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Kouderis C, Tryfon A, Kabanos TA, Kalampounias AG. The Identification of Structural Changes in the Lithium Hexamethyldisilazide-Toluene System via Ultrasonic Relaxation Spectroscopy and Theoretical Calculations. Molecules 2024; 29:813. [PMID: 38398565 PMCID: PMC10892886 DOI: 10.3390/molecules29040813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Ultrasonic absorption measurements were carried out over a wide concentration and temperature range by means of a pulse technique to examine the structural mechanisms and the dynamical properties in lithium hexamethyldisilazide (LiHMDS)-toluene solutions. Acoustic spectra revealed two distinct Debye-type relaxational absorptions attributed to the formation of trimers from dimeric and monomer units and to the formation of aggregates between a LiHMDS dimer and one toluene molecule in low and high frequencies, respectively. The formation of aggregates was clarified by means of molecular docking and DFT methodologies. The aggregation number, the rate constants and the thermodynamic properties of these structural changes were determined by analyzing in detail the concentration-dependent relaxation parameters. The low-frequency relaxation mechanism dominates the acoustic spectra in the high LiHMDS mole fractions, while the high-frequency relaxation influences the spectra in the low LiHMDS mole fractions. In the intermediate mole fraction region (0.25 to 0.46), both relaxations prevail in the spectra. The adiabatic compressibility, the excess adiabatic compressibility and the theoretically estimated mean free length revealed a crossover in the 0.25 to 0.46 LiHMDS mole fractions that signified the transition from one structural mechanism related with the hetero-association of LiHMDS dimers with toluene molecules to the other structural mechanism assigned to the formation of LiHMDS trimers. The combined use of acoustic spectroscopy with theoretical calculations permitted us to disentangle the underlying structural mechanisms and evaluate the volume changes associated with each reaction. The results were compared with the corresponding theoretically predicted volume changes and discussed in the context of the concentration effect on intermolecular bonding.
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Affiliation(s)
- Constantine Kouderis
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - Afrodite Tryfon
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - Themistoklis A. Kabanos
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece;
| | - Angelos G. Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), GR-45110 Ioannina, Greece
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Banti CN, Kalampounias AG, Hadjikakou SK. Non-Steroidal Anti-Inflammatory Drugs Loaded to Micelles for the Modulation of Their Water Solubility. Int J Mol Sci 2023; 24:15152. [PMID: 37894836 PMCID: PMC10607354 DOI: 10.3390/ijms242015152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
The low water solubility of aspirin (ASPH) is well known, creating research challenges regarding both its composition and its delivery. Therefore, the development of new aspirin-based formulations that are water soluble is a research, technological, and financial issue. With the aim to improve the water solubility of ASPH, the micelle of formula SLS@ASPH (SLS = Sodium Lauryl Sulfate) was formed. The Critical Micelle Concentration (CMC) of SLS in the presence of ASPH was determined by ultrasonic velocity, complementary, and transient birefringence measurements. The SLS@ASPH was characterized by the melting point (m.p.), attenuated total reflection spectroscopy (FT-IR-ATR), and X-ray fluorescence spectroscopy (XRF) in a solid state and in a solution by ultraviolet-visible (UV-Vis) and 1H NMR spectroscopies. The SLS/ASPH molar ratio was determined to be 5/1 in SLS@ASPH. The inhibitory activity of SLS@ASPH towards lipoxygenase (LOX), an enzyme that takes part in the inflammation mechanism, was studied. The inhibitory activity of SLS@ASPH against LOX is 3.5-fold stronger than that of free SLS. The in vitro toxicity of the SLS@ASPH was tested on immortalized human keratinocyte (HaCaT) cells.
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Affiliation(s)
- Christina N. Banti
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece;
| | - Angelos G. Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 45110 Ioannina, Greece
| | - Sotiris K. Hadjikakou
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece;
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 45110 Ioannina, Greece
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Tsigoias S, Kouderis C, Mylona-Kosmas A, Kalampounias AG. Intermolecular Hydrogen Bonding in Associated Fluids: The Case of Isopentyl Alcohol Dissolved in Carbon Tetrachloride. Molecules 2023; 28:6285. [PMID: 37687113 PMCID: PMC10488694 DOI: 10.3390/molecules28176285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 09/10/2023] Open
Abstract
Fourier-transform infrared (FTIR) spectra of isopentyl-alcohol dissolved in carbon tetrachloride (CCl4) were recorded as a function of concentration and temperature. Dilute isopentyl alcohol/CCl4 solutions were prepared in alcohol at concentrations of 1, 0.5, 0.3, 0.2, 0.1, 0.05, 0.02, 0.01, 0.005, 0.001 and 0.0005 M. Infrared absorption measurements were taken within a temperature range of 17-67 °C below the boiling point of the solutions. Decomposition of the spectral features corresponding to associated and unassociated species was performed to quantitatively follow the effect of temperature and concentration on intermolecular hydrogen bonding (HB) in isopentyl alcohol. The spectral feature in the 3600-3650 cm-1 frequency range attributed to the free OH stretching band was studied in detail to determine changes based on concentration and temperature variations. Computational methodologies were applied to evaluate the energetics and vibrational properties of the species involved in the structure in the gaseous state where no interactions are present. The results are discussed in view of relevant structural models to gain quantitative information concerning the effect of concentration and temperature on intermolecular hydrogen bonding.
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Affiliation(s)
- Stefanos Tsigoias
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | | | - Agni Mylona-Kosmas
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - Angelos G. Kalampounias
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), GR-45110 Ioannina, Greece
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Kalampounias AG. Establishing the role of shear viscosity on the rate constants of conformational fluctuations in unsaturated aldehydes. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Georgakopoulou C, Thomos D, Tsolis T, Ypsilantis K, Plakatouras JC, Kordias D, Magklara A, Kouderis C, Kalampounias AG, Garoufis A. Synthesis, characterization, interactions with the DNA duplex dodecamer d(5'-CGCGAATTCGCG-3') 2 and cytotoxicity of binuclear η 6-arene-Ru(II) complexes. Dalton Trans 2022; 51:13808-13825. [PMID: 36039685 DOI: 10.1039/d2dt02304k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The novel binuclear η6-arene-Ru(II) complexes with the general formula {[(η6-cym)Ru(L)]2(μ-BL)}(PF6)4, and their corresponding water soluble {[(η6-cym)Ru(L)]2(μ-BL)}Cl4, where cym = p-cymene, L = 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), BL = 4,4'-bipyridine (BL-1), 1,2-bis(4-pyridyl)ethane (BL-2) and 1,3-bis(4-pyridyl)propane (BL-3), were synthesized and characterized. The structure of {[(η6-cym)Ru(phen)]2(μ-BL-1)}(PF6)4 was determined by X-ray single crystal methods. The interaction of {[(η6-cym)Ru(phen)]2(μ-BL-i)}Cl4 (i = 1, 2, 3; (4), (5) and (6) correspondingly) with the DNA duplex d(5'-CGCGAATTCGCG-3')2 was studied by means of NMR techniques and fluorescence titrations. The results show that complex (4) binds with a Kb = 12.133 × 103 M-1 through both intercalation and groove binding, while (5) and (6) are groove binders (Kb = 2.333 × 103 M-1 and Kb = 3.336 × 103 M-1 correspondingly). Comparison with the mononuclear complex [(η6-cym)Ru(phen)(py)]2+ reveals that it binds to the d(5'-CGCGAATTCGCG-3')2 with a Kb value two orders of magnitude lower than (4) (Kb = 0.158 × 103 M-1), indicating that for the binuclear complexes both ruthenium moieties participate in the binding. The complexes were found to be cytotoxic against the A2780 and A2780 res. cancer cell line with a selectivity index (SI) in the range of 3.0-5.9.
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Affiliation(s)
| | - Dimitrios Thomos
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece.
| | - Theodoros Tsolis
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece.
| | | | - John C Plakatouras
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece. .,University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, Ioannina, Greece
| | - Dimitris Kordias
- Biomedical Research Institute-Foundation for Research and Technology, 45110 Ioannina, Greece.,Laboratory of Clinical Chemistry, Faculty of Medicine, University of Ioannina, 45110 Ioannina, Greece
| | - Angeliki Magklara
- Biomedical Research Institute-Foundation for Research and Technology, 45110 Ioannina, Greece.,Laboratory of Clinical Chemistry, Faculty of Medicine, University of Ioannina, 45110 Ioannina, Greece.,Institute of Biosciences, University Research Center of Ioannina (U.R.C.I.), Ioannina, Greece
| | | | - Angelos G Kalampounias
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece. .,University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, Ioannina, Greece
| | - Achilleas Garoufis
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece. .,University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, Ioannina, Greece
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Tsigoias S, Papanikolaou MG, Kabanos TA, Kalampounias AG. Structure and dynamics of aqueous norspermidine solutions: an in situultrasonic relaxation spectroscopic study. J Phys Condens Matter 2021; 33:495104. [PMID: 34544061 DOI: 10.1088/1361-648x/ac2863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
Anin situultrasonic relaxation spectroscopic study is presented in an effort to determine the structural changes and the dynamics involved when norspermidine (NSpd) is dissolved in water. Our aim is to elucidate the mechanism responsible for the observed relaxation mechanism in acoustic spectra and estimate the corresponding thermodynamic parameters and the associated volume change. The experimental spectra of aqueous NSpd solutions revealed a single Debye-type relaxation mechanism attributed to proton-transfer reaction. The concentration and temperature dependence of the acoustic parameters supports this assignment. The activation enthalpy and entropy were estimated equal to ΔH*= 1.79 ± 0.20 kcal mol-1and ΔS*= -18.31 ± 0.73 cal mol-1 K-1, respectively. The concentration and temperature dependence of the sound velocity and absorption in the solutions exhibit characteristic features that are related to alterations in the network rigidity due to variations in hydrogen-bonding interactions at molecular level. The volume change associated to proton-transfer reaction for NSpd has been estimated and compared with the volume change observed for an analogous guanidine, the 1,1,3,3 tetramethyl guanidine. The obtained results are discussed in the framework of an existing theoretical structural model highlighting the strong molecular association in these liquid mixtures leading to complementary information on the structure and dynamics of guanidine amines. A comprehensive model of the whole relaxation processes is presented and discussed in detail.
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Affiliation(s)
- S Tsigoias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110, Ioannina, Greece
| | - M G Papanikolaou
- Section of Inorganic and analytical Chemistry, Department of Chemistry, University of Ioannina, 45110, Ioannina, Greece
| | - T A Kabanos
- Section of Inorganic and analytical Chemistry, Department of Chemistry, University of Ioannina, 45110, Ioannina, Greece
| | - A G Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110, Ioannina, Greece
- University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, Ioannina, Greece
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Passadis SS, Hadjithoma S, Siafarika P, Kalampounias AG, Keramidas AD, Miras HN, Kabanos TA. Synthesis, Structural and Physicochemical Characterization of a Titanium(IV) Compound with the Hydroxamate Ligand N,2-Dihydroxybenzamide. Molecules 2021; 26:5588. [PMID: 34577059 PMCID: PMC8465426 DOI: 10.3390/molecules26185588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 11/17/2022] Open
Abstract
The siderophore organic ligand N,2-dihydroxybenzamide (H2dihybe) incorporates the hydroxamate group, in addition to the phenoxy group in the ortho-position and reveals a very rich coordination chemistry with potential applications in medicine, materials, and physical sciences. The reaction of H2dihybe with TiCl4 in methyl alcohol and KOH yielded the tetranuclear titanium oxo-cluster (TOC) [TiIV4(μ-O)2(HOCH3)4(μ-Hdihybe)4(Hdihybe)4]Cl4∙10H2O∙12CH3OH (1). The titanium compound was characterized by single-crystal X-ray structure analysis, ESI-MS, 13C, and 1H NMR spectroscopy, solid-state and solution UV-Vis, IR vibrational, and luminescence spectroscopies and molecular orbital calculations. The inorganic core Ti4(μ-O)2 of 1 constitutes a rare structural motif for discrete TiIV4 oxo-clusters. High-resolution ESI-MS studies of 1 in methyl alcohol revealed the presence of isotopic distribution patterns which can be attributed to the tetranuclear clusters containing the inorganic core {Ti4(μ-O)2}. Solid-state IR spectroscopy of 1 showed the presence of an intense band at ~800 cm-1 which is absent in the spectrum of the H2dihybe and was attributed to the high-energy ν(Ti2-μ-O) stretching mode. The ν(C=O) in 1 is red-shifted by ~10 cm-1, while the ν(N-O) is blue-shifted by ~20 cm-1 in comparison to H2dihybe. Density Functional Theory (DFT) calculations reveal that in the experimental and theoretically predicted IR absorbance spectra of the ligand and Ti-complex, the main bands observed in the experimental spectra are also present in the calculated spectra supporting the proposed structural model. 1H and 13C NMR solution (CD3OD) studies of 1 reveal that it retains its integrity in CD3OD. The observed NMR changes upon addition of base to a CD3OD solution of 1, are due to an acid-base equilibrium and not a change in the TiIV coordination environment while the decrease in the complex's lability is due to the improved electron-donating properties which arise from the ligand deprotonation. Luminescence spectroscopic studies of 1 in solution reveal a dual narrow luminescence at different excitation wavelengths. The TOC 1 exhibits a band-gap of 1.98 eV which renders it a promising candidate for photocatalytic investigations.
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Affiliation(s)
- Stamatis S. Passadis
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece;
| | - Sofia Hadjithoma
- Department of Chemistry, University of Cyprus, Nicosia 2109, Cyprus;
| | - Panagiota Siafarika
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece;
| | - Angelos G. Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece;
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 45110 Ioannina, Greece
| | | | | | - Themistoklis A. Kabanos
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece;
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Pavlidis N, Kofinas A, Papanikolaou MG, Miras HN, Drouza C, Kalampounias AG, Kabanos TA, Konstandi M, Leondaritis G. Synthesis, characterization and pharmacological evaluation of quinoline derivatives and their complexes with copper(ΙΙ) in in vitro cell models of Alzheimer's disease. J Inorg Biochem 2021; 217:111393. [PMID: 33610031 DOI: 10.1016/j.jinorgbio.2021.111393] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/30/2021] [Accepted: 02/05/2021] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder of the central nervous system. The main pathophysiological mechanisms involve cholinergic neurotransmission, beta-amyloid (Αβ) and Tau proteins, several metal ions and oxidative stress, among others. Current drugs offer only relief of symptoms and not a cure of AD. Accumulating evidence suggests that multifunctional compounds, targeting multiple pathophysiological mechanisms, may have a great potential for the treatment of AD. In this study, we report on the synthesis and physicochemical characterization of four quinoline-based metal chelators and their respective copper(II) complexes. Most compounds were non-toxic at concentrations ≤5 μM. In neuroprotection studies employing undifferentiated and differentiated SH-SY5Y cells, the metal chelator N2,N6-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (H2dqpyca) appeared to exert significant neuroprotection against both, Aβ peptide- and H2O2-induced toxicities. The copper(II) complex [CuII(H2bqch)Cl2].3H2O (H2bqch = N,N'-Bis(8-quinolyl)cyclohexane-1,2-diamine) also protected against H2O2-induced toxicity, with a half-maximal effective concentration of 80 nM. Molecular docking simulations, using the crystal structure of the acetylcholinesterase (AChE)-rivastigmine complex as a template, indicated a strong interaction of the metal chelator H2dqpyca, followed by H2bqch, with both the peripheral anionic site and the catalytic active site of AChE. In conclusion, the sufficient neuroprotection provided by the metal chelator H2dqpyca and the copper(II) complex [CuII(H2bqch)Cl2].3H2O along with the evidence for interaction between H2dqpyca and AChE, indicate that these compounds have the potential and should be further investigated in the framework of preclinical studies employing animal models of AD as candidate multifunctional lead compounds for the treatment of the disease.
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Affiliation(s)
- Nikolaos Pavlidis
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece; Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
| | - Aristeidis Kofinas
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece.
| | - Michael G Papanikolaou
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
| | - Haralampos N Miras
- West CHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
| | - Chryssoula Drouza
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol 3036, Cyprus.
| | - Angelos G Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece; Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), Ioannina 45110, Greece.
| | - Themistoklis A Kabanos
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
| | - Maria Konstandi
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece.
| | - George Leondaritis
- Department of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece.
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Kalampounias AG. Exploring conformational change profile of n-propyl ester of formic acid by combining ultrasonic relaxation spectroscopy and molecular orbital calculations. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lampropoulou P, Laskaris N, Petrounias P, Giannakopoulou PP, Rogkala A, Kalampounias AG, Tsigrou P, Katagas CG, Iliopoulos I. Petrogeochemical approaches to the characterization of obsidian derived from Nychia area (Milos Island, Greece) using combined methods. Microchem J 2020. [DOI: 10.1016/j.microc.2020.104843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kalampounias AG, Papatheodorou GN. Spectrophotometric study of the gaseous species over molten HoCl3, LiCl-HoCl3 and CsCl-HoCl3 at temperature up to 1500K. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.127707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Tsigoias S, Kouderis C, Mylona-Kosmas A, Boghosian S, Kalampounias AG. Proton-transfer in 1,1,3,3 tetramethyl guanidine by means of ultrasonic relaxation and Raman spectroscopies and molecular orbital calculations. Spectrochim Acta A Mol Biomol Spectrosc 2020; 229:117958. [PMID: 31865106 DOI: 10.1016/j.saa.2019.117958] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/13/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
In this work, we report on the structure and dynamics of the 1,1,3,3 tetramethyl guanidine (TMG) aqueous solutions in a wide concentration and temperature range by combining vibrational and ultrasonic spectroscopies. The experimental Raman spectra have been compared with the corresponding spectra obtained by ab initio quantum mechanical and density functional theory electronic structure calculations. This comparison indicated that only a single mechanism occurs when dissolving TMG in water and this is the proton transfer reaction, while the formation of byproducts during hydrolysis of TMG is dubious. This observation is further supported by the concentration dependence of the Raman spectra. The analysis of the ultrasonic relaxation data also revealed that the system exhibits a single relaxation process associated with this proton transfer reaction. It has been also observed that both relaxation amplitude and frequency exhibit a clear monotonous increase with increasing amine concentration in the solutions supporting the concept of the proton transfer reaction. The corresponding activation enthalpy was estimated directly from the temperature dependence of the acoustic data and found equal to ΔH* = 5.56 ± 0.34 kcal/mol, which seems to be reasonable for hydrogen-bond formation. Furthermore, the concentration dependence of the acoustic parameters and kinematic viscosity data has been used as a probe for the molecular association in these solutions. The results have been discussed in relation to the ability or inability of water molecules to form stable clathrates after the addition of amine molecules in the solutions.
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Affiliation(s)
- S Tsigoias
- Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece
| | - C Kouderis
- Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece
| | - A Mylona-Kosmas
- Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece
| | - S Boghosian
- Department of Chemical Engineering, University of Patras, Patras GR-26504, Greece; Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras GR-26504, Greece
| | - A G Kalampounias
- Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece; Institute of Chemical Engineering Sciences, FORTH/ICE-HT, Patras GR-26504, Greece.
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Stogiannidis G, Tsigoias S, Kalampounias AG. Conformational energy barriers in methyl acetate – Ethanol solutions: A temperature-dependent ultrasonic relaxation study and molecular orbital calculations. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Rossos AK, Banti CN, Kalampounias AG, Papachristodoulou C, Kordatos K, Zoumpoulakis P, Mavromoustakos T, Kourkoumelis N, Hadjikakou SK. pHEMA@AGMNA-1: A novel material for the development of antibacterial contact lens. Mater Sci Eng C Mater Biol Appl 2020; 111:110770. [PMID: 32279741 DOI: 10.1016/j.msec.2020.110770] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/17/2020] [Accepted: 02/22/2020] [Indexed: 12/19/2022]
Abstract
The Metal Organic Framework (MOF) of formula {[Ag6(μ3-HMNA)4(μ3-MNA)2]2-·[(Et3NH)+]2·(DMSO)2·(H2O)} (AGMNA), a known efficient antimicrobial compound which contains the anti-metabolite, 2-thio-nicotinic acid (H2MNA), was incorporated in polymer hydrogels using, hydroxyethyl-methacrylate (HEMA). The material pHEMA@AGMNA-1 was characterized by X-ray fluorescence (XRF) spectroscopy, X-ray powder diffraction analysis (XRPD), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Thermogravimetric Differential Thermal Analysis (TG-DTA), Differential Scanning Calorimetry (DTG/DSC), attenuated total reflection spectroscopy (FT-IR-ATR) and Ultrasonic Imaging. The antimicrobial capacity of pHEMA@AGMNA-1 was evaluated against the Gram negative bacterial strain Pseudomonas aeruginosa and the Gram positive ones of the genus of Staphylococcus epidermidis and Staphylococcus aureus, which are the etiology of the microbial keratitis. The % bacterial viability of P. aeruginosa, S. epidermidis and S. aureus upon their incubation with pHEMA@AGMNA-1 discs is significantly low (0.4 ± 0.1%, 1.5 ± 0.4% and 7.7 ± 0.5% respectively). The inhibition zones (IZ) caused by pHEMA@AGMNA-1 discs against P. aeruginosa, S. epidermidis and S. aureus are 14.0 ± 1.1, 11.3 ± 1.3 and 11.8 ± 1.8 mm respectively. Furthermore, pHEMA@AGMNA-1 exhibits low toxicity. Thus, pHEMA@AGMNA-1 might be an efficient candidate for the development of antimicrobial active contact lenses.
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Affiliation(s)
- A K Rossos
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, Greece
| | - C N Banti
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, Greece.
| | - A G Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, Greece
| | | | - K Kordatos
- Laboratory of Inorganic and Analytical Chemistry, School of Chemical Engineering, National Technical University of Athens, Greece
| | - P Zoumpoulakis
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
| | - T Mavromoustakos
- Organic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens Greece, Greece
| | - N Kourkoumelis
- Medical Physics Laboratory, Medical School, University of Ioannina, Greece
| | - S K Hadjikakou
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, Greece; University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, Ioannina, Greece.
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15
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Mpourazanis P, Stogiannidis G, Tsigoias S, Kalampounias AG. Transverse phonons and intermediate-range order in Sr-Mg fluorophosphate glasses. Spectrochim Acta A Mol Biomol Spectrosc 2019; 212:363-370. [PMID: 30669100 DOI: 10.1016/j.saa.2019.01.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 01/06/2019] [Accepted: 01/14/2019] [Indexed: 06/09/2023]
Abstract
Vibrational and ultrasonic spectroscopies have been employed to study the composition and polarization dependence of the vibrational and elastic properties of the pseudo-binary mixed fluoride-phosphate glass-forming system xSr(PO3)2-(1-x)(0.62MgF2-0.38AlF3) with x: 0, 0.04, 0.06, 0.1, 0.15, 0.2, 0.3, 0.4, 0.8, 0.9 and 1. Composition-induced alterations in the short-range order have been quantitatively followed by means of Raman and IR spectroscopies. The analysis has shown that the incorporation of the phosphate groups in the fluoride network results in a less interconnected network with suppressed rigidity. The specific amorphous materials have been used as a model system in terms of wide glass-forming ability to elucidate the effect of variation in connectivity between the fluoride and phosphate sub-networks on the Boson peak nature. Emphasis has been given in the low-frequency Raman phenomenology, which in conjunction with the elastic properties allowed us to establish a possible link between the Boson peak and the transverse phonons in these glasses.
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Affiliation(s)
- P Mpourazanis
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - G Stogiannidis
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - S Tsigoias
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - A G Kalampounias
- Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece; Institute of Chemical Engineering Sciences, ICE-HT/FORTH, GR-26504 Patras, Greece.
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16
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Passadis SS, Hadjithoma S, Kalampounias AG, Tsipis AC, Sproules S, Miras HN, Keramidas AD, Kabanos TA. Synthesis, structural and physicochemical characterization of a new type Ti6-oxo cluster protected by a cyclic imide dioxime ligand. Dalton Trans 2019; 48:5551-5559. [PMID: 30785155 DOI: 10.1039/c9dt00658c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new type of Ti6-oxo cluster with a structural motif TiIV6O5 was synthesized of which the cyclo-Ti3 metallic cores exhibit metallaromaticity.
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Affiliation(s)
- Stamatis S. Passadis
- Section of Inorganic and Analytical Chemistry
- University of Ioannina
- Ioannina 45110
- Greece
| | | | | | - Athanassios C. Tsipis
- Section of Inorganic and Analytical Chemistry
- University of Ioannina
- Ioannina 45110
- Greece
| | - Stephen Sproules
- West CHEM
- School of Chemistry
- University of Glasgow
- Glasgow G12 8QQ
- UK
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17
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Latsis GK, Banti CN, Kourkoumelis N, Papatriantafyllopoulou C, Panagiotou N, Tasiopoulos A, Douvalis A, Kalampounias AG, Bakas T, Hadjikakou SK. Poly Organotin Acetates against DNA with Possible Implementation on Human Breast Cancer. Int J Mol Sci 2018; 19:ijms19072055. [PMID: 30011935 PMCID: PMC6073380 DOI: 10.3390/ijms19072055] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 07/06/2018] [Accepted: 07/12/2018] [Indexed: 11/16/2022] Open
Abstract
Two known tin-based polymers of formula {[R3Sn(CH3COO)]n} where R = n-Bu– (1) and R = Ph– (2),were evaluated for their in vitro biological properties. The compounds were characterized via their physical properties and FT-IR, 119Sn Mössbauer, and 1H NMR spectroscopic data. The molecular structures were confirmed by single-crystal X-Ray diffraction crystallography. The geometry around the tin(IV) ion is trigonal bi-pyramidal. Variations in O–Sn–O···Sn′ torsion angles lead to zig-zag and helical supramolecular assemblies for 1 and 2, respectively. The in vitro cell viability against human breast adenocarcinoma cancer cell lines: MCF-7 positive to estrogens receptors (ERs) and MDA-MB-231 negative to ERs upon their incubation with 1 and 2 was investigated. Their toxicity has been studied against normal human fetal lung fibroblast cells (MRC-5). Compounds 1 and 2 exhibit 134 and 223-fold respectively stronger antiproliferative activity against MDA-MB-231 than cisplatin. The type of the cell death caused by 1 or 2 was also determined using flow cytometry assay. The binding affinity of 1 and 2 towards the CT-DNA was suspected from the differentiation of the viscosity which occurred in the solution containing increasing amounts of 1 and 2. Changes in fluorescent emission light of Ethidium bromide (EB) in the presence of DNA confirmed the intercalation mode of interactions into DNA of both complexes 1 and 2 which have been ascertained from viscosity measurements. The corresponding apparent binding constants (Kapp) of 1 and 2 towards CT-DNA calculated through fluorescence spectra are 4.9 × 104 (1) and 7.3 × 104 (2) M−1 respectively. Finally, the type of DNA binding interactions with 1 and 2 was confirmed by docking studies.
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Affiliation(s)
- George K Latsis
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
| | - Christina N Banti
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
| | - Nikolaos Kourkoumelis
- Medical Physics Laboratory, Medical School, University of Ioannina, 45110 Ioannina, Greece.
| | | | - Nikos Panagiotou
- Department of Chemistry, University of Cyprus, 1678 Nicosia, Cyprus.
| | | | - Alexios Douvalis
- Mössbauer Spectroscopy and Physics of Material Laboratory, Department of Physics, University of Ioannina, 45110 Ioannina, Greece.
| | - Angelos G Kalampounias
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
| | - Thomas Bakas
- Mössbauer Spectroscopy and Physics of Material Laboratory, Department of Physics, University of Ioannina, 45110 Ioannina, Greece.
| | - Sotiris K Hadjikakou
- Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
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18
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Stathopoulou MEK, Banti CN, Kourkoumelis N, Hatzidimitriou AG, Kalampounias AG, Hadjikakou SK. Silver complex of salicylic acid and its hydrogel-cream in wound healing chemotherapy. J Inorg Biochem 2018; 181:41-55. [PMID: 29407907 DOI: 10.1016/j.jinorgbio.2018.01.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/24/2017] [Accepted: 01/07/2018] [Indexed: 01/06/2023]
Abstract
The known metallotherapeutic [Ag(salH)]2 (AGSAL-1) of salicylic acid (salH2), was used for the development of new efficient silver based material for wounds healing. AGSAL-1 was characterized by spectroscopic techniques and X-ray crystallography. The wound healing epithelialization of AGSAL-1 was investigated by the means of scratch assay against immortalized human keratinocytes (HaCaT) cells. The anti-inflammatory activity of AGSAL-1 was evaluated by monitoring the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX). The antibacterial activity of AGSAL-1 was evaluated against bacterial species which colonize wounds, such as: Pseudomonas aeruginosa (PAO1), Staphylococcus epidermidis and Staphylococcus aureus, by the means of Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and their Inhibition Zone (IZ). Moreover, the influence of AGSAL-1 against the formation of biofilm of PAO1 and St. aureus was also evaluated by the mean of Biofilm Elimination Concentration (ΒΕC). A hydrogel material CMC@AGSAL-1, based on the dispersion of AGSAL-1 in to carboxymethyl cellulose (CMC) was tested for its antimicrobial activity. Molecular Docking was performed, to explore the molecular interaction of AGSAL-1 with (i) the transcriptional regulator of PAO1, LasR. (ii) the mevalonate pathway for the biosynthesis of isoprenoids which is essential for gram-positive bacteria St. epidermidis and St. aureus. The toxicity of AGSAL-1 was examined against the HaCaT cells. Its genotoxicity was evaluated using Allium cepa model, in vivo. No genotoxicity was detected, indicating that AGSAL-1 is a candidate towards the development on a new efficient medication of the silver based metallodrugs.
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Affiliation(s)
| | - Christina N Banti
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
| | - Nikolaos Kourkoumelis
- Medical Physics Laboratory, Medical School, University of Ioannina, Ioannina, Greece.
| | | | | | - Sotiris K Hadjikakou
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
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19
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Tsilomelekis G, Panagiotou GD, Stathi P, Kalampounias AG, Bourikas K, Kordulis C, Deligiannakis Y, Boghosian S, Lycourghiotis A. Molybdena deposited on titania by equilibrium deposition filtration: structural evolution of oxo–molybdenum(vi) sites with temperature. Phys Chem Chem Phys 2016; 18:23980-9. [DOI: 10.1039/c6cp05247a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The temperature evolution of the Mo(vi)–oxo species structures in molybdena/titania catalysts is studied from the wet (prior to drying) to the final calcined catalyst state.
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Affiliation(s)
- George Tsilomelekis
- Department of Chemical Engineering
- University of Patras
- Patras
- Greece
- FORTH/ICE-HT
| | | | - Panagiota Stathi
- Lab of Physical Chemistry
- Materials and Environment
- Department of Physics
- University of Ioannina
- Ioannina
| | | | - Kyriakos Bourikas
- School of Science and Technology
- Hellenic Open University
- GR-26223 Patras
- Greece
| | | | - Yiannis Deligiannakis
- Lab of Physical Chemistry
- Materials and Environment
- Department of Physics
- University of Ioannina
- Ioannina
| | - Soghomon Boghosian
- Department of Chemical Engineering
- University of Patras
- Patras
- Greece
- FORTH/ICE-HT
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20
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Kaseman DC, Retsinas A, Kalampounias AG, Papatheodorou GN, Sen S. Q-Speciation and Network Structure Evolution in Invert Calcium Silicate Glasses. J Phys Chem B 2015; 119:8440-5. [PMID: 26047056 DOI: 10.1021/acs.jpcb.5b02469] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Binary silicate glasses in the system CaO-SiO2 are synthesized over an extended composition range (42 mol % ≤ CaO ≤ 61 mol %), using container-less aerodynamic levitation techniques and CO2-laser heating. The compositional evolution of Q speciation in these glasses is quantified using (29)Si and (17)O magic angle spinning nuclear magnetic resonance spectroscopy. The results indicate progressive depolymerization of the silicate network upon addition of CaO and significant deviation of the Q speciation from the binary model. The equilibrium constants for the various Q species disproportionation reactions for these glasses are found to be similar to (much smaller than) those characteristic of Li (Mg)-silicate glasses, consistent with the corresponding trends in the field strengths of these modifier cations. Increasing CaO concentration results in an increase in the packing density and structural rigidity of these glasses and consequently in their glass transition temperature Tg. This apparent role reversal of conventional network-modifying cations in invert alkaline-earth silicate glasses are compared and contrasted with that in their alkali silicate counterparts.
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Affiliation(s)
- Derrick C Kaseman
- †Department of Materials Science, University of California at Davis, Davis, California 95616, United States
| | - A Retsinas
- ‡Institute of Chemical Engineering and High Temperature Chemical Processes FORTH, P.O. Box 1414, GR-26504, Patras, Greece
| | - A G Kalampounias
- ‡Institute of Chemical Engineering and High Temperature Chemical Processes FORTH, P.O. Box 1414, GR-26504, Patras, Greece.,§Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece
| | - G N Papatheodorou
- ‡Institute of Chemical Engineering and High Temperature Chemical Processes FORTH, P.O. Box 1414, GR-26504, Patras, Greece
| | - S Sen
- †Department of Materials Science, University of California at Davis, Davis, California 95616, United States
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Kalampounias AG, Tsilomelekis G, Boghosian S. Vibrational dephasing and frequency shifts of hydrogen-bonded pyridine-water complexes. Spectrochim Acta A Mol Biomol Spectrosc 2015; 135:31-38. [PMID: 25048405 DOI: 10.1016/j.saa.2014.06.156] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/27/2014] [Accepted: 06/30/2014] [Indexed: 06/03/2023]
Abstract
In this paper we present the picosecond vibrational dynamics and Raman shifts of hydrogen-bonded pyridine-water complexes present in aqueous solutions in a wide concentration range from dense to extreme dilute solutions. We studied the vibrational dephasing and vibrational frequency modulation by calculating time correlation functions of vibrational relaxation by fits in the frequency domain. The concentration induced variations in bandwidths, band frequencies and characteristic dephasing times have been estimated and interpreted as effects due to solute-solvent interactions. The time-correlation functions of vibrational dephasing were obtained for the ring breathing mode of both "free" and hydrogen-bonded pyridine molecules and it was found that sufficiently deviate from the Kubo model. There is a general agreement in the whole concentration range with the modeling proposed by the Rothschild approach, which applies to complex liquids. The results have shown that the reorientation of pyridine aqueous solutions is very slow and hence in both scattering geometries only vibrational dephasing is probed. It is proposed that the spectral changes depend on the perturbations induced by the dynamics of the water molecules in the first hydration cell and water in bulk, while at extreme dilution conditions, the number of bulk water molecules increases and the interchange between molecules belonging to the first hydration cell may not be the predominant modulation mechanism. The evolution of several parameters, such as the characteristic times, the percentage of Gaussian character in the peak shape and the a parameter are indicative of drastic variations at extreme dilution revealing changes in the vibrational relaxation of the pyridine complexes in the aqueous environment. The higher dilution is correlated to diffusion of water molecules into the reference pyridine system in agreement with the jump diffusion model, while at extreme dilutions, almost all pyridine molecules are elaborated in hydrogen bonding. The results are discussed in the framework of the current phenomenological status of the field.
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Affiliation(s)
- A G Kalampounias
- Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26504 Patras, Greece; Foundation for Research and Technology-Hellas, Institute of Chemical Engineering and High-Temperature Chemical Processes, P.O. Box 1414, GR-26504 Patras, Greece.
| | - G Tsilomelekis
- Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26504 Patras, Greece; Foundation for Research and Technology-Hellas, Institute of Chemical Engineering and High-Temperature Chemical Processes, P.O. Box 1414, GR-26504 Patras, Greece
| | - S Boghosian
- Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26504 Patras, Greece; Foundation for Research and Technology-Hellas, Institute of Chemical Engineering and High-Temperature Chemical Processes, P.O. Box 1414, GR-26504 Patras, Greece
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23
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Andrikopoulos KS, Kalampounias AG, Falagara O, Yannopoulos SN. The glassy and supercooled state of elemental sulfur: vibrational modes, structure metastability, and polymer content. J Chem Phys 2014; 139:124501. [PMID: 24089780 DOI: 10.1063/1.4821592] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report a detailed investigation of vibrational modes, structure, and dynamics of elemental sulfur in the glassy and the supercooled state, using Raman scattering and ab initio calculations. Polarized Raman spectra are recorded--for sulfur quenched from 473 K--over a broad temperature range from 93 K to 273 K where the supercooled liquid crystallized. The temperature induced shifts of the majority of the vibrational modes are determined and compared with the corresponding ones of crystalline sulfur. Analysis of the reduced isotropic spectra showed that the structure of the quenched product is composed of eight member rings (S8) and polymeric chains (Sμ) with a relative fraction comparable to that of the parent liquid at 473 K. Low temperature spectra, where spectral line broadening due to thermal effects is limited, revealed that two different polymeric species are present in the glass with distinct vibrational frequencies. Their interpretation was assisted by ab initio calculations used to simulate the vibrational frequencies of polymeric chains S(8k) (k = 1, ..., 7). Theoretical results exhibit an increasing breathing mode frequency for sulfur chains up to k = 2, although it remains constant beyond the above value. The polymeric content is metastable; heating the glass above its glass transition temperature, T(g), destabilizes the chains and drives them back to the more thermodynamically stable rings. This bond interchange mechanism provides the structural origin of a secondary relaxation process in supercooled sulfur reported long ago, which has been also considered as a complication in the correct fragility estimation of this material. Finally, the Boson peak of the glass was found to exhibit strong temperature dependence even at temperatures below T(g).
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Affiliation(s)
- K S Andrikopoulos
- Foundation for Research and Technology Hellas, Institute of Chemical Engineering Sciences (FORTH-ICE∕HT), P.O. Box 1414, GR - 26504 Rio-Patras, Greece
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Kalampounias AG, Tsilomelekis G, Berg RW, Boghosian S. Molybdenum(VI) Oxosulfato Complexes in MoO3–K2S2O7–K2SO4 Molten Mixtures: Stoichiometry, Vibrational Properties, and Molecular Structures. J Phys Chem A 2012; 116:8861-72. [DOI: 10.1021/jp306701k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Angelos G. Kalampounias
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500
Patras, Greece
| | - George Tsilomelekis
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500
Patras, Greece
| | - Rolf W. Berg
- Chemistry
Department, The Technical University of Denmark, DK-2800 Kongens
Lyngby, Denmark
| | - Soghomon Boghosian
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500
Patras, Greece
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26
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Paulsen AL, Kalampounias AG, Berg RW, Boghosian S. Raman Spectroscopic Study of Tungsten(VI) Oxosulfato Complexes in WO3−K2S2O7−K2SO4 Molten Mixtures: Stoichiometry, Vibrational Properties, and Molecular Structure. J Phys Chem A 2011; 115:4214-22. [DOI: 10.1021/jp109339g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andreas L. Paulsen
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
| | - Angelos G. Kalampounias
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
| | - Rolf W. Berg
- Chemistry Department, The Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Soghomon Boghosian
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
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Kalampounias AG, Boghosian S. Thermodynamic analysis of reaction equilibria in ionic and molecular liquid systems by high-temperature Raman spectroscopy. Appl Spectrosc 2009; 63:1050-1056. [PMID: 19796488 DOI: 10.1366/000370209789379277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A formalism for correlating relative Raman band intensities with the stoichiometric coefficients, the equilibrium constant, and the thermodynamics of reaction equilibria in solution is derived. The proposed method is used for studying: (1) the thermal dissociation of molten KHSO(4) in the temperature range 240-450 degrees C; (2) the dinuclear complex formation in molten TaCl(5)-AlCl(3) mixtures at temperatures between 125 and 235 degrees C. The experimental and calculational procedures for exploiting the temperature-dependent Raman band intensities in the molten phase as well as (if applicable) in the vapors thereof are described and used for determining the enthalpy of the equilibria: (1) 2HSO(4)(-)(l) <--> S(2)O(7)(2-)(l) + H(2)O(g), DeltaH(0)=64.9 +/- 2.9 kJ mol(-1); and (2) 1/2Ta(2)Cl(10)(l) + 1/2Al(2)Cl(6)(l) <--> TaAlCl(8)(l), DeltaH(0)=-12.1 +/- 1.5 kJ mol(-1).
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Affiliation(s)
- Angelos G Kalampounias
- Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26504 Patras, Greece
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Papatheodorou GN, Kalampounias AG. In situ measurements of the D(1) and D(2) Raman band intensities of vitreous and molten silica in the 77-2150 K temperature range. J Phys Condens Matter 2009; 21:205101. [PMID: 21825520 DOI: 10.1088/0953-8984/21/20/205101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In situ quantitative Raman spectra of vitreous and molten silica were measured from LN(2) temperatures up to above melting and used to calculate the intensities of the two 'defect peaks' D(1) and D(2) associated with the corresponding four- and three-membered ring structures. The D(1) intensity decreases with increasing temperature while the D(2) intensity appears to be invariant to temperature. The data are in disagreement with the quenching/fictive temperature experiments and show definitely no abrupt intensity changes at any temperature.
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Affiliation(s)
- G N Papatheodorou
- Foundation for Research and Technology Hellas-Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), PO Box 1414, GR-26504 Patras, Greece. Department of Chemical Engineering, University of Patras, GR-26504, Patras, Greece
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Knudsen CB, Kalampounias AG, Fehrmann R, Boghosian S. Thermal Dissociation of Molten KHSO4: Temperature Dependence of Raman Spectra and Thermodynamics. J Phys Chem B 2008; 112:11996-2000. [DOI: 10.1021/jp801853z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christian B. Knudsen
- Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
| | - Angelos G. Kalampounias
- Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
| | - Rasmus Fehrmann
- Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
| | - Soghomon Boghosian
- Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark, and Department of Chemical Engineering, University of Patras and Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), GR-26500 Patras, Greece
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Kalampounias AG, Yannopoulos SN, Papatheodorou GN. A high-temperature Raman spectroscopic investigation of the potassium tetrasilicate in glassy, supercooled, and liquid states. J Chem Phys 2006; 125:164502. [PMID: 17092100 DOI: 10.1063/1.2360275] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Raman spectra of K2Si4O9 were measured over a broad temperature range including the glassy, supercooled, and molten states in an effort to follow the structural changes caused by temperature variation. Potassium tetrasilicate glass has been prepared using a containerless method and a CO2 laser for heating and melting the samples and thus avoiding contamination induced by the walls of the crucibles. Systematic Raman intensity measurements caused by temperature variation have been performed in order to elucidate the induced structural changes in the high-frequency stretching and in the three- and four-membered ring breathing vibration regions. The high-frequency symmetric stretching vibrations of the nonbridging Si-O bond are associated to the presence of two distinct types of tetrahedral units with terminal oxygen atoms. The low-frequency Raman spectra reveal the, well resolved, presence of the boson peak at temperatures above the melting point. The temperature dependence of the boson peak energy has also been determined and compared with that of the sound velocities of potassium tetrasilicate. The results are discussed in the context of recent experimental and theoretical works.
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Affiliation(s)
- A G Kalampounias
- Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology-Hellas, and Department of Chemical Engineering, University of Patras, GR-26504 Patras, Greece.
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Andrikopoulos KS, Kalampounias AG, Yannopoulos SN. On the extent of polymerization of liquid sulfur at very high temperatures. J Chem Phys 2006; 124:146101. [PMID: 16626253 DOI: 10.1063/1.2185097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The extent of polymerization of liquid sulfur up to 731 K has been obtained using Raman scattering. The data reveal the absence of a maximum in the polymerization curve. The obtained results are discussed in the spirit of computer simulations that suggest the existence of a maximum which depends on the bond breaking energy.
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Affiliation(s)
- K S Andrikopoulos
- Foundation for Research and Technology Hellas-Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), P.O. Box 1414, GR-26504 Patras, Greece
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Kalampounias AG, Yannopoulos SN, Papatheodorou GN. Temperature-induced structural changes in glassy, supercooled, and molten silica from 77 to 2150 K. J Chem Phys 2006; 124:14504. [PMID: 16409038 DOI: 10.1063/1.2136878] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In situ polarized and depolarized Raman spectra of glassy, supercooled, and molten SiO2 have been measured over the broad temperature range 77-2150 K in an effort to examine possible structural changes caused by temperature variation. A new experimental setup using a CO2 laser for heating the sample has been designed allowing measurement with controllable blackbody radiation background at temperatures up to 2200 K. Careful and systematic relative intensity measurements and the use of the isotropic and anisotropic Raman representation of the spectra revealed hidden bands in the bending mode region and resolved bands in the stretching region of the spectra. Overall the spectra behavior shows similarities with the spectra of the recently studied tetrahedral glasses/melts of ZnCl2 and ZnBr2. Increasing temperature causes subtle changes of the relative intensities within the silicon-oxygen stretching region at approximately 750-850 cm(-1) and gives rise to a new band at approximately 930 cm(-1). The spectral behavior is interpreted to indicate that the "SiO42" tetrahedra are bound to each other to form the network by apex-bridging and partly by edge-bridging oxygens. The network structure of the glass/melt is formed by mixing a variety of tetrahedra participating in "open" (cristobalitelike), "cluster" (supertetrahedra), and "chain" edge-bridged substructures bound to each other by bridging oxygens. A weak in intensity but strongly polarized composite band is resolved at approximately 1400 cm(-1) and is assigned to Si[Double Bond]O terminal bond frequency. Temperature rise increases the concentration of the terminal bonds by breaking up the network. These structural changes are reminiscent of the polyamorphic transformations occurring in silica as has recently been predicted by computer simulations. At low frequencies the Raman spectra reveal the presence of the Boson peak at approximately 60 cm(-1) which is well resolved even above melting temperature up to 2150 K.
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Affiliation(s)
- A G Kalampounias
- Department of Chemical Engineering, University of Patras, GR-26 504 Patras, Greece
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