Coordination‐Based Molecular Assemblies of Oligofurans and Oligothiophenes

Molecular assemblies (MAs) of oligofurans and oligothiophenes were formed from solutions on various substrates. These films were obtained by alternating deposition of organic chromophores (oligofurans or oligothiophenes) and a palladium salt. These coordination‐based MAs were characterized by UV/Vis spectroscopy, spectroscopic ellipsometry, atomic force microscopy (AFM), X‐ray reflectivity (XRR), X‐ray photoelectron spectroscopy (XPS), and electrochemistry. The MAs exhibit similar electrochemical behavior and their growth and structure are apparently not affected when different organic template layers are used. The density of the MAs is a function of the structure of the molecular component. The oligothiophene density is approximately 50 % higher than that observed for the oligofuran‐based assemblies. The optical and electrochemical properties of the MAs scale linearly with their thickness. The UV/Vis data indicate that upon increasing the film thickness, there is no significant conjugation between the metal‐separated organic chromophores. DFT calculations confirmed that the HOMO–LUMO gap of the surface‐bound oligofuran and oligothiophene metal oligomers do not change significantly upon increasing their chain length. However, electrochemical measurements indicate that the susceptibility of the MAs towards oxidation is dependent on the number of chromophore units.     

Facile Synthesis of 4‐Functionalized Cyclopentenones

1-8-Diazabicyclo[5.4.0]undec-7-ene(DBU)‐catalyzed Michael addition of nitroalkanes to dicyclopentadienone (1) followed by flash vacuum pyrolysis (FVP) provided a high‐yielding synthesis of extremely pure 4‐nitroalkyl cyclopentenones (3). The optimized Nef reaction of the nitro adducts (2) provided 4‐ketoalkyl cyclopentenones (5) in the similar way.     

Annulation of furan-bridged 10-membered rings on N-heterocycles through [8+2] cycloaddition of dienylazaisobenzofurans and dimethyl acetylenedicarboxylate

One-pot three-component coupling of o-alkynylheteroaryl carbonyl derivatives with α,β-unsaturated Fischer carbene complexes and dimethyl acetylenedicarboxylate leading to the synthesis of heterocyclic analogues of furanophane derivatives has been explored. This involves the generation of conformationally flexible dienylazaisobenzofuran intermediate as transient intermediates, which undergo [8+2] cycloaddition reaction with dienophile. In some cases, this intermediate undergoes twofold Diels-Alder reaction to afford heterolignan derivatives in a single step.     

Bifurcation diagrams in relation to synchronization in chaotic systems

We numerically study some of the three-dimensional dynamical systems which exhibit complete synchronization as well as generalized synchronization to show that these systems can be conveniently partitioned into equivalent classes facilitating the study of bifurcation diagrams within each class. We demonstrate how bifurcation diagrams may be helpful in predicting the nature of the driven system by knowing the bifurcation diagram of driving system and vice versa. The study is extended to include the possible generalized synchronization between elements of two different equivalent classes by taking the Rössler-driven-Lorenz-system as an example.     

Expedient Access to Enantioenriched 1-Azaspiro Cyclobutanones Enabled by Modified Heyns Rearrangement

Leveraging the unexplored regions of chemical space, the integration of spirocyclic cyclobutane in a molecular scaffold opens up a new vista in modern drug discovery. Despite recent advancements in achieving the synthesis of such motifs, strategies for their asymmetric construction have not been well-recognized and remain a formidable challenge. Herein, for the first time, we have demonstrated a chiral Brønsted acid-catalyzed enantioselective synthesis of 1-azaspiro cyclobutanone enabled by an unusual reactivity of enamine that explore the potentiality of Heyns rearrangement upon electrophilic modification. This design strategy offers viable access to a wide range of cyclobutanone containing spiroindoline and spiropyrrolidine derivatives in good yields with excellent stereoselectivities (up to >99 % ee, >20 : 1 dr). Furthermore, the practicality of this methodology has been shown by a scale-up synthesis of spirocyclic products and their facile post-synthetic modifications.     

Ligand-Mediated Revival of Degraded α-CsPbI3 to Stable Highly Luminescent Perovskite

Although α-CsPbI₃ is regarded as an attractive optical luminophore, it is readily degraded to the optically inactive δ-phase under ambient conditions. Here, we present a simple approach to revive degraded (“optically sick”) α-CsPbI₃ through “medication” with thiol-containing ligands. The effect of different types of thiols is systematically studied through optical spectroscopy. The structural reconstruction of degraded α-CsPbI₃ nanocrystals to cubic crystals in the presence of thiol-containing ligands is visualized through high-resolution transmission electron microscopy and supported by X-ray diffraction analysis. We found that 1-dodecanethiol (DSH) effectively revives degraded CsPbI₃ and results in high immunity towards moisture and oxygen, hitherto unreported. DSH facilitates the passivation of surface defects and etching of degraded Cs₄PbI₆ phase, thus reverting them back to the cubic CsPbI₃ phase, leading to enhanced PL and environmental stability.     

Rearrangement of dicarboranyl methyl cation to icosahedral C3B9H12+: An ab initio dynamics view

Closo-carborane anions are prominent, whereas the cations of the same are less abundant in the literature. As these ions have similar size and are weakly coordinating, the ionic liquids of these two ions could have important applications in many areas of chemistry. In view of limited number of polyhedral carborane cations available, we revisited the rearrangement of dicarboranyl methyl cation (7-CH₂ 7,9-nido-C₂B₉H₁₀⁺) using ab initio molecular dynamics calculations with metadynamics. Our simulations confirmed the concerted mechanism of the rearrangement. We believe this work will resume the interest in its synthesis and carborane cations in general.