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Keywords = CO2 molecular absorption spectroscopy

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17 pages, 1725 KiB  
Article
Ring Opening upon Valence Shell Excitation in β-Butyrolactone: Experimental and Theoretical Methods
by Pedro A. S. Randi, Márcio H. F. Bettega, Nykola C. Jones, Søren V. Hoffmann, Małgorzata A. Śmiałek and Paulo Limão-Vieira
Molecules 2025, 30(15), 3137; https://doi.org/10.3390/molecules30153137 - 26 Jul 2025
Viewed by 262
Abstract
The valence-shell electronic state spectroscopy of β-butyrolactone (CH3CHCH2CO2) is comprehensively investigated by employing experimental and theoretical methods. We report a novel vacuum ultraviolet (VUV) absorption spectrum in the photon wavelength range from 115 to 320 nm (3.9–10.8 [...] Read more.
The valence-shell electronic state spectroscopy of β-butyrolactone (CH3CHCH2CO2) is comprehensively investigated by employing experimental and theoretical methods. We report a novel vacuum ultraviolet (VUV) absorption spectrum in the photon wavelength range from 115 to 320 nm (3.9–10.8 eV), together with ab initio quantum chemical calculations at the time-dependent density functional (TD-DFT) level of theory. The dominant electronic excitations are assigned to mixed valence-Rydberg and Rydberg transitions. The fine structure in the CH3CHCH2CO2 photoabsorption spectrum has been assigned to C=O stretching, v7a, CH2 wagging, v14a, C–O stretching, v22a, and C=O bending, v26a modes. Photolysis lifetimes in the Earth’s atmosphere from 0 km up to 50 km altitude have been estimated, showing to be a non-relevant sink mechanism compared to reactions with the OH radical. The nuclear dynamics along the C=O and C–C–C coordinates have been investigated at the TD-DFT level of theory, where, upon electronic excitation, the potential energy curves show important carbonyl bond breaking and ring opening, respectively. Within such an intricate molecular landscape, the higher-lying excited electronic states may keep their original Rydberg character or may undergo Rydberg-to-valence conversion, with vibronic coupling as an important mechanism contributing to the spectrum. Full article
(This article belongs to the Special Issue Advances in Density Functional Theory (DFT) Calculation)
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31 pages, 8352 KiB  
Article
Novel Trimethoprim-Based Metal Complexes and Nanoparticle Functionalization: Synthesis, Structural Analysis, and Anticancer Properties
by Abbas M. Abbas, Hossam H. Nasrallah, A. Aboelmagd, W. Christopher Boyd, Haitham Kalil and Adel S. Orabi
Inorganics 2025, 13(5), 144; https://doi.org/10.3390/inorganics13050144 - 1 May 2025
Viewed by 896
Abstract
In this study, we synthesized a novel trimethoprim derivative, 4-(((2-amino-5-(3,4,5-trimethoxybenzyl) pyrimidine-4-yl)imino)methyl)benzene-1,3-diol (HD), by the reaction of trimethoprim with 2,4-dihydroxybenzaldehyde. We then prepared metal complexes of this derivative with Cu(II), Co(II), Ni(II), Ag(I), and Zn(II) and functionalized them with ZnO and Au nanoparticles. Their [...] Read more.
In this study, we synthesized a novel trimethoprim derivative, 4-(((2-amino-5-(3,4,5-trimethoxybenzyl) pyrimidine-4-yl)imino)methyl)benzene-1,3-diol (HD), by the reaction of trimethoprim with 2,4-dihydroxybenzaldehyde. We then prepared metal complexes of this derivative with Cu(II), Co(II), Ni(II), Ag(I), and Zn(II) and functionalized them with ZnO and Au nanoparticles. Their structures were confirmed through 1H NMR, mass spectrometry, FTIR, conductivity, thermal analysis, magnetic susceptibility, X-ray diffraction, UV-Vis spectroscopy, and TEM, revealing octahedral geometries for all complexes. Surface features were investigated using density functional theory (DFT) analysis. Pharmacokinetic parameters and target enzymes for HD and its complexes were computed using the SwissADME web tool, with the BOILED-Egg model indicating that HD and its Cu complex should be passively permeable via the blood-brain barrier and highly absorbed by the gastrointestinal tract (GIT), unlike the Ni, Co, Ag, and Zn complexes, which are predicted to show low GIT absorption. Molecular docking studies with the Caspase-3 enzyme (PDB code: 3GJQ) using the AutoDock 4.2 software demonstrated binding energies of −7.66, −8.36, −9.05, −8.62, −6.90, and −7.81 kcal/mol for HD and the Cu, Co, Ni, Ag, and Zn complexes, respectively, compared to −6.54 and −4.63 kcal/mol for TMP and 5-FU (5-fluorouracil), indicating a potential superior anticancer potential of the novel compounds. The anticancer activities of these complexes were evaluated using the MTT assay. The IC50 values for 5-FU, TMP, HD, Cu-HD, HD@ZnONPs, Cu-HD@ZnONPs, HD@AuNPs, and Cu-HD@AuNPs were found to be 32.53, 80.76, 114.7, 61.66, 77, 53.13, 55.06, and 50.81 µg/mL, respectively. Notably, all derivatives exhibited higher activity against the HepG-2 cancer cell line than TMP, except for HD, which showed similar effectiveness to TMP. Real-time PCR analysis revealed that the Au-HD@AuNPs and Cu-HD@AuNPs significantly increased caspase-3 inhibition by 4.35- and 4.5-fold and P53 expression by 3.05- and 3.41-fold, respectively, indicating enhanced pro-apoptotic gene expression and apoptosis induction in HepG2 cells. Our findings demonstrate that these novel derivatives possess significant anticancer properties, with some complexes showing superior activity compared to standard drugs such as 5-Fluorouracil (5-FU) and Trimethoprim (TMP). This study highlights the potential of these nanocomposites as promising candidates for cancer therapy. Full article
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18 pages, 9250 KiB  
Article
Defect-Engineered Z-Scheme Heterojunction of Fe-MOFs/Bi2WO6 for Solar-Driven CO2 Conversion: Synergistic Surface Catalysis and Interfacial Charge Dynamics
by Ting Liu, Yun Wu, Hao Wang, Jichang Lu and Yongming Luo
Nanomaterials 2025, 15(8), 618; https://doi.org/10.3390/nano15080618 - 17 Apr 2025
Viewed by 653
Abstract
The urgent need for sustainable CO2 conversion technologies has driven the development of advanced photocatalysts that harness solar energy. This study employs a CTAB-assisted solvothermal method to fabricate a Z-scheme heterojunction Fe-MOFs/VO-Bi2WO6 (FM/VO-BWO) for photocatalytic [...] Read more.
The urgent need for sustainable CO2 conversion technologies has driven the development of advanced photocatalysts that harness solar energy. This study employs a CTAB-assisted solvothermal method to fabricate a Z-scheme heterojunction Fe-MOFs/VO-Bi2WO6 (FM/VO-BWO) for photocatalytic CO2 reduction. Positron annihilation lifetime spectroscopy (PALS) was employed to confirm the existence of oxygen vacancies, while spherical aberration-corrected transmission electron microscope (STEM) characterization verified the successful construction of heterointerfaces. X-ray absorption fine structure (XAFS) spectra confirmed that the defect configuration and heterostructure changed the surface chemical valence state. The optimized 1.0FM/VO-BWO composite demonstrated exceptional photocatalytic performance, achieving CO and CH4 yields of 60.48 and 4.3 μmol/g, respectively, under visible-light 11.8- and 1.5-fold enhancements over pristine Bi2WO6. The enhanced performance is attributed to oxygen vacancy-induced active sites facilitating CO₂ adsorption/activation. In situ molecular spectroscopy confirmed the formation of critical CO2-derived intermediates (COOH* and CHO*) through surface interactions involving four-coordinated and two-coordinated hydrogen-bonded water molecules. Furthermore, the accelerated interfacial charge transfer efficiency mediated by the Z-scheme heterojunction has been conclusively demonstrated. This work establishes a paradigm for defect-mediated heterojunction design, offering a sustainable route for solar fuel production. Full article
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9 pages, 2301 KiB  
Communication
Heteroleptic Cobalt Complexes with Catecholate and 1,4-Diaza-1,3-butadiene Ligands
by Irina V. Ershova, Maxim V. Arsenyev, Ilya A. Yakushev and Alexandr V. Piskunov
Molbank 2025, 2025(1), M1972; https://doi.org/10.3390/M1972 - 23 Feb 2025
Viewed by 741
Abstract
Two new heteroleptic cobalt(II) complexes (3,6-Cat)Co(R-DAD) (where (3,6-Cat)2− is a dianion of 3,6-di-tert-butyl-o-benzoquinone, R-DAD is diisopropyl-1,4-diaza-1,3-butadiene (R = i-Pr (1)) or dicyclohexyl-1,4-diaza-1,3-butadiene (R = c-Hex (2)) have been synthesized and characterized in [...] Read more.
Two new heteroleptic cobalt(II) complexes (3,6-Cat)Co(R-DAD) (where (3,6-Cat)2− is a dianion of 3,6-di-tert-butyl-o-benzoquinone, R-DAD is diisopropyl-1,4-diaza-1,3-butadiene (R = i-Pr (1)) or dicyclohexyl-1,4-diaza-1,3-butadiene (R = c-Hex (2)) have been synthesized and characterized in detail by IR, UV–Vis–NIR spectroscopy, and elemental analysis. The molecular structure of 1 was determined by X-ray diffraction analysis. Magnetic properties of 1 and 2 were measured both in a solid state and in a solution. According to the single-crystal X-ray diffraction analysis, the metal ion in 1 has a planar coordination environment, but magnetic susceptibility measurements of the microcrystalline samples of 1 and 2 indicate the formation of both forms with tetrahedral (d7, h.s., SCo = 3/2) and planar (d7, l.s., SCo = ½) coordination environments of the metal ion. Absorption spectra of crystalline samples of 1 and 2 possess intense absorption band in the NIR region. Electrochemical measurements of 1 and 2 were also performed. Full article
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20 pages, 3501 KiB  
Article
Development of a Comprehensive Approach to Quality Control of Dermorphin Derivative—Representative of Synthetic Opioid Peptides with Non-Narcotic Type of Analgesia
by Vasilisa A. Sukhanova, Elena V. Uspenskaya, Safdari Ainaz, Hoang Thi Ngoc Quynh and Aleksey A. Timofeev
Sci. Pharm. 2025, 93(1), 3; https://doi.org/10.3390/scipharm93010003 - 31 Dec 2024
Viewed by 1968
Abstract
Peptides occupy a significant share of the pharmaceutical market and are among the top-200 selling drugs in the group of non-insulin drugs with analgesic, antibacterial and cardiovascular effects. The aim of this work is to develop a comprehensive analytical approach for quality control [...] Read more.
Peptides occupy a significant share of the pharmaceutical market and are among the top-200 selling drugs in the group of non-insulin drugs with analgesic, antibacterial and cardiovascular effects. The aim of this work is to develop a comprehensive analytical approach for quality control of novel synthetic peptides with non-narcotic types of analgesia and to provide docking simulations of dermorphin complex formation at the μ-opioid receptor (MOR) binding site. The materials and methods used include the pharmaceutical substance dermorphin tetrapeptide (DMTP) (tyrosyl-D-arginyl-phenylalanyl-glycinamide); Fourier transform infrared spectroscopy (FT-IR); static and dynamic laser light scattering (DLS, LALLS); scanning optical microscopy (SEM); X-ray fluorescence elements analysis; polarimetry for optical activity determining; and Spirotox method for sample biotesting. FT-IR-Spectra indicated specific amino acid chemical groups in the tetrapeptide sequence at 3300–2700 cm−1, 1670 cm−1. UV-absorption spectra of aqueous solutions of dermorphin tetrapeptide showed an absorption maximum at 275 nm, which is in good agreement with the presented spectrum of the bovine serum albumin (BSA) standard; the Pearson’s r of calibration line “A-C%” in 0.0125% to 0.0500% concentration range is 0.999; and the calculated specific extinction value E1cm 1% = 18.38 ± 0.23. Of the 11 elements detected by X-rays, the elements copper (Cu) and cobalt (Co) have the highest X-ray intensity. Dispersion characteristics of dermorphin solutions were studied in the submicron and micron range. Conglomerates and druzes were detected by SEM, ranging in size from 2 µm to 100 µm. The specific optical activity index was calculated αD20 = +36.18 ± 2.04 [°·mL·g−1·dm−1], according to Biot’s Law. Additionally, the orientation and conformation of the dermorphin molecule in the active binding site of the 8E0G receptor were predicted using molecular modeling, revealing that the contact area affects the key amino acid residue arginine (ARG 182). This comprehensive approach to analytical methods for qualitative and quantitative analysis of dermorphin tetrapeptide can be applied in pharmacies to enhance the understanding of its biological activity and aid in the development of regulatory documentation for a new, non-narcotic analgesic based on the dermorphin tetrapeptide. Full article
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13 pages, 4291 KiB  
Article
Diffusion and Spectroscopy of H2 in Myoglobin
by Jiri Käser, Kai Töpfer and Markus Meuwly
Oxygen 2024, 4(4), 389-401; https://doi.org/10.3390/oxygen4040024 - 31 Oct 2024
Viewed by 1581
Abstract
The diffusional dynamics and vibrational spectroscopy of molecular hydrogen (H2) in myoglobin (Mb) is characterized. Hydrogen has been implicated in a number of physiologically relevant processes, including cellular aging or inflammation. Here, the internal diffusion through the protein matrix was characterized, [...] Read more.
The diffusional dynamics and vibrational spectroscopy of molecular hydrogen (H2) in myoglobin (Mb) is characterized. Hydrogen has been implicated in a number of physiologically relevant processes, including cellular aging or inflammation. Here, the internal diffusion through the protein matrix was characterized, and the vibrational spectroscopy was investigated using conventional empirical energy functions and improved models able to describe higher-order electrostatic moments of the ligand. Depending on the energy function used, H2 can occupy the same internal defects as already found for Xe or CO (Xe1 to Xe4 and B-state). Furthermore, four additional sites were found, some of which had been discovered in earlier simulation studies. Simulations using a model based on a Morse oscillator and distributed charges to correctly describe the molecular quadrupole moment of H2 indicate that the vibrational spectroscopy of the ligand depends on the docking site it occupies. This is consistent with the findings for CO in Mb from experiments and simulations. For H2, the maxima of the absorption spectra cover ∼20 cm−1 which are indicative of a pronounced Stark effect of the surrounding protein matrix on the vibrational spectroscopy of the ligand. Electronic structure calculations show that H2 forms a stable complex with the heme iron (stabilized by ∼−12 kcal/mol), but splitting of H2 is unlikely due to a high activation energy (∼50 kcal/mol). Full article
(This article belongs to the Special Issue Interaction of Oxygen and Other Gases with Haem Containing Proteins)
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12 pages, 4067 KiB  
Article
Binary Mixtures of Meloxicam and L-Tartaric Acid for Oral Bioavailability Modulation of Pharmaceutical Dosage Forms
by Cristina Macasoi, Viorica Meltzer, Ioana Stanculescu, Cosmin Romanitan and Elena Pincu
J. Funct. Biomater. 2024, 15(4), 104; https://doi.org/10.3390/jfb15040104 - 16 Apr 2024
Cited by 2 | Viewed by 2098
Abstract
Binary mixtures of active pharmaceutical ingredients (API) are researched to improve the oral bioavailability of pharmaceutical dosage forms. The purpose of this study was to obtain mixtures of meloxicam and L-tartaric acid because tartaric acid improves intestinal absorption and meloxicam is more soluble [...] Read more.
Binary mixtures of active pharmaceutical ingredients (API) are researched to improve the oral bioavailability of pharmaceutical dosage forms. The purpose of this study was to obtain mixtures of meloxicam and L-tartaric acid because tartaric acid improves intestinal absorption and meloxicam is more soluble in a weakly basic environment. The mixtures in the 0–1 molar fraction range, obtained from solvent-assisted mechanosynthesis, were investigated by differential scanning calorimetry (DSC), Fourier Transform Infrared (FTIR) spectroscopy, Fourier Transform Raman spectroscopy (FT-Raman), X-ray powder diffraction (XRD) and solubility tests. The physicochemical characteristics of the compounds obtained from DSC data reveal, for the first time, the formation of a co-crystal at meloxicam molar fraction of 0.5. FTIR spectroscopy data show the existence of hydrogen bonds between the co-crystal components meloxicam and L-tartaric acid. FT-Raman spectroscopy was used complementary with FT-IR spectroscopy to analyze the pure APIs and their mixtures, to emphasize the appearance/disappearance and the shifts of the position/intensity of vibrational bands, following the formation of hydrogen-bonded structures or van der Waals interactions, and to especially monitor the crystal lattice vibrations below 400 cm−1. The experimental results obtained by X-ray powder diffraction confirmed the formation of the co-crystal by the loss and, respectively, the apparition of peaks from the single components in the co-crystal diffractogram. The solubility tests showed that the co-crystal product has a lower aqueous solubility due to the acidic character of the other component, tartaric acid. However, when the solubility tests were performed in buffer solution of pH 7.4, the solubility of meloxicam from the co-crystal mixture was increased by 57% compared to that of pure meloxicam. In conclusion, the studied API mixtures may be considered potential biomaterials for improved drug release molecular solids. Full article
(This article belongs to the Special Issue Biomaterials for Translational Medicine)
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22 pages, 5950 KiB  
Article
Design, Synthesis, Anti-Inflammatory Activity, DFT Modeling and Docking Study of New Ibuprofen Derivatives
by Abbas M. Abbas, Hossam H. Nasrallah, Ahmed Aboelmagd, Safaa M. Kishk, W. Christopher Boyd, Haitham Kalil and Adel S. Orabi
Int. J. Mol. Sci. 2024, 25(6), 3558; https://doi.org/10.3390/ijms25063558 - 21 Mar 2024
Cited by 7 | Viewed by 3163
Abstract
A new ibuprofen derivative, (E)-2-(4-isobutylphenyl)-N′-(4-oxopentan-2-ylidene) propane hydrazide (IA), was synthesized, along with its metal complexes with Co, Cu, Ni, Gd, and Sm, to investigate their anti-inflammatory efficacy and COX-2 inhibition potential. Comprehensive characterization, including 1H NMR, MS, FTIR, UV–vis spectroscopy, [...] Read more.
A new ibuprofen derivative, (E)-2-(4-isobutylphenyl)-N′-(4-oxopentan-2-ylidene) propane hydrazide (IA), was synthesized, along with its metal complexes with Co, Cu, Ni, Gd, and Sm, to investigate their anti-inflammatory efficacy and COX-2 inhibition potential. Comprehensive characterization, including 1H NMR, MS, FTIR, UV–vis spectroscopy, and DFT analysis, were employed to determine the structural configurations, revealing unique motifs for Gd/Sm (capped square antiprismatic/tricapped trigonal prismatic) and Cu/Ni/Co (octahedral) complexes. Molecular docking with the COX-2 enzyme (PDB code: 5IKT) and pharmacokinetic assessments through SwissADME indicated that these compounds have superior binding energies and pharmacokinetic profiles, including BBB permeability and gastrointestinal absorption, compared to the traditional ibuprofen standalone. Their significantly lower IC50 values further suggest a higher efficacy as anti-inflammatory agents and COX-2 inhibitors. These research findings not only introduce promising ibuprofen derivatives for therapeutic applications but also set the stage for future validation and exploration of this new generation of ibuprofen compounds. Full article
(This article belongs to the Section Molecular Pharmacology)
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13 pages, 5691 KiB  
Article
Temperature-Dependent Vibrational Dynamics of Rutile (TiO2) from Molecular Dynamics Simulations and Two-Dimensional Correlation Analysis Techniques
by Ljupcho Pejov, Petre Makreski and Gligor Jovanovski
Minerals 2024, 14(2), 118; https://doi.org/10.3390/min14020118 - 23 Jan 2024
Cited by 1 | Viewed by 1421
Abstract
The vibrational dynamics of rutile (TiO2) as a function of temperature has been studied by combining molecular dynamics (MD) simulations in conjunction with the generalized two-dimensional correlation spectroscopy analysis (2D COS) technique. Molecular dynamics simulations within the microcanonical ensemble were performed [...] Read more.
The vibrational dynamics of rutile (TiO2) as a function of temperature has been studied by combining molecular dynamics (MD) simulations in conjunction with the generalized two-dimensional correlation spectroscopy analysis (2D COS) technique. Molecular dynamics simulations within the microcanonical ensemble were performed with the self-consistent charge density functional tight binding formalism at a series of different temperatures. To validate the DFTB MD results against the experimental data, the method of atomic pair distribution functions (PDFs) was used. IR absorption spectra were calculated implementing the time correlation function formalism. Subsequently, the generalized two-dimensional correlation approach was applied to obtain further insights into the temperature-dependent vibrational dynamics. The static DFTB calculations of the vibrational force field of the rutile reproduced excellently the experimental data and allowed for more exact assignments of the corresponding experimental IR/Raman spectral bands. Through the detailed analysis of the synchronous and asynchronous 2D spectra computed on the basis of MD-generated anharmonic spectra, we have provided new insights into the couplings between the modes in the studied system, as well as into the sequential character of the temperature-induced changes in the vibrational force field. The sensitivity of IR active modes to the temperature-induced perturbation of the system decreases in the order 685 cm−1Eu mode > 370 cm−1Eu mode > 982 cm−1A2u mode. The results presented in this study clearly demonstrate the usefulness of the combination of periodic SCC DFTB MD simulations coupled to the 2D COS analysis techniques in solid-state vibrational spectroscopy. Full article
(This article belongs to the Special Issue Vibrational Spectroscopy in Mineralogy and Archaeology)
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17 pages, 11129 KiB  
Article
Plasma-Deposited CoO–(Carbon Matrix) Thin-Film Nanocatalysts: The Impact of Nanoscale p-n Heterojunctions on Activity in CO2 Methanation
by Niloofar Mohammadpour, Hanna Kierzkowska-Pawlak, Jacek Balcerzak, Paweł Uznański and Jacek Tyczkowski
Catalysts 2024, 14(1), 38; https://doi.org/10.3390/catal14010038 - 4 Jan 2024
Cited by 4 | Viewed by 2307
Abstract
Addressing the challenges associated with the highly exothermic nature of CO2 methanation, there is considerable interest in innovative catalyst designs on structural metallic supports. One promising solution in this regard involves thin films containing cobalt oxide within a carbon matrix, fabricated using [...] Read more.
Addressing the challenges associated with the highly exothermic nature of CO2 methanation, there is considerable interest in innovative catalyst designs on structural metallic supports. One promising solution in this regard involves thin films containing cobalt oxide within a carbon matrix, fabricated using the cold plasma deposition method (PECVD). The objective of this study was to search for a relationship between the molecular structure, nanostructure, and electronic structure of such films and their catalytic activity. The investigations employed various techniques, including X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), X-ray diffraction (XRD), UV-VIS absorption, and catalytic tests in the CO2 methanation process. Three types of films were tested: untreated as-deposited (ad-CoO), thermally post-treated (TT-CoO), and argon plasma post-treated (PT-CoO) films. Among these, TT-CoO exhibited the most favorable catalytic properties, demonstrating a CO2 conversion rate of 83%, CH4 selectivity of 98% at 400 °C, and stability during the catalytic process. This superior performance was attributed to the formation of nanoscale heterojunctions in the TT-CoO film, where p-type CoO nanocrystallites interacted with the n-type carbon matrix. This work provides compelling evidence highlighting the key role of nanoscale heterojunctions in shaping the properties of nanocatalysts in thermal catalysis. These findings suggest promising prospects for designing new catalytic systems by manipulating interactions at the nanoscale. Full article
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18 pages, 8432 KiB  
Article
Cheminformatics-Based Design and Synthesis of Hydroxyapatite/Collagen Nanocomposites for Biomedical Applications
by Mohamed Aaddouz, Khalil Azzaoui, Rachid Sabbahi, Moulay Hfid Youssoufi, Meryem Idrissi Yahyaoui, Abdeslam Asehraou, Mohamed El Miz, Belkheir Hammouti, Sergey Shityakov, Mohamed Siaj and Elmiloud Mejdoubi
Polymers 2024, 16(1), 85; https://doi.org/10.3390/polym16010085 - 27 Dec 2023
Cited by 7 | Viewed by 2550
Abstract
This paper presents a novel cheminformatics approach for the design and synthesis of hydroxyapatite/collagen nanocomposites, which have potential biomedical applications in tissue engineering, drug delivery, and orthopedic and dental implants. The nanocomposites are synthesized by the co-precipitation method with different ratios of hydroxyapatite [...] Read more.
This paper presents a novel cheminformatics approach for the design and synthesis of hydroxyapatite/collagen nanocomposites, which have potential biomedical applications in tissue engineering, drug delivery, and orthopedic and dental implants. The nanocomposites are synthesized by the co-precipitation method with different ratios of hydroxyapatite and collagen. Their mechanical, biological, and degradation properties are analyzed using various experimental and computational techniques. Attenuated total reflection–Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction unveil the low crystallinity and nanoscale particle size of hydroxyapatite (22.62 nm) and hydroxyapatite/collagen composites (14.81 nm). These findings are substantiated by scanning electron microscopy with energy-dispersive X-ray spectroscopy, confirming the Ca/P ratio between 1.65 and 1.53 and attesting to the formation of non-stoichiometric apatites in all samples, further validated by molecular simulation. The antimicrobial activity of the nanocomposites is evaluated in vitro against several bacterial and fungal strains, demonstrating their medical potential. Additionally, in silico analyses are performed to predict the absorption, distribution, metabolism, and excretion properties and the bioavailability of the collagen samples. This study paves the way for the development of novel biomaterials using chemoinformatics tools and methods, facilitating the optimization of design and synthesis parameters, as well as the prediction of biological outcomes. Future research directions should encompass the investigation of in vivo biocompatibility and bioactivity of the nanocomposites, while exploring further applications and functionalities of these innovative materials. Full article
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17 pages, 5217 KiB  
Article
Effects of Graphene Oxide (GO) and Reduced Graphene Oxide (rGO) on Green-Emitting Conjugated Copolymer’s Optical and Laser Properties Using Simulation and Experimental Studies
by Saradh Prasad, Raya H. Alhandel, Nassar N. Asemi and Mohamad S. AlSalhi
Polymers 2023, 15(23), 4572; https://doi.org/10.3390/polym15234572 - 29 Nov 2023
Cited by 5 | Viewed by 2002
Abstract
The properties of a conjugated copolymer (CP), poly[(9,9-Dioctyl-2,7-divinylenefluorenylene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene) (PDVF-co-MEH-PV), were investigated in the presence of graphene oxide (GO) and reduced graphene oxide (rGO) using absorption, fluorescence, laser, and time-resolved spectroscopy. CPs are usually dissolved in low-polar solvents. Although GO does not dissolve well, [...] Read more.
The properties of a conjugated copolymer (CP), poly[(9,9-Dioctyl-2,7-divinylenefluorenylene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene) (PDVF-co-MEH-PV), were investigated in the presence of graphene oxide (GO) and reduced graphene oxide (rGO) using absorption, fluorescence, laser, and time-resolved spectroscopy. CPs are usually dissolved in low-polar solvents. Although GO does not dissolve well, rGO and PDVF-co-MEH-PV dissolve in chloroform due to their oxygen acceptor sites. Hence, we studied rGO/PDVF-co-MEH-PV (CP/rGO), performing all experiments and simulations in chloroform. We performed simulations on PDVF-co-MEH-PV, approximate GO, and rGO using time-dependent density-functional theory calculations to comprehend the molecular dynamics and interactions at the molecular level. The simulation polymer used a tail-truncated oligomer model with up to three monomer units. The simulation and experimental results were in agreement. Further, the PDVF-co-MEH-PV exhibited fluorescence, laser quenching, rGO-mediated laser blinking, and spectral broadening effects when GO and rGO concentrations increased. The experimental and simulation results were compared to provide a plausible mechanism of interaction between PDVF-co-MEH-PV and rGO. We observed that for lower concentrations of rGO, the interaction did not considerably decrease the amplified spontaneous emissions of PDVF-co-MEH-PV. However, the fluorescence of PDVF-co-MEH-PV was considerably quenched at higher concentrations of rGO. These results could be helpful for future applications, such as in sensors, solar cells, and optoelectronic device design. To demonstrate the sensor capability of these composites, a paper-based sensor was designed to detect ethanol and nitrotoluene. An instrumentation setup was proposed that is cheap, reusable, and multifunctional. Full article
(This article belongs to the Special Issue Novel Copolymers: Preparation, Characterization, and Applications)
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17 pages, 6694 KiB  
Article
The Effect of Temperature on Molecular Structure of Medium-Rank Coal via Fourier Transform Infrared Spectroscopy
by Meng Wu, Yong Qin, Yunhu Qin, Naicen Xu and Lele Feng
Materials 2023, 16(20), 6746; https://doi.org/10.3390/ma16206746 - 18 Oct 2023
Cited by 3 | Viewed by 1880
Abstract
Fourier transform infrared spectroscopy (FTIR) was used to study the molecular structure of four medium- and low-temperature heat-treated medium-rank coals. The FTIR spectral parameters, which consist of CH2/CH3, aromaticity (fa), aromatic carbon rate (fC [...] Read more.
Fourier transform infrared spectroscopy (FTIR) was used to study the molecular structure of four medium- and low-temperature heat-treated medium-rank coals. The FTIR spectral parameters, which consist of CH2/CH3, aromaticity (fa), aromatic carbon rate (fC), aromatic hydrogen rate (fH), oxygen-containing (C–O) rate (IR), organic matter maturity (M), and the degree of aromatic condensation (Dc), indicate different characteristics, including changes in the aromatic hydrocarbon structure, fatty hydrocarbon structure, hydroxyl structure, and oxygen-containing functional groups of medium-rank coal. The results show that with the increase in heat treatment temperature, the sulfur content in coal gradually decreases, but the C/H ratio gradually increases. Meanwhile, the content of kaolinite and pyrite in coal gradually decreases, whereas the content of dolomite and hematite gradually increases. With the increase in heat treatment temperature, the relative content of ether oxygen hydroxyl groups in the hydroxyl structure significantly decreases, but the relative content of self-associated hydroxyl groups increases. The relative content of alkyl ether (C–O) in oxygen-containing functional groups gradually increases, whereas the relative content of aromatic nucleus C=C vibration presents a trend of first increasing and then decreasing. In addition, –CH2– is the majority in the structure of fatty hydrocarbons, and the absorption peak intensity of asymmetric –CH3 stretching vibration increases with the increase in heat-treated temperature. The structure of aromatic hydrocarbons mainly consists of four substituted benzene rings (except for R-303.15 K), in which the relative content of the trisubstituted benzene ring decreases with the increase in heat treatment temperature. With the increase in the heat-treated temperature of medium-rank coal, Dc, fH, fC, and fa show a trend of first increasing and then decreasing, M and IR reveal a trend of first decreasing and then increasing, and CH2/CH3 present a gradually decreasing trend. In conclusion, during the increase in the heat treatment temperature of medium-rank coal, the length of the fatty side chains in the fatty hydrocarbon structure becomes shorter, the number of branch chains continuously increases, and the maturity and condensation degree of organic matter first increases and then decreases. On this basis, further research on the effect of coal gasification suggests combining various technologies such as 13C NMR, XRD, and TG-MS to obtain semi-quantitative structural information of molecules in coal from different perspectives. Full article
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12 pages, 10025 KiB  
Article
CO Oxidation Catalyzed by Au Dispersed on SBA-15 Modified with TiO2 Films Grown via Atomic Layer Deposition (ALD)
by Xiangdong Qin, Wang Ke, Yovanny Vazquez, Ilkeun Lee and Francisco Zaera
Catalysts 2023, 13(7), 1106; https://doi.org/10.3390/catal13071106 - 15 Jul 2023
Cited by 5 | Viewed by 1939
Abstract
It has been established that gold, when in nanoparticle (NP) form and in contact with reducible oxides, can promote oxidation reactions under mild conditions. Here, we report results from our exploration of the catalytic oxidation of carbon monoxide using catalysts where Au NPs [...] Read more.
It has been established that gold, when in nanoparticle (NP) form and in contact with reducible oxides, can promote oxidation reactions under mild conditions. Here, we report results from our exploration of the catalytic oxidation of carbon monoxide using catalysts where Au NPs were combined with thin titanium oxide films deposited on SBA-15 using atomic layer deposition (ALD). Both orders of deposition, with TiO2 added either before or after Au dispersion, were tested for two titania film thicknesses amounting to about half and full TiO2 monolayers. The resulting catalysts were characterized using various techniques, mainly electron microscopy and N2 adsorption–desorption isotherms, and the kinetics of the oxidation of CO with O2 were followed using infrared absorption spectroscopy. A synergy between the Au and TiO2 phases as it relates to the bonding and conversion of CO was identified, the tuning of which could be controlled by varying the synthetic parameters. The ALD of TiO2 films proved to be an effective way to maximize the Au-TiO2 interface sites, and with that help with the activation of molecular oxygen. Full article
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17 pages, 5122 KiB  
Article
Photoelectrocatalytic Dioxygen Reduction Based on a Novel Thiophene-Functionalized Tricarbonylchloro(1,10-phenanthroline)rhenium(I)
by Yu-Qin Li and Ke-Zhi Wang
Molecules 2023, 28(7), 3229; https://doi.org/10.3390/molecules28073229 - 4 Apr 2023
Cited by 1 | Viewed by 2235
Abstract
A novel Re (I) complex of [Re(CO)3Cl(L)], {L = 2-([2,2’-bithiophen]-5-yl)-1-phenyl-1H-imidazo [4,5-f][1,10]phenanthroline}, was synthesized, and its optical (UV–Visible absorption and emission spectroscopy), cyclovoltammetric and photoelectrochemical oxygen reduction properties were studied. The geometric and electronic properties were also investigated [...] Read more.
A novel Re (I) complex of [Re(CO)3Cl(L)], {L = 2-([2,2’-bithiophen]-5-yl)-1-phenyl-1H-imidazo [4,5-f][1,10]phenanthroline}, was synthesized, and its optical (UV–Visible absorption and emission spectroscopy), cyclovoltammetric and photoelectrochemical oxygen reduction properties were studied. The geometric and electronic properties were also investigated by density functional theory calculations. It was found that the ITO electrode coated with drop-casted [Re(CO)3Cl(L)] film exhibited cathodic photocurrent generation characteristics. The illuminated film exhibited a maximum cathodic photocurrent up to 30.4 μA/cm2 with an illumination intensity of 100 mW/cm2 white light at a bias potential of −0.4 V vs. SCE in O2-saturated electrolyte solution, which was reduced by 5.1-fold when thoroughly deoxygenated electrolyte solution was used, signaling that the electrode performed well on the photoelectrochemical oxygen reduction. The photo-electrocatalytic hydrogen peroxide production was proved with a maximum H2O2 concentration of 6.39 μM during 5 h of the photoelectrocatalytic process. This work would guide the construction of more efficient rhenium-based photo(electro)catalytic molecular systems for O2 sensing, hydrogen peroxide production and other types of photoelectrochemical energy conversion and storage. Full article
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