Cycloaddition profile of pentafulvenes with 3-oxidopyrylium betaine: experimental and theoretical investigations

A detailed investigation on the effect of solvent polarity, temperature, and microwave irradiation on periselectivity in cycloaddition reactions of pentafulvenes with 3-oxidopyrylium betaine is described. The base catalyzed generation of 3-oxidopyrylium betaine in CHCl₃ resulted in the exclusive formation of [6+3] adducts. With increase in solvent polarity and temperature, mixtures of [6+3] and [3+2] adducts were formed, where as under microwave irradiation, [3+2] adducts were formed exclusively. The experimental results have been rationalized on the basis of theoretical calculations.     

Transition metal catalyzed carboannulation of diazabicyclic alkenes with ambiphilic bifunctional reagents: a facile route towards functionalized indanones and indanols

Functionalized indanones are readily prepared in good to excellent yields by the Pd/Rh catalyzed carboannulation of bicyclic and tricyclic hydrazines with 2-iodobenzonitrile, 2-cyanophenylboronic acid and 2-formylphenylboronic acid. The reaction with 2-formylphenylboronic acid afforded 3,4-disubstituted cyclopentenes as minor product along with indanones under Rh catalyzed conditions, whereas indanols were obtained as the major product under Pd catalyzed conditions. The products obtained can be synthetically manipulated easily to pharmaceutically important molecules.     

Visible-Light-Mediated Self-Sensitized Oxidative and Regioselective C(sp2)−H Selenylation and Sulfenylation of Substituted 2-Amino-1,4-Naphthoquinones

A photochemical method based on visible-light (white LEDs/sunlight) irradiation has been developed for the regioselective and oxidative C(sp²)−H selenylation and sulfenylation of substituted 2-amino-1,4-naphthoquinones under oxygen atmosphere. The photochemical process does not require any external photoredox catalysts. The other notable advantages of this protocol are metal-free synthesis, visible light/sunlight as energy sources, good substrate scope, and moderate to good yields (41–91 %) with high regioselectivity.     

Ab initio lifetimes in the interatomic Coulombic decay of neon clusters computed with propagators

Interatomic Coulombic decay (ICD) is a radiationless decay mechanism occurring via electron emission in an inner-valence ionized weakly bound cluster. The ICD has been studied for the neon clusters Nen (n=2,...,5). The decay widths of the neon clusters are calculated using ab initio Green's function method. The non-Dyson version of Green's function is employed. This propagator is analytically continued into the complex energy plane with the aid of a complex absorbing potential, and the decaying states are found as resonance states in this plane.     

Synthesis and biological evaluation of carbohydrate appended hydrazinocyclopentenes with potent glycation and α-glucosidase inhibition activities

Synthesis and biological evaluation of novel alkylidenecyclopentene glycohybrids via palladium and click chemistry are described. Out of the six molecules synthesized, four molecules were screened against α-glucosidase, α-amylase, and glycation reactions. The results showed that the compound 7f with a galactose appendage is a good α-glucosidase inhibitor and a potent anti-glycation agent under in vitro conditions with an IC₅₀ value of 0.075 μM and 0.022 μM, respectively. The toxicity of the compounds against normal cell lines was checked by MTT assay.     

Synthesis of novel zerumbone derivatives via regioselective palladium catalyzed decarboxylative coupling reaction: a new class of α-glucosidase inhibitors

A new strategy for the synthesis of novel zerumbone derivatives via a regioselective palladium catalyzed decarboxylative coupling reaction using arene carboxylic acids is described. The current methodology involves the repositioning of endocyclic double bond to exocyclic double bond of zerumbone. Preliminary in vitro analysis revealed that most of the newly synthesized derivatives are potent α-glucosidase enzyme inhibitors.     

Fock space multireference coupled cluster theory: Study of shape resonance

The complex absorbing potential along with correlated independent particle potential (CIP) Fock space multireference coupled cluster method is used for the study of resonances. We have studied shape resonance of e^?‐ F₂, e^?‐ N₂O and e^?‐CO molecules. In particular, we have studied e^?‐ F₂ scattering at different bond lengths to know whether is bound at the equilibrium bond length of F₂. © 2013 Wiley Periodicals, Inc.     

Quantum Secure Direct Communication with Mutual Authentication using a Single Basis

In this paper, we propose a new theoretical scheme for quantum secure direct communication (QSDC) with user authentication. Different from the previous QSDC protocols, the present protocol uses only one orthogonal basis of single-qubit states to encode the secret message. Moreover, this is a one-time and one-way communication protocol, which uses qubits prepared in a randomly chosen arbitrary basis, to transmit the secret message. We discuss the security of the proposed protocol against some common attacks and show that no eavesdropper can get any information from the quantum and classical channels. We have also studied the performance of this protocol under realistic device noise. We have executed the protocol in IBMQ Armonk device and proposed a repetition code based protection scheme that requires minimal overhead.

     

Effect of Protonation and Deprotonation on Electron Transfer Mediated Decay and Interatomic Coulombic Decay

Electronically excited atoms or molecules in an environment are often subject to interatomic/intermolecular Coulombic decay (ICD) and/or electron transfer mediated decay (ETMD) mechanisms. A few of the numerous variables that can impact these non-radiative decay mechanisms include bond distance, the number of nearby atoms or molecules, and the polarisation effect. In this paper, we have studied the effect of protonation and deprotonation on the ionization potential (IP), double ionization potential (DIP), and lifetime (or decay width) of the temporary bound state in these non-radiative decay processes. We have chosen LiH-NH₃ and LiH-H₂O as test systems. The equation of motion coupled cluster singles and doubles method augmented by complex absorbing potential (CAP-EOM-CCSD) has been used in calculating the energetic position of the decaying state and the system's decay rate. Deprotonation of LiH-NH₃/LiH-H₂O either from the metal center (LiH) or from ammonia/water lowers the IP and DIP compared to the neutral systems. In contrast, protonation increases these quantities compared to neutral systems. The protonation closes the inner valence state relaxation channels for ICD/ETMD. For example, the decay of the O-2s/N-2s state stops in protonated systems (LiH₂⁺-H₂O, LiH₂⁺-NH₃, and LiH-NH₄⁺). Our study also shows that the efficiency, i. e., the rate of ICD/ETMD, can be altered by protonation and deprotonation. It is expected to have implications for chemical and biological systems.     

Use of HPTLC to Establish a Distinct Chemical Profile for Shankhpushpi and for Quantification of Scopoletin in Convolvulus pluricaulis Choisy and in Commercial Formulations of Shankhpushpi

JPC – Journal of Planar Chromatography – Modern TLC - Convolvulus pluricaulis is a highly valued rasayana drug of the Ayurvedic system of medicine. It is one of the four drugs...