Recent publications
Functionalized naphthols are prominent scaffolds in organic synthesis and materials chemistry. Herein, we demonstrated continuous flow alkylation of α‐ and β‐naphthols by using various primary and secondary benzylic alcohols in the presence of environmentally benign granular β‐zeolite as a reusable catalyst. For a variety of β‐naphthols, the respective alkylated products with good regioselectivity were obtained in high yields under mild reaction conditions. This protocol proceeded via the classical Friedel‐Crafts type alkylation process and generated stable carbocations as intermediates. Applying this protocol, versatile naphthol derivatives have been synthesized using primary and secondary benzylic alcohols (50 and 44 examples in batch and continuous flow process, respectively), with good yields. Key advantages of this process includes rapid and efficient transformation, facilitates gram‐scale synthesis, and generates water as the sole by‐product. The most significant advantage is the continuous reusability of granular β‐zeolite, which further emphasizes the sustainability of the method. The application of alkylated naphthols for quaternary functionalization was demonstrated through peroxidation, azidation, and halogenation reactions under the continuous flow module, which yielded the respective peroxynaphthalen‐2(1H)‐one, azidonaphthalen‐2(1H)‐one and fluoronaphthalen2(1H)‐one derivatives.
Voltage‐gated ion channels (VGICs) are allosterically modulated by glycosaminoglycan proteoglycans and sialic acid glycans. However, the structural diversity and heterogeneity of these biomolecules pose significant challenges to precisely delineate their underlying structure‐activity relationships. Herein, we demonstrate how heparan sulfate (HS) and sialic acid synthetic glycans appended on amphiphilic glycopeptide backbone influence cell membrane persistence and modulate the gating of the Kv2.1 channel. Utilizing a panel of amphiphilic glycopeptides comprising HS disaccharides and sialic acid trisaccharide glycans, we observed that sulfation of HS and flexible α(2‐6) sialylation result in prolonged persistence of glycopeptides on the cell membrane compared to non‐sulfated HS and α(2–3) sialylation respective. This variation in glycocalyx composition was associated with a noticeable difference in the effects of these compounds on the activation and deactivation properties of the voltage‐gated Kv2.1 channel with our strongest membrane associating compound demonstrating the most potent channel‐activation propensity. Our findings demonstrate that sulfation charges on glycopeptide play a critical role in their membrane association propensities and endow them with VGIC activation properties. These results provide a valuable insight into the role of cell surface glycans in VGIC activities.
A squaramide‐based monomer, designed for topochemical azide‐alkyne cycloaddition (TAAC) polymerization, crystallizes as two polymorphs, M1 and M2, both having crystal packing suitable for topochemical polymerization. The hydrogen‐bonding between squaramide units bias the molecular organization in both the polymorphs. 3D packing of H‐bonded stacks of monomer lead to juxtaposition of azide and alkyne units of adjacent molecules in a transition‐state‐like arrangement for their regiospecific cycloaddition reaction. The monomers are arranged as supramolecular sheets and supramolecular helices in polymorph M1 and M2 respectively. Both the polymorphs undergo slow and spontaneous regiospecific TAAC polymerization at room temperature, but react quickly at higher temperatures, resulting in 1,4‐traizolyl‐linked polymer, with distinct mechanical responses. Upon heating, single crystals of polymorph M1 show expansion followed by contraction without any permanent dimensional change, whereas crystals of polymorph M2 undergo splitting. At moderate temperatures, both the polymorphs undergo single‐crystal‐to‐single‐crystal (SCSC) polymerization, resulting in two polymer‐polymorphs with distinct topologies that can be studied at atomic resolution by single‐crystal X‐ray crystallography. The polymorph M1 reacts to polymer P1 with β‐sheet‐like topology, and polymorph M2 reacts to polymer P2 having polymer chains of helical conformation. Nanoindentation experiments with crystals of these polymers revealed their distinct mechanical properties.
We report a mild, transition metal-free, organophotoredox-catalyzed visible light mediated strategy for accessing thiocyano-thioesters from cyclic thioacetals, using aryl thiocyanate as an organic ‘CN’ source. Additionally, the by-product diaryl disul-fide is efficiently repurposed as a recyclable and reusable substrate for the sustainable synthesis of phenyl thiocyanates, supporting the circular chemical economy. This method exhibits broad functional group tolerance and is applicable to 5- to 8-membered cyclic thioacetals. The reaction is also scalable to gram quantity. A series of control experiments, fluorescence quenching and cyclic voltammetry analysis supported a plausible reaction mechanism.
White‐light (WL) generation using small organic molecules has gained significant attention from researchers working on the interface of supramolecular chemistry and organic materials. Self‐assembled multi‐chromophoric materials utilizing a drug molecule and microenvironment‐sensitive intramolecular charge transfer dye as an emitter offer the possibility of tunable emission. In this investigation, we focused on WL generation via the combination of a polarity‐sensitive red‐emitting styryl chromone (SC) and a blue‐emitting anticancer and psychotherapeutic drug Norharmane (NHM) in a self‐assembled micellar system. A detailed spectroscopic investigation allows us to understand the premicellar aggregation process of different types of surfactants with varying charges using the SC dye. Encapsulation of SC and NHM emitters inside the micellar system offers an improved fluorescent behavior, resulting in WL emission due to complementary wavelength overlap. The generated WL is highly photostable and thermally reversible in the self‐assembled system. This investigation highlights the significance of the co‐assembly of SC dye and NHM drug for the generation of a highly stable WL.
Most of the research on color vision related behaviors in dogs has involved training the dogs to perform visual discrimination tasks. We investigated the importance of color to untrained Indian free-ranging dogs (FRDs). Using one-time multi-option choice tests for color preference in 134 adult dogs, we found the dogs to prefer yellow objects over blue or gray ones while there was no preference between blue and gray. We next pitted a yellow object against a gray object that had food. Here, the dogs ignored the food (biscuit or chicken) to approach the yellow object first indicating the color preference to be quite strong. Color preference has previously been investigated in many other animals and has implications for behaviors like mate choice and foraging. Our study provides a new perspective into the ecology of Indian FRDs and might have implications for companion dogs as well, if they too show this preference.
Hydrogen evolution reaction (HER) is a key reaction in electrochemical water splitting for hydrogen production leading to the development of potentially sustainable energy technology. Importantly, the catalysts required for HER must be earth‐abundant for their large‐scale deployment; silicates representing one such class. Herein, we have synthesized a series of transition mono‐ and bi‐ metal metasilicates (with SiO3²⁻ group) using facile wet‐chemical method followed by calcination at a higher temperature. The structural and morphological studies show their unique crystal structure and distinctive morphology, as well as the surface texture, with the band gap ranges of 1.49–2.24 eV. Interestingly, CuZnSiO3, with all earth‐abundant elements, exhibits a band gap of 1.67 eV, shows impressive electrocatalytic properties. We show that CuZnSiO3 exhibits HER activity with much lower overpotential (η=151 mV) at 10 mA cm⁻² under alkaline conditions. The CuZnSiO3 electrode also shows good electrocatalytic stability (ΔE=24 mV) even after 25 hours of chronoamperometric stability test and the performance is comparable to the commercial Pt/C catalyst under similar conditions. Finally, detailed electronic structure studies employing density functional theory (DFT) as well as electronic transport studies were performed to understand and elucidate the superior performance of CuZnSiO3 over the CuSiO3 and ZnSiO3 electrocatalysts.
We introduce and study a game-theoretic model to understand the spread of an epidemic in a homogeneous population. A discrete-time stochastic process is considered where, in each epoch, first, a randomly chosen agent updates their action trying to maximize a proposed utility function, and then agents who have viral exposures beyond their immunity get infected. Our main results discuss asymptotic limiting distributions of both the cardinality of the subset of infected agents and the action profile, considered under various values of two parameters (initial action and immunity profile). We also show that the theoretical distributions are almost always achieved in the first few epochs.
Olfaction and diel‐circadian rhythm regulate different behaviors, including host‐seeking, feeding, and locomotion, in mosquitoes that are important for their capacity to transmit disease. Diel‐rhythmic changes of the odorant‐binding proteins (OBPs) in olfactory organs are primarily accountable for olfactory rhythmicity. To better understand the molecular rhythm regulating nocturnal and diurnal behaviors in mosquitoes, we performed a comparative RNA‐sequencing study of the peripheral olfactory and brain tissues of female Anopheles culicifacies and Aedes aegypti. Data analysis revealed a significant upregulation of genes encoding: OBPs and xenobiotic‐metabolizing enzymes including Cytochrome P450 (CYP450) during photophase in Aedes aegypti and the dusk‐transition phase in Anopheles culicifacies, hypothesizing their possible function in the regulation of perireceptor events and olfactory sensitivity. RNA interference studies and application of CYP450 inhibitors, coupled with electroantennographic recordings with Anopheles gambiae and Aedes aegypti, established that CYP450 plays a role in odorant detection and antennal sensitivity. Furthermore, brain tissue transcriptome and RNAi‐mediated knockdown revealed that daily temporal modulation of neuronal serine proteases may have a crucial function in olfactory signal transmission, thereby affecting olfactory sensitivity. These findings provide a rationale to further explore the species‐specific rhythmic expression pattern of the neuro‐olfactory encoded molecular factors, which could pave the way to develop and implement successful mosquito control methods.
Kinetic asymmetry is crucial in chemical systems where the selective synthesis of one product over another, or the accelera-tion of specific reaction(s) is necessary. However, obtaining precise information with current experimental methods about the behavior of such systems as a function of time, substrate concentration and other relevant parameters is not possible. Computational chemistry provides a powerful means to address this problem. The current study unveils a two-pronged computational approach: (i) full quantum chemical studies with density functional theory (DFT), followed by (ii) stochastic simulations with a validated Gillespie algorithm (GA) (using representative model systems where necessary), to study the behavior of a unidirectional molecular motor (1-phenylpyrrole2,2′-dicarboxylic acid) (Nature 2022, 604 (7904), 80–85). Our approach allows us to understand what is really taking place in the system, showing that its behavior is dependent on the concentration of one of the substrates (“fuel”): when the fuel concentration is high, the rotating molecule behaves more like a switch (undesirable), but when low, it behaves primarily as a motor (desired outcome). These insights allow us to propose recipes to significantly improve the ability of the molecule to behave as a motor. They further serve to explain the efficient rotation of the very recently reported gel-embedded molecular motor (Nature 2025, 637 (8046), 594–600), and thus to also possibly provide insight into the functioning of bio-molecular motors. The current work therefore provides a template for carefully and properly studying a wide variety of important, kinetic asymmetry driven systems in the future.
Metal‐organic frameworks (MOFs) are a fascinating class of structured materials with diverse functionality originating from their distinctive physicochemical properties. This review focuses on the specific chemical design of geometrically frustrated MOFs along with the origin of the intriguing magnetic properties. We have discussed the arrangement of spin centres (metal and ligand) which are responsible for the unusual magnetic phenomena in MOFs. Both two‐dimensional (2D) and three‐dimensional (3D) MOFs with frustrated magnetism, their synthetic routes, and evaluation of magnetic properties are highlighted. Such spin‐frustrated MOFs may find applications in the field of memory devices, transistors, sensors, and the development of unconventional superconductors.
We designed and synthesized three diacetylene monomers M1‐M3 having two NH2 groups. As anticipated, the NH2 groups aided the preorganization of these monomers by N−H…N hydrogen bonding. In the crystals of monomer M1 and M2, the intermolecular N−H…N hydrogen bonding preorganized the diyne units in an orientation suitable for their topochemical polymerization, but in the case of monomer M3, the distance was slightly larger than that recommended for the topochemical reaction. However, upon heating, all the three monomers underwent topochemical polymerization to yield polydiacetylenes P1‐P3 respectively. All three polymers have been characterized using PXRD, Raman, MALDI‐TOF and solid‐state UV spectroscopy. Furthermore, we investigated the abilities of these amine‐functionalized polymers to capture CO2 gas. Polymer P1, which had a larger surface area, demonstrated the highest CO2 adsorption capacity of 1.28 mmol g⁻¹ at 273 K and 1 bar, compared to the other two polymers.
A squaramide‐based monomer, designed for topochemical azide‐alkyne cycloaddition (TAAC) polymerization, crystallizes as two polymorphs, M1 and M2, both having crystal packing suitable for topochemical polymerization. The hydrogen‐bonding between squaramide units bias the molecular organization in both the polymorphs. 3D packing of H‐bonded stacks of monomer lead to juxtaposition of azide and alkyne units of adjacent molecules in a transition‐state‐like arrangement for their regiospecific cycloaddition reaction. The monomers are arranged as supramolecular sheets and supramolecular helices in polymorph M1 and M2 respectively. Both the polymorphs undergo slow and spontaneous regiospecific TAAC polymerization at room temperature, but react quickly at higher temperatures, resulting in 1,4‐traizolyl‐linked polymer, with distinct mechanical responses. Upon heating, single crystals of polymorph M1 show expansion followed by contraction without any permanent dimensional change, whereas crystals of polymorph M2 undergo splitting. At moderate temperatures, both the polymorphs undergo single‐crystal‐to‐single‐crystal (SCSC) polymerization, resulting in two polymer‐polymorphs with distinct topologies that can be studied at atomic resolution by single‐crystal X‐ray crystallography. The polymorph M1 reacts to polymer P1 with β‐sheet‐like topology, and polymorph M2 reacts to polymer P2 having polymer chains of helical conformation. Nanoindentation experiments with crystals of these polymers revealed their distinct mechanical properties.
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