This thematic issue of Chemical Reviews does not
come with the customary Guest Editor, normally a
prominent researcher in the field. Rather, it is edited
by an informed spectator, one of the regular Editorial
staff. This might be viewed as a less auspicious
strategy. However, the expertise of the authors is
widely known, and their outstanding collection of
articles speaks for itself. The subject is so topical and
important, both in academic and industrial contexts,
that little introduction is actually needed