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A modified neglect of differential overlap has been parameterized specifically for water and its oligomers with the addition of polarization functions on both hydrogen and oxygen, Feynman dispersion, and a slight modification of the treatment of the hydrogen nucleus. The results show that it is possible to easily obtain good geometries and energies for hydrogen-bonded water aggregates. Data from the Benchmark Energy and Geometry Database water-cluster database were used to parameterize the new Hamiltonian for water clusters from the dimer to the decamer using MP2/aug-cc-pVDZ optimized geometries and CCSD(T)/CBS oligomerization energies. Seventy five oligomerization and rearrangement energies derived from the parameterization data are reproduced with a root mean-square error (RMSE) of 0.79 kcal mol−1 and the geometries of 38 oligomers with an RMSE of 0.17 Å. Interestingly, the Feynman dispersion term adopts a role different from that intended and tunes the atomic polarizability. The implications of these results in terms of future dedicated neglect of diatomic differential overlap Hamiltonians and those that use force-field-like atom types are discussed. [ABSTRACT FROM AUTHOR]

The synthesis of covalent organic frameworks (COFs) based on a novel thiophene‐extended benzotrithiophene (BTT) building block is described, which in combination with triazine‐based amines (1,3,5‐triazine‐2,4,6‐triyl)trianiline (TTA) or (1,3,5‐triazine‐2,4,6‐triyl)tris(([1,1´‐biphenyl]‐4‐amine)) (TTTBA)) affords crystalline, and porous imine‐linked COFs, BTT TTA and BTT TTTBA, with surface areas as high as 932 and 1200 m2 g−1, respectively. Oriented thin films are grown successfully on different substrates, as indicated by grazing incidence diffraction (GID). Room‐temperature in‐plane electrical conductivity of up to 10−4 S m−1 is measured for both COFs. Temperature‐dependent electrical conductivity measurements indicate activation energies of ≈123.3 meV for BTT TTA and ≈137.5 meV for BTT TTTBA and trap‐dominated charge transport via a hopping mechanism for both COFs. Moreover, conductive atomic force microscopy reveals directional and defect‐dominated charge transport in the oriented BTT COF films with a strong preference for the in‐plane direction within the molecular 2D‐planes. Quantum mechanical calculations predict BTT TTTBA to conduct holes and electrons effectively in both in‐plane and out‐of‐plane directions. In‐plane, charge carrier transport is of hopping character where the triazine cores represent the barrier. Out‐of‐plane, a continuous charge‐carrier pathway is calculated that is hampered by an imposed structural defect simulated by a rotated molecular COF layer. [ABSTRACT FROM AUTHOR]

We report the synthesis of a unique cubic metal–organic framework (MOF), Fe‐HHTP‐MOF, comprising hexahydroxytriphenylene (HHTP) supertetrahedral units and FeIII ions, arranged in a diamond topology. The MOF is synthesized under solvothermal conditions, yielding a highly crystalline, deep black powder, with crystallites of 300–500 nm size and tetrahedral morphology. Nitrogen sorption analysis indicates a highly porous material with a surface area exceeding 1400 m2 g−1. Furthermore, Fe‐HHTP‐MOF shows broadband absorption from 475 up to 1900 nm with excellent absorption capability of 98.5 % of the incoming light over the visible spectral region. Electrical conductivity measurements of pressed pellets reveal a high intrinsic electrical conductivity of up to 10−3 S cm−1. Quantum mechanical calculations predict Fe‐HHTP‐MOF to be an efficient electron conductor, exhibiting continuous charge‐carrier pathways throughout the structure. [ABSTRACT FROM AUTHOR]

The rising demand for clean water for a growing and increasingly urban global population is one of the most urgent issues of our time. Here, we introduce the synthesis of a unique nanoscale architecture of pillar‐like Co‐CAT‐1 metal–organic framework (MOF) crystallites on gold‐coated woven stainless steel meshes with large, 50 μm apertures. These nanostructured mesh surfaces feature superhydrophilic and underwater superoleophobic wetting properties, allowing for gravity‐driven, highly efficient oil–water separation featuring water fluxes of up to nearly one million L m−2 h−1. Water physisorption experiments reveal the hydrophilic nature of Co‐CAT‐1 with a total water vapor uptake at room temperature of 470 cm3 g−1. Semiempirical molecular orbital calculations shed light on water affinity of the inner and outer pore surfaces. The MOF‐based membranes enable high separation efficiencies for a number of liquids tested, including the notorious water pollutant, crude oil, affording chemical oxygen demand (COD) concentrations below 25 mg L−1 of the effluent. Our results demonstrate the great impact of suitable nanoscale surface architectures as a means of encoding on‐surface extreme wetting properties, yielding energy‐efficient water‐selective large‐aperture membranes. [ABSTRACT FROM AUTHOR]

Density functional theory (DET) and ab initio (CBS-RAD) calculations have been used to investigate a series of "radical clock" reactions. The calculated activation energies suggest that the barriers for these radical rearrangements are determined almost exclusively by the enthalpy effect with no evidence of significant polar effects. The ring-closure reactions to cyclopentylmethyl radical derivatives and the ring opening of cyclopropylmethyl radicals give different correlations between the calculated heat of reaction and barrier, but the two types of reaction are internally consistent. [ABSTRACT FROM AUTHOR]

Determines the solvation effect of N-alkylation on the redox properties of nickel (Ni) and chromium (Cr) cyclam complexes. Structures of the anhydrous and hydrated complexes in the gas phase; Elongation of the metal-nitrogen (N) bond following the axial binding of water molecules in the Cr complexes; Shortening of the Ni-N bond lengths by Ni oxidation.

Experimental and theoretical evidence is presented for a novel metal-dependent intramolecular reactivity of π-bonded, unsaturated P-heterocycles like 1,3-diphosphete and 1,3,5-triphosphinine. The nucleophilic attack of a P lone pair of 1,3-diphosphete toward a neighboring ligand leads to new bicyclic ligands with unique structural features. A metal-initiated intramolecular hydrogen transfer and C--C bond formation are observed for (1,3,5-triphosphinine)(COD)Fe to result in the formation of [(CO) 5 Cr(4,5,6-trihydro-1,3,5-triphosphinine)(trihydropentalene)Fe]. [ABSTRACT FROM AUTHOR]

Descriptors derived from semiempirical (AM1) molecular orbital calculations have been used to construct a quantitative structure-property relationship (QSPR) for the thermodynamic hydrogen-bond basicity, p KHB, of a series of six-membered aromatic nitrogen-heterocycles. The resulting model uses four-descriptors (the Coulson charge on the nitrogen atom, the energy of the localized nitrogen lone-pair orbital, the p-orbital contribution to this MO and an accessibility angle). The model gives r2 cv=0.95 for 51 compounds with a standard deviation between calculation and experiment of 0.13 log units. [ABSTRACT FROM AUTHOR]

Keywords: electrical conductivity; iron-catecholate; metal-organic frameworks; porosity; three-dimensional framework EN electrical conductivity iron-catecholate metal-organic frameworks porosity three-dimensional framework 17893 17893 1 08/05/21 20210809 NES 210809 B Fe-HHTP-MOF b , ein einzigartiges kubisches metallorganisches Gerüst (MOF), das aus supertetraedrischen Hexahydroxytriphenylen(HHTP)-Einheiten und in Rautentopologie angeordneten Fe SP III sp -Ionen aufgebaut ist, wird im Forschungsartikel auf S. 18213 von Thomas Bein, Dana D. Medina et al. vorgestellt. GLO:OL3/09aug21:ange202106478-toc-0001.jpg PHOTO (COLOR): . gl GLO:OL3/09aug21:ange202106478-toc-0001.jpg PHOTO (COLOR): . gl B Fe-HHTP-MOF b , ein einzigartiges kubisches metallorganisches Gerüst (MOF), das aus supertetraedrischen Hexahydroxytriphenylen(HHTP)-Einheiten und in Rautentopologie angeordneten Fe SP III sp -Ionen aufgebaut ist, wird im Forschungsartikel auf S. 18213 von Thomas Bein, Dana D. Medina et al. vorgestellt. Fe-HHTP-MOF ist ein hochkristallines, poröses und tiefschwarzes Material, das eine hohe elektrische Leitfähigkeit aufweist. [Extracted from the article]

Fe-HHTP-MOF is a highly crystalline, porous, and deep black material featuring high electrical conductivity. Keywords: electrical conductivity; iron-catecholate; metal-organic frameworks; porosity; three-dimensional framework EN electrical conductivity iron-catecholate metal-organic frameworks porosity three-dimensional framework 17749 17749 1 08/05/21 20210809 NES 210809 B Fe-HHTP-MOF b , a unique cubic metal-organic framework (MOF) comprising hexahydroxytriphenylene (HHTP) supertetrahedral units and Fe SP III sp ions arranged in a diamond topology, is reported by Thomas Bein, Dana D. Medina et al. in their Research Article on page 18065. Fe-HHTP-MOF is a highly crystalline, porous, and deep black material featuring high electrical conductivity. [Extracted from the article]