10 research outputs found
Top-Down Preparation of Self-Supporting Supramolecular Polymeric Membranes Using Highly Selective Photocyclic Aromatization of Cis–Cisoid Helical Poly(phenylacetylene)s in the Membrane State
A novel, highly selective photocyclic aromatization (SCAT)
of π-conjugated
polymers from phenylacetylene having two hydroxyl groups to exclusively
yield a 1,3,5-trisubstituted benzene derivative was developed, and
its success was confirmed by <sup>1</sup>H NMR, GPC, and TOF-MS. The
SCAT reaction has many unique characteristics. (1) It is a quantitative
reaction: it gave only the corresponding cyclic trimer, i.e., a 1,3,5-trisubstituted
benzene derivative, quantitatively (100%). No byproducts were produced
under the best conditions. (2) It is an intramolecular reaction: it
occurred between three adjacent monomer units in one macromolecule.
(3) It is a stereospecific and topochemical or template reaction:
the reactivity strongly depended on the configuration and conformation
of the starting polymer substrates. (4) It is a photoreaction: high
selectivity (100%) was observed only by the use of visible light irradiation,
not by heating. (5) It is a solid-state reaction: high selectivity
(100%) was observed only in the solid state, not in solution. <i>In addition</i>, (6) the resulting cyclic trimers could form
a self-supporting membrane, despite their low molecular weights. This
new approach resulted in a new class of supramolecular polymers consisting
of a 1,3,5-trisubstituted benzene derivative, numbers of which were
linearly linked by hydrogen bonds and stacked benzene derivatives.
Since SCAT has such high selectivities and is useful for the preparation
of a self-supporting supramolecular polymer membrane, many applications
can be expected