Multivalent hydrogen-bonded architectures directed by self-complementarity between [Cu(2,2'-biimidazole)] and malonate building blocks.

The synthesis and structural characterization of four novel supramolecular hydrogen-bonded arrangements based on self-assembly from molecular `[Cu(2,2'-biimidazole)]' modules and malonate anions are presented, namely, tetrakis(2,2'-biimidazole)di-µ-chlorido-dimalonatotricopper(II) pentahydrate, [Cu3(C3H2O4)2Cl2(C6H6N4)4]·5H2O or [Cu(H2biim)2(µ-Cl)Cu0.5(mal)]2·5H2O, aqua(2,2'-biimidazole)malonatocopper(II) dihydrate, [Cu(C3H2O4)(C6H6N4)(H2O)]·2H2O or [Cu(H2biim)(mal)(H2O)]·2H2O, bis[aquabis(2,2'-biimidazole)copper(II)] dimalonatodiperchloratocopper(II) 2.2-hydrate, [Cu(C6H6N4)2(H2O)]2[Cu(C3H2O4)(ClO4)2]·2.2H2O or [Cu(H2biim)2(H2O)]2[Cu(mal)2(ClO4)2]·2.2H2O, and bis(2,2'-biimidazole)copper(II) bis[bis(2,2'-biimidazole)(2-carboxyacetato)malonatocopper(II)] tridecahydrate, [Cu(C6H6N4)2][Cu(C3H2O4)(C3H3O4)(C6H6N4)2]·13H2O or [Cu(H2biim)2][Cu(H2biim)2(Hmal)(mal)]2·13H2O. These assemblies are characterized by self-complementary donor-acceptor molecular interactions, demonstrating a recurrent and distinctive pattern of hydrogen-bonding preferences among the carboxylate, carboxylic acid and N-H groups of the coordinated 2,2'-biimidazole and malonate ligands. Additionally, coordination of the carboxylate group with the metallic centre helps sustain remarkable supramolecular assemblies, such as layers, helices, double helix columns or 3D channeled architectures, including mixed-metal complexes, into a single structure.

Effect of Terminal Hydroxy Groups on the Structural Properties of Acyl Thioureas.

The 1-acyl thiourea family [R1C(O)NHC(S)NR2R3] exhibits the flexibility to incorporate a wide variety of substituents into their structure. The structural attributes of these compounds are intricately tied to the type and extent of substitution. In the case of 3-mono-substituted thioureas (R2=H), the conformational behavior is predominantly shaped by the presence of an intramolecular N-H ⋅ ⋅ ⋅ O=C hydrogen bond. This study delves into the structural consequences stemming from the inclusion of substituents possessing hydrogen-donor capabilities within four novel 1-acyl-3-mono-substituted thiourea derivatives. A comprehensive suite of analytical techniques, encompassing FTIR, Raman spectroscopy, multinuclear (1H and 13C) NMR spectroscopy, single-crystal X-ray diffraction, and supported by computational methods, notably NBO (Natural Bond Orbital) population analysis, Hirshfeld analysis, and QTAIM (Quantum Theory of Atoms in Molecules), was harnessed to scrutinize and characterize these compounds. In the crystalline state, these compounds exhibit an intricate interplay of intermolecular interactions, prominently featuring an expansive network of hydrogen bonds between the hydroxy (-OH) groups and the carbonyl and thiocarbonyl bonds within the 1-acyl thiourea fragment. Notably, the topological analysis underscores significant distinctions in the properties of the acyl thiourea fragment and the intramolecular >C=O ⋅ ⋅ ⋅ H-N bond when transitioning from the isolated molecule to the crystalline environment.

In vitro assessment of NaF/Chit supramolecular complex: Colloidal stability, antibacterial activity and enamel protection against S. mutans biofilm.

OBJECTIVES: This study assessed the effect of NaF/Chit suspensions on enamel and on S. mutans biofilm, simulating application of a mouthrinse. METHODS: The NaF/Chit particle suspensions were prepared at molar ratio [NaF]/Chitmon]≈0.68 at nominal concentrations of 0.2 % and 0.05 % NaF and characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering and zeta potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. The S. mutans biofilm was formed for 7 days on eighty human enamel blocks that were divided into eight groups (n = 10/group): i) 0.05 % NaF solution; ii) 0.31 % Chit solution; iii) NaF/Chit(R=0.68) suspension at 0.05 % NaF; iv) 1.0 % HAc solution (Control); v) 0.2 % NaF solution; vi) 1.25 % Chit solution; vii) NaF/Chit(R=0.68) suspension at 0.2 % NaF; viii) 0.12 % chlorhexidine digluconate. The substances were applied daily for 90 s. S. mutans cell counts (CFU/mL) were performed, and the Knoop microhardness (KHN) of enamel samples were measured before and after biofilm formation. The KHN and CFU/mL data were analyzed by repeated measure ANOVA and Tukey's test (α = 0.05). RESULTS: Interactions between NaF and Chit were evidenced in solid state by FTIR spectra. The NaF/Chit complexes showed spontaneous microparticle formation and colloidal stability. The MIC and MBC ranged from 0.65 to 1.31 mg/mL. The NaF/Chit(R=0.68) suspension at 0.2 %NaF Group showed lower CFU/mL values than other groups. The NaF/Chit(R=0.68) suspensions Groups had the highest KHN values after biofilm formation. CONCLUSIONS: The NaF/Chit(R=0.68) complexes exhibited an antibacterial effect against S. mutans biofilm and reduced the enamel hardness loss. CLINICAL SIGNIFICANCE: The NaF/Chit(R=0.68) suspensions showed potential to be used as a mouthrinse for caries prevention.

Probing Self-Assembly of Ammeline in Chloroform and Aqueous Media: Interplay Between Hydrogen Bonding Diversity and Dimerization.

Ammeline (AM) is a molecule with a very low reputation in the field of supramolecular community, but with a recently proven potential both experimentally and theoretically. In this work, dispersion-corrected density functional theory (DFT-D) computations and molecular dynamics (MD) simulations were employed to understand the aggregation mechanism of AM in chloroform and water media. Our DFT-D and MD analyzes show that the most important interactions are those formed by the amine groups (-NH2) with both the pyridine-type nitrogen atoms and the carbonyl groups (C=O). In the more polar solvent, the interactions between water molecules and the C=O group prevent the AM from forming more interactions with itself. Nevertheless, four types of dimers involving N-H∙∙∙O interactions were found to exist in water solutions. The overlooked tetrel bond between endocyclic N and C atoms can also stabilize dimers in solution. Moreover, while most AM dimers are enthalpy-driven, our results indicate that the unique DD-AA dimer (D=donor, A=acceptor) that originates cyclic rosettes is entropy-driven.

Bioactivity and Bioavailability of Carotenoids Applied in Human Health: Technological Advances and Innovation.

This article presents a groundbreaking perspective on carotenoids, focusing on their innovative applications and transformative potential in human health and medicine. Research jointly delves deeper into the bioactivity and bioavailability of carotenoids, revealing therapeutic uses and technological advances that have the potential to revolutionize medical treatments. We explore pioneering therapeutic applications in which carotenoids are used to treat chronic diseases such as cancer, cardiovascular disease, and age-related macular degeneration, offering novel protective mechanisms and innovative therapeutic benefits. Our study also shows cutting-edge technological innovations in carotenoid extraction and bioavailability, including the development of supramolecular carriers and advanced nanotechnology, which dramatically improve the absorption and efficacy of these compounds. These technological advances not only ensure consistent quality but also tailor carotenoid therapies to each patient's health needs, paving the way for personalized medicine. By integrating the latest scientific discoveries and innovative techniques, this research provides a prospective perspective on the clinical applications of carotenoids, establishing a new benchmark for future studies in this field. Our findings underscore the importance of optimizing carotenoid extraction, administration, bioactivity, and bioavailability methods to develop more effective, targeted, and personalized treatments, thus offering visionary insight into their potential in modern medical practices.

trans-Di-chlorido-bis-(secnidazole-κN 3)copper(II).

The use of acetic acid (HOAc) in a reaction between CuCl2·2H2O and secnid-azole, an active pharmaceutical ingredient useful in the treatment against a variety of anaerobic Gram-positive and Gram-negative bacteria, affords the title complex, [CuCl2(C7H11N3O3)2]. This compound was previously synthesized using ethanol as solvent, although its crystal structure was not reported [Betanzos-Lara et al. (2013 ▸). Inorg. Chim. Acta, 397, 94-100]. In the mol-ecular complex, the Cu2+ cation is situated at an inversion centre and displays a square-planar coordination environment. There is a hydrogen-bonded framework based on inter-molecular O-H⋯Cl inter-actions, characterized by H⋯Cl separations of 2.28 (4) Šand O-H⋯Cl angles of 175 (3)°. The resulting supra-molecular network is based on R2 2 (18) ring motifs, forming chains in the [010] direction.

Chlorido-(2-{(2-hy-droxy-eth-yl)[tris-(hy-droxy-meth-yl)meth-yl]amino}-ethano-lato-κ5 N,O,O',O'',O''')copper(II).

The title complex, [Cu(C8H18NO5)Cl] or [Cu(H4bis-tris-)Cl], was obtained starting from the previously reported [Cu(H5bis-tris-)Cl]Cl compound. The deprotonation of the amino-polyol ligand H5bis-tris {[bis-(2-hy-droxy-eth-yl)amino]-tris-(hy-droxy-meth-yl)methane, C8H19NO5} promotes the formation of a very strong O-H⋯O inter-molecular hydrogen bond, characterized by an H⋯O separation of 1.553 (19) Šand an O-H⋯O angle of 178 (4)°. The remaining hy-droxy groups are also engaged in hydrogen bonds, forming R 2 2(8), R 4 4(16), R 4 4(20) and R 4 4(22) ring motifs, which stabilize the triperiodic supra-molecular network.

Synthesis, characterization and structural analysis of complexes from 2,2':6',2''-terpyridine derivatives with transition metals.

The synthesis and structural characterization of three families of coordination complexes synthesized from 4'-phenyl-2,2':6',2''-terpyridine (8, Ph-TPY), 4'-(4-chlorophenyl)-2,2':6',2''-terpyridine (9, ClPh-TPY) and 4'-(4-methoxyphenyl)-2,2':6',2''-terpyridine (10, MeOPh-TPY) ligands with the divalent metals Co2+, Fe2+, Mn2+ and Ni2+ are reported. The compounds were synthesized from a 1:2 mixture of the metal and ligand, resulting in a series of complexes with the general formula [M(R-TPY)2](ClO4)2 (where M = Co2+, Fe2+, Mn2+ and Ni2+, and R-TPY = Ph-TPY, ClPh-TPY and MeOPh-TPY). The general formula and structural and supramolecular features were determinated by single-crystal X-ray diffraction for bis(4'-phenyl-2,2':6',2''-terpyridine)nickel(II) bis(perchlorate), [Ni(C21H15N3)2](ClO4)2 or [Ni(Ph-TPY)2](ClO4)2, bis[4'-(4-methoxyphenyl)-2,2':6',2''-terpyridine]manganese(II) bis(perchlorate), [Mn(C22H17N3O)2](ClO4)2 or [Mn(MeOPh-TPY)2](ClO4)2, and bis(4'-phenyl-2,2':6',2''-terpyridine)manganese(II) bis(perchlorate), [Mn(C21H15N3)2](ClO4)2 or [Mn(Ph-TPY)2](ClO4)2. In all three cases, the complexes present distorted octahedral coordination polyhedra and the crystal packing is determined mainly by weak C-H...π interactions. All the compounds (except for the Ni derivatives, for which FT-IR, UV-Vis and thermal analysis are reported) were fully characterized by spectroscopic (FT-IR, UV-Vis and NMR spectroscopy) and thermal (TGA-DSC, thermogravimetric analysis-differential scanning calorimetry) methods.

L-Lactate Electrochemical Biosensor Based on an Integrated Supramolecular Architecture of Multiwalled Carbon Nanotubes Functionalized with Avidin and a Recombinant Biotinylated Lactate Oxidase.

L-Lactate is an important bioanalyte in the food industry, biotechnology, and human healthcare. In this work, we report the development of a new L-lactate electrochemical biosensor based on the use of multiwalled carbon nanotubes non-covalently functionalized with avidin (MWCNT-Av) deposited at glassy carbon electrodes (GCEs) as anchoring sites for the bioaffinity-based immobilization of a new recombinant biotinylated lactate oxidase (bLOx) produced in Escherichia coli through in vivo biotinylation. The specific binding of MWCNT-Av to bLOx was characterized by amperometry, surface plasmon resonance (SPR), and electrochemical impedance spectroscopy (EIS). The amperometric detection of L-lactate was performed at -0.100 V, with a linear range between 100 and 700 µM, a detection limit of 33 µM, and a quantification limit of 100 µM. The proposed biosensor (GCE/MWCNT-Av/bLOx) showed a reproducibility of 6.0% and it was successfully used for determining L-lactate in food and enriched serum samples.

Synthesis, characterization and supra-molecular analysis for (E)-3-(pyridin-4-yl)acrylic acid.

The title compound, C8H7NO2, crystallizes as prismatic colourless crystals in space group P , with one mol-ecule in the asymmetric unit. The pyridine ring is fused to acrylic acid, forming an almost planar structure with an E-configuration about the double bond with a torsion angle of -6.1 (2)°. In the crystal, strong O-H⋯N inter-actions link the mol-ecules, forming chains along the [101] direction. Weak C-H⋯O inter-actions link adjacent chains along the [100] direction, generating an R 2 2(14) homosynthon. Finally, π-π stacking inter-actions lead to the formation of the three-dimensional structure. The supra-molecular analysis was supported by Hirshfeld surface and two-dimensional fingerprint plot analysis, indicating that the most abundant contacts are associated with H⋯H, O⋯H/H⋯O, N⋯H/H⋯N and C⋯H/H⋯C inter-actions.

Methyl N-{(1R)-2-[(meth-oxy-carbon-yl)-oxy]-1-phenyleth-yl}carbamate.

The title mol-ecule, C12H15NO5, is a methyl carbamate derivative obtained by reacting (R)-2-phenyl-glycinol and methyl chloro-formate, with calcium hydroxide as heterogeneous catalyst. Supra-molecular chains are formed in the [100] direction, based on N-H⋯O hydrogen bonds between the amide and carboxyl-ate groups. These chains weakly inter-act in the crystal, and the phenyl rings do not display significant π-π inter-actions.

Calixarenes and cyclodextrins as off- and on-fluorescence probes for carbazole.

Absorption and fluorescence spectra of the nitrogen polycyclic aromatic hydrocarbon carbazole (CZL) were analyzed with native cyclodextrins (CD;α,ß,γ); derivatizedCD(hydroxypropyl-ß-cyclodextrin,HPCD; methyl-ß-cyclodextrin,MeCD) and p-sulfonated calixarenes (SCAn, with n = 6 and 8) macrocycles. The results showed a slight increase in the absorbance ofCZLwithCD, but the mixture ofCZLwithSCAshowed lower absorption than the sum of the individual spectra. Also, changes in fluorescence were observed by adding the macrocycles, quenching withSCA, and significant increases withCD. The higher fluorescence enhancement was withHPCDrationalized as a complex formation with 1:1 stoichiometry, with an average value for the association constant (KA) of (12 ± 1) x 102M-1, and a quantum yield ratio between the complexedCZLand freeCZL(ΦCZL-HPCD/ΦCZL) of (1.56 ± 0.02) at neutral pH and 25.0 °C. These increases in fluorescence were used as an on-fluorescence switch to develop a supramolecular analytical method forCZLin aqueous samples. The best analytical parameters were inHPCD(LOD = 1.41 ± 0.01 ng mL-1). The method was validated in aqueous samples of river and tap water with recoveries between 96%-104%. The proposed supramolecular method is quick, direct, selective and represents an alternative and low-cost analysis method.

Distearoyl phosphatidylglycerol and dioleoyl phosphatidylglycerol increase the retention and reduce the toxicity of amphotericin B-loaded in nanoemulsions.

Aim: To develop nanoemulsions (NEs) loading amphotericin B (AmB) and to evaluate the influence of different excipients on the stability and the supramolecular organization, retention and toxicity of AmB. Materials & methods: The NEs were developed from different oils, surfactants, external media and anionic lipids (disteaoryl phosphatidylglycerol [DSPG] and dioleoyl phosphatidylglycerol [DOPG]). Their impact on the size, pH, zeta potential, AmB encapsulation efficiency, AmB retention and hemolytic potential of the NEs was evaluated. Results & conclusion: The use of soybean oil (lipid matrix), Span 80 (surfactant), phosphate buffer (external phase) and DSPG or DOPG (hydrophobic ion pair) provided better NE stability, higher AmB retention within the NEs and a safer formulation profile in hemolysis tests.

Self-assembling peptides: Perspectives regarding biotechnological applications and vaccine development.

Self-assembly involves a set of molecules spontaneously interacting in a highly coordinated and dynamic manner to form a specific supramolecular structure having new and clearly defined properties. Many examples of this occur in nature and many more came from research laboratories, with their number increasing every day via ongoing research concerning complex biomolecules and the possibility of harnessing it when developing new applications. As a phenomenon, self-assembly has been described on very different types of molecules (biomolecules including), so this review focuses on what is known about peptide self-assembly, its origins, the forces behind it, how the properties of the resulting material can be tuned in relation to experimental considerations, some biotechnological applications (in which the main protagonists are peptide sequences capable of self-assembly) and what is yet to be tuned regarding their research and development.

Exploring the Influence of Spacers in EDTA-ß-Cyclodextrin Dendrimers: Physicochemical Properties and In Vitro Biological Behavior.

The synthesis of a new family of ethylenediaminetetraacetic acid (EDTA) core dimers and G0 dendrimers end-capped with two and four ß-cyclodextrin (ßCD) moieties was performed by click-chemistry conjugation, varying the spacers attached to the core. The structure analyses were achieved in DMSO-d6 and the self-inclusion process was studied in D2O by 1H-NMR spectroscopy for all platforms. It was demonstrated that the interaction with adamantane carboxylic acid (AdCOOH) results in a guest-induced shift of the self-inclusion effect, demonstrating the full host ability of the ßCD units in these new platforms without any influence of the spacer. The results of the quantitative size and water solubility measurements demonstrated the equivalence between the novel EDTA-ßCD platforms and the classical PAMAM-ßCD dendrimer. Finally, we determined the toxicity for all EDTA-ßCD platforms in four different cell lines: two human breast cancer cells (MCF-7 and MDA-MB-231), human cervical adenocarcinoma cancer cells (HeLa), and human lung adenocarcinoma cells (SK-LU-1). The new EDTA-ßCD carriers did not present any cytotoxicity in the tested cell lines, which showed that these new classes of platforms are promising candidates for drug delivery.

Preparation and characterization of NaF/Chitosan supramolecular complex and their effects on prevention of enamel demineralization.

Fluoridated mouthrinse is indicated for individuals with high risk of caries. Chitosan (Chit) exhibits antibacterial properties, but little is known about its effects on enamel when combined with sodium fluoride (NaF) to form NaF/Chit supramolecular complexes. In our study, NaF/Chit supramolecular complexes structured as microparticles were synthetized and characterized, and their effects on human enamel were evaluated after cariogenic challenge simulating the daily mouthrinse use. Initially, NaF/Chit complex formation was investigated based on several titrations by measuring the zeta potential, electrical conductivity (κ), hydrodynamic diameter (Dh), viscosity (η) and heat flow (by isothermal titration calorimetry) against the molar ratio [NaF]/[Chitmonomer], which allowed us to identify the interactions between Chit-NaF with a stoichiometry of approximately 0.68. Spontaneous microparticle formation was observed. Samples of enamel blocks were prepared and divided into eight groups (n = 10/group): (i) 0.2% Chit; (ii) 0.2% NaF; (iii) 0.2% NaF/Chit suspension; (iv) 0.2% acetic acid; (v) 0.05% Chit; (vi) 0.05% NaF; (vii) 0.05% NaF/Chit suspension; and (viii) 0.05% acetic acid. Cariogenic challenge was performed in each sample by cycling in demineralization and remineralization solutions for 7 days. Before each demineralization cycle, the corresponding substances were passively applied daily for 90 s, even in groups with 0.02% concentration. After 7 days, samples were examined for Knoop hardness (KHN) measurements. The data were analyzed by repeated-measures ANOVA and Tukey tests (α = 0.05). The 0.2% NaF and 0.2% NaF/Chit groups showed higher KHNpost-challenge values than the other groups. The 0.2% NaF/Chit microparticle suspension reduced the enamel hardness loss after cariogenic challenge as effectively as the 0.2% NaF solution and demonstrated potential for use in a formulation with anti-caries effects.

Combining Polymer and Cyclodextrin Strategy for Drug Release of Sulfadiazine from Electrospun Fibers.

This study reports the fabrication of polymeric matrices through electrospinning using polymethyl methacrylate (PMMA) and poly(lactic-co-glycolic acid) (PLGA), biocompatible polymers commonly used in medical systems. These polymers were combined with an antibacterial drug, sulfadiazine sodium salt (SDS) or its supramolecular system formed with hydroxypropyl-ß-cyclodextrin (HPß/CD) at 1:1 molar ratio, aiming to assemble a transdermal drug delivery system. The formation of fibers was confirmed by scanning electron microscopy (SEM), and the fibers' surface properties were analyzed using contact angle and water vapor permeability techniques. Drug release tests and cell viability assays were performed to evaluate the potential toxicity of the material. SEM images demonstrated that the obtained fibers had nanoscale- and micrometer-scale diameters in PLGA and PMMA systems, respectively. The contact angle analyses indicated that, even in the presence of hydrophilic molecules (SDS and HPßCD), PMMA fibers exhibited hydrophobic characteristics, while PLGA fibers exhibited hydrophilic surface properties. These data were also confirmed by water vapor permeability analysis. The drug release profiles demonstrated a greater release of SDS in the PLGA system. Moreover, the presence of HPßCD improved the drug release in both polymeric systems and the cell viability in the PMMA SDS/HPßCD system. In terms of antibacterial activity, all membranes yielded positive outcomes; nevertheless, the PLGA SDS/HPßCD membrane exhibited the most remarkable results, with the lowest microbial load values. Additionally, the pseudo wound healing analysis demonstrated that the PLGA SDS/HPßCD fiber exhibited results similar to the control group. Consequently, these findings exemplify the substantial potential of the obtained materials for use in wound healing applications.

Reduced Graphene Oxide as a Platform for the Immobilization of Amino-Cyclodextrins.

In the present work, we reported on a method to combine amino ß-cyclodextrins (CD1) with reduced graphene oxide (obtained by the electrochemical reduction of graphene oxide, erGO) to produce a glassy carbon electrode (GCE) modified with both CD1 and erGO (CD1-erGO/GCE). This procedure avoids the use of organic solvents such as hydrazine or long reaction times and high temperatures. The material combining both CD1 and erGO (CD1-erGO/GCE) was characterized by SEM, ATR-FTIR, Raman, XPS, and electrochemical techniques. As proof-of-concept, the determination of the pesticide carbendazim was carried out. The spectroscopic measurements, especially XPS, proved that CD1 was covalently attached to the surface of the erGO/GCE electrode. The attachment of cyclodextrin at the reduced graphene oxide produced an increase in the electrochemical behavior of the electrode. The cyclodextrin-functionalized reduced graphene oxide, CD1-erGO/GCE, showed a larger sensitivity (1.01 µA/µM) and a lower limit of detection for carbendazim (LOD = 0.50 µM) compared with the non-functionalized material, erGO/GCE, (sensitivity = 0.63 µA/µM and LOD = 4.32 µM, respectively). Overall, the results of the present work show that this simple method is suitable to attach cyclodextrins to graphene oxide, maintaining their inclusion abilities.

Spectroscopic Insights of an Emissive Complex between 4'-N,N-Diethylaminoflavonol in Octa-Acid Deep-Cavity Cavitand and Rhodamine 6G.

Excited-state chemistry relies on the communication between molecules, making it a crucial aspect of the field. One important question that arises is whether intermolecular communication and its rate can be modified when a molecule is confined. To explore the interaction in such systems, we investigated the ground and excited states of 4'-N,N-diethylaminoflavonol (DEA3HF) in an octa acid-based (OA) confined medium and in ethanolic solution, both in the presence of Rhodamine 6G (R6G). Despite the observed spectral overlap between the flavonol emission and the R6G absorption, as well as the fluorescence quenching of the flavonol in the presence of R6G, the almost constant fluorescence lifetime at different amounts of R6G discards the presence of FRET in the studied systems. Steady-state and time-resolved fluorescence indicate the formation of an emissive complex between the proton transfer dye encapsulated within water-soluble supramolecular host octa acid (DEA3HF@(OA)2) and R6G. A similar result was observed between DEA3HF:R6G in ethanolic solution. The respective Stern-Volmer plots corroborate with these observations, suggesting a static quenching mechanism for both systems.

2-[3-(1H-Benzimidazol-2-yl)prop-yl]-1H-benzimidazol-3-ium 3,4,5-tri-hydroxy-benzoate-1,3-bis-(1H-benzimidazol-2-yl)propane-ethyl acetate (2/1/2.94): co-crystallization between a salt, a neutral mol-ecule and a solvent.

The chemical formula of the title compound, 2C17H17N4 +·2C7H5O5 -·C17H16N4·2.94C4H8O2, was established by X-ray diffraction of a single-crystal obtained by reacting 1,3-bis-(benzimidazol-2-yl)propane (L) and gallic acid (HGal) in ethyl acetate. The mol-ecular structure can be described as a salt (HL)+(Gal)- co-crystallized with a mol-ecule L, with a stoichiometric relation of 2:1. Moreover, large voids in the crystal are filled with ethyl acetate, the amount of which was estimated by using a solvent mask during structure refinement, affording the chemical formula (HL +·Gal-)2·L·(C4H8O2)2.94. The arrangement of components in the crystal is driven by O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds rather than by π-π or C-H⋯π inter-actions. In the crystal, mol-ecules and ions shape the boundary of cylindrical tunnels parallel to [100] via R (rings) and D (discrete) supra-molecular motifs. These voids, which account for about 28% of the unit-cell volume, contain disordered solvent mol-ecules.