A new aza-BODIPY derivative substituted at its periphery with triphenylamine (TPA) units was synthesized in high yield on a preparative scale. The first step involved a Claisen–Schmidt condensation between commercially available 6′-methoxy-2′-acetonaphthone and 4-(diphenylamino)benzaldehyde, affording the corresponding chalcone derivative. This α,β-unsaturated ketone was then subjected to a Michael addition in the presence of CH₃NO₂, yielding diaryl-4-nitrobutan-1-ones. Subsequent treatment with NH₄OAc in refluxing butanol afforded the corresponding tetraarylazadipyrromethene intermediate. Finally, complexation with BF₃·OEt₂ and N,N-diisopropylethylamine in dry dichloroethane led to the target aza-BODIPY bearing two TPA moieties. These substituents were introduced to enable radical coupling reactions under electrochemical conditions. The monomer was electropolymerized onto Pt and ITO electrodes via cyclic voltammetry within an appropriate potential window. During electrochemical cycling, a progressive increase in the redox currents was observed with each scan, indicating the growth of a polymer film on the electrode surface. Polymer formation was confirmed by CV and UV–Vis spectroscopy. Spectroelectrochemical studies revealed changes in the absorption spectra at different wavelengths as a function of the applied potential. These optical transitions, occurring in both the visible and near-infrared regions of the electromagnetic spectrum. Our outcome highlight that this new aza-BODIPY-based electropolymer is a promising candidate for application in electrochromic devices, particularly those requiring NIR absorption capabilities

The incidence of infections caused by resistant pathogens has been steadily increasing. In this context, the accurate detection of microorganisms is essential to optimize antimicrobial therapy. This approach enables a rapid response to infections, reduces the indiscriminate use of antimicrobials, and allows for efficient treatment monitoring. Therefore, the development of fluorophores capable of detecting pathogens represents a promising strategy for the diagnosis and control of resistant infections. In this work, 8-pentafluorophenyl-1,3,5,7-tetramethyl pyrromethene fluoroborate (BDP) was synthesized from pentafluorobenzaldehyde and 2,4-dimethylpyrrole in dichloromethane, catalyzed by trifluoroacetic acid. The mixture was then treated with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone as an oxidizing agent. After 6 h, triethylamine and boron trifluoride diethyl etherate were added to close the dipyrromethene ring, yielding BDP (14%). The conjugation of BDP to polyethylenimine (PEI) was carried out by stirring at room temperature for 72 h. At the end of the reaction, TLC analysis showed complete consumption of the starting BDP, with the resulting conjugate (BDP-PEI) remaining at the origin of the chromatographic plate. The UV-visible absorption spectra of these compounds in N,N-dimethylformamide showed a main absorption band around 505 nm. The fluorescence emission band at 515 nm was assigned to the 0-0 vibrational band of the S₁→S₀ electronic transition. Fluorescence quantum yields of 0.98 and 0.18 were obtained for BDP and BDP-PEI, respectively. Furthermore, BDP-PEI exhibited strong green fluorescence emission in Staphylococcus aureus cells, indicating its potential application as a fluorophore for pathogen sensing.

In this study, a novel hydrogel-based nanocomposite was successfully synthesized by integrating polyvinyl alcohol (PVA) and graphene oxide (GO), aiming to develop an efficient, reusable adsorbent for lithium ion (Li⁺) removal from aqueous environments. Graphene oxide was synthesized using a modified Hummers’ method and incorporated into a hydrogel matrix to enhance surface area and provide functional groups for metal ion binding.The synthesized nanocomposite was structurally characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), which confirmed the successful formation of a porous, functionalized network with good structural stability and uniform dispersion of GO.Batch adsorption experiments were performed to investigate the effects of contact time, initial lithium concentration, solution pH, and temperature on adsorption performance. The kinetic data were best fitted to a pseudo-second-order model, indicating that chemisorption is the rate-limiting step. Isotherm studies revealed that the adsorption followed the Langmuir model, suggesting monolayer adsorption on a homogeneous surface. Thermodynamic parameters showed that the process was spontaneous and endothermic in nature.Moreover, the composite exhibited favorable reusability, maintaining high adsorption capacity over multiple adsorption–desorption cycles. These results highlight the potential of the PVA–GO hydrogel nanocomposite as a selective, efficient, and environmentally friendly material for lithium recovery from aqueous sources such as industrial brine, seawater, and battery wastewater. Its green synthesis, high performance, and reusability make it suitable for sustainable environmental remediation and resource recovery applications.

In memorium to my friend, the Professor M.A. Didi deceased in traffic accident in Oran (Algeria) on the 17 january 2023.

Abstract : Tetra (Hydroxymethyl) Phosphinium chloride (THPC) in aqueous solution wasobtained by A. Hoffman (1928) by reacting phosphine with hydrochloric formaldehyde solution¹. THPC is commercially available as a textile flamme retardant agent². It has been used in organometallic chemistry for the synthesis of aminomethylphosphines such as 3,5-triaza-7-phosphaadamantane (PTA), a water-soluble ligand of transition metal.

We previously showed that phosphonic PEIs obtained by the Irani reaction are metal ion complexing agents³. We first studied the reaction of THPC with piperidine⁴ as model of amine. In a second step, we used THPC for PEI crosslinking. THPC easily generate aminomethylphosphine or aminomethylphosphine oxide groups after hydrogen peroxide treatment into the PEI, improving the coordination properties of PEI to metal ions.

The synthesis of PEI crosslinked with aminomethylphosphine oxide groups was described and characterized by spectroscopy (IR,NMR). The metal extraction was tested on large variety metal ions. (Cu+2, Co+2, Fe+3, Sm+3, La+3, Ce+4...)

References :

1. A. Hoffman, J. Amer. Chem. Soc., 1921, 43, 1684 ; 1930, 52, 2995.

2 E.D. Weil, S.V. Levchik, J. Fire Sci. 2008, 26 (3): 243–281.

3.D. Villemin, C. Monteil, N. Bar, M. A. Didi, Phosphorous, Sulfur Silicone 2015, 190, 879-890

4. A. Jullien, Ph D thesis, University of Caen, 16 dec. 2004.

Chitosan is an important natural polymer in research due to its solubility in aqueous acidic solutions and its excellent properties, such as biodegradability, biocompatibility, bioactivity and non-toxicity. Copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition reactions are used to obtain functionalized chitosan derivatives called 1,2,3-triazoles, which have a potential use as food coatings. From shrimp exoskeletons, chitosan was obtained with a yield of 24.66 %, a solubility of 84.11 %, a degree of deacetylation of 90.94% and a molecular weight of 352.28 kDa. From different terminales alkynes and by microwave-assisted 1,3-dipolar cycloaddition reaction (CuAAC), derivatives with shades varying between green-yellow, red-brown with high yields between [79.72 - 88.04] % were obtained. Films were elaborated from the derivatives and PVA which presented tensile strength values in a range between [65.21 - 94.17] MPa, an elongation at break varying between 31.33 % to 55.30 %. Thicknesses between [0.033-0.043] mm. They presented a higher thermal stability than chitosan with a decomposition range between [288.74 - 322.84] ºC, values obtained from differential scanning calorimetry tests. They possess a water vapor permeability between [2.28x10^-8 - 1.21x10^-7] (g/s.m.Pa). The derivatives obtained from microwave-assisted 1,3-dipolar cycloaddition reactions when applied in the manufacture of films possess improved mechanical properties, homogeneous thicknesses, low porous surfaces and good barrier properties, these characteristics would allow the formulation of food coatings.

In this study, three novel oxalyldihydrazone-based ligands were synthesized through the condensation of oxalyldihydrazide with three different aldehydes: 5-bromo-2-hydroxybenzaldehyde, 2-hydroxynaphthaldehyde, and 2-hydroxy-3-methoxybenzaldehyde. These ligands were subsequently reacted with two equivalents of dimethyltin(IV) dichloride, resulting in the formation of symmetrical dinuclear organotin(IV) complexes in a 1:2 metal-to-ligand molar ratio. The synthesized ligands and their corresponding complexes were fully characterized using FT-IR spectroscopy, ¹H NMR, ¹¹⁹Sn NMR, and elemental analysis. The spectral data confirmed successful coordination of the tin centers with donor atoms of the ligands, consistent with the proposed dinuclear structures. The antibacterial activities of the ligands and complexes were evaluated against both Gram-positive bacteria (*Staphylococcus aureus*, *Bacillus subtilis*) and Gram-negative bacteria (*Escherichia coli*, *Pseudomonas aeruginosa*). Notably, the organotin(IV) complexes displayed significantly enhanced antibacterial activity compared to their free ligands, especially against *P. aeruginosa*, a clinically important multidrug-resistant pathogen. This enhanced activity is attributed to the chelation effect, which increases the lipophilicity of the complexes, thus improving their ability to penetrate bacterial cell membranes. Furthermore, the proposed mechanism involves hydrolysis of the organotin complexes in biological media, allowing interaction with cellular enzymes and disruption of bacterial metabolic pathways. The findings suggest that these novel organotin(IV) complexes are promising candidates for further development as potent antibacterial agents.

The interaction between the styryl dye 4-{(E)-2-[4-(dimethylamino)phenyl]vinyl}-1-methylpyridinium iodide (DASPI) and cucurbit[7]uril (CB[7]) in aqueous solution was studied by optical spectroscopy methods. Cucurbit[n]urils are cavitands composed of n glycoluril units linked by methylene bridges [1]. Due to their negatively charged portals, cucurbiturils can form complexes with cationic styryl dyes of suitable size. This complexation alters the dye photophysical properties, such as fluorescence in the case of 1:1 complexes (binding constant logK₁ = 5.5) [2].

It was previously found that the formation of 1:2 inclusion complexes leads to a red shift in the absorption band to around 330 nm and the appearance of an additional fluorescence band at 450 nm (binding constant logK₂ = 5.1) [2]. Such changes were previously attributed to protonation of the dye [3].

However, the direct measurements of pH show that dissolving 10⁻⁵ M CB[7] in water does not significantly change the acidity of the solution (pH = 5.67), so that the observed effects cannot be attributed to dye protonation. Indeed, it can be shown [2], that the molar fraction of the protonated dye ≈1 only when pK_a > pH.

The experimentally determined value of pK_a=3.23 for DASPI at 23°C [2], so that significant protonation of the dye occurs only when pH≲3.5. Therefore, at the working pH of 5.67, protonation contributes is neglected.

To explain the effect, we hypothesize that the effect arises from the influence of the electrostatic field generated by the negatively charged portals of cucurbit[7]uril on the conjugated π-electron system of the dye.

Introduction and Aim
An efficient and eco-friendly synthetic approach was developed for the preparation of tetrahydropyrimidine carboxamide derivatives using a multicomponent reaction (MCR) strategy. This method offers advantages such as high yields, mild conditions, short reaction times, structural stability, and reusability of reagents. The synthesized 1,2,3,4-tetrahydropyrimidine carboxamides were evaluated for their antifungal, antibacterial, and antioxidant activities. Molecular docking studies were also performed to analyze their binding modes and interaction profiles with biological targets.

Materials and Methods
A novel series of 5-carboxamide-substituted 1,2,3,4-tetrahydropyrimidine-2(1H)-ones (DHPMs) was synthesized via MCR. Reaction conditions were optimized to enhance yield and reduce reaction time. Based on preliminary biological screening, selected compounds were subjected to molecular docking using known THPC inhibitors as references. These studies aimed to understand receptor-ligand interactions and support the in vitro findings.

Results
The synthesized THPC derivatives were characterized by IR, mass spectrometry, ¹³C NMR, and ¹H NMR spectroscopy. The compounds were evaluated for in vitro antioxidant, antibacterial, and antifungal activities. Antibacterial activity was tested against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Pseudomonas aeruginosa. Several derivatives exhibited significant antimicrobial activity, comparable or superior to standard drugs. Molecular docking revealed stable hydrogen bonding and π–π interactions with target proteins.

Conclusion
The synthesized tetrahydropyrimidine carboxamide derivatives, particularly those with heterocyclic substitutions, demonstrated potent biological activity. Molecular docking confirmed favorable interactions, supporting their potential as leads in drug development. This integrated approach provides a foundation for further structure–activity relationship (SAR) studies.