Fizik Bölümü / Department of Physics

Permanent URI for this collectionhttps://hdl.handle.net/11413/6785

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4-Hydroxyquinolin-2(1H)-One Isolated in Cryogenic Argon and Xenon Matrices: Tautomers and Photochemistry
(Elsevier, 2024) Secrieru, A.; Lopes, S.; Nikitin, T.; Cristiano, Maria L. S.; FAUSTO, RUI
4-Hydroxyquinolin-2(1H)-one (4HQ2O) was synthesized, isolated in cryogenic matrices (argon and xenon), and studied by infrared spectroscopy. Quantum chemical calculations carried out at the DFT(B3LYP)/6-311++G (3df,3pd) level of theory were used to determine the conformational and tautomeric properties of the molecule. Two tautomeric forms were identified in the as-deposited matrices with the help of the theoretical data. To investigate the photochemistry of the compound, in situ broadband ultraviolet (lambda > 283 nm) irradiation of the asdeposited argon matrix was performed. This irradiation led to the generation of an additional tautomer, together with the products of fragmentation of the heterocyclic ring of the molecule, specifically isocyanic acid and carbon monoxide. Photoproducts such as 1,3-dihydro-2H-indol-2-one and cyclohepta-1,2,4,6-tetraene were also observed in the photolyzed argon matrix. A comprehensive assignment of the infrared spectra of all the species observed experimentally is presented.
Hydrogen Tunneling Exhibiting Unexpectedly Small Primary Kinetic Isotope Effects
(Wiley - VCH Verlag GmbH, 2024) Roque, Jose P. L.; Nunes, Claudio M.; Schreiner, Peter R.; FAUSTO, RUI
Probing quantum mechanical tunneling (QMT) in chemical reactions is crucial to understanding and developing new transformations. Primary H/D kinetic isotopic effects (KIEs) beyond the semiclassical maximum values of 7–10 (room temperature) are commonly used to assess substantial QMT contributions in one-step hydrogen transfer reactions, because of the much greater QMT probability of protium vs. deuterium. Nevertheless, we report here the discovery of a reaction model occurring exclusively by H-atom QMT with residual primary H/D KIEs. 2-Hydroxyphenylnitrene, generated in N2 matrix, was found to isomerize to an imino-ketone via sequential (domino) QMT involving anti to syn OH-rotamerization (rate determining step) and [1,4]-H shift reactions. These sequential QMT transformations were also observed in the OD-deuterated sample, and unexpected primary H/D KIEs between 3 and 4 were measured at 3 to 20 K. Analogous residual primary H/D KIEs were found in the anti to syn OH-rotamerization QMT of 2-cyanophenol in a N2 matrix. Evidence strongly indicates that these intriguing isotope-insensitive QMT reactivities arise due to the solvation effects of the N2 matrix medium, putatively through coupling with the moving H/D tunneling particle. Should a similar scenario be extrapolated to conventional solution conditions, then QMT may have been overlooked in many chemical reactions.
Recycling Ophthalmic Lens Wastewater in a Circular Economy Context: A Case Study with Microalgae Integration
(MDPI, 2024) FAUSTO, RUI
Water pollution poses a global threat to ecosystems and human health and is driven by the presence of various contaminants in wastewater, including nano- and microplastics. Despite the magnitude of this problem, the majority of global wastewater is released untreated into water bodies. To combat this issue, a multi-strategy approach is needed. This study explores a circular economy-based solution for treating emerging pollutants, particularly wastewater from ophthalmic spectacle lens production. Our approach integrates solid waste materials into polymeric and cement matrices while also utilising wastewater for microalgae cultivation. This innovative strategy focuses on biomass generation and economic valorisation. By adopting a circular economy model, we aim to transform environmental pollutants from wastewater into valuable organic products. A key component of our approach is the utilisation of microalgae, specifically Nannochloropsis sp., known for its high lipid content and resilience. This microalgae species serves as a promising biobased feedstock, supporting the production of innovative biobased products, such as biopolymers, for ophthalmic lens manufacturing. Our interdisciplinary approach combines microalgae technology, analytical chemistry, cement production, and polymer processing to develop a sustainable circular economy model that not only addresses environmental concerns, but also offers economic benefits. This study underscores the potential of harnessing high-value products from waste streams and underscores the importance of circular economy principles in tackling pollution and resource challenges.
Solid-Liquid Phase Equilibrium: Alkane Systems for Low-Temperature Energy Storage
(Springer/Plenum Publishers, 2024) Sequeira, Maria C. M.; Nogueira, Bernardo A.; Caetano, Fernando J. P.; Diogo, Herminio P.; Fareleira, Joao M. N. A.; FAUSTO, RUI
The thermal characterization of two binary systems of n-alkanes that can be used as Phase Change Materials (PCMs) for thermal energy storage at low temperatures is reported in this work. The construction of the solid-liquid binary phase diagrams was achieved using differential scanning calorimetry (DSC) and Raman spectroscopy. The solidus and liquidus equilibrium temperatures were determined using DSC for thirty-nine different samples, three for the pure n-alkanes and the remaining for binary mixtures at selected molar compositions and used to acquire the corresponding solid-liquid phase diagrams. The two binary systems of n-octane/n-decane (C8/C10) and n-decane/n-dodecane (C10/C12) are characterized by a eutectic behavior at low temperatures. The eutectic temperature for the system C8/C10 was found at 211.95 K and the eutectic composition appeared at the molar fraction xoctane = 0.87. For the system C10/C12, the eutectic temperature was found at 237.85 K, and the eutectic composition appeared for the molar fraction xdecane = 0.78. This work aims to fulfill the lack of available data in the existing literature, considering the potential application of these systems for low-temperature thermal energy storage. Raman spectroscopy was used to complement the DSC data for the construction of the solid-liquid phase equilibrium diagrams, enabling the identification of the solid and liquid phases of the system. Additionally, the liquidus curve of the phase diagram was successfully described using a modified freezing point depression curve as fitting equation, the absolute root mean square deviation for the data correlation of the C8/C10 and C10/C12 systems being 2.56 K and 1.22 K, respectively. Ultimately, the fitting procedure also enabled a good prediction of the eutectic point for both studied systems.
Graphene-Assisted Chemical Stabilization of Liquid Metal Nano Droplets for Liquid Metal Based Energy Storage
(Wiley, 2024) Sanati, Afsaneh L.; Nikitin, Timur; FAUSTO, RUI; Majidi, Carmel; Tavakoli, Mahmoud
Energy storage devices with liquid-metal electrodes have attracted interest in recent years due to their potential for mechanical resilience, self-healing, dendrite-free operation, and fast reaction kinetics. Gallium alloys like Eutectic Gallium Indium (EGaIn) are appealing due to their low melting point and high theoretical specific capacity. However, EGaIn electrodes are unstable in highly alkaline electrolytes due to Gallium oxide dissolution. In this letter, this bottleneck is addressed by introducing chemically stable films in which nanoscale droplets of EGaIn are coated with trace amounts of graphene oxide (GO). It is demonstrated that a GO to EGaIn weight ratio as low as 0.01 provides enough protection for a thin film formed by GO@EGaIn nanocomposite against significantly acidic or alkaline environments (pH 1-14). It is shown that GO coating significantly enhances the surface stability in such environments, thus improving the energy storage capacity by over 10x. Microstructural analysis confirms GO@EGaIn composite stability and enhanced electrochemical performance. Utilizing this, a thin-film supercapacitor is fabricated. Results indicate that when coating the EGaIn with GO to EGaIn ratio of 0.001, the areal capacitance improves by 10 times, reaching 20.02 mF cm(-2). This breakthrough paves the way for advanced liquid metal-based thin-film electrodes, promising significant improvements in energy storage applications.
Conformational Analysis of Milk Derived Tripeptides, IPP, VPP and LPP, and Investigation of Their Anti-COVID-19 Potentials by Molecular Docking and Molecular Dynamics Studies
(Taylor & Francis Ltd., 2024) Çelik, Sefa; AKYÜZ, SEVİM; Agaeva, Gulshen; E. Özel, Ayşen; Qocayev, Niftali M.; Agaeva, Ulker
Milk derived tripeptides IPP(Ile-Pro-Pro), VPP(Val-Pro-Pro) and LPP(Leu-Pro-Pro) have inhibitory effects on angiotensin converting enzyme, which plays a fundamental role in blood pressure systems. To discover the potentiality of the tripeptides as SARS-CoV-2 inhibitors, molecular docking analyses of IPP, VPP and LPP tripeptides with variety of SARS-CoV-2 enzymes, namely with Main protease, papain-like protease and Spike glycoprotein, were performed. Molecular dynamics simulations were performed to validate the stability of the IPP, LPP and VPP tripeptides docked into SARS-CoV-2 main protease within 50 ns time scale and ligand-receptor interactions were evaluated. Molecular docking and molecular dynamics studies showed that these food-derived tripeptides may be effective against COVID-19.
Unveiling the Red and Brownish-Green Polymorphs of a Novel ROY Derivative: 2-(4-((3-Cyanothiophen-2-yl)amino)-3-nitrophenyl)Acetic Acid
(American Chemical Society, 2024) Nogueira, Bernardo A.; Lopes, Susana M. M.; Rodrigues, Ana Clara B.; Eusebio, M. Ermelinda S.; Andre, Vania; Duarte, Teresa; Paixao, J. A.; Melo, Teresa M. V. D. Pinho e; FAUSTO, RUI
Polymorphism has been the subject of many studies in the last decades, including a particular type of polymorphism where the colors exhibited by the polymorphs differ. However, only relatively limited or narrow differences in color were observed in color polymorphs of the same compound. Indeed, to this date, almost all compounds known to show color polymorphism exhibit red, orange, or yellow tones, as is the case of the notable ROY molecule (5-methyl-2-[(2-nitrophenyl)-amino]-3-thiophenecarbonitrile), which is the compound with more polymorphs reported and structurally characterized hitherto. In this work, we report a new color polymorphic material derived from ROY, (2-(4-((3-cyanothiophen-2-yl)-amino)-3-nitrophenyl)-acetic acid; or ROY-CAM), synthesized for the first time by nucleophilic aromatic substitution reaction between 2-(4-fluoro-3-nitrophenyl)-acetic acid and 2-aminothiophene-3-carbonitrile, which exhibits a red (P21/n, m.p.: 184 C-degrees and theta = -4.4(degrees) and 3.0(degrees)) and a brownish-green polymorph (P1, m.p.: 190 C-degrees and theta = -66.1(degrees)). This is the first time a member of the ROY family of compounds was observed to exhibit a brownish-green polymorph and, more importantly, the first time that a molecular compound exhibits a red and a greenish polymorphs, i.e., this is the first example of an organic molecule that originates polymorphs covering such a wide range of color. The isolated molecule of ROY-CAM has 11 low-energy conformers, which were accessed by DFT calculations, with two of these conformers being identified in the observed polymorphs of the compound: in the brownish-green polymorph, the most stable conformer exists, while the red polymorph is composed of molecules assuming a conformation similar to that of the third most stable conformer. In the latter polymorph, the intramolecularly disfavored conformation assumed by the molecules is stabilized in the crystal lattice through interactions between carboxylic acid groups of neighboring molecules, resulting in dimeric units formed between pairs of the two distinct molecules that constitute the asymmetric unit of the crystal. The two identified polymorphs were characterized vibrationally (by both IR and Raman spectroscopies), and a thermal study is also presented (based on DSC, PLTM, and TGA measurements). Furthermore, the brownish-green and red colors exhibited by the polymorphs of ROY-CAM are explained based on the differences in the structures of the molecules that are present in these crystals.
Benchmarking the Anisotropy of Nitroxyl Radical Solvation With IR Spectroscopy
(The Royal Society of Chemistry, 2024) Bras, Elisa M.; Zimmermann, Charlotte; FAUSTO, RUI; Suhm, Martin A.
Two simple nitroxyl radicals, di-tert-butyl nitroxyl (DTBN) and 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) are solvated by one or two water, methanol, tert-butyl alcohol or phenol molecules. The resulting low temperature IR spectra of the vacuum-isolated microsolvates in the OH stretching range are assigned based on harmonic DFT predictions for closed shell solvent dimers and trimers and their offset from experiment, to minimise theory-guided assignment bias. Systematic conformational preferences for the first and second solvent molecule are observed, depending on the conformational rigidity of the radical. These assignments are collected into an experimental benchmark data set and used to assess the spectral predicting power of different DFT approaches. The goal is to find inexpensive computational methods which provide reliable spectral predictions for this poorly explored class of microsolvates.
Fizik Laboratuvarı Deney Kitabı: Elektrik ve Manyetizma
(İstanbul Kültür Üniversitesi, 2013) Kolektif
Fizik Laboratuvarı Deney Kitabı: Mekanik
(İstanbul Kültür Üniversitesi, 2012) Kolektif
Di-Alkyl Adipates as New Phase Change Material for Low Temperature Energy Storage
(Springer/Plenum Publishers, 2023) Sequeira, Maria C. M.; Nogueira, Bernardo A.; Caetano, Fernando J. P.; Diogo, Herminio P.; Fareleira, Joao M. N. A.; FAUSTO, RUI
This work is a contribution to the thermal characterization of a selected binary system of two di-n-alkyl adipates that can be used as phase change material for thermal energy storage at low temperatures. The construction of the solid-liquid phase diagram using differential scanning calorimetry (DSC), complemented with Raman Spectroscopy studies for the system composed by diethyl and dibutyl adipates is presented. The solidus and liquidus equilibrium temperatures were determined by DSC for the pure components and 30 binary mixtures at selected molar compositions were used to construct the corresponding solid-liquid phase diagram. The binary system of diethyl and dibutyl adipates presents eutectic behaviour at low temperatures. The eutectic temperature was found at 240.46 K, and the eutectic composition was determined to occur at the molar fraction xdibutyl = 0.46. Additionally, the system shows a polymorphic transition, characteristic of dibutyl adipate, occurring at ca. 238 K, confirmed by optical microscopy. To the best of our knowledge, no reference to the phase diagram of the present system could be found in the literature. Raman spectroscopy was essential to complement the construction of the phase equilibrium diagram, enabling the identification of the solid and liquid phases of the system. Finally, the liquidus curve of the phase diagram was also successfully predicted using a suitable fitting equation, being the root mean square deviation of the data from the correlation equal to 0.54 K. In addition, this fitting operation enabled a correct prediction of the eutectic composition of the system.
On the Carbenic Nature of Nitrile Ylides: Experimental and Computational Characterization of Hydroxy and Amino Nitrile Ylides
(Wiley-VCH Verlag, 2024) Nunes, Claudio M.; Jesus, A. J. Lopes; Rosado, Mario T. S.; FAUSTO, RUI
Nitrile ylides are 1,3-dipolar species with structures that are commonly described by propargylic and/or allenic resonance forms. Nevertheless, certain nitrile ylides exhibit a tendency to form dimers, suggesting the existence of structures characterized by an important carbenic contribution. To address the nitrile ylide carbenic nature, here we investigate two derivatives with OH and NH2 electron-donating substituents. These nitrile ylides were generated in cryogenic matrices by UV-irradiation of 3-hydroxy- and 3-amino-isoxazole precursors and were found to photoisomerize to the corresponding oxazoles. The IR spectral characterization of the photogenerated nitrile ylides reveals the absence of the characteristic strong nu as(CNC) absorption, which is associated with allenic and propargylic type structures. Computed geometries for the two experimentally investigated nitrile ylides and for analogues with different substituents at C3 and C1, together with NBO and NRT electronic structure analyses, performed at the CCSD(T) level of theory, reveal substantial carbenic character exclusively for nitrile ylides bearing OH and NH2 substituents at C3. As a whole, the results shed light on the factors determining the structural features of nitrile ylides, which play a major role in defining the reactivity of these important elusive compounds.
Investigations of Black and Red Figure Pottery Shards and Local Clay, Excavated at Ainos (Enez-Turkey), by Multiple Analytical Techniques
(Elsevier, 2023) AKYÜZ, SEVİM; Çelik, Sefa; Kurap, Gülnur; Özel, Ayşen E.; Başaran, Sait
Mineralogical compositions as well as firing conditions of black and red figure pottery shards, belonging to 4th6th century BC, excavated at the archeological site Ainos (Enez-Turkey), were investigated using Fourier Transform Infrared (FT-IR), micro-Raman, and X-Ray Powder Diffraction (XRPD) techniques. Raw clay, obtained from a clay bed, that was unearthed during the archeological excavations at the same site, was also analyzed for comparison. To determine the firing temperature of the pottery shards, ceramic tablets were prepared from this raw clay sample (in three different firing temperatures: 650, 700 and 900 degrees C) and analyzed. The results allowed us to identify the mineral composition and to discuss the firing conditions. Chemometric analysis on the IR data was performed for revealing the distinct groups.
The Importance of Polymers in Medicine and their FTIR and Raman Spectroscopic Investigations
(IGI Global, 2023) Çelik, Sefa; AKYÜZ, SEVİM; Özel, Ayşen E.
Polymers are macromolecules with a very high molecular weight that are formed as a result of one or more small molecules bonding to each other, typically by covalent bonds. The concept of macromolecules consisting of many repeating units are published in the article titled "Uber Polymerization," which was first published in 1920 by Hermann Staudinger. The idea of polymers, which have been in our lives for a long time, has thus become an important field of study. Polymers are commonly used in tissue engineering because of their properties such as biocompatibility and biodegradability. In addition, polymers have a wide range of applications in tissue regeneration, drug delivery, and wound healing. Polymers have varying structural properties based on their backbone structure, molecular weight, and crystallinity. For this cause, a great deal of study in the medicine has been based on this category of materials. This workfocuses on the importance of polymers in the medicine, 3D printed polymer composites and Fourier transform infrared, and Raman spectroscopic investigations of polymeric structures.
Phenylpropiolic Acid Isolated in Cryogenic Nitrogen and Xenon Matrices: NIR and UV-Induced Study
(AIP Publishing, 2023) Lopes S.; Nikitin T.; FAUSTO, RUI
Phenylpropiolic acid (C6H5C≡CCOOH, PPA) isolated in nitrogen and xenon cryogenic matrices was studied by infrared spectroscopy. The experimental studies were complemented by a series of quantum chemical calculations carried out at the density functional theory (B3LYP) and MP2 levels of theory (with different basis sets). The calculations predicted the existence of two planar PPA conformers, differing in the arrangement of the carboxylic group. The higher-energy trans-PPA conformer has a negligible population in the gas phase at room temperature and was prepared in situ in the N2 cryomatrix through vibrationally-induced rotamerization of the lower-energy cis-PPA conformer, achieved using selective narrowband infrared excitation of the OH stretching coordinate of the latter species. Broadband UV (λ > 235 nm) irradiation of matrix-isolated cis-PPA was also undertaken, leading to the observation of cis-PPA → trans-PPA isomerization. No other UV-induced photoreactions were observed. The in situ generated trans-PPA conformer was found to decay back to cis-PPA in the dark by tunneling, and its lifetimes under different experimental conditions were determined. The assignment of the infrared spectra of both conformers is presented, considerably extending the vibrational information available on this molecule.
Sandwich-Type Double-Layer Piezoelectric Nanogenerators Based on One- and Two-Dimensional ZnO Nanostructures With Improved Output Performance
(Nature Research, 2023) Fakhri, Parisa; Eaianli, Naeimeh; Bagherzadeh, Roohollah; Jaleh, Babak; Kashfi, Mohammad; FAUSTO, RUI
Piezoelectric nanogenerators (PENGs) have attracted great interest owing to their broad range application in environmental mechanical energy harvesting to power small electronic devices. In this study, novel flexible and high-performance double-layer sandwich-type PENGs based on one-dimensional (1-D) and two-dimensional (2-D) zinc oxide (ZnO) nanostructures and Ni foam as the middle layer have been developed. The morphology and structure of 1- and 2-D ZnO nanostructures have been studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). To investigate the effect of structural design on the piezoelectric performance, single-layer PENGs were also fabricated. The piezoelectric output of all prepared PENGs were evaluated under different human impacts at various forces and frequencies. The double-layer designed PENGs showed a two times larger voltage output compared to the single-layer PENGs, and the use of Ni foam as middle-layer and of 2-D ZnO nanosheets (compared to 1-D nanorods) was also found to increase the performance of the designed PENGs. The working mechanism of the prepared PENGs is also discussed. The design of nanogenerators as double-layer sandwich structures instead of two integrated single-layer devices reduces the overall preparation time and processing steps and enhances their output performance, thus opening the gate for widening their practical applications.
Synthesis, Characterization and Sensing Mechanism of a Novel Fluorescence Probe for Fe(III) in Semi-Aqueous Solution Based on a Schiff Base Hexadentate Receptor
(Elsevier Science SA, 2023) Ooshall, Farkhondeh; Jamehbozorgi, Saeed; Golbedaghi, Reza; Justino, Licinia L. G.; Feshalame, Keyvan Mirzaei; Liyaghati-Delshad, Mozhdeh; Anaraki-Ardakani, Hossein; Jaleh, Babak; FAUSTO, RUI
A new acyclic Schiff base chemosensor L was synthesized by the one pot condensation reaction of 2-[3-(formyl phenoxy)2-hydroxypropoxy]benzaldehyde and 2-aminophenol in a 1:2 molar ratio and was characterized by elemental analysis, FTIR, 1H- and 13C NMR, and fluorescence spectroscopies. These studies were complemented with a thorough conformational study at the molecular mechanics and density functional theory (DFT) levels of theory to further elucidate the structure of the compound in solution. The chemosensor L displays high sensitivity and selectivity for Fe3+ in semi-aqueous (H2O-DMF, 1:1) solution, except in the presence of a significant amount of Ni2+, with the presence of Fe3+ being signaled through the total fluorescence quenching of the fluorophore when Fe3+ binds to the recognition unit. The synthesized ligand also shows high selectivity for Fe3+ compared to the metal ions Cu2+, Zn2+, Mg2+, Mn2+, Pb2+, Hg2+, Na+, Ba2+ and Cd2+, and reasonable selectivity in the presence of Ag+, Co2+ and Cr3+. The stoichiometry and structure of the complex formed between Fe3+ and the probe L were determined from a Job's plot and DFT calculations, respectively. The complex was characterized as a high-spin 1:1 octahedral species, in which the ligand coordinates to the metal through the two ether oxygen atoms, two nitrogen atoms and two terminal hydroxyl groups. Time dependent (TD-DFT) calculations were performed to provide information on the type of mechanism causing the quenching of the fluorescence in the presence of Fe3+.
Nanoscale Study of the Polar and Electronic Properties of a Molecular Erbium(III) Complex Observed via Scanning Probe Microscopy
(MDPI, 2023) Ivanov, Maxim; Grempka, Arkadiusz; Buryakov, Arseniy; Nikitin, Timur; Justino, Licinia L. G.; FAUSTO, RUI; Vilarinho, Paula M.; Paixao, Jose A.
We successfully synthesized millimeter-sized single crystals of the molecular erbium(III) complex Er(acac)(3)(cphen), where acac = acetylacetonate and cphen = 5-chloro-1,10-phenanthroline. The novelty of this work stems from the exhaustive examination of the polar and electronic properties of the obtained samples at the macro-, micro-, and nanoscale levels. The single crystal X-ray diffraction method demonstrates the monoclinic (noncentrosymmetric space group P2(1)) crystallographic structure of the synthesized samples and scanning electron microscopy exhibits the terrace-ledge morphology of the surface in erbium(III) crystals. By using the piezoelectric force microscopy mode, the origin of the polar properties and the hyperpolarizability in the synthesized samples were assigned to the internal domain structure framed by the characteristic terrace-ledge topography. The direct piezoelectric coefficient (similar to d33) was found to be intensely dependent on the local area and was measured in the range of 4-8 pm/V. A nanoscale study using the kelvin probe force and capacitance force (dC/dz) microscopy modes exposed the effect of the Er ions clustering in the erbium(III) complex. The PFM method applied solely to the Er ion revealed the corresponding direct piezoelectric coefficient (similar to d33) of about 4 pm/V. Given the maximum piezoelectric coefficient in the erbium(III) complex at 8 pm/V, we highlight the significant importance of the spatial coordination between the lanthanide ion and the ligands. The polar coordination between the lanthanide ion and the nitrogen and oxygen atoms was also corroborated by Raman spectroscopy supported by the density functional theory calculations. The obtained results can be of paramount importance for the application of molecular erbium(III) complex crystals in low-magnitude magnetic or electric field devices, which would reduce the energy consumption and speed up the processing switching in nonvolatile memory devices.
The Effects of Conformation and Intermolecular Hydrogen Bonding on the Structure and IR Spectra of Flutamide; A Study Based on the Matrix Isolation Technique, Ab Initio and DFT Calculations
(Pergamon-Elsevier Science Ltd., 2023) Arman, C.; Balcı, K.; Akkaya, Y.; AKYÜZ, SEVİM; Reaves-Mckee, T.; Frankamp, AH; Coates, JT; Collier, WB; Ritzhaupt, G.; Klehm, CE; Desman, P.
In this study, stable conformers of flutamide referred to as an anticancer drug were searched through a relaxed potential energy surface scan carried out at the B3LYP/6-31G(d) level of theory. This was followed by geometry optimization and thermochemistry calculations performed with the HF-SCF, MP2, B3LYP methods and the 6-31G (d), 6-311++G(d,p), aug-cc-pvTZ basis sets for each of the determined minimum energy conformers. The results revealed that flutamide has at least five stable conformers and two of them provide the major contribution to the observed matrix isolation infrared (IR) spectra of the molecule. The effects of conformational variety and intermolecular hydrogen bonding interactions on the observed IR spectra of flutamide were interpreted in the light of the vibrational spectral data obtained for the most stable monomer and dimer forms of the molecule at the same levels of theory. Pulay's "Scaled Quantum Mechanical-Force Field (SQM-FF)" method was used in the refinement of the calculated harmonic wavenumbers, IR intensities and potential energy distributions. This scaling method which proved its superiority to both anharmonic frequency calculations and other scaling methods helped us to correctly interpret the remarkable differences between the matrix IR spectra of flutamide in argon and the condensed phase IR spectra of the molecule in solvents such as KBr, H2O, D2O, ethanol and methanol.
Crystallization Kinetics: Relationship Between Crystal Morphology and the Cooling Rate-Applications for Different Geological Materials
(MDPI, 2023-01-24) Aysal, Namık; Kurt, Yiğit; ILDIZ, GÜLCE ÖĞRÜÇ; Öztürk, Hüseyin; Yeşiltaş, Mehmet; Laçin, Davut; Öngen, Sinan; Nikitin, Timur; FAUSTO, RUI
Crystal morphology is controlled by several physicochemical parameters such as the temperature, pressure, cooling rate, nucleation, diffusion, volatile composition, and viscosity. The development of different crystal morphologies is observed as a function of the cooling rate in many different rock types (i.e., glassy volcanic rocks, and archeometallurgical slags). Crystallization is a two-stage kinetic process that begins with the formation of a nucleus and then continues with the accumulation of ions on it. The shapes of the crystals depend on the degree of undercooling (& UDelta;T), and euhedral crystals, having characteristic forms that reflect their crystallographic internal structure, that grow just below their liquidus temperature. In this study, crystal morphologies in different minerals (e.g., quartz, sanidine, olivine, pyroxene, magnetite, etc.) that had developed in silicic volcanic rocks (spherulites) and slags from ancient mining were investigated and characterized using optical microscopy, X-ray diffraction, and Fourier-transform infrared (FTIR), Raman, and scanning electron microscope-energy dispersive X-ray fluorescence (SEM-EDX) spectroscopic techniques. Depending on the increase in the cooling rate, quartz, feldspar, olivine, pyroxene, and magnetite minerals were found to crystallize in subhedral, skeletal, dendritic, spherical, bow-tie and fibrous forms in glassy volcanic rocks and archeometallurgical slags.

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