Herringbone motif

Sandwich herringbone herringbone motif is comprised of sandwich-like diads shortest axis >... 

There has been little work on the functionalization of higher acenes, owing to the poor stability and very low solubility of the non-benzannelated derivatives. A poorly refined crystal structure of unsubstituted hexacene has been reported (without atomic coordinates), implying that it too arranges in a herringbone motif analogous to the lower acenes [87]. 

Figure 1.20 (a) Limiting types of tt-tt interaction. Note the offset to the face-to-face mode (direct overlap is repulsive), (b) X-ray crystal structure of benzene showing herringbone motif arising from edge-to-face interactions. 

The ef conformation is responsible for the herringbone motif in crystalline benzene and for the crystal structures of other aromatic hydrocarbons [88]. In the gas phase the benzene dimer, (C(jHg)2, also has the ef structure [89]. The benzene dimer in various solvent environments has been successfully modelled [82, 90]. 

In some instances, a compound of a given hydration state may crystallize in more than one form, so that the hydrates themselves exhibit polymorphism. One such example is nitrofurantoin, which forms two monohydrates that have distinctly different temperatures and enthalpies of dehydration. The monohydrates have quite different packing arrangements, with Form I possessing a layer structure and Form II exhibiting a herringbone motif The included water molecules play a major role in stabilizing the crystal structures. Whereas water molecules are contained in isolated cavities in Form II, in Form I they are located in continuous channels, and this apparently facilitates the escape of water when these crystals are heated [60]. 

Fig.6 Steady state voltammogram for Au(lll)-(1 x 1)/ 0.05M H2SO4 in the presence of 3 mM TMA. The stability regions of the various adlayer phases are labeled I, Ila-c, III and IV, scan rate lOmVs. These adlayers are illustrated with typical in-situ STM images (Ila) hexagonal honeycomb phase, 5=-0.18 V (Ilb) ribbon-type motif, 5= 0.03 V (lie) herringbone motif, s = 0.21V (III) hydrogen-bonded linear dimers, 5= 0.34 V (IV) ordered chemisorbed striped phase of TMA at s = 0.80 V. Tunneling currents were below 200 pA [67]...

PolycrystaUine films of the oUgomers with four (a4T, 1) [49], five (a5T, 2) [49], six (a6T, 3) [27b], and eight (a8T, 4) [43c, 50] thiophene rings have been widely examined as semiconductors for OFETs [51]. The crystal structures of oinTs from n = 2 to 8 have been obtained and exhibit similar features with very planar molecules packing in the characteristic herringbone motif (Figure 16.6) [52],... 

In the sohd state, jr-surfaces tend to self-organize into either a stacked or herringbone motif. Desiraju and Gavez-zoti have shown that the assembly of fused-ring aromatics (e.g., naphthalene) depends on the number and positioning of C- and H-atoms within a molecule. The predictive nature is, thus, based on topological and shape considerations of molecules. The relative ability of molecules to participate in C- C and C- H forces was also a... 

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