Hydrogen bonding linearity

Mather BD, Elkins CL, Beyer FL, Long TE. Morphological analysis of telechelic ureidopyr-imidone functional hydrogen bonding linear and star-shaped poly(ethylene-co-propylene)s. Macromol Rapid Commun 2007 28 1601-1606. 

A—H.M Hydrogen bond linear A is electronegative M is a transition metal... 

The effect on rate shown in Table 8 must be due to hydrogen-bond donation, but it may be more subtle than H-bonding between anion and solvent. Pormamide probably exists in the liquid phase as a non-symmetrical, hydrogen-bonded, linear polymer (Dawson, 1963). This accounts for its high boiling point, large viscosity and very high dielectric... 

The X-ray crystal structure of the complex between benzene and the linear tetramer from p-cresol shows the benzene to be in a cavity formed by two intermolecularly hydrogen-bonded linear tetramers Usui, S. Deyama, K. Fukazawa, Y. Sone, T. Ohba, Y. Chem. Lett. 1991, 1387. Vocanson, F. Lamartine, R. Supramol. Chem. 1996,7,19. 

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]...

Although the mechanism of the base-induced formation of calixarenes has been studied in some detail, the reaction pathways remain uncertain. The most intuitively reasonable proposal is that the immediate precursor of any particular calixarene, regardless of size, is the linear oligomer carrying the requisite number of aryl residues. Another proposal, however, postulates that calix[8]arenes, for example, arise from intermolecularly hydrogen-bonded dimers (hemicalixarenes) formed from a pair of crescent-shaped, intramolecularly hydrogen-bonded linear tetramers. Calix[4]arenes, formed under considerably more strenuous conditions, have been postulated to be the result not of direct cyclization of the linear tetramer but of reversion of the calix[8]arene. The cyclic octamer is viewed as the product of kinetic control, and the cyclic tetramer is viewed as the product of thermodynamic control. The particular efficacy of KOH and RbOH for the formation of calix[6]arenes suggests that the hexamer is the product of template control. 

In another report, carboxylic acids were used to self-assemble azo dyes, which could be controlled by photoisomerization of the azobenzene dye [70]. The frans-azobenzene isomer 33 of this dye associates into hydrogen-bonded linear tapes, while the czs-azobenzene 34 yields hydrogen-bonded self-assembled tetramers that form rodlike aggregates by additional n-n stacking interactions (Fig. 23). 

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