Influence of the attachment of a gold(I) phosphine moiety at the upper rim of a calix[4]pyrrole on the binding of tetraalkylammonium chloride salts

We report the synthesis of an unprecedent mono-gold(I) phosphine complex based on a 'two wall' aryl-ethynyl extended calix[4]pyrrole. We describe and compare the binding properties of the parent 10α,20α-bis-aryl-ethynyl calix[4]pyrrole ligand and the prepared organometallic compound as receptors for tetraalkylammonium chloride salts in dichloromethane and acetone solutions. We describe the results of 1H NMR, UV-vis titrations and isothermal titration calorimetry (ITC) experiments in DCM and acetone solution, aiming at thermodynamically characterize the formed complexes. The obtained results indicate a noticeable decrease in the binding affinity of the chloride for the mono-gold(I) receptor 1 compared to the parent ligand 2. The increase in the negative value of the electrostatic surface potential at the center of the aromatic ring of the gold(I) meso-aryl-ethynyl substituent serves to explain the observed results and the presence in solution of the chloride complex of 1 as a mixture of two conformers

Current Addiction in Youth : Online Sports Betting

Background: Gambling landscape has changed in recent years with the emergence of online gambling (OG). Greater accessibility and availability of this betting modality can increase the risk of developing a gambling disorder (GD). Online sports betting (OSB) is currently the most common type of OG, but little is known about the clinical characteristics of OSB compared to slot-machine (SM) gamblers, the most common offline gambling disorder. Methods: This was a prospective study conducted between October 2005 and September 2019, and included outpatients diagnosed with GD seen in a Pathological Gambling and Behavioral Addictions referral unit. Only patients with OSB and SM disorders were included. The main objective was to assess the clinical profile of OSB compared to SM gamblers, and to define clinical predictors for developing OSB gambling disorder. Logistic regression was performed to determine the effects of variables on the likelihood of this disorder. Results: Among 1,186 patients attended in our Unit during the study period, 873 patients were included; 32 (3.7%) were OSB gamblers and 841 (96.3%) were SM gamblers. Overall, mean age was 45 ± 13 years and 94.3% were men. Compared to SM patients, OSB patients were younger (34.9 ± 9.5 vs. 45.3 ±13), more frequently single (43.8 vs. 20.6%) and had a university education level (43.8 vs. 4.5%); they were also more frequently non-smokers (18.7 vs. 66.7%) and had fewer psychiatric comorbidities (12.5 vs. 29.4%) than SM gamblers. GD duration before treatment initiation was shorter in OSB patients than in SM gamblers, most of them (81.3 vs. 42.4%) with ≤ 5 years of GD duration. OSB gamblers showed significant differences in weekly gambling expenditure, spending higher amounts than SM patients. Younger age (OR: 0.919; 95% CI: 0.874-0.966), university education level (OR: 10.658; 95% CI: 3.330-34.119), weekly expenditure >100€ (OR: 5.811; 95% CI:1.544-21.869), and being a non-smoker (OR:13.248; 95% CI:4.332-40.517) were associated with an increased likelihood of OSB gambling behavior. Conclusions: We identified different profiles for OSB and SM gamblers. Younger age, university education level, higher weekly expenditure, and non-smoking habit were associated with OSB compared to SM disorders. Prevention strategies should help young people become aware of the severe risks of OSB

El fondo personal Emili Teixidor como experiencia de trabajo conjunto entre Biblioteca y Archivo

The article describes the collaborative experience between the Library and the Archive of the University of UVic-UCC in the processing and dissemination of Emili Teixidor’s Personal Archive. Teixidor, a renowned Catalan writer, bequeathed his personal library and various documents. Both services developed a work plan that encompassed defining the collection, the method of acquisition, required facilities, and the purchase of preservation materials. Additionally, a comprehensive dissemination plan was implemented, including cataloguing the bibliographic collection, publishing a guide, digitizing photographs, organizing exhibitions, and engaging in external collaborations. The collaboration between the Library and the Archive was crucial in ensuring proper processing and access to the collection, thereby preserving Emili Teixidor’s memory and cultural legacy.El artículo describe la experiencia de colaboración entre la Biblioteca y el Archivo de la Universidad de Vic – UCC en el tratamiento y difusión del Fondo personal de Emili Teixidor. El legado de Teixidor, reconocido escritor catalán, incluye su biblioteca personal y diversos documentos. Ambos servicios elaboraron un plan de trabajo que abarcó la definición del fondo, el método de adquisición, las instalaciones necesarias y la compra de material de preservación. Además, se desarrolló un plan de difusión que incluyó la catalogación del fondo bibliográfico, la publicación de una guía, la digitalización de fotografías, exposiciones y colaboraciones externas. La colaboración entre la Biblioteca y el Archivo fue fundamental para garantizar un adecuado tratamiento y acceso al fondo, preservando así la memoria y el legado cultural de Emili Teixidor

Palladium-Mediated Catalysis Leads to Intramolecular Narcissistic Self-Sorting on a Cavitand Platform

Palladium-catalyzed aminocarbonylation reactions have been used to directly convert a tetraiodocavitand intermediate into the corresponding carboxamides and 2-ketocarboxamides. When complex mixtures of the amine reactants are employed in competition experiments, no ‘mixed’ products possessing structurally different amide fragments are detected either by 1H or 13C NMR. Only highly symmetrical cavitands are sorted out of a large number of potentially feasible products, which represents a rare example of intramolecular, narcissistic self-sorting. The reactivity order of the amine reactants and the changes in the Gibbs energies calculated using the semiempirical PM6 model suggest that this self-sorting process is kinetically controlled

Screen-printed electrodes incorporated in a flow system for the decentralized monitoring of lead, cadmium and copper in natural and wastewater samples

Mercury-based screen-printed electrodes (SPE) combined with square-wave anodic stripping voltammetry (SWASV) techniques for the analysis of copper, cadmium, lead, and zinc in different water samples have been applied. The detection system has been implemented in a flow cell and different experimental conditions have been tested in view of its application for in-situ monitoring. In particular, an acetate buffer together with a low chloride concentration (0.025 M NaCl) provided best performance and reproducible results. Additionally, the flow system was validated for the first time in terms of limits of detection, linearity, repeatability and recovery. Limits of detection of 2.8 μg L-1, 4.1 μg L-1, and 7.5 μg L-1 for cadmium, lead and copper respectively and repeatabilities lower than 10% (as RSD) were found. Good recoveries have been obtained for the three cations and in particular for copper, even in the presence of zinc. Finally, the method has shown its efficiency for the rapid screening of lead, cadmium and copper contained in both natural waters and wastewater samples. © 2013 Copyright Taylor and Francis Group, LLC.Financial support from CTQ2008-06847-C02-02/TECNO, MAT2008-03079/NAN and WARMER project (FP6-034472) are acknowledged.Peer Reviewe

Recent Trends in Macro-, Micro-, and Nanomaterial-Based Tools and Strategies for Heavy-Metal Detection

26 páginas, 17 figuras, 3 tablas.The financial support of the Spanish Ministry of Science and Innovation through projects MAT-2008-128 03079NAN are acknowledged. G.A. thanks the Generalitat de Catalunya for the predoctoral fellowship (FI 2009).Peer reviewe

Resolving the magnetic asymmetry of the inner space in self-assembled dimeric capsules based on tetraurea-calix[4]pyrrole components

The encapsulation of N,N, N&#39;,N&#39;-tetramethyl-1,5-pentanediamine-N,N&#39;-dioxide 2 in a non-chiral capsular assembly formed by dimerization of tetraurea-calix[4]pyrrole 1a produced the observation of the N-methyl groups of the encapsulated guest as two separated singlets resonating highly upfield in the 1H NMR spectrum. In order to clarify the origin of the observed signal splitting we assembled and studied a series of structurally related dimeric capsules. We used the tetraurea-calix[4]pyrrole 1a , the enantiomerically pure tetraurea-calix[4] pyrrole R-1b and the tetraurea-bisloop calix[4]pyrrole 1c as components of the produced assemblies. The 1H NMR spectra of the assembled encapsulation complexes with bis-N-oxide 2 evidenced diverse splitting patterns of the N-methyl groups. In addition, 2D EXSY/ROESY NMR experiments revealed the existence of chemical exchange processes involving the separated methyl signals of the encapsulated guest. The capsular assemblies were mainly stabilized by a belt of eight head-to-tail hydrogen-bonded urea groups. The interconversion between the two senses of rotation of the unidirectionally oriented urea groups was slow on the 1H NMR timescale. These characteristics determined the appearance of a new asymmetry element (supramolecular conformational chirality) in the assemblies that accounted for some of the magnetic asymmetries featured by the capsule&#39;s inner space. The racemization of the supramolecular chirality element was fast on the EXSY timescale and produced the chemical exchange processes detected for the encapsulation complexes.</p

Study of the coordination of quinuclidine to a chiral zinc phthalocyanine dimer

We attempted the calculation of an accurate equilibrium constant for the dimerization process of enantiomerically pure Zn-1 using UV-vis dilution experiments. At millimolar concentration Zn-1 is involved in a chemical exchange process between its monomeric and dimeric state that is slow on the 1H NMR timescale. We performed variable-temperature 1H NMR experiments in CDCl3 solution to determine the dimerization constant value at different temperatures and performed a van&rsquo;t Hoff plot to derive the thermodynamic parameters of the process. The calculated thermodynamic data revealed that the dimerization process is entropy-driven and enthalpically opposed. We also probed the coordination of quinuclidine, 1-azabicyclo[2.2.2]octane, 2, to the Zn-phthalocyanine using UV-vis and 1H NMR titrations in CDCl3 solution. At micromolar concentration the Zn-1 exclusively exists in solution as a monomer and forms a simple 1:1, 2&bull;1-Zn, complex with quinuclidine having a stability constant of K(2&bull;1-Zn) = 106 M-1. On the other hand, the 1H NMR titrations carried out at 298 K and at millimolar concentration showed that Zn-1 was present in solution as the dimer and formed 2:1, 2&bull;(1-Zn)2, and 2:2, 22&bull;(1-Zn)2, complexes by coordination to 2. In addition, the 1:1 complex, 2&bull;(1-Zn), showed a reduced dimerization constant compared to the uncoordinated parent monomer 1-Zn. At high quinuclidine concentration, the 1:1 complex, 2&bull;1-Zn, derived from the coordinated dimer dissociation was also detected. The 1H NMR spectra of the titrations displayed separate signals for some hydrogen atoms of the Zn-phthalocyanine in each one of the four species. Remarkably, the chemical exchange processes involving free and bound quinuclidine in the monomeric and dimeric complexes showed different kinetics on the NMR timescale.</p

Switching from Negative-Cooperativity to No-Cooperativity in the Binding of Ion-Pair Dimers by a Bis(calix[4]pyrrole) Macrocycle

We report the synthesis of a macrocyclic receptor containing two di-meso-phenylcalix[4]pyrrole units linked by two triazole spacers. The 1,4-substitution of the 1,2,3-triazole spacers conveys different binding affinities to the two heteroditopic binding sites. These features make the receptor an ideal candidate to investigate allosteric cooperativity in the binding of ion-pair dimers. We probed the interaction of tetraalkylammonium salts (TBA·Cl, TBA·OCN, and MTOA·Cl) with the tetra-heterotopic macrocyclic receptor in chloroform solution using 1H NMR spectroscopic titration experiments. The results obtained show that, at millimolar concentration, the addition of 2 equiv of the salt to the receptor’s solution induced the quantitative pairwise binding of the ion-pairs. The 2:1 (ion-pair:receptor) complexes feature different binding geometries and binding cooperativities depending on the nature of the alkylammonium cation. The binding geometries assigned to the complexes of the ion-pair dimers in solution are fully supported by X-ray diffraction analyses of single crystals. The thermodynamic features of the binding processes (separate or concomitant formation of 1:1 and 2:1 complexes), derived from isothermal titration calorimetry (ITC) experiments, are rationalized by combining the different ion-pair binding modes of the salt dimers with the dissimilar electronic properties of the two nearby heteroditopic binding sites of the receptor

Unexpected Emission Properties of a 1,8-Naphthalimide Unit Covalently Appended to a Zn-Salophen

We report the synthesis, characterization, and binding properties of a Zn&ndash;salophen complex, 1a, functionalized with a 1,8-naphthalimide unit. Unexpectedly, the emission spectrum of 1a shows a remarkable quenching of the band assigned to the naphthalimide unit. To better understand this phenomenon, a supramolecular model system constituted by a symmetric Zn&ndash;salophen and a pyridyl derivative of 1,8-naphthalimide, 1b&middot;2a, was investigated. We propose the existence of a photoinduced energy transfer process between the naphthalimide (donor) and the salophen (acceptor) units in 1b&middot;2a. A similar process must be operative in the covalent receptor 1a. Nevertheless, the results deriving from steady-state fluorescence experiments do not rule out the occurrence of a photoinduced electron transfer process as alternative pathway for the quenching. We also describe the chemosensing properties of receptor 1a and the supramolecular system 1b&middot;2a towards acetate. The nonsymmetrically substituted salophen receptor 1a only transduces the binding of the anion to the Zn metal center in significant spectroscopic changes in its absorption spectrum. On the other hand, we exploit the strong emission quenching experienced by the naphthalimide component in the supramolecular complex 1b&middot;2a to detect anions (e.g. acetate) by means of a typical &ldquo;turn-on&rdquo; fluorescent indicator displacement assay.</p