Five new proton transfer compounds, (Hapy)[Cr(pydc)2]·5H2O·[pydcH2] (1), (Hacr)[Cr(pydc)2]·2H2O (2), (H9a-acr)[Cr(pydc)2]·4.27H2O (3), [Co(pydc)(pydcH2)]·3H2O (4) and [Ni(pydcH)2]·H3O·2H2O (5) (where pydcH2 = pyridine-2,6-dicarboxylic acid; apy 2-aminopyridine; acr acridine 9a-acr 9-aminoacridine) have been synthesized characterized by elemental analysis, IR spectroscopy single crystal X-ray diffraction techniques. Crystallographic analysis revealed that compounds 1–5 distorted octahedral...

A novel heterometallic oxalate-based compound of the formula {[Co(bpy)3][Mn2(C2O4)3]·H2O}n (1; bpy = 2,2′-bipyridine) was synthesized and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction (XRD), magnetization measurement. The molecular structure 1 is made a three-dimensional (3D) anionic network, [Mn2(C2O4)3]n2n–, tris-chelated cations [Co(bpy)3]2+ occupying vacancies framework. Splitting between zero-field-cooled (ZFC) field-cooled (FC) branches...

The present review is aimed to compare crystal packing interactions contributing stacking arrangements of primarily nonaromatic systems referring only briefly classical aromatic stacking. mainly based on weak dispersion (E ≤ 1 kcal mol–1) whereas heteroaromatics reveal more electrostatic (or specifically dipolar) contributions = 5–10 mol–1). Based our charge density studies and DFT calculations, the results show that (i) all planar rings stack, regardless aromaticity delocalization π...

On supramolecular chemistry grounds proton donors (chloranilic acid) and acceptors (organic bases) were combined to generate multi-component hydrogen bonded systems. Two steps of deprotonation chloranilic acid, leading the monoanion dianion, are coupled by a single or double electron delocalization, respectively. The dissociation acid is accompanied transfer from an organic base if their ΔpKa value large enough support salt formation. A series salts with bases such as dimethylamine,...

Salts and ionic cocrystals simultaneously comprising N-oxide carboxylic acid functional groups constitute a very fertile ground for the investigation of various proton transfer phenomena. This is because such compounds combine two types transfer: that is, inter- intramolecular hydrogen bonding in acid–base systems. To this end, series novel salts based on pyridine-2,5-dicarboxylic (H2pydco) as an organic 2,4,6-triamino-1,3,5-triazine (tata), 2-aminopyrimidine (2a-pym),...

Objective: The purpose of this study was to analyze morphological, chemical, and crystallographic changes bone tissue after osteotomy performed with an erbium:yttrium-aluminium-garnet (Er:YAG) laser a low speed pilot drill. Materials methods: Bone blocks were prepared from porcine ribs, on each block, two tunnel preparations using the Er:YAG (pulse energy: 1000 mJ, pulse duration: 300 μs, repetition rate: 20 Hz) or low-speed surgical morphological cortical spongious surface analyzed under...

X-ray charge density was determined and analyzed for two polymorphs of the N-methylpyridinium salt tetrachlorosemiquinone radical anion its analogous closed-shell relatives, tetrachloroquinone (chloranil) tetrachlorohydroquinone. The study, which combined with calculations electron delocalization, electrostatic potentials, aromaticity, presents details electronic structure semiquinoid ring. This comparative study reveals that negative is delocalized over entire semiquinone chlorine...

A novel oxalate-based complex of the formula {Ba(2)(H(2)O)(5)[NbO(C(2)O(4))(3)]HC(2)O(4)}·H(2)O (1) was prepared from an aqueous solution containing [NbO(C(2)O(4))(3)](3-) and Ba(2+) entities in molar ratio 1:2, characterized by X-ray single-crystal diffraction, IR spectroscopy, thermal analysis. The crystal packing 1 reveals a three-dimensional (3D) network: Nb polyhedron is connected to eight neighboring Ba polyhedra through oxalate ligands oxo-oxygen group, whereas share edges vertices....

Five new (2-adamantyl)naphthol derivatives (5-9, quinone methide precursors, QMP) were synthesized and their photochemical reactivity was investigated by preparative photolyses, fluorescence spectroscopy, laser flash photolysis (LFP). Excitation of QMP 5 to S(1) leads efficient excited state intramolecular proton transfer (ESIPT) coupled with dehydration, giving QM5 which characterized LFP (in CH(3)CN-H(2)O, λ(max) = 370 nm, τ 0.19 ms). On irradiation in CH(3)OH-H(2)O (4:1), the quantum...

Two salts of tetrachloro- (chloranil, Cl4Q) and tetrabromosemiquinone (bromanil, Br4Q) radical anions with an organic cation N-methylpyridinium (N-MePy), displaying a variety tunable electrical magnetic properties, are characterized. These systems comprise π-stacks equidistant semiquinone anions, without Peierls deformation diamagnetic spin coupling. Both stable up to 150 120 °C in air, respectively, semiconductors conductivities 10–6–10–7 (Ω cm)−1 the single crystals. The room-temperature...

The crystal structure of [4-damp])2 [Cl4 Q]3 (4-damp=4-dimethylamino-N-methylpyridinium, Cl4 Q=tetrachloroquinone) salt is built up from slipped columnar stacks quinoid rings composed closely bound trimers with the intra-trimer separation distance 2.84 Å and total charge -2 whereas inter-trimer 3.59 Å. individual exhibit partial negative charges that are distributed unevenly among three Qs in trimer. strong interactions within a trimer (Cl4 Q)32- have partially covalent character...

This study aims to test the inhibition potency of new thienobenzo/naphtho-triazoles toward cholinesterases, evaluate their selectivity, and interpret obtained results by molecular modeling. The synthesis 19 two different approaches resulted in a large group molecules with functionalities structure. As predicted, most prepared show better enzyme butyrylcholinesterase (BChE), considering that were designed according previous results. Interestingly, binding affinity BChE for even seven...

Crystal structures of alkali salts tetrahaolgenosemiquinone anion radical acetone solvates and their solvent-free are determined. p-Semiquinone reveals enhanced aromaticity the ring compared to quinone. A pair π-stacked (p-semiquinone) rings occurs in crystal potassium rubidium tetrachlorosemiquinone tetrabromo analogue. The centroid separation distances about 3.2 Å carbon–carbon contacts between contiguous 0.3 shorter than sum van der Waals radii. spin-coupling two unpaired electrons...

The anion radicals with nonaromatic π-systems, such as semiquinones, are interesting in the design of functional materials. Magnetic properties solvates alkali salts tetrachlorosemiquinone (chloranil) radical tuned by crystal engineering using different solvents (2-butanone and acetonitrile) and/or cations (potassium ammonium) crystals. structural magnetic characteristics two were studied variable-temperature single X-ray diffraction susceptibility measurements. DFT CAS-MP2 calculations used...

A series of copper(<sc>ii</sc>) complexes with chloranilic acid different topologies is prepared and a design strategy for the preparation such discussed.

We present a solvent-free thermo-mechanochemical approach for the direct coupling of carboxylic acids and amines, which avoids activators additives. Non-covalent interactions between reagents guide formation amide bond.

Hydrogen bonding and proton transfer in the solid state are studied on crystals of isostructural anhydrous potassium rubidium complex chloranilates by variable-temperature single crystal X-ray diffraction, 1H NMR IR spectroscopies, periodic DFT calculations equilibrium geometries, potentials, chemical shifts. Their structures reveal neutral molecules chloranilic acid its dianions connected into a chain O−H···O hydrogen bond. A strong bond with large-amplitude movement shift 13−17 ppm broad...

Abstract A series of peptides that contain homo‐ and heterochiral Ala−Pro sequences attached to the turn‐inducing ferrocene‐1,1′‐diamine scaffold were synthesized. The effects backbone chirality N‐terminal group (Boc/Ac) on conformational properties novel peptidomimetics thoroughly explored by IR, NMR, CD spectroscopy experimental observations corroborated DFT studies in solution. most stable conformers homochiral adopted interstrand hydrogen‐bond patterns, realized through ten‐...

First anion···π contacts with quinoid rings have been described in novel co-crystals of tetrabromo- and tetrachloroquinone iodide salts substituted N-methylpyridinium cations. In seven crystal structures these co-crystals, a centrosymmetric unit I–···quinone···I– is observed involving close between anions electron-depleted carbon skeletons the rings. However, salt N-methyl-4-methylcarboxypyridinium base crystallizes two polymorphs characterized by O═C···quinone···C═O interaction instead one....

Herein, we present a detailed X-ray charge density study of the electron delocalization in five species chloranilic acid: neutral molecule, mono- and dianion, two chelating modes: bidendate (bis)bidentate. The experiments provide at bond critical points, which yields an accurate measure order (and therefore delocalization), complement previous literature our data on lengths extracted from crystal structures infrared spectra. Mapping electrostatic potential indicates electron-rich...