A New Family of Chalcogen Bearing Macrocycles: Synthesis and Characterization of N 4 O 2 E 2 (E = Se,Te) Type Compounds

A new series of 24- and 28-membered macrocyclic systems associated with "hard" (N and O) and "soft" (Se or Te) donor atoms have been developed via template free (2 + 2) condensation reactions of bis(aminoalkyl)selenides/tellurides, {NH 2 (CH 2 ) n } 2 E (E = Se, Te; n = 2,3) with 2,6-diacetyl-4-methylphenol. A macroacycle, Se{(CH 2 ) 2 N=C(CH 3 )C 6 H 2 (OH)(CH 3 )C=O(CH 3 )} 2 , has also been obtained. These compounds have been characterized by ESMS, IR, and 1 H, 13 C, and 77 Se NMR spectroscopy.     

Steric as well as n→π* Interaction Controls the Conformational Preferences of Phenyl Acetate: Gas‐phase Spectroscopy and Quantum Chemical Calculations

Herein, we report that the conformational preference of phenyl acetate is governed by steric effect and n→π* interaction. Conformation‐specific electronic and IR spectroscopy combined with quantum chemistry calculations confirm the presence of only the cis conformer of phenyl acetate in the experiment. The cis conformer of phenyl acetate has n→π* interaction between the lone‐pair electrons on the carbonyl oxygen atom and the π* orbitals of the phenyl group. The n→π* interaction is absent in the trans conformer which has additional steric repulsion between the methyl group and phenyl ring. The trans conformer is higher in energy than the cis conformer by ≈3 kcal mol^?1. We have found the effect of methyl substitution on the strength of the n→π* interaction, steric repulsion, and hyperconjugation in phenyl acetate. The red‐shift observed in the cis conformer of phenyl acetate with respect to the trans conformer is affected due to the influence of the methyl substituent on the strength of the n→π* interaction as well as hyperconjugation. The present result demonstrates that the introduction of a bulkier substituent can induce steric as well as electronic control to reduce conformational heterogeneity of a molecular system. Understanding the effect of bulkier substituents to promote defined conformations having specific non‐covalent interactions may have implication in better perception of the optimum structure and function of biomolecules as well as recognition of drugs by biomolecules.     

Efficient Preparation of Isothiocyanates From Dithiocarbamates Using Bromineless Brominating Reagent

For the first time, the crystal structure of a ditribromide reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) has been determined. Utilizing this thiophilic bromineless brominating agent EDPBT, highly useful synthetic intermediates (alkyl and aryl isothiocyanates) have been achieved directly from dithiocarbamates. EDPBT can be easily prepared from readily available reagents. It has been used as a thiophilic reagent, and its thiophilicity dominates over its brominating ability for substrates amenable to bromination. This is a sustainable process for the preparation of isothiocyantes because the spent reagent can be recovered, regenerated, and reused.     

Highly reactive and enantioselective kinetic resolution of terminal epoxides with H2O and HCl catalyzed by new chiral (salen)Co complex linked with Al

The asymmetric hydrolytic kinetic resolution (HKR) of racemic terminal epoxides by new easily synthesized dimeric chiral (salen)Co bearing Al, provides a practical and straightforward method for the synthesis of enantiomerically enriched terminal epoxides (>99% ee) and diols. An inorganic acid, HCl is applied first time for the asymmetric ring opening reaction of terminal epoxides. Reactions are conveniently carried out at room temperature under an air atmosphere.     

Multiobjective optimization of a free radical bulk polymerization reactor using genetic algorithm

A multiobjective optimization technique has been developed for free radical bulk polymerization reactors using genetic algorithm. The polymerization of methyl methacrylate in a batch reactor has been studied as an example. The two objective functions which are minimized are the total reaction time and the polydispersity index of the polymer product. Simultaneously, end‐point constraints are incorporated to attain desired values of the monomer conversion (x_m) and the number average chain length (μ_n). A nondominated sorting genetic algorithm (NSGA) has been adapted to obtain the optimal control variable (temperature) history. It has been shown that the optimal solution converges to a unique point and no Pareto set is obtained. It has been observed that the optimal solution obtained using the NSGA for multiobjective function optimization compares very well with the solution obtained using the simple genetic algorithm (SGA) for a single objective function optimization problem, in which only the total reaction time is minimized and the two end‐point constraints on x_m and μ_n are satisfied.     

Upgraded charge transport in g-C3N4 nanosheets by boron doping and their heterojunction with 3D CdIn2S4 for efficient photodegradation of azo dye

The facilitation of charge transport toward the targeted chemical reaction is a challenging task for two-dimensional (2D) nanomaterials. We demonstrate the effectiveness of two different strategies, non-metal doping and heterojunction formation, to adjust the electronic and molecular structures of g-C₃N₄ nanosheets (CN), which could widen the visible-light response and improve the photo-induced electron–hole separation. The g-C₃N₄ nanosheets containing impurity levels (boron doping (BCN)) were prepared by a high-temperature solid-state reaction. Additionally, by anchoring the 3D dichalcogenide structures (CdIn₂S₄) elicited by a wet chemical route, hybrid BCN/CdIn₂S₄ nanostructures were obtained. The resulting BCN/CdIn₂S₄ (BCN–CIS3) nanostructures exhibited an excellent degradation efficiency (95%) for methyl orange (MO) compared to pristine g-C₃N₄ nanosheets (CN) (28%) and boron-doped g-C₃N₄ (BCN) (35%). All the optimized photocatalysts were thoroughly characterized using various techniques and investigated for comparative structural, optical, morphological, and catalytic properties. Our results reveal that introducing boron atoms into the lattice of g-C₃N₄ nanosheets leads to reduction in the band-gap energy and rapid electron transfer. The formation of heterojunctions with the 3D CdIn₂S₄ further assists in improving the degradation efficiency by minimizing the undesired electron–hole recombination, as confirmed by time-resolved photoluminescence (TRPL) analysis. This work proposes feasible strategies and their synergy to develop innovative materials for sustainable energy conversion and environmental remediation applications.     

Facile convergent route to indoloquinolines

A convergent route to indoloquinolines is developed through aldol condensation. This two-step method utilizes commercially available 2-oxoindole and o-nitrobenzaldehyde as starting materials. Chromatography-free method is accomplished for preparing several derivatives of indoloquinolines with desirable aromatic substitutions on indole as well as quinoline ring.     

Phospholipid/Polydiacetylene Vesicle-Based Colorimetric Assay for High-Throughput Screening of Bacteriocins and Halocins

Multi-phase anaerobic reactor for H₂ and CH₄ production from paperboard mill wastewater was studied. The reactor was operated at hydraulic retention times (HRTs) of 12, 18, 24, and 36 h, and organic loading rates (OLRs) of 2.2, 1.5, 1.1, and 0.75 kg chemical oxygen demand (COD)/m³ day, respectively. HRT of 12 h and OLR of 2.2 kg COD/m³ day provided maximum hydrogen yield of 42.76?±?14.5 ml/g COD_removed and volumetric substrate uptake rate (?rS) of 16.51?±?4.43 mg COD/L h. This corresponded to the highest soluble COD/total COD (SCOD/TCOD) ratio of 56.25?±?3.3 % and the maximum volatile fatty acid (VFA) yield (Y_VFA) of 0.21?±?0.03 g VFA/g COD, confirming that H₂ was mainly produced through SCOD conversion. The highest methane yield (18.78?±?3.8 ml/g COD_removed) and ?rS of 21.74?±?1.34 mgCOD/L h were achieved at an HRT of 36 h and OLR of 0.75 kg COD/m³ day. The maximum hydrogen production rate (HPR) and methane production rate (MPR) were achieved at carbon to nitrogen (C/N) ratio of 47.9 and 14.3, respectively. This implies the important effect of C/N ratio on the distinction between the dominant microorganism bioactivities responsible for H₂ and CH₄ production.     

Photoactivatable prodrug for simultaneous release of mertansine and CO along with a BODIPY derivative as a luminescent marker in mitochondria: a proof of concept for NIR image-guided cancer therapy

Controlled and efficient activation is the crucial aspect of designing an effective prodrug. Herein we demonstrate a proof of concept for a light activatable prodrug with desired organelle specificity. Mertansine, a benzoansamacrolide, is an efficient microtubule-targeting compound that binds at or near the vinblastine-binding site in the mitochondrial region to induce mitotic arrest and cell death through apoptosis. Despite its efficacy even in the nanomolar level, this has failed in stage 2 of human clinical trials owing to the lack of drug specificity and the deleterious systemic toxicity. To get around this problem, a recent trend is to develop an antibody-conjugatable maytansinoid with improved tumor/organelle-specificity and lesser systematic toxicity. Endogenous CO is recognized as a regulator of cellular function and for its obligatory role in cell apoptosis. CO blocks the proliferation of cancer cells and effector T cells, and the primary target is reported to be the mitochondria. We report herein a new mitochondria-specific prodrug conjugate (Pro-DC) that undergoes a photocleavage reaction on irradiation with a 400 nm source (1.0 mW cm⁻²) to induce a simultaneous release of the therapeutic components mertansine and CO along with a BODIPY derivative (BODIPY(PPH₃)₂) as a luminescent marker in the mitochondrial matrix. The efficacy of the process is demonstrated using MCF-7 cells and could effectively be visualized by probing the intracellular luminescence of BODIPY(PPH₃)₂. This provides a proof-of-concept for designing a prodrug for image-guided combination therapy for mainstream treatment of cancer.

Simultaneous release of two therapeutic reagents, mertansine and CO through photo-induced cleavage of a mitochondria-specific prodrug with improved drug efficacy.