Unveiling the Noncovalent Interaction of Thiazol-2-ylidene and Its Derivatives as N-heterocyclic Carbene with Different Proton Donor Molecules

The importance of noncovalent interaction has gained attention in various domains covering drug and novel catalyst design. The present study mainly characterizes the role of hydrogen bond (H-bond) and other intermolecular interactions in different (1 : 1) complex analogues formed between the N-aryl-thiazol-2-ylidene (YR) and five proton donor (HX) molecules. The analysis of the singlet-triplet energy gap ( ) confirmed the stability of the singlet state for this class of N-aryl-thiazol-2-ylidenes than the triplet state. The interaction energy values of the YR-HX complexes follow the order: YR-NH₃<YR-HCN<YR-H₂O<YR-MeOH<YR-HF. In addition, substituting the H-atom of the N−H bond with bulky groups (−R) leads to an increase in the interaction energy of the YR-HX complexes. Hence, it was found that the replacement of N-atom in N-heterocyclic carbene (NHC) by S-atom forming N-aryl-thiazol-2-ylidene results in comparable intermolecular interactions with proton donor molecules similar to imidazole-2-ylidene (NHC). The current study enlightened the role of noncovalent interactions in carbene complexes with proton donor molecules. We hope that our work on carbene chemistry will pave the way for its application in the designing and synthesis of efficient catalysts.     

Copper-Catalyzed Acceptorless Dehydrogenative Coupling of 2-Aminoaryl Methanols with Nitriles for Accessing Quinazolines and Quinolines

A copper acetate monohydrate catalyzed simple, effective and economic protocol has been developed for the construction of quinazoline derivatives via acceptorless dehydrogenative coupling of easily available 2-aminoaryl methanols and nitriles. The methodology was also highly effective for the synthesis of medicinally important quinolines analogues. The reactions proceeded in presence of KO^tBu in toluene at 110 °C for 5 h without the requirement of inert condition, external additives and ligands.     

A pharmacokinetic study to correlate the hypoglycemic effect of phlorizin in rats: Identification of metabolites as inhibitors of sodium/glucose cotransporters

Phlorizin (PRZ) is a natural product that belongs to a class of dihydrochalcones. The unique pharmacological property of PRZ is to block glucose absorption or reabsorption through specific and competitive inhibitors of the sodium/glucose cotransporters (SGLTs) in the intestine (SGLT1) and kidney (SGLT2). This results in glycosuria by inhibiting renal reabsorption of glucose and can be used as an adjuvant treatment for type 2 diabetes. The pharmacokinetic profile, metabolites of the PRZ, and efficacy of metabolites towards SGLTs are unknown. Therefore, the present study on the characterization of hitherto unknown in vivo metabolites of PRZ and pharmacokinetic profiling using liquid chromatography-electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) and accurate mass measurements is undertaken. Plasma, urine, and feces samples were collected after oral administration of PRZ to Sprague–Dawley rats to identify in vivo metabolites. Furthermore, in silico efficacy of the identified metabolites was evaluated by docking study. PRZ at an intraperitoneal dose of 400 mg/kg showed maximum concentration in the blood to 439.32 ± 8.84 ng/mL at 1 h, while phloretin showed 14.38 ± 0.33 ng/mL at 6 h. The pharmacokinetic profile of PRZ showed that the maximum concentration lies between 1 and 2 h after dosing. Decreased blood glucose levels and maximum excretion of glucose in the urine were observed when the PRZ and metabolites were observed in plasma. The identification and characterization of PRZ metabolites by LC/ESI/MS/MS further revealed that the phase I metabolites of PRZ are hydroxy (mono-, di-, and tri-) and reduction. Phase II metabolites are O-methylated, O-acetylated, O-sulfated, and glucuronide metabolites of PRZ. Further docking study revealed that the metabolites diglucuronide metabolite of mono-hydroxylated PRZ and mono-glucuronidation of PRZ could be considered novel inhibitors of SGLT1 and SGLT2, respectively, which show better binding affinities than their parent compound PRZ and the known inhibitors.     

Variable Temperature Crystal Structure of Cu4TiTe4

A variable temperature single crystal X-ray diffraction study of the ternary compound, Cu₄TiTe₄ is reported between 200–400 K. The temperature dependent study indicates the compound undergoes an order-disorder phase transition at ∼320 K. Below the transition temperature, the phase that crystallizes in the primitive cubic space group P 3 m with lattice parameter of a≈5.9 Å, transforms into the two-fold superstructure. It is modeled as a fourfold twinned rhombohedral structure. The transition is reversible. To relate the phases, a group-subgroup symmetry relations are established. Upon decreasing temperature, the atomic ordering is noticed in the occupationally disordered Cu-sites of Cu₄TiTe_4. This characteristic structural rearrangement may have a significant impact on the electronic structure of Cu₄TiTe₄. Hence, the detailed structural characterization is supposed to be useful for further understanding of thermoelectric transport properties in the Cu₄TiTe₄.     

ChemInform Abstract: Reactivity,Selectivity, and Aromaticity of Be32‐ and Its Complexes

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