Structural investigation of the cocrystal formed between 5-fluorocytosine and fumaric acid based on vibrational spectroscopic technique

Du, Yong; Cai, Qiang; Xue, Jingling; Zhang, Qi; Qin, Dan

doi:10.1016/j.saa.2017.02.004

Cited by 28 publications

(18 citation statements)

References 24 publications

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“…20 Its molecular structure contains a conjugated maleyl group and a carbonyl group at both ends of the double bond. 21 As a result, it is very active in chemical properties. In addition, fumaric acid has the advantages of nontoxic and low cost so that it is widely used in food, coatings, resins, plasticizers, and other fields.…”

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Thermal degradation and flame retardancy of fumaric acid in thermoplastic polyurethane elastomer

Wei

Chen

Jiao

2018

Polymers for Advanced Techs

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In this paper, fumaric acid (FA) which was a new type of environmental and low-cost flame retardant was applied for thermoplastic polyurethane elastomer (TPU). The flame-retardant properties of TPU were tested using limiting oxygen index, cone calorimeter test, smoke density test, and thermogravimetric/Fourier transform infrared spectroscopy. It has been proved that FA could improve the difficulty of the ignition of the sample; the limiting oxygen index value of the sample (FA-4) increased by 29.7% when 2.0 wt% FA was added to TPU. The cone calorimeter test showed that FA can greatly reduce heat release and smoke production during the combustion process of TPU composites. For example, compared with the pure TPU, the peak heat release rate and total smoke release of the sample (FA-4) with 2.0 wt% FA were decreased by 50.8% and 51.5% respectively. The results of smoke density test showed that the luminous flux of the samples contained 0.5 wt% FA was increased by 79.2% compared with the pure TPU. The TG results revealed that the sample of FA-4 had higher char residue content compared with the sample of TPU. The results of thermogravimetric/Fourier transform infrared spectroscopy proved that FA could decrease the initial decomposition temperature for TPU composites and increase the release of CO 2 and H 2 O. All results of test illustrated that FA had good flameretardant effect on TPU. KEYWORDS environmental, flame retardant, fumaric acid, thermoplastic polyurethane elastomer 1 | INTRODUCTIONThermoplastic polyurethane elastomer (TPU) is a polymer formed by the copolymerization of diisocyanate and polyol, which is an elastic material between rubber and plastic. 1 Thermoplastic polyurethane elastomer has good prospects for development in daily life because of its superior performance, such as high wear resistance, high strength, high elasticity, and good hydrolysis stability. 2 However, as a combustible material, during the combustion process, TPU can produce a lot of smoke, heat, and poisonous gas, which easily cause the suffocation and even death of the personnel, and it has a serious droplet phenomenon, which limits its application in some fields. 3 Therefore, it is very important to improve the flame retardancy of TPU. [4][5][6][7] At present, the traditional flame retardants used for TPU include halogen flame retardants, phosphorus flame retardants, etc. 8,9 Halogen flame retardants are more popular in flame-retardant TPU because of the high flame-retardant efficiency, moderate price, and variety.However, halogen flame retardants will release corrosive gases such as halogenated hydrogen and a large amount of smoke under high temperature or open fire, which will bring great harm to the human body and the environment. 10 The phosphorus flame retardant has the characteristics of halogen-free and low toxicity, but it needs a high amount of addition, which has an effect on the mechanical properties of the materials. 11,12 As a result, the elongation at break of the composite system, especially the impact strength, will...

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Thermal degradation and flame retardancy of fumaric acid in thermoplastic polyurethane elastomer

Wei

Chen

Jiao

2018

Polymers for Advanced Techs

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“…In particular, it has potential applications in the pharmaceutical field for the analysis of crystalline compounds throughout the pharmaceutical development and research processes [22]. With the help of THz spectroscopic technology, it is possible to directly detect and differentiate different solid-state forms of APIs and their corresponding co-crystals, and to exploit structural change information for such specific pharmaceutical co-crystals whose crystal structures are stabilized by weak inter- and/or intra-molecular interactions between APIs and various CCFs [24,25].…”

Section: Resultsmentioning

confidence: 99%

“…Du et al [22] investigated the structure and dynamic formation process of the NF-4-aminobenzoic acid co-crystal with typical vibrational spectroscopy, and the results indicated that the spectroscopic techniques could offer an attractive experimental method to identify and characterize pharmaceutical co-crystal formation and its dynamic process. Vibrational spectroscopic techniques include mid-infrared, Raman and terahertz (THz) spectroscopy, which have already been successfully used to explain co-crystallization of different solid-state pharmaceuticals [23,24,25,26].…”

Section: Introductionmentioning

confidence: 99%

Co-Crystal Formation of Antibiotic Nitrofurantoin Drug and Melamine Co-Former Based on a Vibrational Spectroscopic Study

et al. 2019

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The co-crystallization of active pharmaceutical ingredients (APIs) has received increasing attention due to the modulation of the relative physicochemical properties of APIs such as low solubility, weak permeability and relatively inferior oral bioavailability. Crystal engineering plays a decisive role in the systematic design and synthesis of co-crystals by means of exerting control on the inter-molecular interactions. The characterization and detection of such co-crystal formations plays an essential role in the field of pharmaceutical research and development. In this work, nitrofurantoin (NF), melamine (MELA) and their hydrated co-crystal form were characterized and analyzed by using terahertz time-domain spectroscopy (THz-TDS) and Raman vibrational spectroscopy. According to the experimental THz spectra, the hydrated co-crystal form has characteristic absorption peaks at 0.67, 1.05, 1.50 and 1.73 THz, while the THz spectra for the two raw parent materials (NF and MELA) are quite different within this spectral region. Similar observations were made from the experimental Raman vibrational spectra results. Density functional theory (DFT) calculation was performed to help determine the major vibrational modes of the hydrated co-crystal between nitrofurantoin and melamine, as well as identify the structural changes due to inter- and/or intra-molecular hydrogen bonding motifs between NF and MELA. The results of the theoretical frequency calculations corroborate the THz and Raman experimental spectra. The characteristic bands of the NF–MELA-hydrated co-crystal between nitrofurantoin and melamine were also determined based on the DFT simulated calculation. The reported results in this work provide us with a wealth of structural information and a unique vibrational spectroscopic method for characterizing the composition of specific co-crystals and inter-molecular hydrogen bonding interactions upon pharmaceutical co-crystallization.

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“…Meanwhile, the emerging terahertz time-domain spectroscopy (THz-TDS) is pretty sensitive to the weak inter-molecular interactions, skeleton-vibration for materials, and also dipole transitions within low-frequency vibrational regions. What is more, THz spectroscopy has become a potential method to analyze pharmaceutical cocrystals both non-invasively and non-destructively as well as investigate the collective vibrations and the whole structural interactions shown within various materials [19,20]. Combining Raman with THz spectroscopy together, Du et al [20] investigated molecular structures of the cocrystal formed between 5-fluorocytosine and fumaric acid, and also analyzed the hydrogen bonding effects during the forming of such a solid-state pharmaceutical cocrystallization process.…”

Section: Introductionmentioning

confidence: 99%

Pharmaceutical Cocrystal Formation of Pyrazinamide with 3-Hydroxybenzoic Acid: A Terahertz and Raman Vibrational Spectroscopies Study

et al. 2019

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Vibrational modes of pyrazinamide (PZA), 3-hydroxybenzoic acid (3-hBA), and their cocrystal were characterized using terahertz time-domain (THz-TDS) and Raman vibrational spectroscopic techniques. In experimental THz spectra, the cocrystal has characteristic absorption bands at around 0.81, 1.47, and 1.61 THz, respectively, meanwhile the raw materials are absolutely different in this region. Raman spectra also show similar results about differences between the cocrystal and corresponding starting parent materials. Density functional theory (DFT) was used to simulate both optimized structures and vibrational modes of the cocrystal formed between PZA and 3-hBA. The vibrational modes of such cocrystal are assigned through comparing the simulation DFT frequency results with experimental vibrational spectra. The calculation of the theoretical THz spectrum shows that the hydrogen bonding effect established between H11–N12–H13 and the carboxyl group -COOH makes contributions to the formation of absorption peaks in 0.49, 0.62, 0.83, and 1.61 THz, which agrees pretty well with experimental results. The theoretical Raman result also matches well with experimental observations. The results provide a fundamental benchmark for the study of pharmaceutical cocrystal formation and also inter-molecular hydrogen bonding interactions between active pharmaceutical ingredients and various cocrystal coformers based on Raman and terahertz vibrational spectroscopic techniques combined with theoretical simulations.

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Structural investigation of the cocrystal formed between 5-fluorocytosine and fumaric acid based on vibrational spectroscopic technique

Cited by 28 publications

References 24 publications

Thermal degradation and flame retardancy of fumaric acid in thermoplastic polyurethane elastomer

Thermal degradation and flame retardancy of fumaric acid in thermoplastic polyurethane elastomer

Co-Crystal Formation of Antibiotic Nitrofurantoin Drug and Melamine Co-Former Based on a Vibrational Spectroscopic Study

Pharmaceutical Cocrystal Formation of Pyrazinamide with 3-Hydroxybenzoic Acid: A Terahertz and Raman Vibrational Spectroscopies Study

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