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Water and glycerol permeation through human AQP3 are described by exploiting advanced metadynamics approaches, which enabled both to explore the free energies involved in pore permeation and to achieve a description of the mechanisms with an atomistic level of detail., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The use of a template that bears pre-programmed receptor sites for selectively accommodating chromophores at given positions is an attractive approach for engineering artificial-light-harvesting systems. Indulging this line of thought, this work tackles the creation of tailored antenna architectures with yellow, red and blue chromophores, exploiting three dynamic covalent reactions simultaneously, namely disulfide exchange, acyl hydrazone, and boronic ester formations. The effect of various structural modifications, such as the chromophores as well as their spatial organization (distance, orientation, order) on the energy transfer within the antennas was studied by means of steady-state UV/Vis absorption and fluorescence spectroscopies. This systematic study allowed for a significant improvement of the energy-transfer efficiencies to a noticeable 22 and 15 % for the yellow and red donors, respectively, across the chromophores to the blue acceptor. Metadynamics simulations suggested that the conformational properties of the antennas are driven by intramolecular chromophoric stacking interactions that, upon forcing the α-helix to fold on itself, annul any effects deriving from the programming of the spatial arrangement of the receptor sides in the peptide backbone., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The binding modes and free-energy landscape of two Au I /N-heterocyclic carbene complexes interacting with G-quadruplexes, namely a human telomeric (hTelo) and a promoter sequence (C-KIT1), are studied here for the first time by metadynamics. The theoretical results are validated by FRET DNA melting assays and provide an accurate estimate of the absolute gold complex/DNA binding free energy. This advanced in silico approach is valuable to achieve rational drug design of selective G4 binders., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report on a new series of isoreticular frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate (IFP-1-4, IFP = imidazolate framework Potsdam) that form one-dimensional, microporous hexagonal channels. Varying R in the 2-substitued linker (R = Me (IFP-1), Cl (IFP-2), Br (IFP-3), Et (IFP-4)) allowed the channel diameter (4.0-1.7 Å), the polarisability and functionality of the channel walls to be tuned. Frameworks IFP-2, IFP-3 and IFP-4 are isostructural to previously reported IFP-1. The structures of IFP-2 and IFP-3 were solved by X-ray crystallographic analyses. The structure of IFP-4 was determined by a combination of PXRD and structure modelling and was confirmed by IR spectroscopy and (1)H MAS and (13)C CP-MAS NMR spectroscopy. All IFPs showed high thermal stability (345-400 °C); IFP-1 and IFP-4 were stable in boiling water for 7 d. A detailed porosity analysis was performed on the basis of adsorption measurements by using various gases. The potential of the materials to undergo specific interactions with CO(2) was investigated by measuring the isosteric heats of adsorption. The capacity to adsorb CH(4) (at 298 K), CO(2) (at 298 K) and H(2) (at 77 K) at high pressure were also investigated. In situ IR spectroscopy showed that CO(2) is physisorbed on IFP-1-4 under dry conditions and that both CO(2) and H(2)O are physisorbed on IFP-1 under moist conditions., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A combination of topological rules and quantum chemical calculations has facilitated the development of a rational metal-organic framework (MOF) synthetic strategy using the tritopic benzene-1,3,5-tribenzoate (btb) linker and a neutral cross-linker 4,4'-bipyridine (bipy). A series of new compounds, namely [M(2)(bipy)](3)(btb)(4) (DUT-23(M), M = Zn, Co, Cu, Ni), [Cu(2)(bisqui)(0.5)](3)(btb)(4) (DUT-24, bisqui = diethyl (R,S)-4,4'-biquinoline-3,3'-dicarboxylate), [Cu(2)(py)(1.5)(H(2)O)(0.5)](3)(btb)(4) (DUT-33, py = pyridine), and [Cu(2)(H(2)O)(2)](3)(btb)(4) (DUT-34), with high specific surface areas and pore volumes (up to 2.03 m(3)  g(-1) for DUT-23(Co)) were synthesized. For DUT-23(Co), excess storage capacities were determined for methane (268 mg g(-1) at 100 bar and 298 K), hydrogen (74 mg g(-1) at 40 bar and 77 K), and n-butane (99 mg g(-1) at 293 K). DUT-34 is a non-cross-linked version of DUT-23 (non-interpenetrated pendant to MOF-14) that possesses open metal sites and can therefore be used as a catalyst. The accessibility of the pores in DUT-34 to potential substrate molecules was proven by liquid phase adsorption. By exchanging the N,N donor 4,4'-bipyridine with a substituted racemic biquinoline, DUT-24 was obtained. This opens a route to the synthesis of a chiral compound, which could be interesting for enantioselective separation., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The structural chemistry of calcium nitrides is represented by just two different intermediate phases: cubic Ca(3)N(2) (referred to as alpha-Ca(3)N(2), Mn(2)O(3) type structure) and Ca(2)N (CdCl(2) type structure). Other binary phases ("gamma-Ca(3)N(2)", "Ca(11)N(8)") have been proven to represent cyanamide nitrides, Ca(4)N(2)[CN(2)] and Ca(11)N(6)[CN(2)](2), respectively. The metastable nitride beta-Ca(3)N(2) is prepared either by reaction of freshly distilled calcium metal with nitrogen at 700 K, or by reaction of Ca(2)N with N(2) at 500 K. beta-Ca(3)N(2) transforms monotropically (T(trans) approximately 810 K) to cubic alpha-Ca(3)N(2). The crystal structure of beta-Ca(3)N(2) (rhombohedral R3c, no. 167, a=619.884(3) pm, c=1662.958(10) pm) is an isotype of the corundum structure (alpha-Al(2)O(3)) and comprises a network of NCa(6/4) octahedra that share common faces and edges. Magnetic susceptibility and electrical resistivity measurements confirm that beta-Ca(3)N(2) is a diamagnetic semiconductor.

Finding new pathways to novel materials is an open challenge in modern solid-state chemistry. Among the reasons that still prevent a rational planning of synthetic routes is the lack of an atomistic understanding at the moment of phase formation. Metastable phases are, in this respect, powerful points of access to new materials. For the synthetic efforts to fully take advantage of such peculiar intermediates, a precise atomistic understanding of critical processes in the solid state in its many facets, that is, nucleation patterns, formation and propagation of interfaces, intermediate structures, and phase growth, is mandatory. Recently we have started a systematic theoretical study of phase transitions, especially of processes with first-order thermodynamics, to reach a firm understanding of the atomistic mechanisms governing polymorphism in the solid state. A clear picture is emerging of the interplay between nucleation patterns, the evolution of domain interfaces and final material morphology. Therein intermediate metastable structural motifs with distinct atomic patterns are identified, which become exciting targets for chemical synthesis. Accordingly, a new way of implementing simulation strategies as a powerful support to the chemical intuition is emerging. Simulations of real materials under conditions corresponding to the experiments are shedding light onto yet elusive aspects of solid-solid transformations. Particularly, sharp insights into local nucleation and growth events allow the formulation of new concepts for rationalizing interfaces formed during phase nucleation and growth. Structurally different and confined in space, metastable interfaces occurring during polymorph transformations bring about distinct diffusion behavior of the chemical species involved. More generally, stable structures emerge as a result of the concurrence of the transformation mechanism and of chemical reactions within the phase-growth fronts.

Li(3)[ScN(2)] was prepared from Li(3)N with Sc or ScN in a nitrogen atmosphere at 1020 K as a light yellow powder with an optical band gap of about 2.9 eV. The crystal structure was refined based on X-ray and neutron powder diffraction data (Ia$\bar 3$, Z=16, X-ray diffraction: R(profile)=0.078, R(Bragg)=0.070; Neutron diffraction: R(profile)=0.077, R(Bragg)=0.074; Rietfeld: a=1003.940(8) pm, Guinier: a=1004.50(3) pm). Li(3)[ScN(2)] is an isotype of Li(3)[AlN(2)] and Li(3)[GaN(2)] and crystallizes in an ordered superstructure of the Li(2)O structure type, leading to a three-dimensional framework of all-vertex-sharing tetrahedra 3[infinity[ScN[4/2][3-]]. Li is displaced from the center of a tetrahedron of N atoms in the direction of one trigonal face. Li(3)[ScN(2)] decomposes above 1050 K to form ScN and Li(3)N. Calculations of the periodic nodal surface (PNS) and of the electron localization function (ELF) support the picture of a covalent Sc-N network separated from isolated Li cations, whereby scandium d orbitals are involved in the chemical bonding.