The complexes cis-[Ru(dmbpy)2Cl(bpy)](PF6) (Rubpy) and cis-[Ru(dmbpy)2Cl(bpe)](PF6) (Rubpe) (dmbpy = 4,4′-Dimethyl-2,2′-dipyridyl, bpy= 4,4′-dipyridyl and bpe = 1,2-bis(4-pyridyl)ethane) were synthesized and spectroelectrochemically characterized. Both Ru(II) complexes exhibited absorption bands assigned to intraligand and metal-to-ligand charge transfer (MLCT) transitions, and their spectral stability in PBS buffer (pH 7.4) supports their suitability for biological studies involving biomolecules or living cells. Fluorescence quenching assays revealed strong interactions with bovine serum albumin (BSA), with binding constants (Kb) values were 2.89 × 105 M−1 for Rubpy and 1.97 × 105 M−1 for Rubpe, and a stoichiometry of one binding site per albumin molecule. DNA-binding studies demonstrated non-covalent interactions with ss-DNA, evidenced by a hyperchromic effect in the MLCT bands, suggesting a partial intercalation or groove-binding mechanism. Cellular uptake assays indicated moderate incorporation of both complexes in tumor cells, with uptake levels of 52% (Rubpy) and 47% (Rubpe) in HeLa cells, and 42% (Rubpy) and 32% (Rubpe) in MDA-MB-231 cells. Despite the similar uptake profiles, cytotoxicity assays showed that Rubpe is approximately 2.4 times more potent than Rubpy, with IC50 values of 9 μM (HeLa) and 12 μM (MDA-MB-231), compared to 22 μM and 29 μM for Rubpy, respectively. These results highlight the relevance of these Ru(II) complexes as molecular platforms for exploring structure–activity relationships in anticancer agents.

The 4,5-diamine-2,6-dimercaptopyrimidine (DAD) molecule contains an aromatic N-heterocyclic center with two amino and two thiol groups, providing an attractive multifunctional ligand to be explored in coordination chemistry and molecular recognition studies. It reacts with [Ru(bipy)2Cl2] in the presence of air, yielding a [Ru(bipy)2DAD]2+ complex, which converts into the corresponding Ru(II)-diimine form, leaving the pyrimidine N-atoms and thiol groups available for participating in intermolecular association through selective hydrogen bonding. This expectation has been confirmed by resonance Raman spectroscopy in solution and the solid state through the detailed analysis of the vibrational peaks of the Ru(II)-bipy and Ru(II)-DAD chromophores under resonance Raman condition. Accordingly, it was observed that the DAD vibrational profiles are sensitive to molecular interactions in the solid state and the presence of species, such as creatinine, thus expressing a typical molecular recognition behavior.

A comparison of the chemistry of the tetraruthenated zinctetrapyridilporphyrin and zinctetrapyridylporphyrazine species has been performed, aiming to improve the understanding of the electronic coupling (or back-bonding) between the macrocyclic center and the peripheral [Ru(bipy)(2)Cl]+ complexes. In the case of the supramolecular tetrapyridylporphyrins, the bridging pyridyl groups are located at the meso-carbon position so that their rotational properties decrease the electronic coupling between the peripheral complexes and the porphyrin center. However, in the tetrapyridylporphyrazine system, the interaction with pi-backbonding Ru(II) complexes is greatly enhanced because the pyridyl groups are fused into the macrocyclic ring with stronger electron acceptor properties. Consequently, the fluorescence emission from the porphyrazine center can be directly pumped from the peripheral complexes by exciting in the Ru-II -> ZnTPyPz(pi*) MLCT band, in contrast with the analogous porphyrin species. The electrochemical behavior of the ZnTRuPyPz complex exhibits the characteristic redox waves of [Ru-III/II(bipy)(2)Cl] at 1.00 V, showing a 0.080 V increase in comparison with the ZnTRuPyP complex, consistent with stronger pi-back bonding interactions with the porphyrazine center. This observation was also corroborated by the pronounced spectroelectrochemical changes in the porphyrazine Q bands induced by the oxidation of the peripheral ruthenium complexes to Ru(III). The spectroscopic and electrochemical results indicate that the porphyrazines can be better than the porphyrins for developing electronically conjugated supramolecular systems.

Ultrafast intersystem crossing and radical formation from DRAc revealed by femtosecond spectroscopy and computational modeling, highlighting the role of solvent in excited-state dynamics.

The sustainable production of clean, easy-to-store, and carbon-free fuels capable of meeting the needs of future generations is one of the most significant scientific challenges of the 21st century. Among the emerging strategies, the development of efficient electrocatalysts for the water-splitting reaction has attracted considerable attention. The absence of pollutant emissions during energy production underscores the potential of oxygen and hydrogen evolution reactions (OER and HER) as promising solutions to address growing global energy demands. Noble metals, such as ruthenium, have demonstrated superior performance in this application compared to transition metals, such as iron, cobalt, and nickel. While noble metals are scarce and expensive, their superior intrinsic activity often translates to enhanced catalytic performance per unit mass, improving the cost-benefit ratio when optimized amounts are employed. In this study, we investigated the effectiveness of iron oxide doped with ruthenium oxide for the OER. A hexanuclear complex composed of ruthenium and iron was synthesized and subsequently anchored onto iron oxide nanoparticles through Prussian blue-like (FeII-CN-M) interactions. The composite was calcined to fully oxidize the organic structure, yielding a material composed entirely of metal oxides. Using a 3 h heat treatment, the resulting catalyst achieved a favorable overpotential for the OER. Specifically, we observed an overpotential of 280 mV at 1 mA and favorable kinetics with a Tafel slope of 72 mV dec-1. The catalytic response was further enhanced by employing a magnetic field to craft the electrode, suggesting that this approach can optimize the performance of ruthenium-based catalysts. Ongoing efforts are focused on improving catalytic efficiency while minimizing material usage, addressing both performance and economic considerations.

Similarly to coordination compounds, metal nanoparticles can exhibit labile or inert character concerning the ligands' substitution behavior, as exemplified by the Turkevich AuNP@citrate (labile) and the gold ranelate AuNP@ran (inert) nanoparticles. The latter are unusual because they encompass a multifunctional thiophene ligand that binds to gold nanoparticles through Au-C bonds. This differential aspect is responsible for their inert character. In this work, two molecular probes, [Ru(bipy)3]2+ and [Ru(bipy)2DAD]2+, have been employed to compare the SERS response of the labile and inert Turkevich and gold ranelate nanoparticles, respectively. In this comparison, it is essential to note that the Ru(bipy)3]2+ probe has no external binding atom since all the bipyridine (bipy) N-atoms are coordinated to the metal center. Therefore, it can only interact with the Turkevich nanoparticles through electrostatic forces. A plasmonic coupling band was observed at around 620 nm, showing a significant SERS response, which can only be ascribed to the electromagnetic mechanism. On the other hand, DAD or 4,5-diamine-2,6-dimercaptopyrimidine, exhibits several thiol and diazo groups capable of binding metal atoms. The [Ru(bipy)2DAD]2+ probe binds covalently to the Turkevich nanoparticles through the S atoms, inducing a plasmon coupling band around 650 nm and a strong SERS response compatible with the chemical mechanism. However, no plasmonic coupling band or SERS effect was observed when the inert AuNP@ran species replaced the labile Turkevich nanoparticles. Therefore, lability should be relevant for allowing electronic contact between the interacting species, contributing to the light scattering mechanism observed in plasmonics and SERS.

Magnetic nanohydrometallurgy (MNHM) can be seen as a nanotechnological version of hydrometallurgy employing complexing molecules attached to superparamagnetic nanoparticles instead of conventional chemical agents and extracting solvents. In essence, the functionalized nanoparticles preserve chemical mobility and provide a high surface concentration of complexing groups for interacting with metal ions. After the capture, because of their strong magnetism, the particles can be easily removed with a magnet, allowing a rapid and clean separation of the sequestered metal ions. In MNHM, similarly to hydrometallurgy, the metal ions are discriminated by and released from the complexing nanoparticles according to their relative stability constants, affording a round operational scheme. MNHM, however, exhibits greater advantages due to its simplicity and greener performance than hydrometallurgy since it does not use solvent extraction or ionic exchange procedures. In addition, on the laboratory scale, the whole process can be completely automated. However, although both MNHM and hydrometallurgy apply complexing agents to capture metal ions, the fundamental aspects of the coordination chemistry of complexing nanoparticles are still missing in the literature. Since they are essential to understanding the kinetics and equilibrium reactions involved, this paper is dedicated to their appreciation, providing an updated overview of the MNHM process and its possible application in the recovery of strategic elements, such as Cu, Co, Ag, Hg, Au, and the lanthanide ions.

Nanoporous gold electrodes are of great interest in electroanalytical chemistry, because of their unusual activity and large surface area. The electrochemical activity can be further improved by coating with molecular catalysts such as the tetraruthenated cobalt-tetrapyridylporphyrazines investigated in this work. The plasmonic enhancement of the scattered light at the nanoholes and borders modifies the electrode's optical characteristics, improving the transmission through the surface-enhanced Raman scattering (SERS) effect. When monitored by hyperspectral dark-field and confocal Raman microscopy, this effect allows probing of the porphyrazine species at the plasmonic nanholes, improving the understanding of the chemically modified gold electrodes.

Naphthalenediimide amphiphiles (NDI-as) with quaternary ammonium groups (DC4, DaP, and DaO) display unprecedented UV light-induced aggregation in solutions of water, acetonitrile and THF.

Metformin (MF) is one of the most important medicaments in the market. It has been extensively employed in the treatment of type -2 diabetes, but its analytical detection is rather complicated, requiring, for instance, highperformance chromatographic methods. Here, we report that metformin reacts with the pentacyanidoferrate (II) complex, generating a deep red product in the presence of sodium percarbonate, Na2CO3.1.5H2O2. A colorimetric assay has been performed by measuring the absorption band at 520 nm, with a limit of detection (LOD) of 0.018 mmol/L. The reaction can also be probed by Raman spectroscopy, since the [FeIII(CN)5MF]3- complex, exhibits a strong resonance effect which enhances the vibrational peaks of the iron(III)-guanidine chromophore. The Raman spectral features are associated with the Fe(III)-N--C-bonds and the metal-to-ligand charge-transfer transition, as confirmed by DFT calculations.

Microplastics are commonly referred to as tiny plastic fragments polluting our environment, although their nanometric forms have also been found in our drinking water supplies and many living systems. Their removal is relevant for preserving our health and sustainability and is being pursued according to many different strategies, including filtration through selective porous materials or agglomeration using flocculant agents. An alternative nanotechnological approach described in this paper deals with the capture and degradation of micro and nanoplastics by enzyme-immobilized magnetic nanoparticles. Magnetic nanoparticles (Fe3O4) were functionalized with polydopamine (PDA) and Lipase enzyme straightforwardly to generate agents capable of removing and degrading µPET from an aqueous solution. In addition to synthesizing and characterizing the Fe3O4@PDA-Lipase nanoparticles and performing the µPET degradation, the novelty encompassed in this work is the successful use of confocal Raman microscopy to monitor the process, in real-time, through in situ hyperspectral images.

The development of new methodologies and sustainable processes is a priority in the field of chemical engineering and nanotechnology. In this study, via an easy route, the nanohydrometallurgy process was applied to recover La from a real spent catalyst. The synthesis of superparamagnetic iron nanoparticles (Si@FeNPs) with different precursors was evaluated. The average particle diameter value was smaller when using sulfate precursors. La acid leaching extracted 76

Transition metal complexes, such as the low-spin bis (phenylterpyridine) (A) and bis (pyridylterpyrazine)iron (II) (B) complexes, provide didactic chromophore species for demonstrating the Raman, resonance Raman, and the surface-enhanced Raman scattering (SERS) behavior in coordination chemistry, as well as for elucidating the nature of inner-sphere and outer-sphere association with plasmonic nanoparticles. Their electrostatically stabilized ion pairs with citrate-gold nanoparticles have been studied in an aqueous solution, from the pronounced changes in the plasmonic band at 540 nm. Complex A, lacking any coordinating site, can only generate outer-sphere complexes with citrate-gold nanoparticles, but they are stable enough to give a strong SERS response, even at 10-8 M. At 10-6 M, agglomeration accompanies the decrease of the electrostatic repulsion, resulting in a sharp decay of the plasmon resonance band at 540 nm. This is followed by the rise of a plasmon coupling band above 700 nm. However, at 10-4 M, the excess of the complex in the adsorption layer produces a reverse effect, decreasing agglomeration. The observed Raman spectra are essentially similar for the several concentrations employed because the outer-sphere interaction implies a SERS electromagnetic mechanism. In contrast, complex B exhibits several pyridine and pyrazine N-atoms available to form inner-sphere-associated species. A selective enhancement of the SERS signals is observed at 10-8 M, clearly indicating a chemical mechanism, consistent with a bridging mode. At 10-6 M and above, the agglomeration leads to a plasmon coupling band at 800 nm, while the SERS response indicates a change in the binding modes dictated by the excess of the complexing molecules. The complex can form inner-sphere gold nanoparticle-associated species through the pyridine and pyrazine N-atoms, showing a strong, selective enhancement of the SERS signals, even at 10-8 M, involving a bridging mode mechanism. image

An organoclay was obtained by intercalating a cationic Ni(ii) porphyrin into a natural smectite sheets using batch method. Stable organoclay film modified GCEs were then prepared for the determination of dopamine, acetaminophen and tryptophan.

Metformin (MF) is one of the most important medicaments in the market and has been extensively employed in treating type 2 diabetes. In this work, we have observed that, because of its positive charge, MF interacts with negatively charged gold nanoparticles, leading to agglomeration even at low concentrations (< 0.01 mmol L−1). This is accompanied by the rise of a plasmon coupling band at 645 nm, allowing its colorimetric monitoring with a limit of detection, LOD, of 1.9 µmol L−1. However, above 0.01 mmol L−1, aggregation takes place, shifting the plasmonic band to 700 nm. Consequently, in this range of concentration, the optical correlation departs from that observed in the agglomeration regime. Therefore, for a critical evaluation, a systematic monitoring of the spectral changes is required to differentiate between the agglomeration and aggregation regimes, as reported in this work. The interaction of metformin with gold nanoparticles has also been monitored by Raman spectroscopy, through the SERS effect. The large enhancement of the Raman signals promoted by the plasmonic nanoparticles improved the detection limit to 0.093 µmol L−1. While monitoring the plasmonic band has inherently a low specificity, the Raman technique provides an unequivocal detection of metformin, based on its characteristic vibrational profiles.

Laser-scribed pencil lead electrodes for amperometric

Silver ranelate nanoparticles complexed with Cu(ii) ions and monitored through the SERS effect.

Jacobsite is a relatively rare mineral of composition MnFe2O4, found in Urandi (Bahia State) in Brazil. It is also a common species in the deep-sea manganese nodules, attracting the interest of many mineral-extracting companies. Because of its spinel constitution similar to magnetite, Jacobsite is commonly called a manganese-ferrite. However, the manganese/iron content may vary substantially according to its origin, demanding specific studies in each case. The Jacobsite mineral inspired our laboratory synthesis of the analogous manganese ferrite nanoparticles. The direct synthesis by the coprecipitation method has not been successful; however, it can be carried in the presence of citrate ions, yielding strongly magnetic nanoparticles, with a maximum magnetization of 45.6 emu.g1. Although they were structurally identical to Jacobsite, the mineral from Bahia exhibited a rather weak magnetism, because it involves a ferrimagnetic coupling. For this reason, the synthetic method seems to provide a better way of obtaining strongly magnetic manganese ferrites. These magnetic nanoparticles have been investigated in detail, including their interaction with diatoms, providing interesting magnetic bio-silicate carriers in drug delivery.

Laser engraving is a convenient, fast, one-step, and environmentally friendly technique used to produce more conductive surfaces by local pyrolysis. The laser’s thermal treatment can also remove non-conductive materials from the electrode surfaces and improve electrochemical performance. The improvement was assessed by electrochemical tools such as cyclic voltammograms and electrochemical impedance spectroscopy using [Fe(CN)6]3−/4− and dopamine as redox probes. The electrochemical results observed showed that a treated surface showed an improvement in electron transfer and less resistance to charge transfer. To optimize the electrode performance, it was necessary to search for the most favorable graphite mines and optimize the parameters of the laser machine (laser power, scan rate, and output distance). The resultant material was adequately characterized by Raman spectroscopy and scanning electron microscopy (SEM), where an irregular surface composed of crystalline graphite particles was noticed. Furthermore, as a proof-of-concept, it was applied to detect indapamide (IND) in synthetic urine by flow injection analysis (FIA), a diuretic drug often used by athletes to alter urine composition to hide forbidden substance consumption in doping tests.

Blue dyes are relatively uncommon in nature, and a novel dithiophene dye (RanB) is reported in this paper. This dye is derived from an old anti-osteoporotic drug and is a metal ion complexing agent, displaying a planar molecular structure, with two sets of carboxylate, isonitrile, thiophene, and iminodiacetate groups. The blue color originates from a strong absorption peak at 648 nm, accompanied by an unusual fluorescence at 555 nm, with higher energy compared to the main absorption band. RanB forms complexes with lanthanoid ions through the iminodiacetate groups and serves as an effective sensitizer for Tb3+ ions, heightening their emission and improving their use as luminescent agents. Its photo-physical properties and the interaction with Tb3+ have been investigated using absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, along with computational methods (ZINDO/S and DFT). The RanB toxicity in human umbilical vein endothelial cells has also been tested, showing a lack of toxicity, holding promising prospects for application as a luminescent and coloring agent in pharmaceuticals and food.