In the last few years, organic dyes have been utilized as an attractive alternative to transition metal catalyzed photocatalysis. Rose Bengal, an organic dye has been widely applied as a ...photocatalyst in organic synthesis due to its low cost and easy accessibility. In this review, we summarize the key photophysical properties of the dye and its synthetic applications in the formation of C-C and C-X (N, O, S, P, Si, and Se) bonds.
Chemists are generally familiar with polar reactions and radical reactions, in comparison, are underdeveloped. In the last few years, however, the novel concept of amalgamation of the above two in ...the form of radical‐polar crossover (RPCO) and polar‐radical crossover (PRCO) reactions has emerged as a valuable and powerful tool. This methodology tends to bridge the gap between the two as well as overcomes limitations of both radical and traditional polar chemistry. By bringing together the unorthodox chemistry of radicals with orthodox carbocations and carbanions, the green quotient of such reactions is significantly improved. The development and shaping up of this area in the last few years in the form of synthetically important transformations is summarised in this review.
In the last few decades, photocatalytic radical carbonylation strategies have received considerable attention as they are becoming a formidable tool in the toolbox of organic synthesis. These ...carbonylation strategies involve the incorporation of a carbon monoxide into organic molecules in an atom- and step-economical manner. Mostly, these strategies rely on the generation of an acyl radical as a key intermediate, which would be created via incorporation of CO molecule to an alkyl/aryl radical. The production of alkyl/aryl radical in these methodologies required either the high-intensity light-induced transition-metal (TM)-catalyzed systems or visible-light-induced photocatalytic systems that would be capable of mediating single electron transfer (SET) to the C(sp3)- or C(sp2)-hybridized coupling partners. Here, in this review, the development in the field of photocatalytic carbonylation is described by compiling the literature of the last 40 years, and their reaction mechanisms have been emphatically discussed. In addition, to aid readers, we have assimilated redox potentials of photocatalysts and substrates for a better sense of spontaneity of these photoredox carbonylation reactions.
•Review of fluorescence sensors working through ICT, paramagnetic effect and AIE.•Applications of three recognition mechanisms for fluorimetric detection of Cu2+ ion.•The structure, selectivity and ...sensitivity of such chemosensors have been summarized.•This would be useful for further design of fluorescent sensors for Cu2+ ion.
Copper is the third most abundant and a crucial metal for the biological processes. But, excessive accumulation of copper in body is linked with several disorders. In this article, recent advances (in between 2018 and 2020) on small molecule-based fluorescent sensors for the detection of Cu2+ ion have been reviewed. The probes working on the principle of internal charge transfer (ICT), paramagnetic effect and aggregation induced emission (AIE) are covered. Molecular design, sensitivity and the specificity of the sensors have been focused along with their applications.
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•MoS2 and MoS2-MWCNTs composite were obtained via facile hydrothermal route.•Structural analysis confirmed the presence of various defects in obtained materials.•Electrical ...measurements on 2-Terminal devices revealed their semiconducting nature.•Composite based sensor displayed superior response and selectivity towards ammonia.•Theoretical limit of detection for MoS2 based sensor is found to be 1.2 ppm.
MoS2 and its composite with multi-walled carbon nanotube (MWCNTs) were synthesized using facile hydrothermal approach. Structural and vibrational analysis revealed the presence of various defects in MoS2 and its composite with MWCNT. Two-terminal devices were made on a quartz substrate with pre-deposited silver contacts. The resulting Ag/MoS2/Ag and Ag/MoS2-MWCNT/Ag devices exhibit n-type semiconducting behavior and have shown room-temperature ammonia detection down to 12 ppm level. In case of former, the corresponding response time (tresponse = 400 s) and recovery time (trecovery = 280 s) are very large with limit of detection down to 1.2 ppm. The latter, i.e., Ag/MoS2-MWCNT/Ag device on the other hand exhibits faster response-recovery (65 and 70 s, respectively) features along with enhanced relative response for various ammonia concentrations ranging from 12 to 325 ppm. Further, the composite device also displays superior selectivity to its counterpart. It is argued that these differences might arise from different adsorption energy for different gas molecules on the surface of MoS2 or MoS2-MWCNT semiconducting channel. Present results suggest that composite materials such as MoS2-MWCNT may serve as a novel gas sensing platform with superior sensing characteristics and selectivity features.
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•Classification and outline of MOFs based on N-donor linkers.•Design principles for construction of MOFs based on neutral N-donor linkers.•Structural features of metal azolate ...frameworks.•Recent survey of wide range of applications tested using N-donor ligand based MOFs.•Current trends and future outlook for the progress of this sub-domain of MOFs.
The domain of metal-organic frameworks (MOFs) has witnessed a remarkable upsurge over the last two decades. In particular, the myriad choice of building blocks and the wide applicability of these materials have accelerated the interest both in terms of molecular-level development and research as solid-state materials for practical implementation. In the 80s and 90s of the last century, the domain of porous coordination polymers (PCPs)/metal-organic frameworks (MOFs) emerged with initial research on coordination polymers based on N-donor linkers. Thereafter several donor groups have been tried and employed, including carboxylates, azolates, phosphonates, sulfonates etc. Given the plethora of research devoted to the development of MOFs, the present review aims to focus on a sub-domain of MOFs viz. N-donor linker based MOFs, and present the recent trends based on them. Broadly, N-donor linkers can be classified into two sub-types viz. neutral and charged linkers. The present review summarizes the different structural features obtained from MOFs of both classes of the linkers. Also the compilation provides the recent trends emerging from the applications of these materials and offers future perspectives in this domain.
The use of magnetic nanoparticles as a solid support material for the development of magnetically retrievable catalytic systems has led to a dramatic expansion of their potential applications as they ...enable environmentally-friendly and sustainable catalytic processes. These quasi-homogeneous catalysts possess numerous benefits such as ease of isolation and separation from the desired reaction mixtures using an external magnet and excellent recyclability. Consequently, much effort has been directed towards the synthesis of magnetically isolable nano-sized particles by developing methods such as co-precipitation, thermal decomposition, microemulsion, hydrothermal techniques
etc
. Further, in order to render them suitable for catalytic applications, several protection strategies such as surfactant/polymer, silica and carbon coating of magnetic nanoparticles or embedding them in a matrix/support have been reported in the literature. This review focuses on the substantial progress made in the fabrication of nanostructured catalysts with special emphasis on the protection and functionalization of the magnetite nanoparticles (Fe
3
O
4
). Finally, considering the importance of coupling chemistry in the field of organic synthesis, a broad overview of the applications of these magnetite nanoparticle-based catalysts in several types of coupling reactions has been presented. The future of catalysis lies in the rational design and development of novel, highly active and recyclable nanocomposite catalysts which would eventually pave the pathway for the establishment of green and sustainable technologies.
Fabrication of functionalized magnetite nanocomposites and their applications as catalysts for coupling reactions.
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•2-Mercaptobenzothiazole anchored onto amine functionalized polymeric resin for palladium adsorption.•Physico-chemical characterization using FT-IR, SEM, EDX and optical imaging.•The ...maximum Langmuir adsorption capacity of Pd(II) was 50.00mgg−1.•The process is exergonic and endothermic.•The method was tested to recover palladium from a catalyst.
Palladium is an industrially important precious metal and its recovery is of utmost significance in miscellaneous applications. Polystyrene divinylbenzene resins are known for their high surface area and porosity to effectively capture metal ions after suitable modification. In this work, we report the anchoring of 2-mercaptobenzothiazole onto the amine functionalized Amberlite XAD-1180 resin for the effective adsorption of palladium. The macroreticular resin serves as a good host to welcome palladium (guest) and the proof of concept was established comprehensively using FT-IR, SEM, EDX and optical imaging analysis. The Langmuir adsorption capacity of the functionalized resin for Pd2+ acquired through the linear isotherm model was found to be 50.00mgg−1. Kinetics of the adsorption process synchronized well with the pseudo-second order model and furthermore the exergonic and endothermic nature of the adsorption process was quantified through the negative free energy and positive enthalpy values. Regeneration of the resin surface was done using thiourea and the method was tested in recovering palladium from a spent catalyst containing 5% Pd on activated carbon.
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•Cellulose–Mercaptobenzothiazole adsorbent prepared by ultrasonication.•Adsorbent used to recover palladium from a catalyst.•The system shows adherence to D–R and Langmuir model.•The ...maximum adsorption capacity of Pd(II) was 5.00mg/g.•The process is exothermic.
Cellulose, a natural biodegradable polysaccharide is bestowed with very good features to promote diverse applications. In this work, we report the adsorption of palladium involving its interaction with cellulose and 2-mercaptobenzothiazole. The application of FT-IR, SEM and XRD studies were used to characterize the adsorbent as well as comprehend the mechanism of the adsorption process. The ligand impregnated cellulose was prepared by ultrasonication for 20min. The FT-IR studies showed the participation of hydroxyl functional groups in cellulose and the soft sulfur atom in mercaptobenzothiazole in the bonding between palladium and the ligand impregnated biopolymer. The stable palladium chelate is adsorbed on the surface of the ligand modified biopolymer. The concentration of palladium in the aqueous phase was measured using diphenylthiocarbazone as the complexing agent at a wavelength maximum of 584nm. The other factors affecting adsorption such as the optimum pH, kinetics, isotherm models and thermodynamics were studied in detail. The ligand impregnated biopolymer sorbent could be regenerated using thiourea. The extraction of palladium using thiourea was confirmed from the bathochromic shift of the palladium-thiourea complex to 248nm. As an interesting application, the mercaptobenzothiazole impregnated cellulose could be tested to recover palladium from Bis(triphenylphosphine)palladium(II)dichloride which is used in palladium catalyzed coupling reactions.
With an increase in population, there is an increase in the number of accidents that happen every minute. These road accidents are unpredictable. There are situations where most of the accidents ...could not be reported properly to nearby ambulances on time. In most of the cases, there is the unavailability of emergency services which lack in providing the first aid and timely service which can lead to loss of life by some minutes. Hence, there is a need to develop a system that caters to all these problems and can effectively function to overcome the delay time caused by the medical vehicles. The purpose of this paper is to introduce a framework using IoT, which helps in detecting car accidents and notifying them immediately. This can be achieved by integrating smart sensors with a microcontroller within the car that can trigger at the time of an accident. The other modules like GPS and GSM are integrated with the system to obtain the location coordinates of the accidents and sending it to registered numbers and nearby ambulance to notify them about the accident to obtain immediate help at the location.
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