Binding of a Co(III) Metalloporphyrin to Amines in Water: Influence of the p and Aromaticity of the Ligand, and pH-Modulated Allosteric Effect.

Metalloporphyrins have been widely utilized as building blocks for molecular self-assembly in organic solvents, but their application in water is less common due to competition from water molecules for the metal center. However, Co(III) metalloporphyrins are notable for their strong binding to two aromatic amine ligands in aqueous buffers. In this study, we present a comprehensive investigation of the binding behavior of Co(III) tetraphenyl sulfonic acid porphyrin with selected aromatic and aliphatic amines in aqueous solution.

Diverse Cyclization Pathways Between Nitriles with Active -Methylene Group and Ambiphilic 2-Pyridylselenyl Reagents Enabled by Reversible Covalent Bonding.

Herein, we describe a novel coupling between ambiphilic 2-pyridylselenyl reagents and nitriles featuring an active α-methylene group. Depending on the solvent employed, this reaction can yield two distinct types of cationic pyridinium-fused selenium-containing heterocycles, 1,3-selenazolium or 1,2,4-selenadiazolium salts, in high yields. This is in contrast to what we observed before for other nitriles.

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.

Reaction contest: hydrolysis 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.

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, HL = 4-chloro-2-(((2-(methylamino)ethyl)amino)methyl)phenol and HL = 4-chloro-2-(((2-(dimethylamino)ethyl)amino)methyl)phenol, have been used to synthesize phenolate-bridged dinuclear complexes [Zn(L)Cl] () and [Zn(L)(N)] (). Single-crystal X-ray diffraction analysis confirmed their structures. Both complexes form assemblies in the solid state.

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

A novel nanosized porous supramolecular nonanuclear complex [Pb(HL)Cl(ClO)](ClO)·15HO(solvent) (·15HO(solvent)) is reported that was synthesized by electrochemical oxidation of a Pb anode under the ambient conditions in a CHCN:MeOH solution of '-phenyl(pyridin-2-yl)methylene--phenylthiosemicarbazide (), containing [N(CH)]ClO as a current carrier. The supramolecular aggregate of 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 ClO anion, were revealed.

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)] (1) [HDCTP = 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.

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

The -N(CH) 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(CH) groups and lone pair possessing atoms. These contacts can be rationalized as tetrel bonds (TtBs) thanks to their geometric features.

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) in a 2:1 ratio produces the sodium complexes featuring the cationic selenium-containing triazapentadiene (SeTAP) ligand.

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, NiL (HL = ,'-bis(3-methoxysalicylidene)-1,2-diamino-2-methylpropane) and NiL (HL = ,'-bis(3-methoxysalicylidene)-1,3-diamino-2,2-dimethylpropane) of two NO 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 NiL ( = -1.883 V) is 188 mV more positive than that of NiL ( = -2.

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

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

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.

Light-Dependent Reactivity of Heavy Pnictogen Double Bonds.

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.

Formation of H-bonding networks in the solid state structure of a trinuclear cobalt(iii/ii/iii) complex with NO donor Schiff base ligand and glutaric acid as bridging co-ligand: synthesis, structure and DFT study.

A trinuclear linear mixed-valence centrosymmetric cobalt(iii)-cobalt(ii)-cobalt(iii) complex, [Co{(μ-L)(μ-Hglu)Co(OH)}](ClO)·6HO has been synthesized during tetradentate NO donor 'Schiff base' ligand, HL {,'-bis(salicylidene)-1,3-diaminopropane} and glutaric acid (Hglu) as anionic co-ligand. The complex has been characterized by spectroscopic measurements and its solid state structure has been determined by single crystal X-ray diffraction analysis. The supra-molecular assembly formed by the hydrogen bonding interactions in the solid state of the complex has been analysed using DFT calculations.

Structural Insights on the Role of Halogen Bonding in Protein MEK Kinase-Inhibitor Complexes.

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.

On the Existence of Pnictogen Bonding Interactions in As(III) S-Adenosylmethionine Methyltransferase Enzymes.

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.

One-Dimensional and Two-Dimensional Zn(II) Coordination Polymers with Ditopic Imidazo[1,5-]pyridine: A Structural and Computational Study.

Zn(II) coordination polymers are being increasingly studied for their stability and properties. Similarly, there is a growing interest in imidazo[1,5-]pyridine derivatives, which show great potential in luminescence and pharmaceutical applications. In this work, we successfully synthesized and crystallized three new coordination polymers, using Zn(II) as the metallic node, dicarboxylic acids of different length and nature as linkers, and a linear ditopic imidazo[1,5-]pyridine derivative, to explore the role of this molecule as a propagator of the dimensionality of the structure or as an ancillary ligand.

Biomarkers of axonal damage to favor early diagnosis in variant transthyretin amyloidosis (A-ATTRv).

Early identification of ATTRv amyloidosis disease onset is still often delayed due to the lack of validated biomarkers of this disease. Light chain neurofilament (NfL) have shown promising results in early diagnosis in this disease, but data is still needed, including with alternative measuring methods. Our aim was to study the levels of NfL measured by ELISA.

Triiodide-Based Chair-Like Copper Complex Assembled by Halogen Bonding.

Cocrystallization of the dimeric [Cu(μ-I)(CNXyl)] (Xyl = 2,6-MeCH, ) and polymeric -[Cu(μ-I)(CNCH-2-Cl-6-Me)] () complexes with I at different molar ratios between the reactants resulted in a series of (RNC)CuI-based crystal polyiodides formed along with gradual accumulation of iodine, namely the cocrystals [·I]·[Cu(μ-I)(CNXyl)] followed by the generation of [Cu(μ-I)(CNXyl)]·2I (·2I) or [Cu(μ-I)(CNCH-2-Cl-6-Me)] and then [Cu(μ-I)(CNCH-2-Cl-6-Me)]·/I. The polyiodide ·2I exhibits a novel supramolecular motif─a purely inorganic halogen-bonded Cu(μ-I) core in the chair conformation. The X-ray structure of ·2I featuring I···I contacts was analyzed by a set of theoretical methods and attributed to moderately strong halogen bonding (from -3.

A combined crystallographic and theoretical investigation of noncovalent interactions in 1,3,4-oxadiazole-2-thione--Mannich derivatives: bioactivity and molecular docking.

Two 1,3,4-oxadiazole-2-thione--Mannich derivatives, specifically 5-(4-chlorophenyl)-3-[(2-trifluoromethylphenylamino)methyl]-1,3,4-oxadiazole-2(3)-thione (1) and 5-(4-chlorophenyl)-3-[(2,5-difluorophenylamino)methyl]-1,3,4-oxadiazole-2(3)-thione (2), were synthesized and then characterized by elemental analysis and NMR (H and C) spectroscopy and the single crystal X-ray diffraction method. The formed weak intermolecular interactions in the solid-state structures of these derivatives were thoroughly investigated utilizing a variety of theoretical tools such as Hirshfeld surface analysis and quantum theory of atoms in molecules (QTAIM). Furthermore, the CLP-PIXEL and density functional theory calculations were used to study the energetics of molecular dimers.

Synthesis, X-ray characterization and DFT analysis of dicyanidoaurate telluronium salts: on the importance of charge assisted chalcogen bonds.

In this manuscript we report the synthesis and X-ray characterization of two cyanidoaurate telluronium salts, namely (3-fluorophenyl)(methyl)(phenyl)telluronium dicyanidoaurate [(3-F-Ph)(Me)(Ph)Te][Au(CN)] (1) and methyldiphenyltelluronium dicyanidoaurate [(Me)(Ph)Te][Au(CN)] (2). In the solid state, the tellurium atom establishes three concurrent and directional chalcogen bonds (ChBs) with the adjacent anions, in both compounds. These charge-assisted ChBs (CAChBs) have been analyzed using DFT calculations and several computational tools.

Structure-directing role of CH⋯X (X = C, N, S, Cl) interactions in three ionic cobalt complexes: X-ray investigation and DFT study using QTAIM Vr predictor to eliminate the effect of pure Coulombic forces.

Three cobalt complexes, namely [Co(HL)(N)]ClO (1), [Co(L)(HL)(N)]ClO·1.5HO (2), and [Co(L)(HL)(NCS)] [CoCl(NCS)] (3), where HL = 2-(3-(dimethylamino)propyliminomethyl)-6-methoxyphenol, HL = 2-(2-(dimethylamino)ethyliminomethyl)-4,6-dichlorophenol, and HL = 2-(2-(dimethylamino)ethyliminomethyl)-6-methoxyphenol, as potential tridentate NO-donor Schiff base ligands, were synthesized and characterized using elemental analysis, IR and UV-vis spectroscopy, and single-crystal X-ray diffraction studies. All three were found to be monomeric ionic complexes.

Fluorogenic Thioacetalization: Expanding the Chemical Space of Fluorescent Probes, Including Unorthodox, Bifurcated, and Mechanosensitive Chalcogen Bonds.

Progress with fluorescent flippers, small-molecule probes to image membrane tension in living systems, has been limited by the effort needed to synthesize the twisted push-pull mechanophore. Here, we move to a higher oxidation level to introduce a new design paradigm that allows the screening of flipper probes rapidly, at best . Late-stage clicking of thioacetals and acetals allows simultaneous attachment of targeting units and interfacers and exploration of the critical chalcogen-bonding donor at the same time.

Two-Dimensional Supramolecular Polymerization of a Bis-Urea Macrocycle into a Brick-Like Hydrogen-Bonded Network.

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 CHCl or tetrachloroethane, leading to 2D hydrogen-bonded networks.