Upgrade of Weak σ-hole Bond Donors via Cr(CO)3 Complexation.

Molecular recognition mediated by s-hole interactions is enhanced as the electrostatic potential at the σ-hole becomes increasingly positive. Traditional methods to strengthen σ-hole donor ability of atoms such as halogens often involve covalent modifications, such as, introducing electron-withdrawing substituents (neutral or positively charged) or electrochemical oxidation. Metal coordination, a relatively underexplored approach, offers a promising alternative.

Nucleophilicity of the Nitrile N Atom Whose Lone Pair Is Blocked by Metal Coordination. The π-Hole Interaction between an Arene Carbon and the Metal-Bound Nitrile Nitrogen.

Cocrystallization of CuI with NCNMe in the presence of substituted perfluoroarenes─iodoperfluorobenzene (IFB), 4,4'-diiodoperfluorobiphenyl (4,4'-FIBP), and 4-bromoperfluorobenzonitrile (4-BrFBN)─led to the formation of three types of adducts ·2(IFB), ·4,4'FIBP, and ·4-BrFBN ( is CuI(NCNMe)), all studied by X-ray crystallography. In these cocrystals, the coordinated nitrile N atom (whose electron pair is engaged in metal coordination) still acts as an electron donor, forming π-hole interactions, specifically, π-hole···N, with the perfluoroarenes. These interactions were examined in the context of their occurrence alongside other interactions involving C atoms of the electron-deficient aromatic rings and nucleophilic atoms of the copper cluster.

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-(I)-hole donating iodonium cations with the O-flanked pseudo-lacune rims of [β-MoO] gives halogen-bonded iodonium-beta-octamolybate supramolecular associates. In the occurrence of their tetragonal pyramidal motifs, deep and broad σ-(I)-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.

Intermolecular Metal-Involving Pnictogen Bonding: The Case of σ-(Sb)-Hole···d[Pt] Interaction.

Cocrystallizations of -[PtX'(NCNR)] (R = Me, X' = Cl , Br , I ; R = (CH), X' = I ) with SbX (X = Cl, Br, I) gave 1:2 cocrystals ·2SbCl, ·2SbBr, ·2SbCl, ·2SbBr, ·2SbI, and ·2SbI. In all six X-ray structures, the association of the molecular coformers is achieved mainly by Sb···d[Pt] metal-involving intermolecular pnictogen bonding. Density functional theory (DFT) calculations (based on experimentally determined geometries) using both gas-phase and solid-state approximations revealed that a σ-(Sb)-hole interacts with an area of negative potential associated with the d-orbital of the positively charged platinum(II) sites, thus forming a pnictogen bond whose energy falls in the range between -7.

Metal-Induced Enhancement of Tetrel Bonding. The Case of C⋅⋅⋅X-Ir (X=Cl, Br) Tetrel Bond Involving a Methyl Group.

In X-ray structures of the isomorphic mer-[IrX(THT)(CNXyl)] (X=Cl 1, Br 2; THT=tetrahydrothiophene; Xyl=2,6-MeCH-) 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 C⋅⋅⋅X-Ir (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 C⋅⋅⋅X-Ir interaction was assessed.

Hybrid 2D Supramolecular Organic Frameworks (SOFs) Assembled by the Cooperative Action of Hydrogen and Halogen Bonding and π⋯π Stacking Interactions.

The - and -isomers of 6-(3-(3,4-dichlorophenyl)-1,2,4-oxadiazol-5-yl)cyclohex-3-ene-1-carboxylic acid (- and -) were obtained by the reaction of 3,4-dichloro-'-hydroxybenzimidamide and -1,2,3,6-tetrahydrophthalic anhydride. Cocrystals of - with appropriate solvents (-‧½(1,2-DCE), -‧½(1,2-DBE), and -‧½CH) were grown from 1,2-dichloroethane (1,2-DCE), 1,2-dibromoethane (1,2-DBE), and a -hexane/CHCl mixture and then characterized by X-ray crystallography. In their structures, - is self-assembled to give a hybrid 2D supramolecular organic framework (SOF) formed by the cooperative action of O-H⋯O hydrogen bonding, Cl⋯O halogen bonding, and π⋯π stacking.

Nanoisland SERS-Substrates for Specific Detection and Quantification of Influenza A Virus.

Surface-enhanced Raman spectroscopy (SERS)-based aptasensors for virus determination have attracted a lot of interest recently. This approach provides both specificity due to an aptamer component and a low limit of detection due to signal enhancement by a SERS substrate. The most successful SERS-based aptasensors have a limit of detection (LoD) of 10-100 viral particles per mL (VP/mL) that is advantageous compared to polymerase chain reactions.

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.

Non-Friedländer Route to Diversely 3-Substituted Quinolines through Au(III)-Catalyzed Annulation Involving Electron-Deficient Alkynes.

Gold(III)-catalyzed annulation of electron-deficient alkynes and 2-amino-arylcarbonyls provides general modular one-step access to a broad scope of quinoline products. This highly selective reaction is a useful alternative to the classic Friedländer synthesis, which requires harsh reaction conditions. In contrast, the developed method works under relatively mild PicAuCl-catalyzed conditions and exhibits a high functional group tolerance (40 examples; yields of ≤96%).

PHARMACOLOGY OF POST-TRAUMATIC STRESS DISORDER.

The aim of this study was to evaluate current approaches to the pharmacotherapy of posttraumatic stress disorder. An information search was carried out in the databases PubMed, Ovid, EMBASE by keywords: "posttraumatic stress disorder", "treatment", and "medications". Search depth 2012-2022 years.

Halogen Bond-Involving Self-Assembly of Iodonium Carboxylates: Adding a Dimension to Supramolecular Architecture.

We designed 0D, 1D, and 2D supramolecular assemblies made of diaryliodonium salts (functioning as double σ-hole donors) and carboxylates (as σ-hole acceptors). The association was based on two charge-supported halogen bonds (XB), which occurred between I sites of the iodonium cations and the carboxylate anions. The sequential introduction of the carboxylic groups in the aryl ring of the benzoic acid added a dimension to the 0D supramolecular organization of the benzoate, which furnished 1D-chained and 2D-layered structures when terephthalate and trimesate anions, correspondingly, were applied as XB acceptors.

Rapid SERS Detection of Botulinum Neurotoxin Type A.

Surface-enhanced Raman scattering (SERS) is a powerful technique for decoding of 2-5-component mixes of analytes. Low concentrations of analytes and complex biological media are usually non-decodable with SERS. Recognition molecules, such as antibodies and aptamers, provide an opportunity for a specific binding of ultra-low contents of analyte dissolved in complex biological media.

Halogen Bonding Involving Isomeric Isocyanide/Nitrile Groups.

2,3,5,6-Tetramethyl-1,4-diisocyanobenzene (), 1,4-diisocyanobenzene (), and 1,4-dicyanobenzene () were co-crystallized with 1,3,5-triiodotrifluorobenzene (1,3,5-FIB) to give three cocrystals, ·1,3,5-FIB, ·2(1,3,5-FIB), and ·2(1,3,5-FIB), which were studied by X-ray diffraction. A common feature of the three structures is the presence of I···C or I···N halogen bonds (HaBs), which occurs between an iodine σ-hole and the isocyanide C-(or the nitrile N-) atom. The diisocyanide and dinitrile cocrystals ·2(1,3,5-FIB) and ·2(1,3,5-FIB) are isostructural, thus providing a basis for accurate comparison of the two types of noncovalent linkages of C≡N/N≡C groups in the composition of structurally similar entities and in one crystal environment.

Metal-free and atom-efficient protocol for diarylation of selenocyanate by diaryliodonium salts.

We developed an atom- and reaction mass efficient strategy for the preparation of diarylselenides using iodonium salts as reactants. The developed approach allows the obtaining of diarylselenides from the corresponding trimethoxyphenyl-substituted iodonium salts a two-step one-pot reaction sequence. The proposed metal-free methodology is based on the involvement of both iodonium aryl groups for diarylation.

Incorporation of a Fluorine Atom in a Bridging Ligand of Half-Lantern Pt Complexes Provides up to 10-Fold Enhancement of Electroluminescence Brightness.

The binuclear half-lantern platinum(II) complexes [Pt(pbt)(μ-SN)] (pbtH = 2-phenylbenzothiazole, SN = benzo[]thiazole-2-thiolate , 6-fluorobenzo[]thiazole-2-thiolate , 6-chlorobenzo[]thiazole-2-thiolate , 6-bromobenzo[]thiazole-2-thiolate , and 6-iodobenzo[]thiazole-2-thiolate ) were synthesized by the treatment of the in situ formed [Pt(pbt)(NCMe)]NO complex and appropriate benzo[]thiazole-2-thiole in the presence of BuOK; yield: 51-84%. Complexes - exhibit intense red photoluminescence originated from MMLCT state reaching 22% room temperature quantum yields in a CHCl solution. All complexes display excited-state decay kinetics both in solution and in the solid state; the kinetics was adequately modeled by single exponentials.

Noncovalent Chelation by Halogen Bonding in the Design of Metal-Containing Arrays: Assembly of Double σ-Hole Donating Halolium with Cu-Containing O,O-Donors.

Five new copper(I) complexes─composed of the paired dibenzohalolium and [CuL] (L = 1,2,4-oxadiazolate) counterions in which O,O-atoms of the anion are simultaneously linked to the halogen atom─were generated and isolated as the solid via the three-component reaction between [Cu(MeCN)](BF), sodium 1,2,4-oxadiazolates, and dibenzohalolium triflates (or trifluoroacetates). This reaction is different from the previously reported Cu-catalyzed arylation of 1,2,4-oxadiazolones by diaryliodonium salts. Inspection of the solid-state X-ray structures of the complexes revealed the strong three-center X···O,O (X = Br, I) halogen bonding occurred between the oxadiazolate moieties and dibenzohalolium cation.

Halogen Bond-Involving Supramolecular Assembly Utilizing Carbon as a Nucleophilic Partner of I⋅⋅⋅C Non-covalent Interaction.

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.

Aptamer-coated track-etched membranes with a nanostructured silver layer for single virus detection in biological fluids.

Aptasensors based on surface-enhanced Raman spectroscopy (SERS) are of high interest due to the superior specificity and low limit of detection. It is possible to produce stable and cheap SERS-active substrates and portable equipment meeting the requirements of point-of-care devices. Here we combine the membrane filtration and SERS-active substrate in the one pot.

Lithographic SERS Aptasensor for Ultrasensitive Detection of SARS-CoV-2 in Biological Fluids.

In this paper, we propose a technology for the rapid and sensitive detection of the whole viral particles of SARS-CoV-2 using double-labeled DNA aptamers as recognition elements together with the SERS method for detecting the optical response. We report on the development of a SERS-aptasensor based on a reproducible lithographic SERS substrate, featuring the combination of high speed, specificity, and ultrasensitive quantitative detection of SARS-CoV-2 virions. The sensor makes it possible to identify SARS-CoV-2 in very low concentrations (the limit of detection was 100 copies/mL), demonstrating a sensitivity level comparable to the existing diagnostic golden standard-the reverse transcription polymerase chain reaction.

Structure-Directing Interplay between Tetrel and Halogen Bonding in Co-Crystal of Lead(II) Diethyldithiocarbamate with Tetraiodoethylene.

The co-crystallization of the lead(II) complex [Pb(SCNEt)] with tetraiodoethylene (CI) gave the co-crystal, [Pb(SCNEt)]∙½CI, whose X-ray structure exhibits only a small change of the crystal parameters than those in the parent [Pb(SCNEt)]. The supramolecular organization of the co-crystal is largely determined by an interplay between Pb⋯S tetrel bonding (TeB) and I⋯S halogen bonding (HaB) with comparable contributions from these non-covalent contacts; the TeBs observed in the parent complex, [Pb(SCNEt)], remain unchanged in the co-crystal. An analysis of the theoretical calculation data, performed for the crystal and cluster models of [Pb(SCNEt)]∙½CI, revealed the non-covalent nature of the Pb⋯S TeB (-5.

Polymorph-Dependent Phosphorescence of Cyclometalated Platinum(II) Complexes and Its Relation to Non-covalent Interactions.

Cyclometalated platinum(II) complexes [Pt(ppy)Cl(CNAr)] (ppy = 2-phenylpyridinato-C,; Ar = CH-2-I , CH-4-I , CH-2-F-4-I , and CH-2,4-I ) bearing ancillary isocyanide ligands were obtained by the bridge-splitting reaction between the dimer [Pt(ppy)(μ-Cl)] and 2 equiv any one of the corresponding CNAr. Complex was crystallized in two polymorphic forms, namely, and , exhibiting green (emission quantum yield of 0.5%) and orange (emission quantum yield of 12%) phosphorescence, respectively.

Stacking Interactions: A Supramolecular Approach to Upgrade Weak Halogen Bond Donors.

The co-crystallization of tetracyanobenzene (TCB) with haloarenes ArX provided six new co-crystals TCB ⋅ ArX (ArX=PhCl, PhBr, 4-MeC H Cl, 4-MeC H Br, 4-MeOC H Cl, 1,2-Br C H ) 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⋅⋅⋅N 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.

Halogen Bonding Involving Gold Nucleophiles in Different Oxidation States.

A single-crystal X-ray diffraction (XRD) study of diaryliodonium tetrachloroaurates (or, in the recent terminology, tetrachloridoaurates), [(-XCH)I][AuCl] (X = Cl, ; Br, ), was performed for (the structure is denoted as to show similarity with the isomorphic structure ) and two polymorphs─ (obtained from MeOH) and (from 1,2-CHCl). Examination of the XRD data for these three structures revealed 2-center C-X···Au (X = Cl and Br) and 3-center bifurcated C-Br···(-) halogen bonding (abbreviated as XB) between the -Cl or -Br atoms of the diaryliodonium cations and the gold(III) atom of [AuCl]. The noncovalent nature of Au-involving interactions, the nucleophilicity of the gold(III) atoms, and the electrophilic role of -X atoms of the diaryliodonium cations in the XBs were studied by a set of complementary computational methods.

SERS-based biosensor with Raman-active external responsive element for rapid determination of adenosine monophosphate.

Phosphorylated adenosine derivatives are important biological molecules with diverse biological functions connected with the energetic balance of the cell, biosynthesis of cell components and regulation of protein activity. Measurement of these compounds provides information about the cell signalling in the body as well as the quantity of microorganisms in the environment. Surface-enhanced Raman spectroscopy (SERS) is an optical method that provides a unique spectrum of a substance at low concentrations.