Search

The chemistry of light dipnictenes has been widely investigated in the last century with remarkable achievements especially for azobenzene derivatives. In contrast, distibenes and dibismuthenes are relatively rare and show very limited reactivity. Herein, we have designed a protocol using visible light to enhance the reactivity of heavy dipnictenes. Exploiting the distinctive π–π* transition, we have been able to isolate unique examples of dipnictene‐cobalt complexes. The reactivity of the distibene complex was further exploited using red light in the presence of a diazoolefin to access an unusual four‐membered bicyclo[1.1.0]butane analog, containing only a single carbon atom. These findings set the bases to a conceptually new strategy in heavy element double bonds chemistry where visible light is at the front seat of bond activation. [ABSTRACT FROM AUTHOR]

With the increase in demand of electronic devices in the modern civilization, research in material science is being projected to grow in faster rate. In this facet, coordination polymer (CP) based electronic device is one of the promising candidates to the material researchers. Herein, two new Zn(II) and Cd(II) based one‐dimensional (1D) CPs, denoted as [Zn(4‐avp)2(5‐nip)] ⋅ (solvent)x (1) and [Cd(4‐avp)(5‐nip)(CH3OH)] (2) have been synthesized using relatively less explored highly conjugated polycyclic aromatic hydrocarbon (PAH) based monodentate ligand, 4‐[2‐(9‐anthryl)vinyl]pyridine (4‐avp) and bidentate linker 5‐nitroisophthalic acid (H25‐nip). In this instance, the CP 1 creates 1D chain polymer, while CP 2 is made up with 1D ladder polymer. It is interesting to note that both the CPs exhibit semiconducting nature and generate metal‐semiconductor (MS) junction Schottky barrier diodes (SBDs). However, Cd‐based CP 2 shows higher charge transport as compared to Zn‐CP 1, which could be due to stronger π⋅⋅⋅π contacts as well as larger size of Cd metal in CP 2. The experimental results are well corroborated with theoretical density of states (DOS) calculations. [ABSTRACT FROM AUTHOR]

It is often said that pnictogen‐bonding catalysis, and σ‐hole catalysis in general, would not work in aqueous systems because the solvent would interfere as an overcompetitive pnictogen‐bond acceptor. In this study, we show that the transfer of pnictogen‐bonding catalysis from hydrophobic solvents to aqueous systems is possible by replacing only hydrophobic with hydrophilic substrates, without changing catalyst or reaction. This differs from conventional covalent Lewis acid catalysts, which are instantaneously destroyed by ligand exchange. With their water‐proof substituents in place of exchangeable ligands, pnictogen‐bonding catalysts, the supramolecular counterpart of Lewis acid catalysts, are evinced to catalyze transfer hydrogenation of quinolines in neutral aqueous systems. To secure these results, we introduce a water‐soluble fluorogenic substrate that releases a coumarin upon the reduction of quinolines instead of activated quinolidiniums, and stiborane catalysts with deepened σ holes. They demonstrate that pnictogen‐bonding catalysts can operate in higher‐order architectures for supramolecular systems catalysis under biologically relevant conditions, and provide an operational assay for high‐throughput catalyst screening by fluorescence imaging, in situ under relevant aqueous conditions. [ABSTRACT FROM AUTHOR]

As(III) S‐adenosylmethionine methyltransferases, pivotal enzymes in arsenic metabolism, facilitate the methylation of arsenic up to three times. This process predominantly yields trivalent mono‐ and dimethylarsenite, with trimethylarsine forming in smaller amounts. While this enzyme acts as a detoxifier in microbial systems by altering As(III), in humans, it paradoxically generates more toxic and potentially carcinogenic methylated arsenic species. The strong affinity of As(III) for cysteine residues, forming As(III)‐thiolate bonds, is exploited in medical treatments, notably in arsenic trioxide (Trisenox®), an FDA‐approved drug for leukemia. The effectiveness of this drug is partly due to its interaction with cysteine residues, leading to the breakdown of key oncogenic fusion proteins. In this study, we extend the understanding of As(III)′s binding mechanisms, showing that, in addition to As(III)−S covalent bonds, noncovalent O⋅⋅⋅As pnictogen bonding plays a vital role. This interaction significantly contributes to the structural stability of the As(III) complexes. Our crystallographic analysis using the PDB database of As(III) S‐adenosylmethionine methyltransferases, augmented by comprehensive theoretical studies including molecular electrostatic potential (MEP), quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) analysis, emphasizes the critical role of pnictogen bonding in these systems. We also undertake a detailed evaluation of the energy characteristics of these pnictogen bonds using various theoretical models. To our knowledge, this is the first time pnictogen bonds in As(III) derivatives have been reported in biological systems, marking a significant advancement in our understanding of arsenic's molecular interactions. [ABSTRACT FROM AUTHOR]

In this manuscript we evaluate the X-ray structure of five new pertechnetate derivatives of general formula [M(H2O)4(TcO4)2], M=Mg, Co, Ni, Cu, Zn (compounds 1-5) and one perrhenate compound Zn(H2O)4(ReO4)2 (6). In these complexes the metal center exhibits an octahedral coordination with the pertechnetate units as axial ligands. All compounds exhibit the formation of directional Tc···O Matere bonds (MaBs) that propagate the [M(H2O)4(TcO4)2], into 1D supramolecular polymers in the solid state. Such 1D polymers are linked, generating 2D layers, by combining additional MaBs and hydrogen bonds (HBs). Such concurrent motifs have been analyzed theoretically, suggesting the noncovalent s-hole nature of the MaBs. The interaction energies range from weak (~ - 2 kcal/mol) for the MaBs to strong (~ - 30 kcal/mol) for the MaB+HB assemblies, where HB dominates. In case of M=Zn, the corresponding perrhenate Zn(H2O)4(ReO4)2 complex, has been also synthesized for comparison purposes, resulting in the formation of an isostructural Xray structure, corroborating the structure-directing role of Matere bonds. [ABSTRACT FROM AUTHOR]

Kinases are enzymes that play a critical role in governing essential biological processes. Due to their pivotal involvement in cancer cell signaling, they have become key targets in the development of anti‐cancer drugs. Among these drugs, those containing the 2,4‐dihalophenyl moiety demonstrated significant potential. Here we show how this moiety, particularly the 2‐fluoro‐4‐iodophenyl one, is crucial for the structural stability of the formed drug‐enzyme complexes. Crystallographic analysis of reported kinase‐inhibitor complex structures highlights the role of the halogen bonding that this moiety forms with specific residues of the kinase binding site. This interaction is not limited to FDA‐approved MEK inhibitors, but it is also relevant for other kinase inhibitors, indicating its broad relevance in the design of this class of drugs. [ABSTRACT FROM AUTHOR]

H‐selenite anions (HSeO3−) form in the solid unprecedented anionic supramolecular chains wherein single units are assembled via alternating short Se⋅⋅⋅O and H⋅⋅⋅O contacts. Crystallographic analyses and computational studies (the quantum theory of "atoms‐in‐molecules", QTAIM, and the noncovalent interaction plot, NCIPlot) consistently prove the attractive nature of these chalcogen bonds (ChBs) and hydrogen honds (HBs), the Janus‐type character of HSeO3− anions which act as both donors and acceptors of ChB and HB, and the possible stability of anion dimers in solution. The effectiveness of the ChBs herein described may lead to consider the HSeO3− moiety as a new entry in the toolbox of crystal engineering based on ChB. [ABSTRACT FROM AUTHOR]

Homoleptic [L−I−L]+ iodine(I) complexes (where L is a R3R2R1N tertiary amine) were synthesized via the [L−Ag−L]+→ [L−I−L]+ cation exchange reaction. In solution, the amines form [R3R2R1N−Ag−NR1R2R3]+ silver(I) complexes, which crystallize out from solution as the meso‐[L−Ag−L]+complexes, as characterized by X‐ray crystallography. The subsequent [L−I−L]+ iodine(I) analogues were extremely reactive and could not be isolated in the solid state. Density functional theory (DFT) calculations were performed to study the Ag+−N and I+−N interaction energies in silver(I) and iodine(I) complexes, with the former ranging from −80 to −100 kJ mol−1 and latter from −260 to −279 kJ mol−1. The X‐ray crystal structures revealed Ag+⋅⋅⋅Cπ and Ag+⋅⋅⋅H−C short contacts between the silver(I) cation and flexible N‐alkyl/N‐aryl groups, which are the first of their kind in such precursor complexes. [ABSTRACT FROM AUTHOR]

We report on a dendronized bis‐urea macrocycle 1 self‐assembling via a cooperative mechanism into two‐dimensional (2D) nanosheets formed solely by alternated urea‐urea hydrogen bonding interactions. The pure macrocycle self‐assembles in bulk into one‐dimensional liquid‐crystalline columnar phases. In contrast, its self‐assembly mode drastically changes in CHCl3 or tetrachloroethane, leading to 2D hydrogen‐bonded networks. Theoretical calculations, complemented by previously reported crystalline structures, indicate that the 2D assembly is formed by a brick‐like hydrogen bonding pattern between bis‐urea macrocycles. This assembly is promoted by the swelling of the trisdodecyloxyphenyl groups upon solvation, which frustrates, due to steric effects, the formation of the thermodynamically more stable columnar macrocycle stacks. This work proposes a new design strategy to access 2D supramolecular polymers by means of a single non‐covalent interaction motif, which is of great interest for materials development. [ABSTRACT FROM AUTHOR]

Analyses of the Cambridge Structural Database and theoretical calculations (PBE0‐D3/def2‐TZVP level, atoms‐in‐molecules, natural bond orbital studies) prove the formation of net attractive noncovalent interactions between group 5 elements and electron‐rich atoms (neutral or anionic). These kinds of bonding are markedly different from coordination bonds formed by the same elements and possess the distinctive features of σ‐hole interactions. The term erythronium bond is proposed to denote these bonds. X‐ray structures of vanadate‐dependent bromoperoxidases show that these interactions are present also in biological systems. [ABSTRACT FROM AUTHOR]

[Cu2(μ‐2‐chlorobenzoato‐O,O')4Cl2].2(4‐DMAPH) (1) and [Zn2(μ‐2‐chlorobenzoato‐O,O')4(4‐DMAP)2] (2) (4‐DMAP=4‐Dimethylaminopyridine) were synthesized from CuCl2/Zn(NO)3)2. 6H2O, 2‐chlorobenzoic acid and 4‐dimethylaminopyridine in methanol under reflux. Compounds were comprehensively characterized by elemental analyses, conductance measurement, spectroscopic and X‐ray diffraction studies. Complexes crystallized in the monoclinic space group P21/n having dinuclear paddle‐wheel structure. DFT studies along with NCI plot, QTAIM analysis indicate presence of N−H⋯Cl, C−H⋯O, C−H⋯π interactions in 1 and CH3⋯π, π⋯π and C−H⋯Cl in 2. The charge distribution in the complexes was shown via MEP analysis. Complexes interact with CT‐DNA in moderately strong non‐intercalative mode of binding. Antimicrobial study against Shigella flexneri (B), Streptococcus pneumoniae (K), Klebsiella pneumoniae (P) and Shigella boydii (Q) shows appreciable activity of 1 whereas compound 2 is comparatively less active. In vitro cytotoxicity study against cell lines (L‐132) exhibits moderate activity by the complexes, but compound 2 shows significant cell inhibition activity against cell lines K‐562. The complexes are emissive in nature. [ABSTRACT FROM AUTHOR]

The relevance of hydrogen‐bonding, π‐π stacking and aurophilic interactions in the solid‐state of two new heterobimetallic (AuI−MnII) complexes is analyzed in this manuscript. They are discrete complexes of formulae [Mn(bipy)2(H2O){Au(CN)2}][Au(CN)2] and [Mn(dmbipy)2{Au(CN)2}] ⋅ H2O, (bipy=2,2′‐bipyridine and dmbipy=5,5′‐dimethyl‐2,2′‐bipyridine), which are based on dicyanidoaurate(I) groups and 2,2′‐bipyridyl‐like co‐ligands. They have been synthesized in good yields and X‐ray characterized. In both compounds, aurophilic, OH⋅⋅⋅N hydrogen bonding and π‐π interactions governed the supramolecular assemblies in the solid state. These contacts with special emphasis on the aurophilic interactions have been studied using density functional theory calculations and characterized using the quantum theory of atoms‐in‐molecules and the noncovalent interaction plot. The aurophilic contacts have been also rationalized from an orbital point of view using the natural bond orbital methodology, evidencing stabilization energies up to 5.7 kcal/mol. Moreover, the interaction energies have been decomposed using the Kitaura‐Morokuma energy decomposition analysis, confirming the importance of electrostatic and orbital effects. [ABSTRACT FROM AUTHOR]

Background: Heart failure (HF) and atrial arrhythmias (AAs) are two clinical conditions that characterize the daily clinical practice of cardiologists. In this perspective review, we analyze the shared etiopathogenetic pathways of atrial arrhythmias, which are the most common cause of atrial arrhythmias‐induced cardiomyopathy (AACM) and HF. Hypothesis: The aim is to explore the pathophysiology of these two conditions considering them as a "unicum", allowing the definition of a cardiovascular continuum where it is possible to predict the factors and to identify the patient phenotype most at risk to develop HF due to atrial arrhythmias. Methods: Potentially eligible articles, identified from the Electronic database (PubMed), and related references were used for a literature search that was conducted between January 2022 and January 2023. Search strategies were designed to identify articles that reported atrial arrhythmias in association with heart failure and vice versa. For the search we used the following keywords: atrial arrhythmias, atrial fibrillation, heart failure, arrhythmia‐induced cardiomyopathy, tachycardiomyopathy. We identified 620 articles through the electronic database search. Out of the 620 total articles we removed 320 duplicates, thus selecting 300 eligible articles. About 150 titles/abstracts were excluded for the following reasons: no original available data, no mention of atrial arrhythmias and heart failure crosstalk, very low quality analysis or evidence. We excluded also non‐English articles. When multiple articles were published on the same topic, the articles with the most complete set of data were considered. We preferentially included all papers that could provide the best evidence in the field. As a result, the present review article is based on a final number of 104 references. Results: While the pathophysiology of AACM and Heart Failure with reduced ejection fraction (HFrEF) has been studied in detail over the years, the causal link between atrial arrhythmias and heart failure with Preserved Ejection Fraction (HFpEF) has been often subject of interest. HFpEF is strictly related to AAs, which has always been considered significant risk factor. In this review we described the pathophysiological links between atrial fibrillation and heart failure. Furthermore, we illustrated and discussed the preclinical and clinical predicting factors of AF and HFpEF, and the corresponding targets of the available therapeutic agents. Finally, we outlined the patient phenotype at risk of developing AF and HFpEF (Central Illustration). Conclusions: In this review, we underline how these two clinical conditions (AF and HFpEF) represent a "unicum" and, therefore, should be considered as a single disease that can manifest itself in the same phenotype of patients but at different times. Furthermore, considering that today we have few therapeutic strategies to treat these patients, it would be good to make an early diagnosis in the initial stages of the disease or intervene even before the development of signs and symptoms of HF. This is possible only by paying greater attention to patients with predisposing factors and carrying out a targeted screening with the correct diagnostic methods. A systemic approach aimed at improving the immuno‐metabolic profile of these patients by lowering the body mass index, threatening the predisposing factors, lowering the mean heart rate and reducing the sympathetic nervous system activation is the key strategy to reduce the clinical impact of this disease. [ABSTRACT FROM AUTHOR]

Co‐crystallization of 180°‐orienting σ‐hole‐accepting tectons, namely, 1,4‐diisocyanobenzene (1) and 1,4‐diisocyanotetramethylbenzene (2), with such homoditopic halogen bond donors as 1,4‐diiodotetrafluorobenzene (1,4‐FIB) and 4,4'‐diiodoperfluorobiphenyl (4,4'‐FIBP) afforded co‐crystals 1 ⋅ 1,4‐FIB, 1 ⋅ 4,4'‐FIBP, and 2 ⋅ 1,4‐FIB. Their solid‐state structures exhibit 1D‐supramolecular arrangements, which are based on poorly explored I⋅⋅⋅C halogen bonding; this study is the first in which the supramolecular assembly utilizing halogen bonding with a terminal C atom was performed. The use of the potentially tetrafunctional σ‐hole accepting tetraiodoethylene (TIE) leads to supramolecular architecture of a higher dimension, 3D‐framework, observed in the structure of 1 ⋅ TIE. DFT calculations, used to characterize the halogen bonding situation, revealed that the I⋅⋅⋅C non‐covalent interactions are moderately strong, ranging from −4.07 in 1 ⋅ TIE to −5.45 kcal/mol in 2 ⋅ 1,4‐FIB. The NBO analysis disclosed that LP(C)→σ* charge transfer effects are relevant in all co‐crystals. [ABSTRACT FROM AUTHOR]

Herein, the synthesis and X‐ray structures of three α,β "two wall" aryl‐extended calix[4]pyrroles having either identical (symmetrically substituted) or different (non‐symmetrically substituted) meso‐aryl substituents (aryl=4‐ethynylphenyl and 4‐iodophenyl) are reported. The X‐ray structure of the co‐crystal formed by the two symmetrically substituted calix[4]pyrroles is also described. In the solid state, all studied α,β‐calix[4]pyrroles exhibit a 1,3‐alternate conformation with two co‐crystallized acetonitrile solvent molecules H‐bonded to adjacent cis‐pyrrole rings. Remarkably, the 1,3‐conformer of the non‐symmetrically substituted iodophenyl/ethynylphenyl compound is intrinsically chiral. The two enantiomers are present in the average asymmetric unit in a 65 : 35 occupancy ratio displaying a head‐to‐tail directional disorder. This is due to the functional complementarity and the isosteric and isoelectronic properties of the para‐substituents: iodo and ethynyl. That is, the negative belt of iodine is similar to the negative π‐system of the C≡C triple bond and the σ‐hole in the iodine atom is similar to the positive proton at the C≡C−H group. [ABSTRACT FROM AUTHOR]

The co‐crystallization of tetracyanobenzene (TCB) with haloarenes ArX provided six new co‐crystals TCB ⋅ ArX (ArX=PhCl, PhBr, 4‐MeC6H4Cl, 4‐MeC6H4Br, 4‐MeOC6H4Cl, 1,2‐Br2C6H4) which were studied by X‐ray diffraction. In these systems, the strong collective effect of π⋅⋅⋅π stacking interactions and lone pair‐(X)⋅⋅⋅π‐hole‐(C) bondings between TCB and ArX promote the strength of X⋅⋅⋅Ncyano halogen bonding (HaB). Theoretical studies showed that the stacking interactions affect the σ‐hole depth of the haloarenes, thus significantly boosting their ability to function as HaB donors. According to the molecular electrostatic potential calculations, the σ‐ hole‐(Cl) value (1.5 kcal/mol) in the haloarene 4‐MeOC6H4Cl (featuring an electron‐rich arene moiety and exhibiting very poor σ‐hole‐(Cl) ability) increases significantly in the stacked trimer (TCB)2 ⋅ 4‐MeOC6H4Cl (12.5 kcal/mol). Theoretical DFT calculations demonstrate the dramatic increase of X⋅⋅⋅Ncyano HaB strength for stacked trimers in comparison with parent unstacked haloarenes. [ABSTRACT FROM AUTHOR]

A hyperresponsive tool to assess supramolecular catalysis, the cyclization of di‐epoxides into cyclic ethers is used to elucidate the difference between pnictogen‐bonding and Lewis acid catalysis systematically. For all stereoisomers, most tested catalysts follow the Baldwin rules. Brønsted acid and anion–π catalysis afford almost only Baldwin products. Lewis acids such as SbCl3, BF3 and BiCl3 give the poorest selectivity, with at least 50 % Baldwin (B) products for all stereoisomers. In clear contrast, optimized pnictogen‐bonding catalysts operating on the Sb(III) and the Sb(V) level give the fused anti‐Baldwin (A) bicycles as the main product of trans epoxides, independent of syn or anti relation of the two epoxides. In the cis series, Sb(III) pnictogen‐bonding catalysts afford BA products almost exclusively for syn diastereomers, while anti diastereomers give equal amounts of BA and AB products. Sb(V) pnictogen‐bonding catalysts show similarly special trends. These unique characteristics support that pnictogen‐bonding catalysis differs from Lewis acid catalysis and can arguably be defined as its non‐covalent counterpart, just like hydrogen‐bonding catalysis is understood and appreciated as the non‐covalent counterpart of Brønsted acid catalysis. Computational studies on the origin of anti‐Baldwin selectivity reveal Sb(V) catalysts with an introvert deep σ hole surrounded by an almost planar ring of ligands. Central pnictogen‐bond attraction against peripheral steric repulsion then forces the epoxide to break open. In contrast, transient antimony oxidation in cyclic intermediates accounts for the chemoselectivity of Sb(III) catalysts. Presumably due to insufficient accessibility of their σ holes, the activity of tetrel‐bonding catalysts is negligible. The division between powerful pnictogen‐bonding and irrelevant tetrel‐bonding catalysts does not exist with the respective orthodox Lewis acids and thus supports that σ‐hole and Lewis acid catalysis are not the same. [ABSTRACT FROM AUTHOR]

The synthetic protocol and solid state characterization of two new coumarin‐pyrazolylthiazole hybrids (1‐2) are detailed in this manuscript. Synthesized compounds were characterized applying nuclear magnetic resonance, Fourier‐transform infrared spectroscopy and single‐crystal X‐ray diffraction techniques. A detailed structural analysis of 3‐(2‐(5‐(4‐bromophenyl)‐3‐(4‐fluorophenyl)‐4,5‐dihydropyrazol‐1‐yl)thiazol‐4‐yl)‐2H‐chromen‐2‐one (1) and 3‐(2‐(3,5‐bis(4‐bromophenyl)‐4,5‐dihydropyrazol‐1‐yl)thiazol‐4‐yl)‐2H‐chromen‐2‐one (2) is reported along with a detailed description of the noncovalent interactions and their evaluation using Hirshfeld surface analysis, emphasizing the structure‐directing role of C−H⋅⋅⋅O, Br⋅⋅⋅π and π–π interactions. Finally, DFT energetics, molecular electrostatic potential (MEP), quantum theory of "atoms‐in‐molecules" (QTAIM) and noncovalent interaction plot (NCIplot) index computations have been used to further investigate the relative importance of two different π‐stacking complexes observed in the solid state of both compounds, which are recurrent binding motifs in their crystal packing. [ABSTRACT FROM AUTHOR]

In this study we propose to coin the term Wolfium bond (WfB) to refer to a net attractive force (noncovalent interaction) between any element of group 6 and electron donor atoms (neutral molecules or anions) and to differentiate it from a coordination bond (metal‐ligand interaction). We provide evidence of the existence of this interaction by inspecting the X‐ray crystal structure of proteins containing Molybdopterin and Tungstopterin cofactors from the Protein Data Bank (PDB). The plausible biological role of the interaction as well as its physical nature (antibonding Wf‐Ligand orbital involved) are also analyzed by means of ab initio calculations (RI‐MP2/def2‐TZVP level of theory), Atoms in Molecules (AIM), Natural Bond Orbital (NBO) and Noncovalent Interactions plot (NCIplot) analyses. [ABSTRACT FROM AUTHOR]

A new PbII coordination complex [PbL(OAc)], which was readily synthesized from a mixture of Pb(OAc)2·3H2O and 1‐(pyridin‐2‐yl)benzylidene‐4‐phenylthiosemicarbazide (HL) is reported. The crystal structure analysis of [PbL(OAc)] showed that the PbII cation is N,N′,S‐chelated by the tridentate pincer‐type ligand L and by the oxygen atoms of the acetate anion. In addition, the metal centre forms Pb...O and Pb...S tetrel bonds with an adjacent complex molecule, yielding a 1D zigzag polymeric chain, which is reinforced by N—H...O hydrogen bonds and π...π interactions. These chains are interlinked by C—H...py non‐covalent interactions, realized between one of the acetate hydrogen atoms and the pyridine rings. According to the Hirshfeld surface analysis, the crystal packing is mainly characterized by intermolecular H...H, H...C and H...O contacts, followed by H...N, H...S, C...C, C...N, Pb...H, Pb...O and Pb...S contacts. The FTIR and 1H NMR spectra of [PbL(OAc)] testify to the deprotonation of the parent ligand HL, while the acetate ligand exhibits an anisobidentate coordination mode as established by means of single‐crystal X‐ray diffraction and FTIR spectroscopy. Lastly, theoretical calculations at the PBE0‐D3/def2‐TZVP level of theory have been used to analyze and characterize the Pb...O and Pb...S tetrel bonds observed in the crystal of [PbL(OAc)], using a combination of QTAIM (Quantum Theory of Atoms in Molecules) and NCIPlot (Non‐Covalent Interaction Plot) computational tools. [ABSTRACT FROM AUTHOR]

We report a series of rotaxane‐based anion–π catalysts in which the mechanical bond between a bipyridine macrocycle and an axle containing an NDI unit is intrinsic to the activity observed, including a [3]rotaxane that catalyses an otherwise disfavoured Michael addition in >60 fold selectivity over a competing decarboxylation pathway that dominates under Brønsted base conditions. The results are rationalized by detailed experimental investigations, electrochemical and computational analysis. [ABSTRACT FROM AUTHOR]

Introduction: Electrogram (EGM) fractionation is often associated with diseased atrial tissue; however, mechanisms for fractionation occurring above an established threshold of 0.5 mV have never been characterized. We sought to investigate during sinus rhythm (SR) the mechanisms underlying bipolar EGM fractionation with high‐density mapping in patients with atrial fibrillation (AF). Methods: Forty‐five patients undergoing AF ablation (73% paroxysmal, 27% persistent) were mapped at high density (18562 ± 2551 points) during SR (Rhythmia). Only bipolar EGMs with voltages above 0.5 mV were considered for analysis. When fractionation (> 40 ms and >4 deflections) was detected, we classified the mechanisms as slow conduction, wave‐front collision, or a pivot point. The relationship between EGM duration and amplitude, and tissue anisotropy and slow conduction, was then studied using a computational model. Results: Of the 45 left atria analyzed, 133 sites of EGM fragmentation were identified with voltages above 0.5 mV. The most frequent mechanism (64%) was slow conduction (velocity 0.45 m/s ± 0.2) with mean EGM voltage of 1.1 ± 0.5 mV and duration of 54.9 ± 9.4 ms. Wavefront collision was the second most frequent (19%), characterized by higher voltage (1.6 ± 0.9 mV) and shorter duration (51.3 ± 11.3 ms). Pivot points (9%) were associated with the highest degree of fractionation with 70.7 ± 6.6 ms and 1.8 ± 1 mV. In 10 sites (8%) fractionation was unexplained. The EGM duration was significantly different among the 3 mechanisms (p =.0351). Conclusion: In patients with a history of AF, EGM fractionation can occur at amplitudes > 0.5 mV when in SR in areas often considered not to be diseased tissue. The main mechanism of EGM fractionation is slow conduction, followed by wavefront collision and pivot sites. [ABSTRACT FROM AUTHOR]

This review highlights recent studies discovering unconventional halogen bonding (HaB) that involves positively charged metal centers. These centers provide their filled d‐orbitals for HaB, and thus behave as nucleophilic components toward the noncovalent interaction. This role of some electron‐rich transition metal centers can be considered an oxymoron in the sense that the metal is, in most cases, formally cationic; consequently, its electron donor function is unexpected. The importance of Ha⋅⋅⋅d‐[M] (Ha=halogen; M is Group 9 (Rh, Ir), 10 (Ni, Pd, Pt), or 11 (Cu, Au)) interactions in crystal engineering is emphasized by showing remarkable examples (reported and uncovered by our processing of the Cambridge Structural Database), where this Ha⋅⋅⋅d‐[M] directional interaction guides the formation of solid supramolecular assemblies of different dimensionalities. [ABSTRACT FROM AUTHOR]

Background: Left atrial appendage (LAA) thrombosis increases the risk of stroke and its management has to be assessed. The aim of the present study is to evaluate short and long‐term safety and efficacy of a standardized approach of percutaneous LAA closure (LAAC) routinely using a cerebral protection device (CPD) in patients with LAA thrombosis or sludge (LAAT). Methods: We prospectively enrolled 14 consecutive patients with atrial fibrillation complicated by LAAT presenting in a high‐volume tertiary center. In seven patients (50%) LAAT was found after anticoagulant withdrawal for severe bleedings and in the remaining half LAAT was found despite appropriate anticoagulant therapy. All patients were treated with a standardized interventional approach of LAAC routinely using a CPD and guided by transoesophageal echocardiography. Results: Mean age was 68 ± 14 years and nine patients (64%) were male. Mean CHA2DS2‐VASc and HAS‐BLED scores were 3.3 ± 1.6 and 2.3 ± 1.1, respectively. Six patients (42.8%) presented organized thrombi while eight LAA sludge (57.1%). In 13 patients (92.8%) CPD was positioned through a right radial arterial access. Procedural success was achieved in all patients. In one patient we assisted to embolization of the thrombus during deployment of the device in the absence of neurological consequences. During a mean follow up of 426 ± 307 days, one patient died for non‐cardiac cause while no embolic event or major bleeding were reported. Conclusion: In an unselected cohort, LAAC with the systematic use of CPD was a feasible, safe and effective therapeutic option for LAAT both acutely and after long‐term follow‐up. [ABSTRACT FROM AUTHOR]

Introduction: Microstructural abnormalities at the epicardium of the right ventricular outflow tract (RVOT) may provide the arrhythmia substrate in Brugada syndrome (BrS). Endocardial unipolar electroanatomical mapping allows the identification of epicardial abnormalities. We evaluated the clinical implications of an abnormal endocardial substrate as perceived by high‐density electroanatomical mapping (HDEAM) in patients with BrS. Methods: Fourteen high‐risk BrS patients with aborted sudden cardiac death (SCD) (12 males, mean age: 41.9 ± 11.8 years) underwent combined endocardial‐epicardial HDEAM of the right ventricle/RVOT, while 40 asymptomatic patients (33 males, mean age: 42 ± 10.7 years) underwent endocardial HDEAM. Based on combined endocardial‐epicardial procedures, endocardial HDEAM was considered abnormal in the presence of low voltage areas (LVAs) more than 1 cm2 with bipolar signals less than 1 mV and unipolar signals less than 5.3 mV. Programmed ventricular stimulation (PVS) was performed in all patients. Results: The endocardial unipolar LVAs were colocalized with epicardial bipolar LVAs (p =.0027). Patients with aborted SCD exhibited significantly wider endocardial unipolar (p <.01) and bipolar LVAs (p <.01) compared with asymptomatic individuals. A substrate size of unipolar LVAs more than 14.5 cm2 (area under the curve [AUC]: 0.92, p <.001] and bipolar LVAs more than 3.68 cm2 (AUC: 0.82, p =.001) distinguished symptomatic from asymptomatic patients. Patients with ventricular fibrillation inducibility (23/54) demonstrated broader endocardial unipolar (p <.001) and bipolar LVAs (p <.001) than noninducible patients. The presence of unipolar LVAs more than 13.5 cm2 (AUC: 0.95, p <.001) and bipolar LVAs more than 2.97 cm2 (AUC: 0.78, p <.001) predicted a positive PVS. Conclusion: Extensive endocardial electroanatomical abnormalities identify high‐risk patients with BrS. Endocardial HDEAM may allow risk stratification of asymptomatic patients referred for PVS. [ABSTRACT FROM AUTHOR]

Electrophilic fluorophosphonium triflates bearing pyridyl (3[OTf]) or imidazolyl (4[OTf])‐substituents act as intramolecular frustrated Lewis pairs (FLPs) and reversibly form 1 : 1 adducts with CO2 (5+ and 6+). An unusual and labile spirocyclic tetrahedral intermediate (72+) is observed in CO2‐pressurized (0.5–2.0 bar) solutions of cation 4+ at low temperatures, as demonstrated by variable‐temperature NMR studies, which were confirmed crystallographically. In addition, cations 3+ and 4+ actively bind carbonyls, nitriles and acetylenes by 1,3‐dipolar cycloaddition, as shown by selected examples. [ABSTRACT FROM AUTHOR]

This communication reports experimental and theoretical evidences of σ‐hole interactions in adducts between nitrogen or oxygen nucleophiles and tetroxides of osmium or other group 8 elements. Cocrystals between pyridine or pyridine N‐oxide derivatives and osmium tetroxide are characterized through various techniques and rationalized as σ‐hole interactions using DFT calculations and several other computational tools. We propose the term "osme bond" (OmB, Om=Fe, Ru, Os, (Hs)) for naming the noncovalent interactions wherein group 8 elements have the role of the electrophile. The word osme is the transcription of ὀσμή, the ancient Greek word for smell that was used to name the heaviest group 8 element in relation to the smoky odor of its tetroxide. [ABSTRACT FROM AUTHOR]

Premature ventricular complexes (PVCs) are increasingly recognized, as the use of ECG wearables becomes more widespread. In particular, PVCs arising from both the right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT) comprise the majority of these arrhythmias and form a significant component of an electrophysiology practice. A keen understanding of the correlative anatomy of the outflow tracts, in addition to recognizing key ECG indices illustrating PVC sites of origin, are fundamental in preparing for a successful ablation. Patient selection, incorporating symptomatology, structural disease, and PVC burden can pose a challenge, though tools such as the ABC‐VT risk score may help identify those patients with a higher risk of clinical deterioration. Utilizing intracardiac echocardiography to highlight salient anatomic features not visible with fluoroscopy allows for a more precise and safer ablation. Interpretation of intracardiac EGMs, and the careful examination for low amplitude highly fractionated pre‐potentials, enhanced by the advent of new developed mapping/ablation catheters, remains crucial. Utilizing these tools will guide the electrophysiologist to an efficient and effective outflow tract PVC ablation. [ABSTRACT FROM AUTHOR]

In X‐ray structures of the isomorphic mer‐[IrX3(THT)(CNXyl)2] (X=Cl 1, Br 2; THT=tetrahydrothiophene; Xyl=2,6‐Me2C6H3−) complexes, we revealed short intermolecular contacts between the C‐atom of an isocyanide methyl group and halide ligands of another molecule. Geometrical consideration of the X‐ray data and analysis of appropriate DFT studies allowed the attribution of these contacts to CMe⋅⋅⋅X−IrIII (X=Cl, Br) tetrel bond. Specifically, through the application of DFT calculations and various theoretical models, the presence of tetrel bonding interactions was validated, and the contribution of the CMe⋅⋅⋅X−IrIII interaction was assessed. The reinforcement of the tetrel bond upon the isocyanide coordination to iridium(III) is substantiated by molecular electrostatic potential (MEP) surface calculations. To distinguish the tetrel bonding characteristics of CMe⋅⋅⋅X−IrIII (X=Cl, Br) interactions from conventional hydrogen bonding, we employed multiple computational methodologies, including Natural Bond Orbital (NBO) analysis and Electron Localization Function (ELF) analysis. Additionally, Energy Decomposition Analysis (EDA) was applied to selected model systems to explore the underlying physical nature of these interactions. [ABSTRACT FROM AUTHOR]

Cover Feature: Erythronium Bonds: Noncovalent Interactions Involving Group 5 Elements as Electron-Density Acceptors (Chem. Eur. J. 60/2023) Cambridge Structural Database, haloperoxidase, noncovalent interactions, sigma-hole interactions, vanadium Keywords: Cambridge Structural Database; haloperoxidase; noncovalent interactions; sigma-hole interactions; vanadium EN Cambridge Structural Database haloperoxidase noncovalent interactions sigma-hole interactions vanadium 1 1 1 10/31/23 20231026 NES 231026 B Vanadium(V) derivatives b , and to a lesser extent analogous compounds of niobium and tantalum, form attractive interactions with electron-rich atoms (neutral or anionic). [Extracted from the article]

Frontispiece: Metal Centers as Nucleophiles: Oxymoron of Halogen Bond-Involving Crystal Engineering Keywords: halogen bonding; noncovalent interactions; nucleophilic metal centers; -hole interactions; theoretical calculations EN halogen bonding noncovalent interactions nucleophilic metal centers -hole interactions theoretical calculations 1 1 1 01/18/22 20220110 NES 220110 B This minireview b highlights recent examples of nucleophilicity of metal centers toward the noncovalent interaction - even today this property is likely to be perceived as an oxymoron by most chemists. The unconventional halogen bonding (HaB) involves positively charged metal centers, that provide their filled I d i -orbitals for HaB, and thus behave as nucleophilic components toward the noncovalent interaction. [Extracted from the article]