Helical π-Conjugated Structure Based on Complementary Helical Monomers with Circularly Polarized Luminescence.

A fully π-conjugated helical system combining rigid [6]helicenes and a flexible -OPE unit has been developed, yielding enantiopure emitters with up to three helical loops. The compounds display remarkable chiroptical properties in absorption ( up to 2.3 × 10) and emission ( up to 1.

The Essential Oil from the Roots of Ruiz & Pav. Growing in the Paramos of Chimborazo (Ecuador): Chemical Analysis, Enantioselective Profile, and Preliminary Biological Activity.

The essential oil (EO) obtained from the roots of Ruiz & Pav. (Caprifoliaceae), collected in the moorland region of Chimborazo Province, Ecuador, was analyzed for the first time. The chemical profile was qualitatively and quantitatively analyzed using GC-MS and GC-FID, respectively.

Magneto-Structural Correlations, Substitution Effects and Slow Relaxation of the Magnetization on Trinuclear Linear Ni(II) Complexes: An Experimental and Theoretical Study.

We report the preparation of three neutral linear trinuclear Ni(II) complexes [Ni(LX)] (1-3) by self-assembly of Ni(II) ions and NO-tripodal Schiff base ligands, LX, which were obtained by condensation between the triamine tris(methylhydrazine)phosphorylsulfide and salicylaldehyde derivatives with substituents X=H (L1) (1), Br (L2) (2) and NO (L3) (3) in para position to the phenoxo group. Experimental magneto-structural studies carried out on these complexes indicate that the magnetic exchange interactions between the neighboring Ni(II) ions are ferromagnetic in nature, moderate in magnitude and clearly dependent of the electronic properties of the substituent in para position. Thus, the electron-withdrawing NO group decreases the ferromagnetic coupling, whereas the Br substituent, with small electronic effects, does not significantly vary the exchange coupling observed for the unsubstituted complex.

Can Deep Learning Search for Exceptional Chiroptical Properties? The Halogenated [6]Helicene Case.

The relationship between chemical structure and chiroptical properties is not always clearly understood. Nowadays, efforts to develop new systems with enhanced optical properties follow the trial-error method. A large number of data would allow us to obtain more robust conclusions and guide research toward molecules with practical applications.

Can Magnetic Dipole Transition Moment Be Engineered?

The development of chiral compounds with enhanced chiroptical properties is an important challenge to improve device applications. To that end, an optimization of the electric and magnetic dipole transition moments of the molecule is necessary. Nevertheless, the relationship between chemical structure and such quantum mechanical properties is not always clear.

Zero-Field SMM Behavior Triggered by Magnetic Exchange Interactions and a Collinear Arrangement of Local Anisotropy Axes in a Linear Co Complex.

A new linear trinuclear Co(II) complex with a formula of [{Co(μ-L)}Co] has been prepared by self-assembly of Co(II) ions and the NO-tripodal Schiff base ligand HL, which is obtained from the condensation of 1,1,1-tris(aminomethyl)ethane and salicylaldehyde. Single X-ray diffraction shows that this compound is centrosymmetric with triple-phenolate bridging groups connecting neighboring Co(II) ions, leading to a paddle-wheel-like structure with a pseudo- axis lying in the Co-Co-Co direction. The Co(II) ions at both ends of the Co(II) molecule exhibit distorted trigonal prismatic CoNO geometry, whereas the Co(II) at the middle presents an elongated trigonal antiprismatic CoO geometry.

Cell Survival Enabled by Leakage of a Labile Metabolic Intermediate.

Many metabolites are generated in one step of a biochemical pathway and consumed in a subsequent step. Such metabolic intermediates are often reactive molecules which, if allowed to freely diffuse in the intracellular milieu, could lead to undesirable side reactions and even become toxic to the cell. Therefore, metabolic intermediates are often protected as protein-bound species and directly transferred between enzyme active sites in multi-functional enzymes, multi-enzyme complexes, and metabolons.

Magneto-thermal properties and slow magnetic relaxation in Mn(II)Ln(III) complexes: influence of magnetic coupling on the magneto-caloric effect.

A family of Mn(II)Ln(III) dinuclear and tetranuclear complexes (Ln = Gd and Dy) has been prepared from the compartmental ligands ,'-dimethyl-,'-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylenediamine (HL) and ,',''-trimethyl-,''-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (HL). The Mn(II)Gd(III) complexes exhibit antiferromagnetic interactions between Mn(II) and Gd(III) ions in most cases, which are supported by Density Functional Theory (DFT) calculations. Experimental magneto-structural correlations carried out for the reported complexes and other related complexes found in bibliography show that the highest ferromagnetic coupling constants are observed in di-μ-phenoxido bridged complexes, which is due to the planarity of the Mn-(μ-O)-Gd bridging fragment and to the high Mn-O-Gd angles.

Rational design of an unusual 2D-MOF based on Cu(i) and 4-hydroxypyrimidine-5-carbonitrile as linker with conductive capabilities: a theoretical approach based on high-pressure XRD.

Herein, we present, for the first time, a 2D-MOF based on copper and 4-hydroxypyrimidine-5-carbonitrile as the linker. Each MOF layer is perfectly flat and neutral, as is the case for graphene. High pressure X-ray diffraction measurements reveal that this layered structure can be modulated between 3.

Optically active Ag(i): o-OPE helicates using a single homochiral sulfoxide as chiral inducer.

In this work we describe the ability of a simple enantiopure sulfoxide group to promote folding of oligo ortho-phenylene ethynylenes (o-OPEs) with one helical sense. A family of foldamers with up to seven triple bonds was synthesized and fully characterized. Moreover, changes in structure and chiroptical properties caused by Ag(i) coordination have been studied by NMR, UV, VCD and ECD measurements.

Chiral double stapled o-OPEs with intense circularly polarized luminescence.

Intrinsically chiral double stapled ortho-oligo phenylene ethynylenes (o-OPEs) 1 show g values up to 5.5 × 10, the second highest value ever observed for a simple organic molecule (SOM). DFT calculations of molecular spectra and properties encompassing electric and magnetic dipole transition moments account for these observations.

Photocatalytic oxidation of diuron using nickel organic xerogel under simulated solar irradiation.

In this study, a nickel organic xerogel (X-Ni) was used as semiconductor photocatalyst for the degradation of the herbicide diuron (DRN) in aqueous solution. The main objective of this work was to analyze and compare the effectiveness of solar irradiation to remove DRN from water both by direct photolysis and photocatalytic degradation. We examined the influence of the initial concentration of the herbicide, the solution pH, the presence of different ions in the medium, the chemical composition of the water, and the presence of a photocatalyst, after 240 min of irradiation.

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeNS Coordination Sphere.

We present here a novel example of spin crossover phenomenon on a Fe(II) one-dimensional chain with unusual NS coordination sphere. The [{Fe(tpc-OMe)(NCS)(μ-NCS)} ] (1) compound was prepared using the tridentate tpc-OMe ligand (tpc-OMe = tris(2-pyridyl)methoxymethane), FeCl·4HO, and the KSCN salt. Crystallographic investigations revealed that the Fe(II) ions are connected by a single bridging NCS ligand (μ-κN:κS-SCN coordination mode) to afford a zigzag neutral chain running along the [010] direction, in which the thiocyanato bridging groups adopt a cis head-to-tail configuration.

Secondary Oxide Phosphines to Promote Tandem Acyl-Alkyl Coupling/Hydrogen Transfer to Afford (Hydroxyalkyl)rhodium Complexes. Theoretical and Experimental Studies.

Acyl(σ-norbornenyl)rhodium(III) dimer [Rh(μ-Cl)(CHNCO)(CH)L] (1) (CH = σ-norbornenyl; L = 4-picoline, isoquinoline) reacts with diphenylphosphine oxide (SPO) to undergo a one-pot reaction involving (i) cleavage of the chloride bridges and coordination of the phosphine, (ii) C-C bond coupling between acyl and norbornenyl in a 18e species, and (iii) ligand-assisted outer-sphere O(P)-to-O(C) hydrogen transfer, to afford mononuclear 16e species [RhCl{(CHNC(O)CH)(PhPO)H}(L)] (2) containing a quinolinyl-(norbornenylhydroxyalkyl) fragment hydrogen-bonded to a κ- P-phosphinite ligand. Pentacoordinated 2, which adopt a distorted trigonal bipyramidal structure, are kinetic reaction products that transform into the thermodynamic favored isomers 3. Structures 3 contain an unusual weak η-C anagostic interaction involving the rhodium atom and one carbon atom of the olefinic C-H bond of the norbornenyl substituent in the chelating quinolinyl-hydroxyalkyl moiety.

Magneto-Structural Properties and Theoretical Studies of a Family of Simple Heterodinuclear Phenoxide/Alkoxide Bridged MnLn Complexes: On the Nature of the Magnetic Exchange and Magnetic Anisotropy.

A family of MnLn strictly dinuclear complexes of general formula [Mn(μ-L)(μ-OMe)(NO)Ln(NO)(MeOH)] (Ln = Gd, Dy, Er, Ho) has been assembled in a one pot synthesis from a polydentate, multipocket aminobis(phenol)ligand [6,6'-{(2-(1-morpholyl)ethylazanediyl)bis(methylene)}bis(2-methoxy-4-methylphenol)], Mn(NO)·4HO, Ln(NO)· nHO, and NEt in MeOH. These compounds represent the first examples of fully structurally and magnetically characterized dinuclear MnLn complexes. Single X-ray diffraction studies reveal that all complexes are isostructural, consisting of neutral dinuclear molecules where the Mn and Ln metal ions, which exhibit distorted octahedral MnNO and distorted LnO coordination spheres, are linked by phenoxide/methoxide double bridging groups.

On the Magnetic Coupling and Spin Crossover Behavior in Complexes Containing the Head-to-Tail [Fe(μ-SCN)] Bridging Unit: A Magnetostructural Experimental and Theoretical Study.

A new dinuclear complex [{Fe(tpc-OBn)(NCS)(μ-NCS)}] (1) based on the tripodal tpc-OBn ligand (tpc-OBn = tris(2-pyridyl)benzyloxymethane), containing bridging μ-κN:κS-SCN and terminal κN-SCN thiocyanate ligands, has been prepared and characterized by single crystal X-ray diffraction, magnetic studies, and DFT theoretical calculations. This complex represents the first example of dinuclear Fe complex with double μ-κN:κS-SCN bridges in a head-to-tail configuration that exhibits ferromagnetic coupling between metal ions (J = +1.08 cm).

Sulfoxide-Induced Homochiral Folding of ortho-Phenylene Ethynylenes (o-OPEs) by Silver(I) Templating: Structure and Chiroptical Properties.

A new family of homochiral silver complexes based on carbophilic interactions with ortho-phenylene ethynylene (o-OPE) scaffolds containing up to two silver atoms are described. These compounds represent a unique class of complexes with chirality at the metal. Chiral induction is based on the inclusion of chiral sulfoxides, which allow efficient transfer of chirality to the helically folded o-OPE, leading to circularly polarized luminescence (CPL)- and vibrational circular dichroism (VCD)-active compounds.

Intramolecular hydrogen bonding in conformationally semi-rigid α-acylmethane derivatives: a theoretical NMR study.

Conformational mobility is a core property of organic compounds, and conformational analysis has become a pervasive tool for synthetic design. In this work, we present experimental and computational (employing Density Functional Theory) evidence for unusual intramolecular hydrogen bonding interactions in a series of α-acylmethane derivatives, as well as a discussion of the consequences thereof for their NMR spectroscopic properties.

Synthetic ability of dinuclear mesocates containing 1,3-bis(diazinecarboxamide)benzene bridging ligands to form complexes of increased nuclearity. Crystal structures, magnetic properties and theoretical studies.

Triple stranded Ni-metallacyclic complexes Na[Ni(bpcb)]·0.5OH·18.5HO (1) and Na[Ni(bpzcb)]·16HO (2), and double stranded Cu-metallacyclic complexes [Cu(bpcb)(HO)]·8HO (3) and [Cu(bpzcb)(HO)]·4HO (4) have been assembled from the tailored bisbidentate bridging ligands, 1,3-bis(pyrimidine-2-carboxamide)benzene (Hbpcb) and 1,3-bis(pyrazine-2-carboxamide)benzene (Hbpzcb), and the corresponding nitrate salts of the metal ions.

Cubane-like tetranuclear Cu(ii) complexes bearing a CuO core: crystal structure, magnetic properties, DFT calculations and phenoxazinone synthase like activity.

In the present work, two new copper complexes 3a and 3b with a CuO cubane core are reported. Both complexes are obtained by means of the in situ conversion of the imine functionality of Schiff's base ligands 1a [(E)-4-chloro-2-((thiazol-2-ylimino)methyl)phenol] and 1b [(E)-4-bromo-2-((thiazol-2-ylimino)methyl)phenol] into amino alcohols 2a (4-chloro-2-(hydroxy(thiazol-2-ylamino)methyl)phenol) and 2b (4-bromo-2-(hydroxy(thiazol-2-ylamino)methyl)phenol), respectively. The ligand transformation may be metal assisted and the generated ligands show an interesting mode of coordination in which the alkoxo-O atom binds in a μ-manner connecting simultaneously three copper centers and forming a CuO cubane core.

Stapled helical -OPE foldamers as new circularly polarized luminescence emitters based on carbophilic interactions with Ag(i)-sensitivity.

-Oligo(phenylene)ethynylenes (-OPEs) stapled with enantiopure 2,3-dihydroxybutane diethers have highly intense circular dichroism (CD) spectra and excellent circular polarized luminescence (CPL) responses ( values up to 1.1 × 10), which are consistent with homochiral helically folded structures. In the presence of Ag(i), a change in the CPL emission is observed, representing the first example of CPL active small organic molecular emitters, which can be modulated by carbophilic interactions in a reversible manner.

Removal of compounds used as plasticizers and herbicides from water by means of gamma irradiation.

Gamma radiation has been used to induce the degradation of compounds used as plasticizers and herbicides such as phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous solution, determining the dose constants, removal percentages, and radiation-chemical yields. The reaction rate constants of hydroxyl radical (HO), hydrated electron (eaq(-)) and hydrogen atom (H) with these pollutants were also obtained by means of competition kinetics, using 3-aminopyridine and atrazine as reference compounds. The results indicated that the elimination of these pollutants with gamma radiation mainly follows the oxidative pathway through reaction with HO radicals.

Metal-free intermolecular formal cycloadditions enable an orthogonal access to nitrogen heterocycles.

Nitrogen-containing heteroaromatic cores are ubiquitous building blocks in organic chemistry. Herein, we present a family of metal-free intermolecular formal cycloaddition reactions that enable highly selective and orthogonal access to isoquinolines and pyrimidines at will. Applications of the products are complemented by a density functional theory mechanistic analysis that pinpoints the crucial factors responsible for the selectivity observed, including stoichiometry and the nature of the heteroalkyne.

Two-dimensional carbon-based conductive materials with dynamically controlled asymmetric Dirac cones.

The design of two dimensional graphene-type materials with an anisotropic electron flow direction in the X- and Y-axes opens the door for the development of novel electronic materials with multiple functions in nanoelectronics. In the present work, we have studied the electronic transport properties of a new family of 2D graphene-graphyne hybrids presenting conformationally free phenylethylene subunits. This system ensures two different conductive pathways that are perpendicular to each other: an acene nanoribbon subunit, in the X-axis, with graphene-type conduction, and a free to rotate phenylethylene subunit, in the Y-axis, in which the magnitude of the conduction depends dynamically on the corresponding torsion angle.