Sheshanath V. Bhosale

Fabrication of a GNP/Fe–Mg Binary Oxide Composite for Effective Removal of Arsenic from Aqueous Solution

Graphene nanoplates (GNPs) can be used as a platform for homogeneous distribution of adsorbent nanoparticles to improve electron exchange and ion transport for heavy-metal adsorption. In this study, we report a facile thermal decomposition route to fabricate a graphene-supported Fe–Mg oxide composite. The prepared composite was characterizedu2009using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Batch experiments were carried out to evaluate the arsenic adsorption behavior of the GNP/Fe–Mg oxide composite. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, in which the sorption kinetics of the arsenic adsorption process by the composite was found to be pseudo-second-order. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled-column filter test. The GNP/Fe–Mg oxide composite exhibited significant fast adsorption of arsenic over a wide range of solution pHs, with exceptional durability and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solutions.

Generating a three-dimensional non-fullerene electron acceptor by combining inexpensive spiro[fluorene-9,9′-xanthene] and cyanopyridone functionalities

Through the combination of cheaply synthesized structural fragments, spiro[fluorene-9,9′-xanthene] – otherwise termed low-cost spiro – and cyanopyridone, herein we report a new, three-dimensional, small molecule non-fullerene electron acceptor, (5Z,5′Z,5′′E,5′′′E)-5,5′,5′′,5′′′-((((S)-spiro[fluorene-9,9′-xanthene]-2,2′,7,7′-tetrayl)tetrakis(thiophene-5,2-diyl))tetrakis(methaneylylidene))tetrakis(4-methyl-1-octyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile) [A1], which was synthesized for use in solution-processable bulk-heterojunction devices and was fully characterized by proton and carbon NMR spectroscopies together with elemental analysis. A1 was synthesized by a facile synthetic methodology using a Knoevenagel condensation reaction and was found to be highly soluble in a variety of common processing solvents such as chloroform and o-dichlorobenzene. Owing to its envisioned design, A1 displayed promising optoelectronic properties, and energy levels complementing those of the conventional donor polymers poly(3-hexylthiophene) [P3HT] and poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]-thieno[3,4-b]thiophenediyl}) [PTB7]. Given its energy levels, solubility and excellent film forming capability, A1 was used in bulk-heterojunction devices as an n-type semiconducting component. The device performances [Du2006:u2006 A 1u2006:u20061.2 = 5.84% (P3HT); 7.21% (PTB7)] validated the design and use of A1 as an efficient non-fullerene acceptor.

Dynamic multistimuli-responsive reversible chiral transformation in supramolecular helices

The design of new chiral chromophores that allow tunable assembly of higher order helical structures by using natural stimuli offers promising avenue in understanding various biological processes. In particular, access to dynamic multistimuli-responsive systems can provide real-time monitoring of chiral transformation in chemical and biological systems. We report on the synthesis of naphthalenediimide appended L-glutamate (NDI-L-Glu) that self-assembles into chiral supramolecular structures under physiological conditions. Specifically, NDI-L-Glu shows a mixture of left- and right-handed helices under physiological conditions, and any deviation from the ambient biochemical environment has a remarkable influence on the chirality of these structures. For instance, acidic environments shift the helicity to left-handedness while the alkaline conditions reversed the helical structures to right-handedness, thereby mimicking the molecular virulence mechanism of tobacco mosaic virus (TMV). The chirality of these supramolecular assemblies can also be controllably tuned by using temperature as an external stimulus, allowing reversible flip of helicity.

Spermine-directed supramolecular self-assembly of water-soluble AIE-active tetraphenylethylene: nanobelt, nanosheet, globular and nanotubular structures

Tetrasulfonate-tetraphenylethylene (Su-TPE) is non-emissive in water and upon addition of a good solvent such as THF (fTHF = 95%) it displays strong fluorescence emission with a quantum yield of 6.33%. In the presence of spermine, emission of Su-TPE produces higher quantum yields i.e. 1u2006:u200648 molecular ratio gives 7.21%. Furthermore, interaction of spermine with Su-TPE is also shown to be pH dependent. Scanning electron microscopy (SEM) of Su-TPE molecule self-assemblies demonstrates that it produces various supramolecular structures at different Su-TPEu2006:u2006spermine molecular ratios. Nanobelts were obtained at 1u2006:u200612, evolving into microsheets at 1u2006:u200624, microglobular morphology at 1u2006:u200636 and microtubes at 1u2006:u200648 molecular ratios, respectively. Additionally, enhanced fluorescence emission was observed upon increasing the molar ratio of spermine with Su-TPE at pH 7. The physical characterisation of the system was performed using dynamic light scattering and zeta potential measurements.

Functionalized Quinoxaline for Chromogenic and Fluorogenic Anion Sensing

Abstract This Review article provides a comprehensive analysis of recent examples reported in the field of quinoxaline‐based chromogenic and fluorogenic chemosensors for inorganic anions such as fluoride, cyanide, acetate, and phosphate, as well as their utility in biomolecular science. It commences with a discussion of the various structural motifs such as quinoxaline‐based oligopyrroles, polymers, sulfonamides, cationic receptors, and miscellaneous receptors bearing mixed recognition sites in the same receptor. Advances are discussed in depth, where the focus of this review is to tackle mainly solution state anion sensing utilizing quinoxaline‐based receptors using different spectroscopic techniques with reference to anion selectivity by colorimetric and fluorescence response. The various examples discussed in this Review illustrate how the integration of anion binding elements with the quinoxaline chromophore could result in anion responsive chemosensors. Over the years, it has been observed that structural modification of the quinoxaline moiety with different sets of signaling unit and recognition sites has resulted in a few anion specific chemosensors.

A Biomimetic Supramolecular Approach for Charge Transfer between Donor and Acceptor Chromophores with Aggregation-Induced Emission

Supramolecular assembly of chromophores with inherent resistance to aggregation-induced self-quenching is significant to applications such as chemical sensing and organic light emitting diodes (OLEDs). In this work, molecular gels with aggregation-induced emission (AIE) are constructed by simply coassembling AIE chromophores (electron donor or acceptor) with a nonfluorescent molecular gelator. The binary gels are fluorescent even at very low concentrations of the AIE chromophores, indicating that the rotation of their aromatic cores is restricted in the gel network. In tertiary gels, the fluorescence of the donor chromophore can be efficiently reduced by the acceptor chromophore through a combination of static and dynamic quenching process, via charge transfer from the donor to the acceptor. This work demonstrates a convenient approach to fabricate a supramolecular charge transfer system using an AIE donor and acceptor.

Chiral Supramolecular Assemblies from an Achiral Naphthalene Diimide Bearing a Urea Moiety

The ordering of organic molecules in a supramolecular self-assembly determines their physical, chemical, and photonic properties. Here, we report the aggregation of two achiral naphthalene diimides (NDIs), in which phenyl moieties are linked to the NDI core via a urea subunit, leading to chiral supramolecular assemblies in THF/methylcyclohexane. Circular dichroism spectroscopic analysis of twisted ribbons deposited from solutions indicated a mixture of left- and right-handed nanostructures for one NDI, whereas only left-handed structures were observed for the other one. Furthermore, this study also shows the effect of large atoms such as iodine on the self-assembly process, which governs and controls the helicity of the produced microstructures. The supramolecular assemblies were characterized by UV/Vis, fluorescence emission, CD, SEM, and XRD techniques.

Supramolecular chemistry of AIE-active tetraphenylethylene luminophores

This book chapter provides recent progress in the development of chemistry of aggregation-induced emission (AIE)-active tetraphenylethylene luminophores, their synthetic strategies, and their applications in the research fields of optoelectronics, sensing and supramolecular science comprehensively. It begins with a discussion on a collection of synthetic structural motifs. We will also explore novel derivatives, structures, electronic and spectroscopic properties of the TPE luminophores. The practical applications include certain topics in medicinal, sensing, optoelectronic devices and supramolecular architectures. We have illustrated advances in tetraphenylethylene research in the mechanoluminescent materials followed by exploring recent development of functionalization/decoration of AIE-active tetraphenylethylene luminogens onto an aggregation-caused quenching (ACQ) fluorophores, such as PDI, NDI and porphyrins, converting the whole chromophore into AIE luminogens with possible applications.