Acetonitrile Molecules Research Articles

Synthesis and crystal structure of poly[[di-μ3-tetra-thio-anti-monato-tris-[(cyclam)cobalt(II)]] aceto-nitrile disolvate dihydrate] (cyclam = 1,4,8,11-tetra-aza-cyclo-tetra-deca-ne).

Reaction of Co(ClO4)2·6H2O with cyclam (cyclam = 1,4,8,11-tetra-aza-cyclo-tetra-deca-ne) and Na3SbS4·9H2O (Schlippesches salt) in a mixture of aceto-nitrile and water leads to the formation of crystals of the title compound with the composition {[Co3(SbS4)2(C10H24N4)3]·2CH3CN·2H2O} n or {[(Co-cyclam)3(SbS4)2]·2(aceto-nitrile)·2H2O} n . The crystal structure of the title compound consists of three crystallographically independent [Co-cyclam]2+ cations, which are located on centers of inversion, one [SbS4]3- anion, one water and one aceto-nitrile mol-ecule that occupy general positions. The aceto-nitrile mol-ecule is disordered over two orientations and was refined using a split model. The CoII cations are coordinated by four N atoms of the cyclam ligand and two trans-S atoms of the tetra-thio-anti-monate anion within slightly distorted octa-hedra. The unique [SbS4]3- anion is coordinated to all three crystallographically independent CoII cations and this unit, with its symmetry-related counterparts, forms rings composed of six Co-cyclam cations and six tetra-thio-anti-monate anions that are further condensed into layers. These layers are perfectly stacked onto each other so that channels are formed in which acetontrile solvate mol-ecules that are hydrogen bonded to the anions are embedded. The water solvate mol-ecules are located between the layers and are connected to the cyclam ligands and the [SbS4]3- anions via inter-molecular N-H⋯O and O-H⋯S hydrogen bonding.

Specific Noncovalent Association of Truncated exo-Functionalized Triangular Homochiral Isotrianglimines through Head-to-Head, Tail-to-Tail, and Honeycomb Supramolecular Motifs.

Chiral isotrianglimines were synthesized by the [3 + 3] cyclocondensation of (R,R)-1,2-diaminocyclohexane with C5-substituted isophthalaldehyde derivatives. The substituent’s steric and electronic demands and the guest molecules’ nature have affected the conformation of individual macrocycles and their propensity to form supramolecular architectures. In the crystal, the formation of a honeycomb-like packing arrangement of the simplest isotrianglimine was promoted by the presence of toluene or para-xylene molecules. A less symmetrical solvent molecule might force this arrangement to change. Polar substituents present in the macrocycle skeleton have enforced the self-association of isotrianglimines in the form of tail-to-tail dimers. These dimers could be further arranged in higher-order structures of the head-to-head type, which were held together by the solvent molecules. Non-associating isotrianglimine formed a container that accommodated acetonitrile molecules in its cavity. The calculated dimerization energies have indicated a strong preference for the formation of tail-to-tail dimers over those of the capsule type.

Substituted pyrrolyl-cyanopyridines on the platform of acylethynylpyrroles via their 1 : 2 annulation with acetonitrile under the action of lithium metal

A facile one-pot synthesis of 2-(pyrrolyl)-4-aryl(hetaryl)-5-cyano-6-methylpyridines in 63–87% yield via the cyclization of available acylethynylpyrroles with two molecules of acetonitrile under the action of lithium metal at room temperature has been developed.

Acetonitrile-induced structure fine-tuning of a trinuclear zinc complex showing multistimuli responsive luminescence

A trinuclear zinc complex (1) exhibits mechanochromic and acidochromic luminescence properties with five-color switching. The structure of complex 2 shows that the acetonitrile molecules induce fine-tuning of the structures compared with 1.

Hydrogen bonding in the crystal of 1,1'-((1E,1'E)-(pyridine-3,4-diylbis(azanylylidene))bis(methanylylidene))-bis(naphthalen-2-ol) acetonitrile solvate: combined experimental and theoretical study

The title compound, 1,1'-((1E,1'E)-(pyridine-3,4-diylbis(azanylylidene))bis(methanylylidene))­bis(naphthalen-2-ol) (1), was synthesized and structurally characterized. The compound cocrystallized with one MeCN molecule. Interestingly, one of two salicylaldehyde Schiff base fragments exists in enol form, while the other one — in a ketone form. Moreover, cocrystallized acetonitrile molecule forms hydrogen bonding with three hydrogen atoms of the dye molecule. The nature and energies of intermolecular and intramolecular hydrogen bonds were studied theoretically using DFT calculations and topological analysis of the electron density distribution within the formalism of Bader's theory (QTAIM method).

Multinuclear silver N‐heterocyclic carbene complexes provoke potent anticancer activity via mitochondrial dysfunction and cell necrosis induction

AbstractThree silver N‐heterocyclic carbene (NHC) complexes (Ag1–Ag3) were designed and synthesized using quinoline‐functionalized benzoimidazole salts (L1–L3). Both NHC precursors and resultant silver‐NHC complexes were characterized by NMR, FT‐IR spectroscopy, and elemental analysis. X‐ray diffraction analysis was additionally performed to investigate the crystal structures of these silver‐NHC complexes. The results showed that Ag1 is a dinuclear silver complex with a deviated linear geometry. Ag2 has a disilver core in which two silver atoms are coordinated by two quinoline‐functionalized carbene ligands and one acetonitrile molecule. The silver‐NHC complex Ag3 is composed of a silver‐triangle formed by three silver atoms and three carbene ligands. The in vitro cytotoxic studies revealed that silver‐NHC complexes had stronger antitumor activity than their corresponding NHC precursors. Notably, after a 24‐h exposure to cancer cells, Ag2 presented the highest cytotoxicity with a half maximal inhibitory concentration (IC50) at 1.74 ± 0.08 μM in A2780 cells, which was approximately 14‐fold lower than that of the clinically approved metallodrug cisplatin (IC50 = 24.74 ± 1.35 μM). Detailed mechanistic studies suggested that the complex Ag2 provoked intracellular reactive oxygen species (ROS) overproduction and mitochondrial membrane depolarization, which eventually resulted in mitochondrial dysfunction and cell potent necrosis. Overall, our studies show that NHC‐coordinated silver complexes can be readily constructed and used as an attractive class of anticancer agents, which is conductive for further investigation of their therapeutic potential for treating cisplatin‐resistant cancers.

Numerical Estimation of Acetonitrile Adsorption into Simple Artificial Cell Membranes

AbstractThe dynamic behaviour of lipid vesicles in response to the incorporation of toxic acetonitrile is investigated. Shape data from previous observations are used to estimate the incorporation of acetonitrile into a 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) vesicle. A bilayer‐couple model is used to quantify the disparity in incorporation between the outer and inner leaflets. The model assumes that the prolate spheroid corresponds to a reduced volume , when equal numbers of molecules incorporated into outer and inner leaflets. It further assumes a reduced area difference . These disparities suggest that the difference in acetonitrile molecules incorporated into the outer and inner leaflets is . The value indicates that the outer leaflet has more acetonitrile molecules than the inner leaflet because of the polarity of acetonitrile. These findings are the first step to clarifying the mechanism for acetonitrile to invade living cells.

Luminescent Complexes of Europium (III) with 2-(Phenylethynyl)-1,10-phenanthroline: The Role of the Counterions.

New antenna ligand, 2-(phenylethynyl)-1,10-phenanthroline (PEP), and its luminescent Eu (III) complexes, Eu(PEP)2Cl3 and Eu(PEP)2(NO3)3, are synthesized and characterized. The synthetic procedure applied is based on reacting of europium salts with ligand in hot acetonitrile solutions in molar ratio 1 to 2. The structure of the complexes is refined by X-ray diffraction based on the single crystals obtained. The compounds [Eu(PEP)2Cl3]·2CH3CN and [Eu(PEP)2(NO3)3]∙2CH3CN crystalize in monoclinic space group P21/n and P21/c, respectively, with two acetonitrile solvent molecules. Intra- and inter-ligand π-π stacking interactions are present in solid stat and are realized between the phenanthroline moieties, as well as between the substituents and the phenanthroline units. The optical properties of the complexes are investigated in solid state, acetonitrile and dichloromethane solution. Both compounds exhibit bright red luminescence caused by the organic ligand acting as antenna for sensitization of Eu (III) emission. The newly designed complexes differ in counter ions in the inner coordination sphere, which allows exploring their influence on the stability, molecular and supramolecular structure, fluorescent properties and symmetry of the Eu (III) ion. In addition, molecular simulations are performed in order to explain the observed experimental behavior of the complexes. The discovered structure-properties relationships give insight on the role of the counter ions in the molecular design of new Eu (III) based luminescent materials.

Hitting the Trifecta: How to Simultaneously Push the Limits of Schrödinger Solution with Respect to System Size, Convergence Accuracy, and Number of Computed States.

Methods for solving the Schrödinger equation without approximation are in high demand but are notoriously computationally expensive. In practical terms, there are just three primary factors that currently limit what can be achieved: 1) system size/dimensionality; 2) energy level excitation; and 3) numerical convergence accuracy. Broadly speaking, current methods can deliver on any two of these three goals, but achieving all three at once remains an enormous challenge. In this paper, we shall demonstrate how to "hit the trifecta" in the context of molecular vibrational spectroscopy calculations. In particular, we compute the lowest 1000 vibrational states for the six-atom acetonitrile molecule (CH3CN), to a numerical convergence of accuracy 10-2 cm-1 or better. These calculations encompass all vibrational states throughout most of the dynamically relevant range (i.e., up to ∼4250 cm-1 above the ground state), computed in full quantum dimensionality (12 dimensions), to near spectroscopic accuracy. To our knowledge, no such vibrational spectroscopy calculation has ever previously been performed.

Bis(μ-cobaltoceniumseleno-late-1:2κ2 Se:Se)bis[bis-(cobaltoceniumseleno-late-κSe)mercury(II)] tetra-kis-(hexa-fluorido-phosphate) aceto-nitrile disolvate.

The title compound, [Co6Hg2(C5H5)6(C5H4Se)6](PF6)4·2CH3CN or [Hg2(CcSe)6][PF6]4·2CH3CN (Cc = C10H9Co), was obtained as bright-orange needle-shaped crystals. It is a salt containing a tetra-cationic dimercury species with six cobaltoceniumseleno-late ligands, four hexa-fluorido-phosphate counter-ions and two aceto-nitrile solvent mol-ecules. The cation (point group ) has a bi-tetra-hedral {Hg2Se6} core with two bridging Se atoms and four terminal Se atoms.

Bis(isonicotinamide-κN)silver(I) tri-fluoro-methane-sulfonate aceto-nitrile disolvate.

The central AgI atom of the title salt, [Ag(INAM)2](CF3SO3)·2CH3CN, where INAM is isonicotinamide (C6H6N2O), is twofold coordinated by the pyridine N atoms of two isonicotinamide ligands creating a slightly distorted linear mol-ecular geometry. The formation of polymeric chains {[Ag(INAM)2]+} n , held together by discrete hydrogen bonds through the amide group of the INAM ligand leaves voids for non-coordinating aceto-nitrile mol-ecules that inter-act the silver metal center via regium bonds.

Mechanistic Insight on the Solid Electrolyte Interphase (SEI) Formed By a Superconcentrated [Li][TFSI] in Acetonitrile Electrolyte Near Lithium Metal

Superconcentrated salt solutions are promising alternatives to conventional electrolytes in Li-ion batteries because of their enhanced redox stability and tendency to form a stable and rigid solid electrolyte interphase (SEI). Herein, we performed density functional theory-based molecular dynamics (DFT-MD) simulations to understand the initial electrode reactions between the Li metal and superconcentrated electrolyte solution of Li bis(trifluoromethanesulfonyl)imide ([Li][TFSI]) in acetonitrile (AN). We thoroughly analyzed the structure and composition of the SEI formed near the Li metal. We show that reductive decomposition of the TFSI anions contributes majorly in the initial SEI formation and the AN molecules are relatively stable against the redox processes occurring near the Li metal. The atomized C, O, F, and S atoms contributed by the TFSI anions forms the stable inorganic layer leading to highly structured and inhomogeneous SEI. The AN molecules and undissociated N–SO2–CF3 fragments are mostly aligned away from the Li layers. Figure 1

Tunable Proton Conductivity and Color in a Nonporous Coordination Polymer via Lattice Accommodation to Small Molecules.

Nonporous coordination polymers (npCPs) able to accommodate molecules through internal lattice reorganization are uncommon materials with applications in sensing and selective gas adsorption. Proton conduction, extensively studied in the analogue metal‐organic frameworks under high‐humidity conditions, is however largely unexplored in spite of the opportunities provided by the particular sensitivity of npCPs to lattice perturbations. Here, AC admittance spectroscopy is used to unveil the mechanism behind charge transport in the nonporous 1·2CH3CN. The conductance in the crystals is found to be of protonic origin. A vehicle mechanism is triggered by the dynamics of the weakly coupled acetonitrile molecules in the lattice that can be maintained by a combination of thermal cycles, even at low humidity levels. An analogue 1·pyrrole npCP is formed by in situ exchange of these weakly bound acetonitrile molecules by pyrrole. The color and conduction properties are determined by the molecules weakly bonded in the lattice. This is the first example of acetonitrile‐mediated proton transport in an npCP showing distinct optical response to different molecules. These findings open the door to the design of switchable protonic conductors and capacitive sensors working at low humidity levels and with selectivity to different molecules.

Solvent and Guest-Driven Supramolecular Organic Frameworks Based on a Calix[4]arene-tetrol: Channels vs Molecular Cavities

Cone-shaped calix[4]arene-tetrol 3 has the ability to form open structures due to the presence of four OH groups at the upper rim, which allows the construction of H-bonded supramolecular organic frameworks (SOFs). In the presence of water, SOF-1 is formed, which contains hydrophilic channels (mean diameter of 8.5 Å) contoured by the p-phenolic OH groups. In the presence of acetonitrile, SOF-2 is formed, which contains smaller hydrophobic channels (mean diameter of 6.6 Å) delimited by aromatic walls. The Na+@3 complex, which hosts acetonitrile molecules in the calixarene cavities, and dibromo-calix[4]arene-diol 5 give rise to more compact SOFs not containing channels. The H-bond network formed by all four p-phenolic OH groups in a pinched cone conformation of the calixarene is a determinant for the porosity of SOFs based on calix[4]arene-tetrol.

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The dissolution issue of organic materials in conventional electrolytes is a critical obstacle to their applications. In the article EOM2‐2021‐0028., Huang and Zhang introduced a highly concentrated acetonitrile‐based electrolyte barely free solvent molecules to avoid reaction between acetonitrile molecules and lithium metal as well as alleviate the dissolution of Pillar[5]quinone. This provides a reference for the development of organic batteries. image

Solvation of anthraquinone and TEMPO redox-active species in acetonitrile using a polarizable force field.

Redox-active molecules are of interest in many fields, such as medicine, catalysis, or energy storage. In particular, in supercapacitor applications, they can be grafted to ionic liquids to form so-called biredox ionic liquids. To completely understand the structural and transport properties of such systems, an insight at the molecular scale is often required, but few force fields are developed ad hoc for these molecules. Moreover, they do not include polarization effects, which can lead to inaccurate solvation and dynamical properties. In this work, we developed polarizable force fields for redox-active species anthraquinone (AQ) and 2,2,6,6-tetra-methylpiperidinyl-1-oxyl (TEMPO) in their oxidized and reduced states as well as for acetonitrile. We validate the structural properties of AQ, AQ•-, AQ2-, TEMPO•, and TEMPO+ in acetonitrile against density functional theory-based molecular dynamics simulations and we study the solvation of these redox molecules in acetonitrile. This work is a first step toward the characterization of the role played by AQ and TEMPO in electrochemical and catalytic devices.

Double‐effect of highly concentrated acetonitrile‐based electrolyte in organic lithium‐ion battery

AbstractOrganic electrode materials have become a hot research field in lithium‐ion batteries. However, the dissolution issue of organic materials (especially small molecules) in traditional electrolytes has become one of the important reasons to limit their application. The usage of highly concentrated electrolyte (HCE, >3 M) has been demonstrated to solve this problem, where the electrochemical performance of Pillar[5]quinone (P5Q) in 4.2 M LiTFSA/AN electrolyte was investigated. The HCE can avoid the reaction between acetonitrile molecules and lithium metal anode, reduce the dissolution of organic materials, and display excellent battery performance. At a current density of 0.2 C, a high specific capacity of 310 mAh g−1 (Ctheo = 446 mAh g−1) was maintained after 900 cycles, and the reversible capacity is higher than 113 mAh g−1 even at 10 C, indicating a good rate capability. This research would expand the new application of acetonitrile‐based electrolyte in organic secondary battery.image

The influence of cations on the dipole moments of neighboring polar molecules

AbstractIn this article we show how the dipole moment of a single molecule in a cluster can be calculated and used for describing the polarization effect. Additionally, we review the accuracy of the calculation of the dipole moment of several simple protic and aprotic molecules. It is shown that the dipole moment of polar (water, methanol, formamide, acetone and acetonitrile) molecules in the neighborhood of a cation is increased primarily by polarization from the bare electrostatic charge of the cation, although the effective value of the latter is somewhat reduced by “back donation” of electrons from neighboring polar molecules. In other words, the classical picture may be viewed as if a point charge slightly smaller than the nominal charge of the cation would be placed at the cation site. It was found that the geometrical arrangement of the polar molecules in the first solvation shell is such that their mutual polarization reduces the dipole moments of individual molecules, so that in some cases they become smaller than the dipole moment of the free protic or aprotic molecule. We conjecture, for the first time, that this behavior, namely the about 10%–20% decrease of the dipole moment of water in the first shell of cations, with the cation itself removed, is essentially a manifestation of the Le Chatelier–Braun principle. We also remark that if the cation‐molecule bond order is too large then the calculated dipole moment for these complexes can be questionable, due to the questionable definition of a single molecule within the “supermolecule”‐like cluster.

Calixarene-Based lead receptors: an NMR, DFT and X-Ray synergetic approach

ABSTRACT The conformational changes of the homooxa adamantyl ketones 1 and 2, as well as of the calix[4]arene analogue derivative 3, all in the cone conformation, upon Pb2+ complexation were investigated by 1H, 13C, 207Pb NMR and proton spin-lattice relaxation times (T 1) experiments. The X-ray crystal structures of ketones 1 and 3 were determined. The inclusion of an acetonitrile molecule in the hydrophobic cavity of the ligands was observed in the solid state. In solution, inclusion was observed only in the case of Pb2+ ⊂ ketone 3 complex. DFT calculations were also performed to complement the NMR conformational analysis and to bring further insights to the cation complexation. The data confirmed the formation of 1:1 complexes between Pb2+ and the ligands, and that the cation is located inside the cavity defined by the phenoxy and carbonyl oxygen atoms. In general, the ligand conformations became closer to a regular cone upon complexation, with the binding models found for the three ketones through the NMR studies corroborated by the DFT calculations.

Theoretical investigation on the elusive biomimetic iron(III)-iodosylarene chemistry: An unusual hydride transfer triggers the Ritter reaction

Introduction of iodosylarnes into biomimetic nonheme chemistry has made great achievement on identification of the subtle metal-oxygen reaction intermediates. However, after more than three decades of experimental and theoretical efforts the nature of the metal-iodosylarene adducts and the related dichotomous one-oxidant/multiple-oxident controversy have remained a matter of speculation. Herein, we report a theoretical study of the structure-activity relationship of the noted iron(III)-iodsylarene complex, FeIII(PhIO)(OTf)3 (1), in oxygenation of cyclohexene. The calculated results revealed that 1 behaves like a chameleon by adapting its roles as a 2e-oxidant or an oxygen donor, as a response to the regioselective attack of the C–H bond and the C=C bond. The oxidative C–H bond activation by 1 was found, for the first time, to proceed via a novel hydride transfer process to form a cyclohexene carbonium intermediate, such non-rebound step triggers the Ritter reaction to uptake an acetonitrile molecule to form the amide product, or proceeds with the rebound of the hydroxyl group return to the solvent cage to form the hydroxylated product. While in the C=C bond activation, 1 is a normal oxygen donor and shows two-state reactivity to present the epoxide product via a direct oxygen atom transfer mechanism. These mechanistic findings fit and explain the famous Valentine's experiments and enrich the non-rebound scenario in bioinorganic chemistry.