01655nas a2200277 4500008004100000022001400041245015600055210006900211260000900280300001400289490000600303520071700309653001901026653000901045653001101054653002401065653001801089653001901107653002001126100002301146700002001169700002301189700001501212700002401227856012601251 2020 eng d a2574-096200aPhotocatalytic hydrogen generation and CO2 conversion using g-C3N4 decorated dendritic fibrous nanosilica: role of interfaces between silica and g-C3N40 aPhotocatalytic hydrogen generation and CO2 conversion using gC3N cSEP  a8150-81580 v33 a

We have synthesized g-C3N4 decorated over dendritic fibrous nanosilica (DFNS). The generation of C-N-Si interfaces by coating each fiber of DFNS with g-C3N4 not only provided high surface area but also affected the optical and electronic properties of the composite. The catalyst synthesis reproducibility issue of g-C3N4 was resolved using a vacuum-sealed quartz tube. The extended light absorption in the visible region, enhanced lifetime of photogenerated charge carriers due to the formation of interfaces between silica and g-C3N4 (confirmed by solid-state NMR), and increased surface area result in the improved photocatalytic activity of DFNS/g-C(3)N(4)for hydrogen generation and CO2 conversion.

10aCO2 conversion10aDFNS10ag-C3N410aHydrogen generation10ananocatalysts10aphotocatalysts10aSolid-state NMR1 aRawool, Sushma, A.1 aSamanta, Anupam1 aAjithkumar, T., G.1 aKar, Yusuf1 aPolshettiwar, Vivek uhttps://library.ncl.res.in/content/photocatalytic-hydrogen-generation-and-co2-conversion-using-g-c3n4-decorated-dendritic02819nas a2200241 4500008004100000022001400041245009100055210006900146260000900215300001400224490000700238520200900245653002302254653003102277653002302308653001702331653002002348100002702368700002202395700002002417700002302437856011702460 2024 eng d a1543-838400aIn situ monitoring of competitive coformer exchange reaction by 1H MAS solid-state NMR0 aIn situ monitoring of competitive coformer exchange reaction by  cFEB  a1479-14890 v213 a

In a competitive coformer exchange reaction, a recent topic of interest in pharmaceutical research, the coformer in a pharmaceutical cocrystal is exchanged with another coformer that is expected to form a cocrystal that is more stable. There will be a competition between coformers to form the most stable product through the formation of hydrogen bonds. This will cause destabilization of the pharmaceutical products during processing or storage. Therefore, it is important to develop a mechanistic understanding of this transformation by monitoring each and every step of the reaction, employing a technique such as H-1 nuclear magnetic resonance (NMR). In this study, an in situ monitoring of a coformer exchange reaction is carried out by H-1 magic angle spinning (MAS) solid-state NMR (SSNMR) at a spinning frequency of 60 kHz. The changes in caffeine maleic acid cocrystals on addition of glutaric acid and caffeine glutaric cocrystals on addition of maleic acid were monitored. In all of the reactions, it has been observed that caffeine glutaric acid Form I is formed. When glutaric acid was added to 2:1 caffeine maleic acid, the formation of metastable 1:1 caffeine glutaric acid Form I was observed at the start of the experiment, indicating that the centrifugal pressure is enough for the formation. The difference in the end product of the reactions with a similar reaction pathway of 1:1 and 2:1 reactant stoichiometry indicates that a complete replacement of maleic acid has occurred only in the 1:1 stoichiometry of the reactants. The polymorphic transition of caffeine glutaric acid Form II to Form I at higher temperatures was a crucial reason that triggered the exchange of glutaric acid with maleic acid in the reaction of caffeine glutaric acid and maleic acid. Our results are novel since the new reaction pathways in competitive coformer exchange reactions enabled understanding the remarkable role of stoichiometry, polymorphism, temperature, and centrifugal pressure.

10acaffeine cocrystal10acoformer exchange reaction10ain situ monitoring10apolymorphism10aSolid-state NMR1 aHareendran, Chaithanya1 aAlsirawan, Bashir1 aParadkar, Anant1 aAjithkumar, T., G. uhttps://library.ncl.res.in/content/situ-monitoring-competitive-coformer-exchange-reaction-1h-mas-solid-state-nmr01833nas a2200217 4500008004100000022001400041245012700055210006900182260000900251300001400260490000700274520106100281653000901342653002001351653002701371653001601398653002001414100002701434700002301461856013101484 2025 eng d a1543-838400aProbing the effect of fluorine on hydrogen bonding interactions in a pharmaceutical hydrate using Advanced Solid-State NMR0 aProbing the effect of fluorine on hydrogen bonding interactions  cMAR  a1869-18800 v223 a

Structural studies of pharmaceutical hydrates are essential to understanding stability-related issues, especially during the heating process of formulation. A thorough understanding of the hydration and dehydration behavior of active pharmaceutical ingredient (API) hydrate is also important since phase transitions can occur during the formulation process. This is because dehydration could result in a considerable rearrangement in the structure if water-API hydrogen bonding is present. We perform advanced solid-state NMR experiments on regorafenib monohydrate to investigate the role of fluorine in hydrogen bonding interaction, and the results are compared to its anhydrous form and its structural analogue, namely, sorafenib. Our results show that significant structural changes could not be observed on dehydration. Based on our study, it can be concluded that the introduction of fluorine restricts the intramolecular hydrogen bonding and the asymmetry in the structure of regorafenib monohydrate is absent, in comparison to sorafenib.

10aDQSQ10aHydrogenbonding10apharmaceutical hydrate10aregorafenib10aSolid-state NMR1 aHareendran, Chaithanya1 aAjithkumar, T., G. uhttps://library.ncl.res.in/content/probing-effect-fluorine-hydrogen-bonding-interactions-pharmaceutical-hydrate-using-advanced