Synthesis, Crystal Structure, Kamlet-Taft and Catalan Solvatochromic Analysis of Novel Imidazole Derivatives

Novel imidazole derivatives were synthesized and its crystal structure has been studied by single crystal XRD analysis. The photophysical properties of these imidazole derivatives were studied in several solvents, which include a wide range of apolar, polar and protic media. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed to a loss of planarity in the excited state provided by the non co-planarity of the aryl rings attached to C(2) and N(1) atoms of the imidazole ring. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption and reemission effects in the detected emission in highly concentrated solutions. The highest fluorescence quantum yield of the imidazole derivatives are observed in polar media.     

Molecular Analysis and Conformational Dynamics of Human MC4R Disease-Causing Mutations

Obesity is a chronic disease with increasing cases among children and adolescents. Melanocortin 4 receptor (MC4R) is a G protein-coupled transporter involved in solute transport, enabling it to maintain cellular homeostasis. MC4R mutations are associated with early-onset severe obesity, and the identification of potential pathological variants is crucial for the clinical management of patients with obesity. A number of mutations have been reported in MC4R that are responsible for causing obesity and related complications. Delineating these mutations and analyzing their effect on MC4R’s structure will help in the clinical intervention of the disease condition as well as designing potential drugs against it. Sequence-based pathogenicity and structure-based protein stability analyses were conducted on naturally occurring variants. We used computational tools to analyze the conservation of these mutations on MC4R’s structure to map the structural variations. Detailed structural analyses were carried out for the active site mutations (i.e., D122N, D126Y, and S188L) and their influence on the binding of calcium and the agonist or antagonist. We performed molecular dynamics (MD) simulations of the wild-type and selected mutations to delineate the conformational changes, which provided us with possible reasons for MC4R’s instability in these mutations. This study provides insight into the potential direction toward understanding the molecular basis of MC4R dysfunction in disease progression and obesity.     

Free radical accelerated cationic polymerizations

The simultaneous photoinitiated cationic polymerizations of epoxides and vinyl ethers in the presence of diaryliodonium salt photoinitiators results in an acceleration of the ring‐opening epoxide polymerization and a deceleration of the vinyl ether polymerization. These effects are seen both in mixtures of the two monofunctional monomers as well as in hybrid monomers which bear vinyl ether and epoxide groups in the same molecule. A combination of two mechanisms have been proposed to account for these effects. The reversible conversion of alkoxycarbenium to oxiranium ions results in a two‐stage reaction in which first, the epoxide, then the vinyl ether polymerization takes place. Free radical chain induced decomposition of the diaryliodonium salt produces a large incremental number of carbenium ion species which results in the acceleration effect.     

Potassium Persulfate-Glucose Mediated Synthesis of (3)-S-Arylthioindoles from Indole and Thiophenols in Water

An efficient and eco-friendly method has been developed for the preparation of functionalized 3-(S)-arylthioindoles in good to excellent yields from indoles and aryl thiols in water. The coupling reaction was prompted by K₂S₂O₈ in the presence of glucose at room temperature. Broad substrate scope, functional group tolerance, room temperature reactions and metal-free conditions are the salient features of the developed methodology.     

Decoupling Redox Hopping and Catalysis in Metal-Organic Frameworks -based Electrocatalytic CO2 Reduction

Traditional MOF e-CRR, constructed from catalytic linkers, manifest a kinetic bottleneck during their multi-electron activation. Decoupling catalysis and charge transport can address such issues. Here, we build two MOF/e-CRR systems, CoPc@NU-1000 and TPP(Co)@NU-1000, by installing cobalt metalated phthalocyanine and tetraphenylporphyrin electrocatalysts within the redox active NU-1000 MOF. For CoPc@NU-1000, the e-CRR responsive Co^I/0 potential is close to that of NU-1000 reduction compared to the TPP(Co)@NU-1000. Efficient charge delivery, defined by a higher diffusion (D_hop=4.1×10⁻¹² cm² s⁻¹) and low charge-transport resistance ( =59.5 Ω) in CoPC@NU-1000 led FE_CO=80 %. In contrast, TPP(Co)@NU-1000 fared a poor FE_CO=24 % (D_hop=1.4×10⁻¹² cm² s⁻¹ and =91.4 Ω). For such a decoupling strategy, careful choice of the host framework is critical in pairing up with the underlying electrochemical properties of the catalysts to facilitate the charge delivery for its activation.     

Effect of oxalic acid (complexing agent) on anodic dissolution of Cobalt in hydrogen peroxide solutions: mechanism and kinetic analysis by electrochemical impedance spectroscopy

Journal of Solid State Electrochemistry - The anodic dissolution of Cobalt in H2O2 solution is investigated in the presence and absence of a complexing agent, oxalic acid, using various techniques...