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Cyanines comprise a diverse group of small-molecule polymethine dyes combining tunable optical properties with high molar absorptivity and fluorescence emission quantum yield, enabling various applications in bioimaging, diagnostics, molecular electronics, photonics, and nonlinear optics. These applications can be facilitated by adjusting the length of their polymethine chain and their functionalization through their end groups or the polymethine chain. Yet, the latter approach remains largely unexplored, with limited information scattered throughout literature. This review focuses on cyanines substituted on their chain, covering their synthesis, properties, and applications and providing an overview of how substituents on their polymethine chain influences their spectroscopic properties, akin to other factors, such as polymethine length and end groups. Lastly, this review illustrates how substituents on the polymethine chain facilitate the application of cyanine dyes in promising research areas.

A series of 23 heterocyclic derivatives incorporating 1,2,4-triazole and oxadiazole motifs are synthesized via cyclization of thiocarbamoylimidates with hydrazine salts. Reaction parameters including solvent, base, and temperature are systematically optimized and very good results are obtained in the environmentally friendly reaction media composed of water and ethanol, under mild conditions of temperature (40 °C). The reaction is very versatile and allows for the introduction of a wide variety of functional groups. All the new compounds are submitted to in silico evaluation of their drug potential using the SWISS-ADME tool. Several compounds of both families did not violate any drug likeness rules, making them potential candidates for further evaluation of their biological activity and structural optimization.

Lead contamination in the environment severely threatens human health due to its high toxicity, particularly in water sources. Exposure to lead ions (Pb²⁺) can cause neurological disorders, kidney damage, and developmental impairments, necessitating the development of sensitive and selective detection methods. Biomass-derived fluorophores, such as carbon dots (CDs), have emerged as eco-friendly and cost-effective alternative sensors that offer high sensitivity while overcoming the limitations of conventional techniques. This work reports a fluorescence-quenching sensor for lead ion (Pb²⁺) based on CDs synthesized from biomass (Saccharum spontaneum). The CDs are synthesized via a hydrothermal process. Optical studies reveal a fluorescence quenching of CDs in the presence of Pb²⁺ ions due to the complex formation of CDs through functional groups, enabling highly sensitive lead detection. The CDs exhibit a low detection limit of 376 nM, demonstrating its potential as a reliable lead sensor. These CDs are further explored as fluorescent ink for anticounterfeiting applications.

Stimuli-responsive, water-soluble synthetic receptors are key to advancing dynamic molecular recognition in aqueous environments, with implications for self-assembly, molecular machines, and biomedical systems. Herein, a macrocyclic receptor is reported that exhibits pH-dependent binding properties toward saccharides in water, in that it displays markedly different affinities between alkaline and neutral conditions. Spectroscopic and binding studies reveal that the degree of protonation of the solubilizing groups modulates the receptor self-association phenomena, together with concomitant substantial loss of binding ability. This work highlights a rare example of a pH-switchable carbohydrate receptor operating in water and underscores the potentials of such system in the design of smart, responsive molecular architectures.

Cyclodextrin is a typical macrocyclic molecule that can recognize and bind numerous guest molecules with specific structure and functional groups. The cyclodextrin-based supramolecular nanostructures, characterized by well-defined, ordered, compact, and regular molecular arrangements, are widely utilized in drug delivery, sensing, and light-harvesting systems. Their unique physicochemical properties have further expanded the scope of research in both biophysics and chemistry. In this review, we provide an overview of the concepts and applications of cyclodextrin-based supramolecular nanostructures, with a focus on their relevance to biochemistry and chemistry.

This research work demonstrates the engineering of rGO/Fe₃O₄ based heterojunction as cost-effective, highly efficient, and robust photocatalyst with readily recoverable and reusable characteristics. Herein, the Fe₃O₄ nanoparticles have been synthesized from the waste toner powder collected from used cartridges for advancing a magnetically separable photocatalyst. The Fe₃O₄ nanoparticles have been decorated on rGO sheets for enhancing the conductivity and retarding the recombination rate of photogenerated electron-hole pairs, as reflected by the decrease in photoluminescence intensity for rGO/Fe₃O₄ relative to pure rGO and Fe₃O₄. Additionally, the specific surface area has also improved from 12.93 m² g^-1 for Fe₃O₄ to 115.58 m² g^-1 in the case of rGO/Fe₃O₄. Henceforth, the rGO/Fe₃O₄ nanocomposite showcases remarkable performance for the removal of various pollutants like, rhodamine B (RhB) (98.5%), methylene orange (93.8%), methylene blue (99.99%), and tetracycline hydrochloride (95.4%) after 30, 40, 20, and 40 min of simulated solar light exposure, respectively, by utilizing 0.2 mg ml^{- 1} of photocatalyst. Furthermore, it degrades 74.3% of RhB pollutant with very high concentration of 30 mg L^-1 within 80 min of light irradiation. Additionally, this work also manifests the impact of different parameters, like dosage of photocatalyst and initial concentration of the pollutants and mixing of diverse pollutants on the photodegradation efficiency of nanocomposite. The scavenger's study is performed to investigate the active species involved in the photodegradation process. Furthermore, the role of built-in potential at the interface of heterojunction is thoroughly discussed to understand the mechanistic intricacies of the charge transfer process during the photodegradation process.

Electrochromic materials have recently aroused extreme attention due to their exceptional application potential in display screens, architectural glass, and coating stealth materials, etc. Developing electrochromic polymers synchronously sharing blue and second near-infrared (NIR-II) transmissive is urgently in demand but extremely scarce. Herein, three kinds of electrochromic polymers featuring redox electrochemical and electrochromic properties are obtained through electrochemical polymerization of three monomers, ProDOT-TPA, ProDOT-TPPA, and ProDOT-2TPA, which are constructed based on 3,4-ethylenedioxythiophene (ProDOT) and triphenylamine (TPA) derivatives. Electrochemical studies reveal that ProDOT-TPA exhibits low initial oxidation potential of 0.59 V, possessing significant advantages for obtaining high-quality polymers. The optimized polymers [P(ProDOT-TPA)] show significant properties in electrochromic devices with optical contrast of 14.38% at 400 nm and 49.55% at 1100 nm, along with coloration efficiency of 123 cm²C^-1 and response times of 0.5 s.

Reductive amination is crucial for synthesizing amines in pharmaceutical and industry, yet selectively producing primary amines on a large scale remains challenging. This work presents a continuous-flow reductive amination process using benzaldehyde with NH₃ and H₂ as the nitrogen sources and reductant. A cobalt catalyst supported on nitrogen-doped carbon derived from chitosan (Co@CS) was developed. After optimization, a primary amine yield exceeding 99% was achieved under mild reaction conditions. The catalyst demonstrated excellent stability in long-term tests and with various substrates, including the biomass lignin-derived vanillin. Compared to batch reactors, theflow reactor provided superior selectivity. This catalytic flow process minimizes waste, enhances atom economy, avoids hazardous chemical, and improves energy efficiency. The use of a renewable chitosan feedstock and a safer process aligns with multiple principles of green chemistry. The exceptional heat and mass transfer in the Flow system offers an effective strategy for the large-scale production of primary amines from biomass platform compounds.

Stimuli-responsive systems play a crucial role in biological processes. Research on supramolecular cages formed via noncovalent interactions contributes to the development of receptors that mimic these natural systems. Recently, anion-coordination-driven assembly (ACDA) employing oligourea ligands and trivalent phosphate ions (PO₄ ^3-) has emerged as a promising strategy for constructing responsive supramolecular architectures. These assemblies are stabilized through multiple hydrogen bonds and are capable of undergoing structural transformations in response to external stimuli, offering a conceptual framework for understanding flexibility and environmental adaptability in biological contexts. This mini-review highlights the stimuli-responsive properties of anionic self-assemblies, with a focus on systems involving oligourea ligands and PO₄ ^3- ion. Organized by stimulus type, it discusses multistimuli responsiveness, guest-induced transformations, solvent sensitivity, and light-responsive behaviors. Current challenges and identifying future opportunities in the study of ACDA-based stimuli-responsive systems are discussed.

Valorization of biomass-derived chemicals into high-quality compounds and biofuels is enormously fundamental to diminish dependence on fossil-based resources. Furfural is a bio-based valuable compound which can be proficiently upgraded to 4-(2-furyl)-3-buten-2-one (FAc) and 1,4-pentadiene-3-one, 1,5-di-2-furanyl (F₂Ac) via aldol condensation of furfural with acetone. In the present work, efficient Cu-doped MgAl layered double hydroxides (LDH) nanocatalysts are fabricated by coprecipitation and are exploited for furfural conversion to obtained FAc and F₂Ac. The structure-activity relationship is scrutinized by characterizing fresh and spent nanocatalysts via numerous techniques. The good correlation between the amount of weak acidic-weak basic catalytic sites and nanocatalysts performance is established. The superior performance of Cu-0.1 nanocatalyst (Cu-content = 1.85 wt%) in aldol condensation is attributed to the presence of optimum weak acidic sites (0.21 mmol g^-1) and weak basic sites (0.36 mmol g^-1), synergistic acidic-basic effect, nano-sized Cu(OH)₂ nanoparticles (1.6 nm), high BET surface area (181 m²g^-1), and mesoporous architecture of material. Cu-0.1 nanocatalyst delivered 98% FAc selectivity with 100% furfural conversion at 85 °C. Furthermore, at 100 °C, the nanocatalyst gives 55% F₂Ac selectivity with 73% furfural conversion. The catalyst displays good recyclability (7 recycles) and stability. Plausible mechanistic pathway for transformation of furfural to FAc and F₂Ac is proposed.