Encapsulating Au‐Fe3O4 Nanodots into AIE‐active Supramolecular Assemblies: Ambient Visible‐light Harvesting “Dip‐Strip” Photocatalyst for C−C/C−N Bond Formation Reactions

The present study demonstrates the development of a supramolecular porous ensemble consisting of hetero‐oligophenylene derivative 6 and Au‐Fe₃O₄ nanodots. Supramolecular assemblies of AIE‐active hetero‐oligophenylene derivative 6 served as reactors for the generation of Au‐Fe₃O₄ nanodots. The as prepared supramolecular ensemble functioned as an efficient recyclable photocatalytic system for C(sp²)?H bond activation of anilines for the construction of quinoline carboxylates. Interestingly, the “dip catalyst” prepared by depositing PTh‐co‐PANI‐6: Au‐Fe₃O₄ nanodots on a filter paper served as a recyclable strip (up to 10 cycles) for C?C/C?N bond formation reaction.     

Palladium acetate and phosphine assisted synthesis of five-membered N-heterocycles

A wide variety of biological activities are possessed by oxygen, nitrogen, and sulfur heterocyclic compounds and much research has been performed for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal became highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of nitrogen containing five-membered heterocylces in the presence of palladium acetate and phosphine as a catalyst.     

Diversified Synthetic Strategies for Pyrroloindoles: An Overview

In current scenario, heterocyclic compounds' role in medicinal chemistry has been tremendously increased as they possess wide number of pharmacological activities. One of the common heterocycles include indole skeleton with well‐established biological significance in field of medicinal chemistry. Fusion of indole nucleus with pyrrole heterocycle constitutes pyrroloindole scaffold, which further modifies the existing properties of indole alone. Pyrroloindole is a privileged scaffold found in various types of bioactive entities including natural compounds and exhibits wide variety of pharmacological activities like muscle relaxant, antifungal, antitumor, and antibiotic. Therefore, it is considered as attractive template for drug discovery. From several years, numbers of synthetic strategies have been reported for the synthesis of pyrroloindole and its derivatives, including also natural compounds such as amauromine, yuremamine, and chimonanthines. Here, in this review, we have tried to compile various synthetic strategies of pyrroloindole and its derivatives.     

Quantum chemical investigation on the influence of amino substitution on proton affinity of oxazolidin-2-one

The scenarios of preferred protonation sites and the absolute gas-phase proton affinities of C5- and N4-amino derivatives of oxazolidinone (OXA) molecules possessing two oxygen and two nitrogen atoms, are studied to investigate the effect of substitution of amino group on geometry, electronic structure, and proton affinities of these molecules. The natural bond orbital analysis is invoked to obtain the second-order delocalization energies, occupations of lone pairs, charge distribution, and bond orders to rationalize the obtained results. Our findings reveal a strong nucleophilicity of O1 site in C5-amino and N4-amino-substituted OXA isomers just as in un-substituted OXA. The substituent nitrogen in N4-amino-substituted OXA has comparable electrophilicity to O1 site while lesser than acyl oxygen and higher than nitrogen of OXA ring in C5-amino-substituted OXA. The PA values of C5- and N4-amino-substituted OXA isomers span in the range 172.06–205.77 kcal mol^?1 (at CBS-Q). The PA values for the potential sites increase in the range 1.96–27.08 kcal mol^?1 as a result of the amino substitution at C5 and N4 in orientation (b) while exceptionally they decrease by 0.57–2.95 kcal mol^?1 as a result of the amino substitution at N4 in orientation (a). The results for the order of PA values of potential sites have been supported by molecular electrostatic potential maps. Our findings indicate that the factors such as geometrical rearrangements, variations in atomic charge densities and electron delocalization, effect of substituent, intramolecular hydrogen bonding, and electronic changes direct the relative stabilities and proton affinities of N, C5-substituted amino OXA isomers.     

Advances in Microwave-Assisted Synthesis for Five-Membered N-Heterocycle Synthesis

The development of new strategies for the synthesis of small-sized heterocycles hasremained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in the synthesis of nitrogen-containing five-membered heterocyclic compounds is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of N-heterocycles.     

Synthesis of five-membered N-heterocycles using silver metal

The heterocyclic chemistry field has been revolutionized using transition metal catalyst in recent years. Various research groups have focused on the development of general protocols to achieve better functional group compatibilities and greater levels of molecular complexity under mild reaction conditions using easily available starting substrates. These methods afford many advantages as compared to alternative pathways involved in the synthesis of heterocyclic compounds. In this review article, we have concentrated on the synthesis of nitrogen-containing five-membered heterocylces in the presence of silver catalyst.     

Copper(II)acetate complexes with piperazine, 1-methylpiperazine, 1,4-dimethylpiperazine and their monohydrochlorides

New copper(II) acetate complexes with the saturated diheterocyclic bases (L-L): piperazine, 1-methylpiperazine, and 1,4-dimethylpiperazine and their monohydrochlorides, have been prepared and characterised by physico-chemical and spectroscopic methods. They are magnetically dilute and antiferromagnetic, with stoichiometries of the type Cu(OAc)₂(B)_n(B=L-L or L-LHCl and n=2, 1 or 0.5).     

Photochemical Mechanisms of Fluorophores Employed in Single-Molecule Localization Microscopy

Decoding cellular processes requires visualization of the spatial distribution and dynamic interactions of biomolecules. It is therefore not surprising that innovations in imaging technologies have facilitated advances in biomedical research. The advent of super-resolution imaging technologies has empowered biomedical researchers with the ability to answer long-standing questions about cellular processes at an entirely new level. Fluorescent probes greatly enhance the specificity and resolution of super-resolution imaging experiments. Here, we introduce key super-resolution imaging technologies, with a brief discussion on single-molecule localization microscopy (SMLM). We evaluate the chemistry and photochemical mechanisms of fluorescent probes employed in SMLM. This Review provides guidance on the identification and adoption of fluorescent probes in single molecule localization microscopy to inspire the design of next-generation fluorescent probes amenable to single-molecule imaging.     

Analyte Detection: A Decade of Progress in the Development of Optical/Fluorescent Sensing Probes

The development of selective and sensitive chemical sensors capable of detecting metal ions, anions, neutral species, explosives and hazardous substances, selectively and sensitively has attracted considerable interest of various research groups. The presence of such analytes within the permissible limits is often beneficial, but the excess amounts may lead to lethal effects to both the environment as well as the living organisms. Owing to the toxicity of the heavy metal ions, toxic anions and nitro-aromatics which are main constituents of explosives, the timely detection of these materials is most desirable to ensure safety and security of the mankind. In this personal account, we present several classes of molecular sensors that were specifically designed in our lab during the past decade for detecting several species in solutions, solid state as well as biological media. Modulation of the optical properties in response to the presence of guest species, led to selective and sensitive detection protocols, and was supported by the theoretical studies wherever possible. We have also extended the application of some of these probes for the on-site detection of analytes by developing the paper strips, glass slides and even the wool and cotton fabrics loaded with probes. One such development represents detection of palladium in human urine and blood samples collected from clinical samples. Additionally, the sensing events in some cases have successfully been reproduced in the live cancer cells. Based on the ease and cost-effective synthesis of the molecular probes, we hope that this account shall provide significant information to researchers in understanding the structure dependent sensing capabilities of the molecular probes.     

Malachite green as a reagent for detection and spectrophotometric determination of chromium(VI)

A sensitive and inexpensive method of spectrophotometric determination of chromium(VI), based on the absorbance of its complex with malachite green and acetic acid at pH 2.5 is reported. The complex shows a molar absorptivity of 8 x 10(4) l.mole(-1) cm(-1) at 560 nm, using malachite green and acetic acid as reference solution. The effect of time, temperature, pH and reagent concentration is studied and optimum operating conditions are established. Beer's law is applicable in the concentration range 2.0-22.8 mug/ml chromium(VI). The resin beads act as a catalyst and as little as 1.6 mug of chromium(VI) is detected in the resin phase as compared to 4.1 mug in the solution phase. The standard deviation in the determinations is +/-0.40 mug/ml for a 10.35 mug/ml solution.