Multifunctional Coordination Polymer Exhibiting Reversible Mechanical Motion Allowing Selective Uptake of Guests and Leading to Enhanced Electrical Conductivity.

A remarkably flexible, multifunctional, 2D coordination polymer exhibiting an unprecedented mode of reversible mechanical motion, enabling pores to open and close, is reported. Such multifunctional materials are highly sought after, owing to the potential to exploit coexisting electronic and mechanical functionalities that underpin useful technological applications such as actuators and ultrasensitive detectors. The coordination polymer, of composition Mn(F4TCNQ)(py)2 (F4TCNQ = 2,3,5,6-tetrafluoro-7,7,8,8-tetracycanoquinodimethane; py = pyridine), consists of Mn(II) centers bridged by F4TCNQ dianions and coordinated by py molecules that extend above and below the 2D network. Exposure of Mn(F4TCNQ)(py)2, in its collapsed state, to carbon dioxide results in a pore-opening process at a threshold pressure for a given temperature. In addition to carbon dioxide, a variety of volatile guests may be incorporated into the pores, which are lined with electron-rich F4TCNQ dianions. The inclusion of electron-deficient guests such as 1,4-benzoquinone, nitrobenzene, maleic anhydride, and iodine into the pores is accompanied by a striking color change associated with a new host-guest charge-transfer interaction and an improvement in the semiconductor behavior, with the iodine adduct showing an increase in conductivity of almost 5 orders of magnitude. Experimental and density functional theory calculations on this remarkable multifunctional material demonstrate a reduction in the optical band gap with increasing electron affinity of the guest.

Interligand Charge-Transfer Interactions in Electroactive Coordination Frameworks Based on N, N'-Dicyanoquinonediimine (DCNQI).

Coordination frameworks containing DCNQI2- (DCNQI = N, N'-dicyanoquinonediimine ligand) are produced by deprotonation of DCNQIH2 in the presence of a metal center and a co-ligand. This approach has yielded two-dimensional (2D) sheet compounds [Cd(DCNQI)(L)2] (where L = pyridine (py) or isoquinoline (isoquin)) that can be partially oxidized via solid-state electrochemical and in situ spectroelectrochemical methods to materials that contain DCNQI as its radical monoanion. The new frameworks display charge-transfer bands that are indicative of interligand charge-transfer interactions as supported by TD-DFT computational calculations. The redox-state dependent spectral properties of the frameworks have been probed using a newly developed solid-state spectroelectrochemical cell. Coupled with computational calculations, the experimental data provide an understanding of the fundamental charge-transfer processes that may underpin long-range functional properties such as conductivity in framework materials.

Solvent-, Cation- and Anion-Induced Structure Variations in Manganese-Based TCNQF4 Complexes: Synthesis, Crystal Structures, Electrochemistry and Their Catalytic Properties.

The reaction of Mn(BF4 )2 ⋅x H2 O with (Pr4 N)2 TCNQF4 (TCNQF4 =2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) in a mixture of CH3 OH/CH2 Cl2 gives a 2:3 stoichiometric complex of (Pr4 N)2 [Mn2 (TCNQF4 )3 (CH3 OH)2 ] (1). If the solvent system used for the crystallisation of 1 is changed to CH3 OH/DMF, then a different product, [Mn(TCNQF4 )(DMF)2 ]⋅(CH3 OH)2 (2), is obtained. The use of Li2 TCNQF4 instead of (Pr4 N)2 TCNQF4 leads to the generation of [Mn2 (TCNQF4 )2 (DMF)4 ]⋅3 DMF (3). An unexpected mixed oxidation state network with a composition of [MnII 4 MnIII 16 O10 (OH)6 (OCH3 )24 (TCNQF4 )2 ](NO3 )2 ⋅24 CH3 OH (4), is formed if Mn(NO3 )2 ⋅x H2 O is used in place of Mn(BF4 )2 ⋅x H2 O in the reaction that leads to the formation of 3. Compounds 1-3 have been characterised by X-ray crystallography; FTIR, Raman and UV/Vis spectroscopy; and electrochemistry. Compound 4 has only been analysed by X-ray crystallography and vibrational spectroscopy (Raman, FTIR), owing to rapid deterioration of the compound upon exposure to air. These results indicate that relatively minor changes in reaction conditions have the potential to yield products with vastly different structures. Compound 1 adopts an anionic 2D network with unusual π-stacked dimers of the TCNQF4 2- dianion, whereas 2 and 3 are composed of similar neutral sheets of [Mn(TCNQF4 )(DMF)2 ]. Interestingly, the solvent has a significant influence on the stacking of the sheets in the structures of 2 and 3. In compound 4, clusters with a composition of [MnII 4 MnIII 16 O10 (OH)6 (OCH3 )24 (CH3 OH)4 ]6+ serve as eight-connecting nodes, whereas TCNQF4 2- ligands act as four-connecting nodes in a 3D network that has the same topology as fluorite. Compound 3 exhibits an exceptionally high super-catalytic activity for the electron-transfer reaction between ferricyanide and thiosulfate ions in aqueous media.

Magnetic coupling between metal spins through the 7,7,8,8-tetracyanoquinodimethane (TCNQ) dianion.

A family of magnetic metal-organic frameworks, (Ph3PMe)2[M2(TCNQ)3] {M=Fe(2+), Co(2+), Ni(2+) and Zn(2+)} have been prepared and structurally characterized. The honeycomb-like "layers" consist of M(II) ions doubly bridged with dinitrilomethane moieties of two 7,7,8,8-tetracyanoquinodimethane (TCNQ) dianions which are further connected through phenyl rings to form a 3D dianionic framework [M2TCNQ3](2-) with Ph3PMe(+) cations filling cavities that run along the c axis. Studies of the magnetic coupling through the TCNQ dianion in these structures revealed that it can promote long-range magnetic ordering despite the long coupling pathway.

Electrochemically directed synthesis of Cu2(I)(TCNQF4(II-))(MeCN)2 (TCNQF4 = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane): voltammetry, simulations, bulk electrolysis, spectroscopy, photoactivity, and X-ray crystal structure of the Cu2(I)(TCNQF4(II-))(EtCN)2 analogue.

The new compound Cu2(I)(TCNQF4(II-))(MeCN)2 (TCNQF4(2-) = dianion of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) has been synthesized by electrochemically directed synthesis involving reduction of TCNQF4 to TCNQF4(2-) in acetonitrile containing [Cu(MeCN)4](+)(MeCN) and 0.1 M Bu4NPF6. In one scenario, TCNQF4(2-) is quantitatively formed by reductive electrolysis of TCNQF4 followed by addition of [Cu(MeCN)4](+) to form the Cu2(I)(TCNQF4(II-))(MeCN)2 coordination polymer. In a second scenario, TCNQF4 is reduced in situ at the electrode surface to TCNQF4(2-), followed by reaction with the [Cu(MeCN)4](+) present in the solution, to electrocrystallize Cu2(I)(TCNQF4(II-))(MeCN)2. Two distinct phases of Cu2(I)(TCNQF4(II-))(MeCN)2 are formed in this scenario; the kinetically favored form being rapidly converted to the thermodynamically favored Cu2(I)(TCNQF4(II-))(MeCN)2. The postulated mechanism is supported by simulations. The known compound Cu(I)TCNQF4(I-) also has been isolated by one electron reduction of TCNQF4 and reaction with [Cu(MeCN)4](+). The solubility of both TCNQF4(2-)- and TCNQF4(•-)-derived solids indicates that the higher solubility of Cu(I)TCNQF4(I-) prevents its precipitation, and thus Cu2(I)(TCNQF4(II-))(MeCN)2 is formed. UV-visible and vibrational spectroscopies were used to characterize the materials. Cu2(I)(TCNQF4(II-))(MeCN)2 can be photochemically transformed to Cu(I)TCNQF4(I-) and Cu(0). Scanning electron microscopy images reveal that Cu(I)TCNQF4(I-) and Cu2(I)(TCNQF4(II-))(MeCN)2 are electrocrystallized with distinctly different morphologies. Thermogravimetric and elemental analysis data confirm the presence of CH3CN, and single-crystal X-ray diffraction data for the Cu2(I)(TCNQF4(II-))(EtCN)2 analogue shows that this compound is structurally related to Cu2(I)(TCNQF4(II-))(MeCN)2.

Computational Analysis of Amiloride Analogue Inhibitors of Coxsackievirus B3 RNA Polymerase.

Coxsackievirus B3 (CVB3) is a picornavirus that is responsible for a significant proportion of human myocarditis. However, no antiviral treatment is currently available to treat this disease or indeed any picornaviral infections. Previously it was shown that amiloride and its derivative 5-(N-ethyl-N-isopropyl)amiloride inhibit the in vitro enzymatic activity of CVB3 RNA polymerase (3Dpol). Here we measure and compare the inhibitory activity of ten amiloride analogues against CVB3 3Dpol. We show that replacement of the 3,5-diaminopyrazinyl moiety of amiloride causes loss of the inhibitory activity, whereas modifications at the 5-amino and guanidino groups increase or decrease potency. Importantly, a combination of substitutions at both the 5-amino and guanidino groups produced a compound that was more potent than its singly modified precursors. The compounds were computationally-docked into available crystal structures of CVB3 3Dpol in order to obtain a structural explanation for the activities of the analogues. To create a robust model which explained the biological activity, optimization of one of the CVB3 3Dpol crystal structures to take into account active site flexibility was necessary, together with the use of consensus docking from two different docking algorithms. This robust predictive 3D atomic model provides insights into the interactions required for inhibitor binding and provides a promising basis for the development of more potent inhibitors against this important therapeutic target.

The importance of neuropsychological assessment for the evaluation of childhood learning disorders NAN Policy and Planning Committee.

When children experience learning difficulties, an appropriate evaluation of abilities and skills can provide the foundation for an accurate diagnosis and useful recommendations. When comprehensive information about a child's brain-related strengths and weaknesses is necessary to understand potential sources of the problem and implications for functioning, a neuropsychological evaluation is most often the best choice. This paper was written to help parents, educators, health care providers, and third-party payors to understand the nature of neuropsychological assessment and to choose the type of evaluation that will furnish relevant information for the child's educational planning.