Interchain contact

In this compound, no intrachain D+A short contacts were found and the closest interatomic separation between the anion and the Cp ring corresponds to Ni... C contacts (cl) exceeding the sum of the van der waals radii, dw, by 11 %. In this salt the closest interchain arrangements are similar and present an out-of-registry disposition (pairs I—II and I-IV). This arrangement is shown in Fig. 8b. The closer interchain contacts (d2) involve C atoms from the Me groups of the cations and S atoms of the anions, with a separation exceeding dw by 8%. 

The magnetic behavior of [Fe(Cp )2][Ni(edt)2] is consistent with the coexistence of FM intrachain interactions, due to D+A intrachain short contacts, with AF interchain interactions, resulting from the D+A- and A A interchain contacts, as predicted by the McConnell I mechanism [44], In this case the interchain interactions must be particularly large as they seem to be the dominant interactions at high temperatures. The value of the critical field, 14 kG, much higher than any of the... 

The compound [Fe(Cp )2][Ni(a-tpdt)2], although not isostructural with the [Cr(Cp )2] analogue, presents a lower symmetric structure, where one of the crystallographic axis is doubled. This axis doubling is associated with a slight alternation in the D+-A contacts along the chains and consequently also in interchain contacts. Otherwise the network of intermolecular contacts remains similar. There are no full structural refinements for the other compounds of this series but the unit cell parameters of the (M = Fe, M = Au) compound and powder diffraction data of the salt with M = Co, M = Ni indicate that they are isostructural with the M = Fe, M = Ni compound. On the other hand, powder diffraction data on the M = Mn, M = Ni compound indicate that it is isostructural with the M = Cr, M = Ni compound. 

Fig. II (a) View of the crystal structure of [Cr(Cp )2][Ni(a-tpdt)2] along [1 —1 0], where it is possible to see three layers of chains aligned either along [1 —1 0] or [1 1 0], cl correspond to the closest D+A intrachain contacts and c2 to the closest A A interchain interlayer contacts, (b) View of two chain layers along the [1 0 2] direction. The chains of the layer on the right are aligned along [1 — 1 0] and on the left along [1 1 0]. c3 corresponds to the closer interchain contacts within the layers...

Fig. 15 (a) View of the crystal structure of [Fe(Cp )2][Ni(dmit)2] along the stacking direction, (b) View of one layer of the type II chains, cl corresponds to the intradimer (AA) closest contact, c2 to the closer D+A- intrachain contacts, c3 include various S-S short A-A- interchain contacts, and c4 concerns a short S-S interlayer (A A ) contact... 

In this work we will be specially concerned with intra- and interchain contact and dipolar interactions and will ignore the above-mentioned other terms, despite the fact that they may be relevant in particular cases. We should also make clear that the NMR technique gives the total spin-lattice relaxation rate over all q vectors. Therefore, it will be necessary to make a thorough analysis of the data to extract the relevant components. On the other hand, a complete theory of the spin-lattice relaxation rate in organic conductors is still lacking. In our description we try to point out some of the main features, the temperature and field dependence. 

The interchain contact term, T c, can be observed at small enough fields (small we) for which the corresponding intrachain component is saturated. It results from the small probability that the electron may spend... 

This significant low-field conductivity demonstrates that conjugated polymers can be encapsulated in nanometer channels and still support mobile charge carriers. In contrast to the experiments with polypyrrole in zeolite Y and mordenite (see above), the channels in the MCM host provide more space and apparently allow some important interchain contact to occur. 

The theoretical analysis of the relationship between small-scale relaxation processes in polymers PL reveals just these processes) and the intra- or intermolecular inter-actions shows that these processes are sensitive to various changes in the number (probability of formation) of intra- or interchain contacts in polymer solutions. The experimental data reveal that the intramolecular mobility (IMM) of the polymer in solution is highly susceptible to various conformational transformations of macro-molecules and to changes in the intermolecular interactions in complex multicom-... 

The possibility of carrying out investigations in very dilute solutions at a polymer content in solution as low as 0.001%. This means that the effect of interchain contacts superimposed on intramacromolecular interactions is greatly weakened or completely absent. This weakening is particularly important when the polymer-polymer interactions sharply increase, e.g. by the action of the precipitant ... 

TMTSF (Figure lb), the arrangement of interchain contacts in the TCN2 salt... 

The reason for this result is likely to reside in the fact that a single parameter, such as Rg, is inadequate for defining conditions for interchain contact the segment density in the overlap region as a function of center-to-center distance, which in turn is a function of concentration, needs considering instead. The approach to this possibility is as follows. 

Recent work demonstrated that increasing the counter anion (CA) size can decrease the interchain contacts of copolymer PFBT-X (Scheme 1.9), which contains alternating fluorene and BT units, and leads to a substantial increase of quantum yield in the bulk [56]. Size analysis of polymers containing Br and B[(3, 5 — (CF3)2C6H3)]4 (BAr 4 ) in water by DLS techniques indicates suppression of aggregation by the large and hydrophobic BAr 4. The... 

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