Chirality at Solid Surfaces by Jenkins Stephen J

Author:Jenkins, Stephen J.
Language: eng
Format: epub
ISBN: 9781118880142
Publisher: John Wiley & Sons, Inc.
Published: 2018-01-04T00:00:00+00:00

1 Recall that both mirror and glide planes in the space group yield mirror planes in the point group (strictly, the point group of the space group).

2 The chirality of this arrangement was highlighted by Zhang et al. [7], but one may also note earlier comments by Gellman [8] on fcc-{111} ()R19.1 overlayers in general, not to mention fcc-{100} ()R26.6 overlayers.

3 The chirality of an adsorbed prochiral molecule is, of course, bistable. That is, it may flip from one handedness to the other, either spontaneously or under the influence of an external perturbation. In some cases, the activation barrier may be sufficiently small that the situation is essentially fluxional at the temperature of interest, whilst in others there may be considerable thermal stability. A good example of perturbation-driven handedness change may be found in the case of propene adsorption on Cu{211}, where Parschau et al. [12] have induced flipping by means of inelastic electron tunnelling (IET) within an STM experiment.

4 The exception to this general rule is, of course, the case when careful steps have been deliberately taken to prepare the prochiral adsorbate from a chiral precursor in such a way that some degree of asymmetry is preserved, as in the very recent work of Stetsovych et al. [13] (see also the comments of Ernst [14]).

5 For ease of reference, molecular adsorbates discussed in this book are collated in the colour plates. Simple inorganic molecules are omitted, as are species used only as solvents. Most of the remaining cases have been classified according to their dominant functional groups, according to the following hierarchy: (i) acids/esters, (ii) ketones/aldehydes, (iii) alcohols/epoxides. Where a particular molecule falls into two or more categories, it has been placed within only the higher-order grouping, to avoid repetition. A few of the more complicated molecules have been separately gathered under the general headings of either sugars or alkaloids, leaving only a small number of orphans to form a miscellaneous category of their own. Sugars have been represented in their linear form, rather than the cyclic pyranose forms found more typically in solution, simply to avoid the excessive display of the several distinct isomers in which the latter forms occur.

6 In this case, the motif in question is the quartet of guanine molecules; in other cases, the motifs may simply be individual molecules.

7 Replacing guanine with adenine results in an even more complex system, described in detail by Lukas et al. [16], but it would be disproportionate to summarise it here.

8 A wider variety of systems could, of course, be adduced here (see, for example, Bohringer et al. [17], Gopakumar et al. [18], or Yang et al. [19]) but there is merit in offering just two, rather similar, systems to compare and contrast.

9 The surface selection rule for RAIRS tells us that only modes having an out-of-plane component of dynamic dipole moment will give rise to absorption peaks.

10 In this context, homochiral should be taken to imply that all glycinate moieties within a single domain are chirally distorted in the same sense.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.