In Situ Monitoring of Crystalline Transformation of Carbamazepine Using Probe-Type Low-Frequency Raman Spectroscopy

Inoue, Motoki; Hisada, Hiroshi; Koide, Tatsuo; Carriere, James; Heyler, Randy; Fukami, Toshiro

doi:10.1021/acs.oprd.6b00329

Cited by 38 publications

(36 citation statements)

References 26 publications

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“…Long-range order induces AVM enhancement thus revealing otherwise hidden LFRS modes. [21,22] AVMs of Sb2Se3 have been extensively studied using DFT-based theoretical models. Figure 4b represents the LFRS spectrum of the Sb2Se3 samples before and after sulfur treatment.…”

Section: Resultsmentioning

confidence: 99%

Unravelling Defect Passivation Mechanisms in Sulfur-treated Sb2Se3

Prabhakar¹,

Moehl²,

Friedrich³

et al. 2021

Preprint

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Sb2Se3 has emerged as an important photoelectrochemical (PEC) and photovoltaic (PV) material due to its rapid rise in photoconversion efficiencies. However, despite its binary nature, Sb2Se3 has a complex defect chemistry, which reduces the maximum photovoltage that can be obtained. Thus, it is important to understand these defects and to develop passivation strategies in order to further improve this material. In this work, a comprehensive investigation of the charge carrier dynamics of Sb2Se3 and the influence of sulfur treatment on its optoelectronic properties was performed using time resolved microwave conductivity (TRMC), photoluminescence (PL) spectroscopy and low frequency Raman spectroscopy (LFRS). The key finding in this work is that upon sulfur treatment of Sb2Se3, the carrier lifetime is increased by the passivation of deep defects in Sb2Se3 in both the surface region and the bulk, which is evidenced by increased charge carrier lifetime of TRMC decay dynamics, increased radiative recombination efficiency and decreased deep defect level emission (PL), and improved long-range order in the material (LFRS). These findings provide crucial insights into the defect passivation mechanisms in Sb2Se3 paving the way for developing highly efficient PEC and PV devices.

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Section: Resultsmentioning

confidence: 99%

Unravelling Defect Passivation Mechanisms in Sulfur-treated Sb2Se3

Prabhakar¹,

Moehl²,

Friedrich³

et al. 2021

Preprint

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“…The present study shows the capabilities of LFRS for identifying and quantitatively determining crystalline polymorph, directly and rapidly within solid dispersions. It is now recognized that LFRS can be used for the polymorph characterization of APIs 27,28 . We have previously developed a direct method based on LFRS measurements providing very fast and accurate quantification of crystalline fraction along isothermal and non-isothermal devitrification processes 22,29 .…”

Section: Discussionmentioning

confidence: 99%

Contribution of low-frequency Raman spectroscopy to determine the solubility curves of drugs in polymers: The case of paracetamol/PVP

Latreche

willart

Paccou

et al. 2020

European Journal of Pharmaceutics and Biopharmaceutics

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A new method for determining solubility lines of drugs in polymers, based on low-frequency Raman spectroscopy measurements, is described and the results obtained by this method are compared with those obtained using a more classical method based on differential scanning calorimetry investigations. This method was applied to the paracetamol / PVP system using molecular and crystalline dispersions (MCD) rather than usual physical mixtures to reach faster the equilibrium saturated states and make the determination of the solubility line more rapid.

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“…In addition to the characterization techniques discussed above, some of the well-advanced techniques such as pair-distribution function PXRD [ 224 ], Terahertz (THz) spectroscopic imaging [ 225 ], Probe-Type Low-Frequency Raman Spectroscopy [ 226 ], combined near IR and Raman spectroscopies [ 227 ], in situ Raman spectroscopy, in situthermomicroscopy [ 192 ], calorimetric analysis [ 192 ] and PAT [ 75 ] are being used widely by many researchers nowadays in order to understand the phase transition events that possibly occur during a cocrystallization process.…”

Section: Characterization Of Cocrystalsmentioning

confidence: 99%

Engineering Cocrystals of Poorly Water-Soluble Drugs to Enhance Dissolution in Aqueous Medium

2018

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Biopharmaceutics Classification System (BCS) Class II and IV drugs suffer from poor aqueous solubility and hence low bioavailability. Most of these drugs are hydrophobic and cannot be developed into a pharmaceutical formulation due to their poor aqueous solubility. One of the ways to enhance the aqueous solubility of poorlywater-soluble drugs is to use the principles of crystal engineering to formulate cocrystals of these molecules with water-soluble molecules (which are generally called coformers). Many researchers have shown that the cocrystals significantly enhance the aqueous solubility of poorly water-soluble drugs. In this review, we present a consolidated account of reports available in the literature related to the cocrystallization of poorly water-soluble drugs. The current practice to formulate new drug cocrystals with enhanced solubility involves a lot of empiricism. Therefore, in this work, attempts have been made to understand a general framework involved in successful (and unsuccessful) cocrystallization events which can yield different solid forms such as cocrystals, cocrystal polymorphs, cocrystal hydrates/solvates, salts, coamorphous solids, eutectics and solid solutions. The rationale behind screening suitable coformers for cocrystallization has been explained based on the rules of five i.e., hydrogen bonding, halogen bonding (and in general non-covalent bonding), length of carbon chain, molecular recognition points and coformer aqueous solubility. Different techniques to screen coformers for effective cocrystallization and methods to synthesize cocrystals have been discussed. Recent advances in technologies for continuous and solvent-free production of cocrystals have also been discussed. Furthermore, mechanisms involved in solubilization of these solid forms and the parameters influencing dissolution and stability of specific solid forms have been discussed. Overall, this review provides a consolidated account of the rationale for design of cocrystals, past efforts, recent developments and future perspectives for cocrystallization research which will be extremely useful for researchers working in pharmaceutical formulation development.

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In Situ Monitoring of Crystalline Transformation of Carbamazepine Using Probe-Type Low-Frequency Raman Spectroscopy

Cited by 38 publications

References 26 publications

Unravelling Defect Passivation Mechanisms in Sulfur-treated Sb2Se3

Unravelling Defect Passivation Mechanisms in Sulfur-treated Sb2Se3

Contribution of low-frequency Raman spectroscopy to determine the solubility curves of drugs in polymers: The case of paracetamol/PVP

Engineering Cocrystals of Poorly Water-Soluble Drugs to Enhance Dissolution in Aqueous Medium

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