.888 = 1.53 mm 1 T = 120 (2) K 0.23 0.13 0.08 mm 11529 measured reflections 3765 independent reflections 3186 reflections with I>2 (I) R int = 0.069
Tris(ethylenediamine)nickel(II) bis[2-cyano-2-(oxidoimino)acetamidato]nickelate(II) monohydrate
Acta Crystallographica Section C Crystal Structure Communications, 2006
ABSTRACT The title compound, [Ni(C2H8N2)3][Ni(C3HN3O2)2]·H2O, appears to be a modular associate c... more ABSTRACT The title compound, [Ni(C2H8N2)3][Ni(C3HN3O2)2]·H2O, appears to be a modular associate consisting of two complex counter-ions, containing bivalent nickel as the central atom in both cases, and a solvent water molecule. The NiII ion in the complex cation lies on the C2 crystallographic axis. Its coordination environment is formed by six N atoms of three ethylenediamine (en) molecules, representing a distorted octahedral geometry. The NiII ion in the complex anion occupies a position at the center of inversion. It exhibits a distorted square-planar coordination geometry formed by four N atoms belonging to the deprotonated oxidoimine and amide groups of the two doubly charged 2-cyano-2-(oxidoimino)acetamidate anions, situated in trans positions with respect to each other. In the crystal packing, the complex anions are linked by water molecules via hydrogen bonds between the amide O atoms and water H atoms, forming chains translated along the a direction. The [Ni(en)3]2+ cations fill empty spaces between the translational chains, connecting them by hydrogen bonds between the oxime and amide O atoms of the anions and the amine H atoms of the cations, forming layers along the ac plane. The water molecules provide connection between layers through N atoms of the cations, thus forming a three-dimensional modular structure.
The current status of antibiotics innovations in the light of the growing threat of bacterial res... more The current status of antibiotics innovations in the light of the growing threat of bacterial resistance
Article about startups developing machine learning and artificial intelligence technology for dru... more Article about startups developing machine learning and artificial intelligence technology for drug discovery applications.
Crystal structure of poly[diaqua(μ-2-carboxyacetato-κ 3 O , O ′: O ′′)(2-carboxyacetato-κ O )di-μ-chlorido-dicobalt(II)]
Acta Crystallographica Section E Crystallographic Communications, 2016
The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2] n , comprises one Co(II) atom, ... more The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2] n , comprises one Co(II) atom, one water mol-ecule, one singly deprotonated malonic acid mol-ecule (HMal(-); systematic name 2-carb-oxy-acetate) and one Cl(-) anion. The Co(II) atom is octa-hedrally coordinated by the O atom of a water mol-ecule, by one terminally bound carboxyl-ate O atom of an HMal(-) anion and by two O atoms of a chelating HMal(-) anion, as well as by two Cl(-) anions. The Cl(-) anions bridge two Co(II) atoms, forming a centrosymmetric Co2Cl2 core. Each malonate ligand is involved in the formation of six-membered chelate rings involving one Co(II) atom of the dinuclear unit and at the same time is coordinating to another Co(II) atom of a neighbouring dinuclear unit in a bridging mode. The combination of chelating and bridging coordination modes leads to the formation of a two-dimensional coordination polymer extending parallel to (001). Within a layer, O-Hwater⋯Cl and O-Hwater⋯O hydrogen bonds are present. Adjacent layers are linked through O-H⋯O=C hydrogen bonds involving the carb-oxy-lic acid OH and carbonyl groups.
Study of influence of palladium additives in nanosized tin dioxide on sensitivity of adsorption semiconductor sensors to hydrogen
Sensors and Actuators B: Chemical, 2014
Journal of Chemical Education, 2010
Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effe... more Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effects of surface treatments developed as a part of fundamental research in surface science, as well as for industrial applications. An accurate characterization of surfaces is required in a wide range of research fields, such as surface chemistry and biomaterials (1). In addition to techniques such as Fourier-transform infrared spectroscopy (2), second-harmonic generation or sum-frequency generation (3), atomic force microscopy (4), X-ray photoelectron microscopy (5), and ellipsometry (6), contact angle measurement is useful in the evaluation of surface macroscopic properties, such as surface energy (7) and wettability (8).
Sensors and Actuators B: Chemical, 2011
Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of g... more Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption-desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO 3 SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5-95% (recovery time -2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.
Sensors and Actuators B: Chemical, 2012
Co-doped SnO 2 -based sensor materials with various cobalt contents were synthesized via the ethy... more Co-doped SnO 2 -based sensor materials with various cobalt contents were synthesized via the ethylene glycol supported sol-gel method. Electrical resistance, sensor response to hydrogen and catalytic activity towards hydrogen oxidation were studied as a function of cobalt doping and were shown to correlate, exhibiting maxima corresponding to the sensor material with 0.2 wt% Co. It was concluded that there are two major reasons leading to the obtained result. First, the formation of active edge sites between promoter particles (cobalt oxide) and tin dioxide surface, with the assumption that such bordering regions are favorable for oxygen chemisorption. Thus, a change in cobalt concentration in sensor materials can cause a change in a chemisorbed oxygen concentration and, hence the correlation between cobalt content and such parameters as electric resistance, sensor response and catalytic activity of corresponding materials. The second reason is the size of the tin dioxide grains. It was found that addition of small amount of cobalt content to the nanosized sensor material led to drastic increase in the resistance of the sensor and hence it's response because of "electronic sensitization" effect.
Russian Journal of Physical Chemistry A, 2013
The sensitivity to H 2 at 40 ppm concentration of adsorption semiconductor sensors with a gas sen... more The sensitivity to H 2 at 40 ppm concentration of adsorption semiconductor sensors with a gas sensitive layer based on SnO 2 /Sb 2 O 5 nanomaterial obtained by the sol gel method was studied. The hydrogen sensitivity was shown to increase for materials with Co additions and smaller particles.
![Research paper thumbnail of Bis{( E )-3-[2-(hydroxyimino)propanamido]-2,2-dimethylpropan-1-aminium} bis[μ-( E )- N -(3-amino-2,2-dimethylpropyl)-2-(hydroxyimino)propanamido(2−)]bis{[( E )- N -(3-amino-2,2-dimethylpropyl)-2-(hydroxyimino)propanamide]copper(II)} bis(( E )-{3-[2-(hydroxyimino)propanamido]-2,2-dimethylpropyl}ca...](https://attachments.academia-assets.com/39440416/thumbnails/1.jpg)
](Acta Crystallographica Section E Structure Reports Online, 2012
ACS Applied Materials & Interfaces, 2011
A simple and straightforward method of depositing nanostructured thin films, based on LiCl-doped ... more A simple and straightforward method of depositing nanostructured thin films, based on LiCl-doped TiO 2 , on glass and LiNbO 3 sensor substrates is demonstrated. A spin-coating technique is employed to transfer a polymer-assisted precursor solution onto substrate surfaces, followed by annealing at 520°C to remove organic components and drive nanostructure formation. The sensor material obtained consists of coin-shaped nanoparticles several hundred nanometers in diameter and less than 50 nm thick. The average thickness of the film was estimated by atomic force microscopy (AFM) to be 140 nm. Humidity sensing properties of the nanostructured material and sensor response times were studied using conductometric and surface acoustic wave (SAW) sensor techniques, revealing reversible signals with good reproducibility and fast response times of about 0.75 s. The applicability of this nanostructured film for construction of rapid humidity sensors was demonstrated. Compared with known complex and expensive methods of synthesizing sophisticated nanostructures for sensor applications, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), this work presents a relatively simple and inexpensive technique to produce SAW humidity sensor devices with competitive performance characteristics.
Acta Crystallographica Section E Structure Reports Online, 2008
Key indicators: single-crystal X-ray study; T = 120 K; mean (C-C) = 0.005 Å; R factor = 0.070; wR... more Key indicators: single-crystal X-ray study; T = 120 K; mean (C-C) = 0.005 Å; R factor = 0.070; wR factor = 0.175; data-to-parameter ratio = 18.5.
Dimeric versus polymeric coordination in copper(ii) cationic complexes with bis(chelating) oxime and amide ligands
Dalton Transactions, 2010
A series of copper(ii) complexes with earlier reported ligands N,N&am... more A series of copper(ii) complexes with earlier reported ligands N,N'-bis(2-hydroxyiminopropionyl)-1,2-diaminoethane (H(2)pen) and 1,3-diaminopropane (H(2)pap) and novel open chain oxime and amide ligands, N,N'-bis(2-hydroxyiminopropionyl)-1,5-diaminopentane (H(2)papt), 1,6-diaminohexane (H(2)pah) and 1,7-diaminoheptane (H(2)pahp), were prepared and characterized by a variety of spectroscopic methods and X-ray structure analysis. Although a pH-potentiometric study revealed only monomeric species in solution, formation of both binuclear dimeric and 1D-polymeric topologies was found in solid state. In all complexes ligands provide bis-bidentate coordination to Cu(2+) ions via the nitrogen atoms of the oxime groups and the oxygen atoms of the amide groups to form CuN(2)O(2) planar fragments. Compound [Cu(Hpap)(ClO(4))(H(2)O)](x) was isolated in both dimeric (x = 2) and polymeric (x = n) state, representing an example of supramolecular isomerism. All the complexes are additionally stabilized by short intramolecular hydrogen bonds =N-O-H...O-N= between cis-arranged oximato-groups. Stabilization is more effective in the case of dimeric complexes compared to 1D-polymeric chain, which appears to be the reason of preferable dimerization versus polymerization in the studied set of compounds. The effect of polymethylene linker length on the conformation of the dimers is described.
![Research paper thumbnail of Tris(ethylenediamine)nickel(II) bis[2-cyano-2-(oxidoimino)acetamidato]nickelate(II) monohydrate](https://attachments.academia-assets.com/39147147/thumbnails/1.jpg)
](Acta Crystallographica Section C Crystal Structure Communications, 2006
The title compound, [Ni(C 2 H 8 N 2 ) 3 ][Ni(C 3 HN 3 O 2 ) 2 ]ÁH 2 O, appears to be a modular as... more The title compound, [Ni(C 2 H 8 N 2 ) 3 ][Ni(C 3 HN 3 O 2 ) 2 ]ÁH 2 O, appears to be a modular associate consisting of two complex counter-ions, containing bivalent nickel as the central atom in both cases, and a solvent water molecule. The Ni II ion in the complex cation lies on the C 2 crystallographic axis. Its coordination environment is formed by six N atoms of three ethylenediamine (en) molecules, representing a distorted octahedral geometry. The Ni II ion in the complex anion occupies a position at the center of inversion. It exhibits a distorted square-planar coordination geometry formed by four N atoms belonging to the deprotonated oxidoimine and amide groups of the two doubly charged 2-cyano-2-(oxidoimino)acetamidate anions, situated in trans positions with respect to each other. In the crystal packing, the complex anions are linked by water molecules via hydrogen bonds between the amide O atoms and water H atoms, forming chains translated along the a direction. The [Ni(en) 3 ] 2+ cations ®ll empty spaces between the translational chains, connecting them by hydrogen bonds between the oxime and amide O atoms of the anions and the amine H atoms of the cations, forming layers along the ac plane. The water molecules provide connection between layers through N atoms of the cations, thus forming a three-dimensional modular structure.
Theoretical and Experimental Chemistry, 2010
The effect of cobalt additions on the electrical resistance of adsorption–semiconductor sensors b... more The effect of cobalt additions on the electrical resistance of adsorption–semiconductor sensors based on nanosized SnO2 in air, their sensitivity to hydrogen, and the catalytic activity of the corresponding sensor materials in the oxidation of H2 were studied. The extremal nature of the obtained relationships is explained by morphological features of the investigated systems based on nanosized SnO2.
Dimeric versus polymeric coordination in copper(ii) cationic complexes with bis(chelating) oxime and amide ligands
Dalton Transactions, 2010
A series of copper(ii) complexes with earlier reported ligands N,N&am... more A series of copper(ii) complexes with earlier reported ligands N,N'-bis(2-hydroxyiminopropionyl)-1,2-diaminoethane (H(2)pen) and 1,3-diaminopropane (H(2)pap) and novel open chain oxime and amide ligands, N,N'-bis(2-hydroxyiminopropionyl)-1,5-diaminopentane (H(2)papt), 1,6-diaminohexane (H(2)pah) and 1,7-diaminoheptane (H(2)pahp), were prepared and characterized by a variety of spectroscopic methods and X-ray structure analysis. Although a pH-potentiometric study revealed only monomeric species in solution, formation of both binuclear dimeric and 1D-polymeric topologies was found in solid state. In all complexes ligands provide bis-bidentate coordination to Cu(2+) ions via the nitrogen atoms of the oxime groups and the oxygen atoms of the amide groups to form CuN(2)O(2) planar fragments. Compound [Cu(Hpap)(ClO(4))(H(2)O)](x) was isolated in both dimeric (x = 2) and polymeric (x = n) state, representing an example of supramolecular isomerism. All the complexes are additionally stabilized by short intramolecular hydrogen bonds =N-O-H...O-N= between cis-arranged oximato-groups. Stabilization is more effective in the case of dimeric complexes compared to 1D-polymeric chain, which appears to be the reason of preferable dimerization versus polymerization in the studied set of compounds. The effect of polymethylene linker length on the conformation of the dimers is described.
Acta Crystallographica Section E-structure Reports Online, 2008
Sensors and Actuators B-chemical, 2011
Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of g... more Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption-desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO 3 SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5-95% (recovery time -2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.
Journal of Chemical Education, 2010
Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effe... more Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effects of surface treatments developed as a part of fundamental research in surface science, as well as for industrial applications. An accurate characterization of surfaces is required in a wide range of research fields, such as surface chemistry and biomaterials (1). In addition to techniques such as Fourier-transform infrared spectroscopy (2), second-harmonic generation or sum-frequency generation (3), atomic force microscopy (4), X-ray photoelectron microscopy (5), and ellipsometry (6), contact angle measurement is useful in the evaluation of surface macroscopic properties, such as surface energy (7) and wettability (8).
Absorption correction: multi-scan
T min = 0.720, T max = 0.888 = 1.53 mm 1 T = 120 (2) K 0.23 0.13 0.08 mm 11529 measured reflectio... more T min = 0.720, T max = 0.888 = 1.53 mm 1 T = 120 (2) K 0.23 0.13 0.08 mm 11529 measured reflections 3765 independent reflections 3186 reflections with I>2 (I) R int = 0.069
Tris(ethylenediamine)nickel(II) bis[2-cyano-2-(oxidoimino)acetamidato]nickelate(II) monohydrate
Acta Crystallographica Section C Crystal Structure Communications, 2006
ABSTRACT The title compound, [Ni(C2H8N2)3][Ni(C3HN3O2)2]·H2O, appears to be a modular associate c... more ABSTRACT The title compound, [Ni(C2H8N2)3][Ni(C3HN3O2)2]·H2O, appears to be a modular associate consisting of two complex counter-ions, containing bivalent nickel as the central atom in both cases, and a solvent water molecule. The NiII ion in the complex cation lies on the C2 crystallographic axis. Its coordination environment is formed by six N atoms of three ethylenediamine (en) molecules, representing a distorted octahedral geometry. The NiII ion in the complex anion occupies a position at the center of inversion. It exhibits a distorted square-planar coordination geometry formed by four N atoms belonging to the deprotonated oxidoimine and amide groups of the two doubly charged 2-cyano-2-(oxidoimino)acetamidate anions, situated in trans positions with respect to each other. In the crystal packing, the complex anions are linked by water molecules via hydrogen bonds between the amide O atoms and water H atoms, forming chains translated along the a direction. The [Ni(en)3]2+ cations fill empty spaces between the translational chains, connecting them by hydrogen bonds between the oxime and amide O atoms of the anions and the amine H atoms of the cations, forming layers along the ac plane. The water molecules provide connection between layers through N atoms of the cations, thus forming a three-dimensional modular structure.
The current status of antibiotics innovations in the light of the growing threat of bacterial res... more The current status of antibiotics innovations in the light of the growing threat of bacterial resistance
Article about startups developing machine learning and artificial intelligence technology for dru... more Article about startups developing machine learning and artificial intelligence technology for drug discovery applications.
Crystal structure of poly[diaqua(μ-2-carboxyacetato-κ 3 O , O ′: O ′′)(2-carboxyacetato-κ O )di-μ-chlorido-dicobalt(II)]
Acta Crystallographica Section E Crystallographic Communications, 2016
The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2] n , comprises one Co(II) atom, ... more The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2] n , comprises one Co(II) atom, one water mol-ecule, one singly deprotonated malonic acid mol-ecule (HMal(-); systematic name 2-carb-oxy-acetate) and one Cl(-) anion. The Co(II) atom is octa-hedrally coordinated by the O atom of a water mol-ecule, by one terminally bound carboxyl-ate O atom of an HMal(-) anion and by two O atoms of a chelating HMal(-) anion, as well as by two Cl(-) anions. The Cl(-) anions bridge two Co(II) atoms, forming a centrosymmetric Co2Cl2 core. Each malonate ligand is involved in the formation of six-membered chelate rings involving one Co(II) atom of the dinuclear unit and at the same time is coordinating to another Co(II) atom of a neighbouring dinuclear unit in a bridging mode. The combination of chelating and bridging coordination modes leads to the formation of a two-dimensional coordination polymer extending parallel to (001). Within a layer, O-Hwater⋯Cl and O-Hwater⋯O hydrogen bonds are present. Adjacent layers are linked through O-H⋯O=C hydrogen bonds involving the carb-oxy-lic acid OH and carbonyl groups.
Study of influence of palladium additives in nanosized tin dioxide on sensitivity of adsorption semiconductor sensors to hydrogen
Sensors and Actuators B: Chemical, 2014
Journal of Chemical Education, 2010
Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effe... more Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effects of surface treatments developed as a part of fundamental research in surface science, as well as for industrial applications. An accurate characterization of surfaces is required in a wide range of research fields, such as surface chemistry and biomaterials (1). In addition to techniques such as Fourier-transform infrared spectroscopy (2), second-harmonic generation or sum-frequency generation (3), atomic force microscopy (4), X-ray photoelectron microscopy (5), and ellipsometry (6), contact angle measurement is useful in the evaluation of surface macroscopic properties, such as surface energy (7) and wettability (8).
Sensors and Actuators B: Chemical, 2011
Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of g... more Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption-desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO 3 SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5-95% (recovery time -2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.
Sensors and Actuators B: Chemical, 2012
Co-doped SnO 2 -based sensor materials with various cobalt contents were synthesized via the ethy... more Co-doped SnO 2 -based sensor materials with various cobalt contents were synthesized via the ethylene glycol supported sol-gel method. Electrical resistance, sensor response to hydrogen and catalytic activity towards hydrogen oxidation were studied as a function of cobalt doping and were shown to correlate, exhibiting maxima corresponding to the sensor material with 0.2 wt% Co. It was concluded that there are two major reasons leading to the obtained result. First, the formation of active edge sites between promoter particles (cobalt oxide) and tin dioxide surface, with the assumption that such bordering regions are favorable for oxygen chemisorption. Thus, a change in cobalt concentration in sensor materials can cause a change in a chemisorbed oxygen concentration and, hence the correlation between cobalt content and such parameters as electric resistance, sensor response and catalytic activity of corresponding materials. The second reason is the size of the tin dioxide grains. It was found that addition of small amount of cobalt content to the nanosized sensor material led to drastic increase in the resistance of the sensor and hence it's response because of "electronic sensitization" effect.
Russian Journal of Physical Chemistry A, 2013
The sensitivity to H 2 at 40 ppm concentration of adsorption semiconductor sensors with a gas sen... more The sensitivity to H 2 at 40 ppm concentration of adsorption semiconductor sensors with a gas sensitive layer based on SnO 2 /Sb 2 O 5 nanomaterial obtained by the sol gel method was studied. The hydrogen sensitivity was shown to increase for materials with Co additions and smaller particles.
Acta Crystallographica Section E Structure Reports Online, 2012
ACS Applied Materials & Interfaces, 2011
A simple and straightforward method of depositing nanostructured thin films, based on LiCl-doped ... more A simple and straightforward method of depositing nanostructured thin films, based on LiCl-doped TiO 2 , on glass and LiNbO 3 sensor substrates is demonstrated. A spin-coating technique is employed to transfer a polymer-assisted precursor solution onto substrate surfaces, followed by annealing at 520°C to remove organic components and drive nanostructure formation. The sensor material obtained consists of coin-shaped nanoparticles several hundred nanometers in diameter and less than 50 nm thick. The average thickness of the film was estimated by atomic force microscopy (AFM) to be 140 nm. Humidity sensing properties of the nanostructured material and sensor response times were studied using conductometric and surface acoustic wave (SAW) sensor techniques, revealing reversible signals with good reproducibility and fast response times of about 0.75 s. The applicability of this nanostructured film for construction of rapid humidity sensors was demonstrated. Compared with known complex and expensive methods of synthesizing sophisticated nanostructures for sensor applications, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), this work presents a relatively simple and inexpensive technique to produce SAW humidity sensor devices with competitive performance characteristics.
Acta Crystallographica Section E Structure Reports Online, 2008
Key indicators: single-crystal X-ray study; T = 120 K; mean (C-C) = 0.005 Å; R factor = 0.070; wR... more Key indicators: single-crystal X-ray study; T = 120 K; mean (C-C) = 0.005 Å; R factor = 0.070; wR factor = 0.175; data-to-parameter ratio = 18.5.
Dimeric versus polymeric coordination in copper(ii) cationic complexes with bis(chelating) oxime and amide ligands
Dalton Transactions, 2010
A series of copper(ii) complexes with earlier reported ligands N,N&am... more A series of copper(ii) complexes with earlier reported ligands N,N'-bis(2-hydroxyiminopropionyl)-1,2-diaminoethane (H(2)pen) and 1,3-diaminopropane (H(2)pap) and novel open chain oxime and amide ligands, N,N'-bis(2-hydroxyiminopropionyl)-1,5-diaminopentane (H(2)papt), 1,6-diaminohexane (H(2)pah) and 1,7-diaminoheptane (H(2)pahp), were prepared and characterized by a variety of spectroscopic methods and X-ray structure analysis. Although a pH-potentiometric study revealed only monomeric species in solution, formation of both binuclear dimeric and 1D-polymeric topologies was found in solid state. In all complexes ligands provide bis-bidentate coordination to Cu(2+) ions via the nitrogen atoms of the oxime groups and the oxygen atoms of the amide groups to form CuN(2)O(2) planar fragments. Compound [Cu(Hpap)(ClO(4))(H(2)O)](x) was isolated in both dimeric (x = 2) and polymeric (x = n) state, representing an example of supramolecular isomerism. All the complexes are additionally stabilized by short intramolecular hydrogen bonds =N-O-H...O-N= between cis-arranged oximato-groups. Stabilization is more effective in the case of dimeric complexes compared to 1D-polymeric chain, which appears to be the reason of preferable dimerization versus polymerization in the studied set of compounds. The effect of polymethylene linker length on the conformation of the dimers is described.
Acta Crystallographica Section C Crystal Structure Communications, 2006
The title compound, [Ni(C 2 H 8 N 2 ) 3 ][Ni(C 3 HN 3 O 2 ) 2 ]ÁH 2 O, appears to be a modular as... more The title compound, [Ni(C 2 H 8 N 2 ) 3 ][Ni(C 3 HN 3 O 2 ) 2 ]ÁH 2 O, appears to be a modular associate consisting of two complex counter-ions, containing bivalent nickel as the central atom in both cases, and a solvent water molecule. The Ni II ion in the complex cation lies on the C 2 crystallographic axis. Its coordination environment is formed by six N atoms of three ethylenediamine (en) molecules, representing a distorted octahedral geometry. The Ni II ion in the complex anion occupies a position at the center of inversion. It exhibits a distorted square-planar coordination geometry formed by four N atoms belonging to the deprotonated oxidoimine and amide groups of the two doubly charged 2-cyano-2-(oxidoimino)acetamidate anions, situated in trans positions with respect to each other. In the crystal packing, the complex anions are linked by water molecules via hydrogen bonds between the amide O atoms and water H atoms, forming chains translated along the a direction. The [Ni(en) 3 ] 2+ cations ®ll empty spaces between the translational chains, connecting them by hydrogen bonds between the oxime and amide O atoms of the anions and the amine H atoms of the cations, forming layers along the ac plane. The water molecules provide connection between layers through N atoms of the cations, thus forming a three-dimensional modular structure.
Theoretical and Experimental Chemistry, 2010
The effect of cobalt additions on the electrical resistance of adsorption–semiconductor sensors b... more The effect of cobalt additions on the electrical resistance of adsorption–semiconductor sensors based on nanosized SnO2 in air, their sensitivity to hydrogen, and the catalytic activity of the corresponding sensor materials in the oxidation of H2 were studied. The extremal nature of the obtained relationships is explained by morphological features of the investigated systems based on nanosized SnO2.
Dimeric versus polymeric coordination in copper(ii) cationic complexes with bis(chelating) oxime and amide ligands
Dalton Transactions, 2010
A series of copper(ii) complexes with earlier reported ligands N,N&am... more A series of copper(ii) complexes with earlier reported ligands N,N'-bis(2-hydroxyiminopropionyl)-1,2-diaminoethane (H(2)pen) and 1,3-diaminopropane (H(2)pap) and novel open chain oxime and amide ligands, N,N'-bis(2-hydroxyiminopropionyl)-1,5-diaminopentane (H(2)papt), 1,6-diaminohexane (H(2)pah) and 1,7-diaminoheptane (H(2)pahp), were prepared and characterized by a variety of spectroscopic methods and X-ray structure analysis. Although a pH-potentiometric study revealed only monomeric species in solution, formation of both binuclear dimeric and 1D-polymeric topologies was found in solid state. In all complexes ligands provide bis-bidentate coordination to Cu(2+) ions via the nitrogen atoms of the oxime groups and the oxygen atoms of the amide groups to form CuN(2)O(2) planar fragments. Compound [Cu(Hpap)(ClO(4))(H(2)O)](x) was isolated in both dimeric (x = 2) and polymeric (x = n) state, representing an example of supramolecular isomerism. All the complexes are additionally stabilized by short intramolecular hydrogen bonds =N-O-H...O-N= between cis-arranged oximato-groups. Stabilization is more effective in the case of dimeric complexes compared to 1D-polymeric chain, which appears to be the reason of preferable dimerization versus polymerization in the studied set of compounds. The effect of polymethylene linker length on the conformation of the dimers is described.
Acta Crystallographica Section E-structure Reports Online, 2008
Sensors and Actuators B-chemical, 2011
Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of g... more Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) thin films, deposited on the surface of glass slides, were studied using transmission FTIR spectroscopy upon varying relative humidity (RH) from 2 to 70%. The obtained data revealed fast dynamics of water vapor adsorption-desorption with responses on the order of several seconds. Based on the fast FTIR signal intensity changes versus RH, it was proposed that a similar rapid response can be achieved for PVA and PVP coated SAW devices due to changes in mass-loading and film viscoelastic properties upon absorption of water vapor in the films. Sub-micron thickness films were spin-coated onto the surface of LiNbO 3 SAW substrates. Both PVA and PVP based humidity sensors revealed prompt reversible response to variations in humidity, although PVP-based device demonstrated better sensor parameters with total insertion loss variation of about 50 dB over the studied RH range and response time 1.5 s for the humidity step 5-95% (recovery time -2.5 s), representing one of the fastest SAW-based humidity sensors reported to date.
Journal of Chemical Education, 2010
Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effe... more Contact angle measurements are often used to evaluate surface and liquid cleanliness and the effects of surface treatments developed as a part of fundamental research in surface science, as well as for industrial applications. An accurate characterization of surfaces is required in a wide range of research fields, such as surface chemistry and biomaterials (1). In addition to techniques such as Fourier-transform infrared spectroscopy (2), second-harmonic generation or sum-frequency generation (3), atomic force microscopy (4), X-ray photoelectron microscopy (5), and ellipsometry (6), contact angle measurement is useful in the evaluation of surface macroscopic properties, such as surface energy (7) and wettability (8).