Crystallographic Evidence for Bi(I) as the Heaviest Halogen Bond Acceptor.

Complexation of the green bismuthinidene (RBi) with two equivalents of a highly fluorinated aryl iodide at low temperature allows the crystallographic identification of an unstable red species that can be regarded as an intermediate in an overall Bi(I) → Bi(III) oxidation process. Both C-I bonds are orientated toward the filled 6p orbital of bismuth (Bi-I distances 3.44-3.52 Å), leading to an elongation of the C-I bonds by 0.05 and 0.07 Å. Density functional theory (DFT) calculations confirm that the Bi(I) center is indeed acting as an electron donor, establishing two strong and directional halogen bonds. The color change from green to red upon halogen bond formation is a consequence of the energetic stabilization of a Bi(I) lone pair by interactions with the sigma-holes of the halogen bond donors. Overall, this study presents the first structural proof of bismuth, and more generally of heavy organopnictogen(I) compounds, acting as halogen bond acceptors.

Drug therapy and catheter ablation for management of arrhythmias in continuous flow left ventricular assist device's patients. A Clinical Consensus Statement of the European Heart Rhythm Association and the Heart Failure Association of the ESC.

Left ventricular assist devices (LVADs) are an increasingly used strategy for the management of patients with advanced heart failure. Although these devices effectively improve survival, atrial and ventricular arrhythmias are common with a prevalence of 20-50% at one year after LVAD implantation. Arrhythmias predispose these patients to additional risk and are associated with considerable morbidity from recurrent implantable cardioverter-defibrillator (ICD) shocks, progressive failure of the unsupported right ventricle, and herald an increased risk of mortality. Management of patients with arrhythmias and LVAD differs in many aspects from the general population heart failure patients. These include ruling out the reversible causes of arrhythmias that in LVAD patients may include mechanical irritation from the inflow cannula and suction events. For patients with symptomatic arrhythmias refractory to medical treatment, catheter ablation might be relevant. There are specific technical and procedural challenges perceived to be unique to LVAD-related ventricular tachycardia ablation such as vascular and LV access, signal filtering, catheter manoeuvrability within decompressed chambers, and electroanatomic mapping system interference. In some patients, the arrhythmogenic substrate might not be readily accessible by catheter ablation after LVAD implantation. In this regard, the peri-implantation period offers a unique opportunity to surgically address arrhythmogenic substrate and suppress future ventricular tachycardia recurrences. This document aims to address specific aspects of the management of arrhythmias in LVAD patients focusing on anti-arrhythmic drug therapy and ablations.

Synthesis, Structural Characterization, and Theoretical Analysis of Nonconventional Bonding in Dinuclear Zinc(II) Complexes with Tridentate Schiff Bases.

Two tridentate N,N,O-donor ligands, HL1 = 4-chloro-2-(((2-(methylamino)ethyl)amino)methyl)phenol and HL2 = 4-chloro-2-(((2-(dimethylamino)ethyl)amino)methyl)phenol, have been used to synthesize phenolate-bridged dinuclear complexes [Zn2(L1)2Cl2] (1) and [Zn2(L2)2(N3)2] (2). Single-crystal X-ray diffraction analysis confirmed their structures. Both complexes form assemblies in the solid state. Moreover, the existence of nonconventional spodium bonds in 1 and tetrel bonds in 2 has been explored using theoretical calculations, including MEP surface plots and QTAIM and NCIplot analyses.

Reaction contest: hydrolysis versus intramolecular cyclisation reaction in alkyl squaramate esters.

The stability and hydrolytic behavior of squaramate esters in aqueous solutions have been investigated. The structure of squaramates and the nature of adjacent groups significantly influence their aqueous stability and reactivity towards nucleophiles. Squaramate esters, lacking or containing weakly basic neighboring group participation (NGP) substitutions, remain stable up to pH 9. Their hydrolysis rate (k OH ≈ 10-1 M-1 s-1) is 1000 times faster than that of squaramides, following a second-order rate law. Squaramate esters functionalized with basic NGP groups, such as amines, display a pH-dependent hydrolysis rate due to anchimeric assistance of the terminal amino group, reducing stability to pH 5. However, when the squaramate ester has a terminal nucleophilic group in the γ position of the alkyl chain, it undergoes rapid intramolecular cyclization, forming cyclic squaramides.

Cardiac resynchronization therapy in heart failure based on Strauss criteria for left bundle branch block.

AIMS: The left bundle branch block (LBBB) is a strong predictor of response to cardiac resynchronization therapy (CRT). However, a significant number of patients do not respond to the treatment. The study sought to evaluate the impact of the stricter Strauss criteria for left bundle branch block (St-LBBB) on CRT response, hospitalizations, ventricular arrhythmia (VA) events and mortality. METHODS: This study is a retrospective analysis of prospectively collected data on heart failure (HF) patients with LBBB admitted for CRT implantation. Patients were divided into two groups according to the fulfilment or not of St-LBBB criteria. RESULTS: The study included 82 patients with ischaemic (ICM) and non-ischaemic (NICM) cardiomyopathy [46 (56%) with St-LBBB and 36 (44%) with non-St-LBBB]. Patients with St-LBBB showed higher CRT response rates compared with those with non-St-LBBB (P < 0.01), while the group with NICM exhibited the greatest benefit (P < 0.01). St-LBBB CRT responders displayed significantly lower rates of HF hospitalization (P < 0.0001) compared with the non-St-LBBB group. According to Kaplan-Meier time curves, this was primarily evident in patients with NICM (P < 0.0001). CRT responders displayed significantly fewer VA events (P < 0.001) and lower mortality rates (P < 0.0001) than non-responders. Kaplan-Meier estimates demonstrated a significantly lower incidence of VAs in NICM patients with St-LBBB (P = 0.049) compared with ICM patients with St-LBBB (P = 0.25). Lower mortality rates were observed in CRT responders than non-responders (P < 0.0001), with the group of NICM with St-LBBB criteria exhibiting the greatest benefit (P = 0.0238). CONCLUSIONS: Patients with NICM and St-LBBB present the greatest benefit concerning CRT response, HF hospitalizations, VA events and mortality. Although St-LBBB criteria seem to improve patient selection for CRT, more data are needed to elucidate the role of St-LBBB criteria in this setting.

Impact of halogen⋯halogen interaction on the mechanical motion of a 3D Pb(II) coordination polymer of elusive topology.

Herein, we report the synthesis of a Pb(II) based three-dimensional coordination polymer (3D CP), [Pb(DCTP)]n (1) [H2DCTP = 2,5-dichloroterephthalic acid] with an unprecedented topology, which exhibits a photomechanical effect wherein crystals show jumping upon UV irradiation. The Pb(II) CP forms a type II Cl⋯Cl interaction, which weakens further upon UV irradiation to resolve the anisotropic mechanical strain. The work presented here could be a beacon to the nascent field of photoactuating smart materials.

A Nanosized Porous Supramolecular Lead(II)-N'-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide Aggregate, Obtained Under Electrochemical Conditions.

A novel nanosized porous supramolecular nonanuclear complex [Pb9(HL)12Cl2(ClO4)](ClO4)3·15H2O·a(solvent) (1·15H2O·a(solvent)) is reported that was synthesized by electrochemical oxidation of a Pb anode under the ambient conditions in a CH3CN:MeOH solution of N'-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide (H2L), containing [N(CH3)4]ClO4 as a current carrier. The supramolecular aggregate of 1 is enforced by a myriad of Pb···S tetrel bonds (TtBs) established with the thiocarbonyl sulfur atoms of adjacent species, which have been also analyzed by DFT calculations via 2D maps of ELF, Laplacian and RDG properties. Moreover, Pb···Cl TtBs with the central Cl- anion, and Pb···O TtBs with the three oxygen atoms of the ClO4- anion, were revealed. Notably, the molecular structure of 1 differs significantly from that recently reported by us [Pb2(HL)2(CH3CN)(ClO4)2]·2H2O (2·2H2O), which was obtained using a conventional synthetic procedure by reacting Pb(ClO4)2 with H2L in the same CH3CN:MeOH solution, thus highlighting a crucial role of the electrochemical conditions. The optical characteristics of the complex were investigated using UV-vis spectroscopy and spectrofluorimetry in methanol. The complex was found to be emissive when excited at 304 nm, producing a broad emission band ranging from approximately 420 to 600 nm with multiple peaks. The CIE-1931 chromaticity coordinates, calculated as (0.33, 0.24), suggest that the emission lies in the white region of the chromaticity diagram. Further investigation is needed to fully characterize the origin of this emission.

Functional substrate in patients with atrial fibrillation is predictive of recurrences after catheter ablation.

BACKGROUND: Enhanced characterization of the atrial electrical substrate may lead to better comprehension of atrial fibrillation (AF) pathophysiology. OBJECTIVE: With the use of high-density substrate mapping, we sought to investigate the occurrence of functional electrophysiologic phenomena in the left atrium and to assess potential association with arrhythmia recurrences after catheter ablation. METHODS: Sixty-three consecutive patients with AF referred for ablation were enrolled. Analysis of conduction abnormalities relied on 2 acquired left atrial electroanatomic maps (sinus and atrial paced rhythm). We classified conduction abnormalities as fixed (if these were present in both rhythms) or functional rhythm dependent (if unmasked in 1 of the 2 rhythms). Esophagus and aorta locations were recorded to check the correspondence with abnormal conduction sites. RESULTS: There were 234 conduction abnormalities detected, of which 125 (53.4%) were functional rhythm dependent. The most frequent anatomic site of functional phenomena was the anterior wall, followed by the posterior wall, in sinus rhythm and the pulmonary venous antra in paced rhythm. Sites of functional phenomena in 82.6% of cases corresponded with extracardiac structures, such as sinus of Valsalva of ascending aorta anteriorly and the esophagus posteriorly. Most (88%) areas with functional phenomena had normal bipolar voltage. After pulmonary vein ablation, the number of residual functional phenomena is an independent predictor of AF recurrence (hazard ratio, 2.539 [1.458-4.420]; P = .001) with a risk of recurrences at multivariable Cox analysis. CONCLUSION: Dual high-density mapping (during sinus and paced rhythms) is able to unmask functional, rhythm-dependent phenomena that are predictive of AF recurrences during follow-up.

Synthesis, structural characterization, and theoretical analysis of novel zinc(ii) schiff base complexes with halogen and hydrogen bonding interactions.

In this article, we present the synthesis and characterization of three zinc(ii) complexes, [ZnII(HL1)2] (1), [ZnII(HL2)2]·2H2O (2) and [ZnII(HL3)2] (3), with three tridentate Schiff base ligands, H2L1, H2L2, and H2L3. The structures of the complexes were confirmed by single-crystal X-ray diffraction analysis. DFT calculations were performed to gain insights into the self-assembly of the complexes in their solid-state structures. Complex 1 exhibits dual halogen-bonding interactions (Br⋯Br and Br⋯O) in its solid-state structure, which have been thoroughly investigated through molecular electrostatic potential (MEP) surface calculations, alongside QTAIM and NCIPlot analyses. Furthermore, complex 2 features a fascinating hydrogen-bonding network involving lattice water molecules, which serves to link the [ZnII(HL2)2] units into a one-dimensional supramolecular polymer. This network has been meticulously examined using QTAIM and NCIplot analyses, allowing for an estimation of the hydrogen bond strengths. The significance of H-bonds and CH⋯π interactions in complex 3 was investigated, as these interactions are crucial for the formation of infinite 1D chains in the solid state.

Induction of ventricular fibrillation during programmed ventricular stimulation in a patient with CASQ2 heterozygous mutation.

INTRODUCTION: We report the case of a 37-year-old male athlete, who developed during exercise atrial and ventricular arrhythmias. No structural heart disease. RESULTS: Invasive programmed ventricular stimulation induced ventricular fibrillation. A heterozygous mutation in the CASQ2 gene (c.775G>T, p.E259X) was found. CONCLUSIONS: The findings in our patient may suggest some increased ventricular excitability using programmed ventricular stimulation in CASQ2 polymorphic ventricular tachycardia patients.

Key-to-lock halogen bond-based tetragonal pyramidal association of iodonium cations with the lacune rims of beta-octamolybdate.

The structure-directing "key-to-lock" interaction of double σ-(IIII)-hole donating iodonium cations with the O-flanked pseudo-lacune rims of [ß-Mo8O26]4- gives halogen-bonded iodonium-beta-octamolybate supramolecular associates. In the occurrence of their tetragonal pyramidal motifs, deep and broad σ-(IIII)-holes of a cation recognize the molybdate backbone, which provides an electronic pool localized around the two lacunae. The halogen-bonded I⋯O linkages in the structures were thoroughly studied computationally and classified as two-center, three-center bifurcated, and unconventional "orthogonal" I⋯O halogen bonds. In the latter, the O-atom approaches orthogonally the C-IIII-C plane of an iodonium cation and this geometry diverge from the IUPAC criteria for the identification of the halogen bond.

Incidence and predictors of post-surgery atrial fibrillation occurrence: A cohort study in 53,387 patients.

Introduction: Atrial fibrillation (AF) represents the most common arrhythmia in the postoperative setting. We aimed to investigate the incidence of postoperative AF (POAF) and determine its predictors, with a specific focus on inflammation markers. Methods: We performed a retrospective single tertiary center cohort study including consecutive adult patients who underwent a major surgical procedure between January 2016 and January 2020. Patients were divided into four subgroups according to the type of surgery. Results: Among 53,387 included patients (79.4% male, age 64.5 ± 9.5 years), POAF occurred in 570 (1.1%) with a mean latency after surgery of 3.4 ± 2.6 days. Ninety patients died (0.17%) after a mean of 13.7 ± 8.4 days. The 28-day arrhythmia-free survival was lower in patients undergoing lung and cardiovascular surgery (p < .001). Patients who developed POAF had higher levels of C-reactive protein (CRP) (0.70 ± 0.03 vs. 0.40 ± 0.01 log10 mg/dl; p < .001). In the multivariable Cox regression analysis, adjusting for confounding factors, CRP was an independent predictor of POAF [HR per 1 mg/dL increase in log-scale = 1.81 (95% CI 1.18-2.79); p = .007]. Moreover, independent predictors of POAF were also age (HR/1 year increase = 1.06 (95% CI 1.04-1.08); I < .001), lung and cardiovascular surgery (HR 23.62; (95% CI 5.65-98.73); p < .001), and abdominal and esophageal surgery (HR 6.26; 95% CI 1.48-26.49; p = .013). Conclusions: Lung and cardiovascular surgery had the highest risk of POAF in the presented cohort. CRP was an independent predictor of POAF and postsurgery inflammation may represent a major driver in the pathophysiology of the arrhythmia.

Intramural Hematoma and Acute Pulmonary Embolism Following Pacemaker Implantation: A Case Report.

Bleeding complications after pacemaker implantation pose risks, including infection and prolonged hospital stay. A case involving aortic intramural hematoma (IMH) arising from subclavian vein access during implantation and concomitant acute pulmonary embolism (PE) is presented. In the present case, IMH probably resulted from subclavian artery vasa vasorum trauma during vein puncture and guidewire advancement, leading to IMH and hemothorax. PE possibly stemmed from a prothrombotic state caused by the intervention and the IMH. Conservative management with serial CT scans was chosen due to hemodynamic stability and high surgical risk. IMH and PE resolution was confirmed at follow-up.

Introducing Cationic Selenium-Containing Triazapentadiene Ligand Framework: Synthesis, Coordination Chemistry, and Antifungal Activity.

Positively charged ligands are scarce. Here, we report the synthesis of unprecedented cationic selenium-containing triazapentadiene ligand framework. The reaction between 2-pyridylselenyl reagents and NaN(CN)2 in a 2:1 ratio produces the sodium complexes featuring the cationic selenium-containing triazapentadiene (SeTAP) ligand. The sodium-to-metal transmetalation allows facile preparation of SeTAP metal complexes, as exemplified by the reactions with CuCl2, AgNO3, NaAuCl4, and FeCl3. Density functional theory calculations have been used to analyze and characterize the chalcogen bonding interactions observed in the solid state for these compounds. Moreover, antifungal properties of the SeTAP ligand and its metal complexes were screened for in vitro activity against several phytopathogenic fungi. Phoma eupyrena exhibited prominent sensitivity against the action of most of the tested compounds.

Pnictogen-Bonding Enzymes.

The objective of this study was to create artificial enzymes that capitalize on pnictogen bonding, a σ-hole interaction that is essentially absent in biocatalysis. For this purpose, stibine catalysts were equipped with a biotin derivative and combined with streptavidin mutants to identify an efficient transfer hydrogenation catalyst for the reduction of a fluorogenic quinoline substrate. Increased catalytic activity from wild-type streptavidin to the best mutants coincides with the depth of the σ hole on the Sb(V) center, and the emergence of saturation kinetic behavior. Michaelis-Menten analysis reveals transition-state recognition in the low micromolar range, more than three orders of magnitude stronger than the millimolar substrate recognition. Carboxylates preferred by the best mutants contribute to transition-state recognition by hydrogen-bonded ion pairing and anion-π interactions with the emerging pyridinium product. The emergence of challenging stereoselectivity in aqueous systems further emphasizes compatibility of pnictogen bonding with higher order systems catalysis.

N-Confused strapped calix[4]pyrrole: the missing member of calix[4]pyrrole chemistry.

The first example of N-confused strapped calix[4]pyrrole 5 is presented. The structural integrity of 5 and its regular isomer 4 was unambiguously confirmed by single crystal X-ray diffraction analysis. Anion binding studies using 1H NMR titration carried out in CDCl3 revealed a small but detectable tendency of 5 to interact with an anion. Conversely, the isomeric regular strapped calix[4]pyrrole 4 displayed high selectivity for fluoride anions under similar experimental conditions. The high fluoride selectivity of 4 and unexpectedly low anion affinity of 5 were ascribed to the presence of intramolecular hydrogen bonds within strapping subunits.

Tetrel Bond Affects the Self-Assembly of Acetylcholine and its Analogues and is an Ancillary Interaction in Protein Binding.

The -N+(CH3)3 residue is present in acetylcholine (ACh) and in many of its analogues which are used as selective ACh agonist or antagonists for human therapy. The X-ray structures of four ACh derivatives show the presence of short and linear contacts between the C atoms of -N+(CH3)3 groups and lone pair possessing atoms. These contacts can be rationalized as tetrel bonds (TtBs) thanks to their geometric features. Interrogation of the Protein Data Bank suggests that similar -N+-C⋅⋅⋅nucleophile contacts affect the details of the binding of ACh and its derivatives to proteins. Quantum theory of atoms in molecules, noncovalent interaction plot, and natural bond orbital analyses consistently confirm that the -N+-C⋅⋅⋅nucleophile contacts observed in small molecule crystals and in substrate/protein complexes are attractive in nature and can be rationalized as TtBs. TtBs involving methyl groups of the -N+(CH3)3 moiety can be proposed as a new item in the palette of interactions allowing the compounds containing this pharmacophoric unit to bind to their target protein and/or to express their biological/pharmacological properties.

A neutral diphosphene radical: synthesis, electronic structure and white phosphorus activation.

(ClImDipp)P-P(Dipp)˙ (1˙), a rare example of a neutral, mixed substituted diphosphene radical, has been prepared by reduction of (ClImDipp)PP(Dipp)[OTf] (2[OTf]) and (ClImDipp)PP(Cl)(Dipp) (3) with cobaltocene (CoCp2) (ClImDipp = 4,5-dichloro-1,3-bis(1,3-diisopropylphenyl)-imidazol-2-yl, Dipp = 2,6-diisopropylphenyl). Radical compound 1˙ readily activates white phosphorus (P4), resulting in the formation of an intriguing octaphosphane butterfly compound P8(ClImDipp)2(Dipp)2 (4).

Shift of the reduction potential of nickel(II) Schiff base complexes in the presence of redox innocent metal ions.

With the objective of gaining insight into the modulation of the reduction potential of the Ni(II/I) couple, we have synthesized two mononuclear nickel(II) complexes, NiLen (H2Len = N,N'-bis(3-methoxysalicylidene)-1,2-diamino-2-methylpropane) and NiLpn (H2Lpn = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2,2-dimethylpropane) of two N2O4 donor ligands and recorded their cyclic voltammograms. Both the nickel complexes show reversible reduction processes for the Ni(II/I) couple in acetonitrile solution but the reduction potential of NiLpn (E1/2 = -1.883 V) is 188 mV more positive than that of NiLen (E1/2 = -2.071 V). In the presence of redox inactive metal ions (Li+, Na+, K+, Mg2+, Ca2+ and Ba2+), the reduction potentials are shifted by 49-331 mV and 99-435 mV towards positive values compared to NiLen and NiLpn, respectively. The shift increases with the decrease of the pKa of the respective aqua-complexes of the metal ion but is poorly co-linear; however, better linearity is found when the shift of the mono- and bi-positive metal ion aqua complexes is plotted separately. Spectrophotometric titrations of these two nickel complexes with the guest metal ions in acetonitrile showed a well-anchored isosbestic point in all cases, confirming the adduct formation of NiLen and NiLpn with the metal ions. Structural analysis of single crystals, [(NiLen)Li(H2O)2]·ClO4 (1), [(NiLpn)Li(H2O)]·ClO4 (2), [(NiLpn)2Na]·BF4 (3) and [(NiLpn)2Ba(H2O)(ClO4)]·ClO4 (4), also corroborates the heterometallic adduct formation. The orbital energies of the optimised heterometallic adducts from which electron transfers originated were calculated in order to explain the observed reduction process. A strong linear connection between the calculated orbital energies and the experimental E1/2 values was observed. According to MEP and 2D vector field plots, the largest shift for divalent metal ions is most likely caused by the local electric field that they impose in addition to Lewis acidity.

From Coordination to π-Hole Chemistry of Transition Metals: Metalloporphyrins as a Case of Study.

Herein we have evidenced the formation of favorable π-hole Br⋅⋅⋅metal noncovalent interactions (NCIs) involving elements from groups 9, 11 and 12. More in detail, M (M=Co2+, Ni2+, Cu2+ and Zn2+) containing porphyrins have been synthesized and their supramolecular assemblies structurally characterized by means of single crystal X-ray diffraction and Hirshfeld surface analyses, revealing the formation of directional Br⋅⋅⋅M contacts in addition to ancillary hydrogen bond and lone pair-π bonds. Computations at the PBE0-D3/def2-TZVP level of theory revealed the π-hole nature of the Br⋅⋅⋅M interaction. In addition, the physical nature of these NCIs was studied using Quantum Chemistry methodologies, providing evidence of π-hole Spodium and Regium bonds in Zn2+ and Cu2+ porphyrins, in addition to unveiling the presence of a π-hole for group 9 (Co2+). On the other hand, group 10 (Ni2+) acted as both electron donor and acceptor moiety without showing an electropositive π-hole. Owing to the underexplored potential of π-hole interactions in transition metal chemistry, we believe the results reported herein will be useful in supramolecular chemistry, organometallics, and solid-state chemistry by i) putting under the spotlight the π-hole chemistry involving first row transition metals and ii) unlocking a new tool to direct the self-assembly of metalloporphyrins.