Lanthanides have seen rapid growth in the pharmaceutical and biomedical field, thus necessitating the development of hybrid metal–organic materials capable of exerting defined biological activities. Ternary hybrid lanthanide compounds were synthesized through reaction systems of Ln(III) (Ln = La, Nd, Eu) involving the antioxidant flavonoid chrysin (Chr) and 1,10-phenanhtroline (phen) under solvothermal conditions, thus leading to pure crystalline materials. The so-derived compounds were characterized physicochemically in the solid state through analytical (elemental analysis), spectroscopic (FT-IR, UV-visible, luminescence, ESI-MS, circular dichroism, 151Eu Mössbauer), magnetic susceptibility, and X-ray crystallographic techniques. The analytical and spectroscopic data corroborate the 3D structure of the mononuclear complex assemblies and are in line with theoretical calculations (Bond Valence Sum and Hirshfeld analysis), with their luminescence suggesting quenching on the flavonoid-phen electronic signature. Magnetic susceptibility data suggest potential correlations, which could be envisioned, supporting future functional sensors. At the biological level, the title compounds were investigated for their (a) ability to interact with bovine serum albumin and (b) antibacterial efficacy against Gram(−) (E. coli) and Gram(+) (S. aureus) bacteria, collectively revealing distinctly configured biological profiles and suggesting analogous applications in cellular (patho)physiologies.

We present the development and implementation of relativistic coupled cluster linear response theory (CC-LR), which allows the determination of molecular properties arising from time-dependent or time-independent electric, magnetic, or mixed electric-magnetic perturbations (within a common gauge origin for the magnetic properties) as well as taking into account the finite lifetime of excited states in the framework of damped response theory. We showcase our implementation, which is capable to offload the computationally intensive tensor contractions characteristic of coupled cluster theory onto graphical processing units, in the calculation of (a) frequency-(in)dependent dipole-dipole polarizabilities of IIB atoms and selected diatomic molecules, with a particular emphasis on the calculation of valence absorption cross sections for the I2 molecule; (b) indirect spin-spin coupling constants for benchmark systems such as the hydrogen halides (HX, X = F-I) as well the H2Se-H2O dimer as a prototypical system containing hydrogen bonds; and (c) optical rotations at the sodium D line for hydrogen peroxide analogues (H2Y2, Y = O, S, Se, Te). Thanks to this implementation, we are able to show the similarities in performance, but often the significant discrepancies, between CC-LR and approximate methods such as density functional theory. Comparing standard CC response theory with the flavor based upon the equation of motion formalism, we find that for valence properties such as polarizabilities, the two frameworks yield very similar results across the periodic table as found elsewhere in the literature; for properties that probe the core region, such as spin-spin couplings, on the other hand, we show a progressive differentiation between the two as relativistic effects become more important. Our results also suggest that as one goes down the periodic table, it may become increasingly difficult to measure pure optical rotation at the sodium D line due to the appearance of absorbing states.

TeO2 glass has been studied by Raman spectroscopy up to the record pressure of 70 GPa. The boson peak frequency ωb exhibits a decrease of the ∂ωb/∂P slope at 5-6 GPa and saturates above 30 GPa with a practically constant value up to 70 GPa. Experiment and theory indicate that pressures up to 20 GPa induce the transformation of single Te-O-Te bridges to double Te-O2-Te bridges, leading to a more compact structure, while Raman activity developing at higher pressures around 580 cm-1 signals the increase of Te coordination from 4- to 6-fold. Natural bond orbital analysis shows that double Te-O2-Te bridges favor the s → d transition and promote the increase of Te coordination through d2sp3 hybridization. This transition leads to the formation of TeO6 octahedra, in strict difference with crystalline TeO2 at the same pressure range, and to the development of a 3D network that freezes the medium range order.

Water adsorption in metal–organic frameworks has gained a lot of scientific attention recently due to the potential to be used in adsorption-based water capture. Functionalization of their organic linkers can tune water adsorption properties by increasing the hydrophilicity, thus altering the shape of the water adsorption isotherms and the overall water uptake. In this work, a large set of functional groups is screened for their interaction with water using ab initio calculations. The functional groups with the highest water affinities form two hydrogen bonds with the water molecule, acting as H-bond donor and H-bond acceptor simultaneously. Notably, the highest binding energy was calculated to be −12.7 Kcal/mol for the -OSO3H group at the RI-MP2/def2-TZVPP-level of theory, which is three times larger than the reference value. Subsequently, the effect of the functionalization strategy on the water uptake is examined on a selected set of functionalized MOF-74-III by performing Monte Carlo simulations. It was found that the specific groups can increase the hydrophilicity of the MOF and enhance the water uptake with respect to the parent MOF-74-III for relative humidity (RH) values up to 30%. The saturation water uptake exceeded 800 cm3/cm3 for all candidates, classifying them among the top performing materials for water harvesting.

In this paper, we report reimplementation of the core algorithms of relativistic coupled cluster theory aimed at modern heterogeneous high-performance computational infrastructures. The code is designed for parallel execution on many compute nodes with optional GPU coprocessing, accomplished via the new ExaTENSOR back end. The resulting ExaCorr module is primarily intended for calculations of molecules with one or more heavy elements, as relativistic effects on the electronic structure are included from the outset. In the current work, we thereby focus on exact two-component methods and demonstrate the accuracy and performance of the software. The module can be used as a stand-alone program requiring a set of molecular orbital coefficients as the starting point, but it is also interfaced to the DIRAC program that can be used to generate these. We therefore also briefly discuss an improvement of the parallel computing aspects of the relativistic self-consistent field algorithm of the DIRAC program.

Dye-sensitized solar cells and dye-sensitized photoelectrochemical cells have attracted much interest in recent years for solar energy conversion. More effort is still required to increase the efficiency of these devices, which is closely linked to the crucial process of photoinduced charge separation. Computational studies can provide insights into this fundamental process and suggest molecular components and interfaces that feature optimal energy-level alignment before time-consuming trial-and-error experimental realization. Here, we use a combination of density functional based tight binding and an extended Huckel approach to perform quantum classical simulations of photoinduced electron injection in a TiO2 dye-sensitized photoanode with explicit solvation at a reasonable computational cost. In particular, we evaluate injection capabilities of core-extended naphthalene diimide (NDI) dyes with three different anchoring groups. Our results stress the importance of nuclear motion as well as conformational and trajectory sampling for a realistic description of the injection process. Furthermore, explicit solvation highly influences the conformational space explored by the dye and anchoring molecules, especially concerning the adsorption mode. Taking these effects into account, the core-extended NDI with a catechol-based anchoring moiety is shown to be the most promising ultrafast electron injector. Our strategy allows for a more systematic computational search for appropriate molecular chromophores in dye-sensitized devices for solar energy conversion.

Tellurium oxide clusters (TeO2)(6) were investigated through density functional theory to gain information on the structure of TeO2 glass. Among a large number of stable conformers studied, a cyclic, nonsymmetric structure was optimized without terminal Te=O double bonds. The dimer of this structure, (TeO2)(12), gives calculated Raman and infrared spectra in very good agreement with the experimental ones, with its total pair distribution function being also in agreement with results of neutron and high-energy X-ray diffraction studies. The (TeO2)(12) cluster consists mainly of TeO4 units connected by asymmetric and nearly symmetric Te-O-Te bridges as in gamma-TeO2 and involves also edge-sharing through double-oxygen Te-O-2-Te bridges as in the beta-TeO2 polymorph. The optimized cluster structure is slightly unstable compared to the calculated global minimum structure, suggesting a kinetically stable product similar to its corresponding experimental TeO2 glass.

Aim: Barbiturates have a long history of being used as drugs presenting wide varieties of biological activities (antimicrobial, anti-urease and antioxidant). Reactive oxygen species are associated with inflammation implicated in cancer, atherosclerosis and autoimmune diseases. Multitarget agents represent a powerful approach to the therapy of complicated inflammatory diseases. Results: A novel series of barbiturates has been synthesized and evaluated in several in vitro assays. Compound 16b (lipoxygenases inhibitor, 55.0 μM) was found to be a cyclooxygenase-2 inhibitor (27.5 μM). Compound 8b was profiled as a drug-like candidate. Conclusion: The barbiturate core represents a new scaffold for lipoxygenases inhibition, and the undertaken derivatives show promise as multiple-target agents to combat inflammatory diseases.

A series of four photoluminescent binuclear copper(I) compounds bearing phosphorus and sulfur donor atom ligands have been synthesized from reactions of copper(I) halides with the diphosphane dppe [1,2‐bis(diphenylphoshino)ethane] and the anions of three different N‐heterocyclic thiols, namely 5‐methyl‐1,3,4‐thiadiazole‐2‐thiol, 1‐phenyl‐1H‐tetrazole‐5‐thiol and ethyl 2‐thiouracil‐5‐carboxylate. Depending on the nature of the N‐heterocyclic thiol, the resulting compounds adopt two different structural motifs, having either a dppe‐bridged core, that is, [Cu2(κ‐S‐thiolate)2(dppe)2(µ‐dppe)], or a bis(thiolate)‐bridged core, that is, [Cu2(µ‐S‐thiolate)2(dppe)2], with a Cu2(µ‐S)2 cluster‐type core. The stabilization of the latter type of structure is rationalized by the presence of intramolecular hydrogen‐bonding interactions developed between two bridging N‐heterocyclic thiolate ligands positioned at the same side of the Cu2(µ‐S)2 core, which lead to short Cu···Cu interactions (ca. 2.6 Å), as it is evidenced by X‐ray crystallography studies and supported by Density‐Functional Theory (DFT) calculations. All compounds are photoluminescent and, upon UV‐light irradiation, they exhibit emission maxima ranging from about 470 to 510 nm, depending on the structural and geometric characteristics of the complexes. According to DFT calculations, the photoluminescence properties of the dppe‐bridged binuclear compounds originate from excited states having mainly a (M+L)LCT character, which result from [dCuI+π(thiolate)]→π*(phosphane) electronic transitions, while in the case of the thiolate‐bridged, cluster‐like binuclear compound the emitting excited states are also influenced by the short Cu···Cu interactions and appear to have also CC contributions in addition to an MLCT character. Furthermore, in the case of the dppe‐bridged binuclear complexes, the influence of the electronic nature of the thiolate group on the observed emission wavelength is demonstrated.

The induced magnetic field (IMF) of naphthalene, biphenyl, biphenylene, benzocyclobutadiene, and pentalene is dissected to contributions from the total π system, canonical π‐molecular orbitals (CMO), and HOMO→π* excitations, to evaluate and interpret relative global and local diatropicity and paratropicity. Maps of the IMF of the total π system reveal its relative strength and topology that corresponds to global and local diatropic and paratropic ring currents. The total π magnetic response is determined by this of canonical HOMOs and particularly by paratropic contributions of rotational excitations from HOMOs to unoccupied π* orbitals. Low energy excitations and similar nodal structure of HOMO and π* induce strong paratropic fields that dominate on antiaromatic rings. High energy excitations and different nodal structures lead to weak paratropic contributions of canonical HOMOs, which are overwhelmed by diatropic response of lower energy canonical orbitals in aromatic rings. CMO‐IMF analysis is found in agreement with ring current analysis. © 2017 Wiley Periodicals, Inc.

The induced shielding cone is one of the most characteristic aspects of aromatic species. Herein, we explore its behavior under different orientations of the applied magnetic field by evaluating the overall and dissected pi- and sigma-electron contributions. Our results shed light onto the orientation dependence behavior of the shielding cone, unraveling a characteristic pattern upon rotation of the aromatic ring. This pattern decreases the long range of the magnetic response, such that it resembles the behavior under constant molecular tumbling in solution.

DFT calculation of various molecular descriptors was carried out in order to examine the radical scavenging properties of sesame oil lignans and some selected metabolites of sesamin formed in vivo. The major sesame oil lignans, namely sesamin and sesamolin may present antioxidant activity through hydrogen atom transfer, though lacking a phenolic group. This can be achieved via the contribution of allylic hydrogen atoms according to C-H bond dissociation enthalpy (BDE) values. Even so, the predicted activity is not higher than that of some phenolic derivatives (e.g. pinoresinol) or metabolites bearing catechol moieties. The contribution of non-phenolic hydrogen atoms may result in the formation of planar or semi-planar conjugated compounds. Some of the tested lignans (e.g. sesaminol, sesamolinol) may be efficient electron donors comparable to active flavonoids according to ionization potential (IP) values. Neutral sesamol can be an efficient electron donor rather than hydrogen atom donor according to IP and net electrophilicity values. Only computation in water could partially justify literature experimental findings on the higher reactivity of sesamol over that of sesamin. The metabolites of sesamin, bearing one or two catechol groups were found as the most efficient hydrogen atom donors and most prone to ionization. Therefore, they could be capable to act efficiently via hydrogen atom transfer (HAT) or sequential proton loss electron transfer (SPLET) in real systems as shown by gas-phase and calculations in solvents (benzene, water). Thus, these metabolites may account for the high in vivo antioxidant activity of sesamin. Examination of the succeeding products of metabolism indicated the progressive loss of radical scavenging efficiency which was predicted to be negligible in the compounds excreted from the body of mammals. (C) 2015 Elsevier B.V. All rights reserved.

Heteroatoms with increasing electronegativity increased the aromatic behavior in a representative 10π-electron [C8H8]2−organic ring.

Herein we present, an exhaustive docking analysis considering the case of autotaxin (ATX). HA155, a small molecule inhibitor of ATX, is co-crystallized. In order to further extract conclusions on the nature of the bond formed between the ligands and the amino acid residues of the active site, density functional theory (DFT) calculations were undertaken. However, docking does not provide reproducible results when screening boronic acid derivatives and their binding orientations to protein drug targets. Based on natural bond orbital (NBO) calculations, the formed bond between Ser/Thr residues is characterized more accurately as a polar covalent bond instead of a simple nonpolar covalent one. The presented results are acceptable and could be used in screening as an active negative filter for boron compounds. The hydroxyl groups of amino acids are bonded with the inhibitor's boron atom, converting its hybridization to sp(3).

A controllable S,P-coordination environment resulting in selective structural, emissive and antibacterial properties.

The electron delocalization in 1,2-azaborine, 1,3-azaborine, and 1,4-azaborine is studied using canonical molecular orbital contributions to the induced magnetic field (CMO-IMF) method and polyelectron population analysis (PEPA). Contour maps of the out-of-plane component of the induced magnetic field (Bzind) of the π system show that the three azaborines, in contrast with borazine, sustain much of benzene's π-aromatic character. Among them, 1,3-azaborine exhibits the strongest π delocalization, while 1,4-azaborine is the weakest. Contour maps of Bzind for individual π orbitals reveal that the differentiation of the magnetic response among the three isomers originates from the π-HOMO orbitals, whose magnetic response is governed by rotational allowed transitions to unoccupied orbitals. The low symmetry of azaborines enables a paratropic response from HOMO to unoccupied orbitals excitations, with their magnitude depending on the shape of interacting orbitals. 1,3-Azaborine presents negligible paratropic contributions to Bzind from HOMO to unoccupied orbitals transitions, where 1,2- and 1,4-azaborine present substantial paratropic contributions, which lead to reduced diatropic response. Natural bond orbital (NBO) analysis employing PEPA shows that only the 1,3-azaborine contains π-electron fully delocalized resonance structures.

Two heterocyclic thiolate ligands, namely pymt and py2S (pymt = pyrimidine2-thiolate and py2S = pyridine-2-thiolate) and the diphosphines bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), were used in the synthesis of three neutral Pd(II) complexes (cis-[Pd(dppm)(pymt)2] (1), cis-[Pd(dppe)(pymt)2] (2) and cis-[Pd(dppp)(pyrt)2] (3)). Crystallographic analysis of the isolated complexes reveals their square planar arrangement and the coordination of the thiolate moieties through their exocyclic sulfur atom. The complexes absorb in the visible part of the spectrum through charge transfer transitions while after photoexcitation at 385 nm they appear to emit with a broad band located at 465 nm.