Solid-State Photopolymerization of a Shape-Persistent Macrocycle with Two 1,8-Diazaanthracene Units in a Single Crystal

Abstract

A macrocyclic monomer with two opposing 1,8-diazaanthracene units is polymerized in a single crystal by a photochemically induced [4 + 4] cycloaddition reaction between neighboring monomers in which the anthracene units are stacked face-to-face at the critical Schmidt distance. The severe structural changes associated with this are minimized by the monomer design, wherein the linkers between the two opposing photoreactive 1,8-diazaanthracene units are connected to the 4 and 5 positions of the latter, whose spatial positioning is changed the least during dimerization. This helps to keep the monomer's overall shape basically unchanged during the polymerization. The resulting new rigid-rod polymer is soluble in its protonated form, and after counterion exchange with a surfactant, it can be depolymerized back into monomer upon relatively mild thermal treatment (120 °C) in an organic solvent.

Approaching Two‐Dimensional Copolymers: Photoirradiation of Anthracene‐ and Diaza‐Anthracene‐Bearing Monomers in Langmuir Monolayers

“…Many dimerizations between anthracene derivatives have been reported and also between a few nitrogen‐containing anthracene derivatives such as DAA, but there was no report on the photochemically induced formation of a heterodimer between an A and a DAA, which is exactly the kind of chemistry needed for bringing about the intended copolymerization steps between M1 and M2 (see below). Thus, a model reaction between the A derivative 1 and the DAA derivate 2 was carried out in homogeneous solution (Scheme S1, Supporting Information). Gratifyingly, photochemical treatment of equimolar amounts of 1 and 2 in CDCl 3 besides a large quantity of both homodimers afforded sizeable fraction of corresponding heterodimer, the structure of which was unequivocally proven (Figure S5 and S6, Supporting Information).…”

“…a) Macrocycle M1 and b) macrocycle M2 used as monomers for copolymerization. c) Dimerization reactions of anthracene (A) and diaza‐anthracene (DAA) moieties leading to homodimers (top and center) and heterodimer (bottom) reported in the literature . Note that dimerizations of the A and DAA units of monomers M1 and M2 at the interface are likely to take place in the thermodynamically less favored syn fashion due to the orientation of the amphiphilic monomers at the air/water interface with all A and DAA units pointing more or less upwards.…”

Propeller‐Shaped D3h‐Symmetric Macrocycles with Three 1,8‐Diazaanthracene Blades as Building Blocks for Photochemically Induced Growth Reactions

“…Two-dimensional polymers (2DP), [1] covalent monolayer sheets [2] and a novel rigid rod polymer [3] were obtained this way. The growth chemistry in these cases was mainly [4+4] cycloaddition between either two A and two DAA units, or one A and one DAA unit.…”

Synthesis of Shape‐Persistent Macrocycles with Three 1,8‐Diazaanthracene Units and Their Packing in the Single Crystal

“…While in the 2DP case the A units of neighboring monomers were not face‐to‐face ( ftf ) stacked, which resulted in a [4+2]‐cycloaddition between the A of one monomer and the acetylene of another, in the sheet case it is assumed that the As are connected via [4+4]‐cycloaddition. We also polymerized the shape‐persistent C 2 v ‐symmetric macrocycle 1 with two DAA units towards a rigid rod polymer by photo‐irradiation in the single crystal,11 whereby the DAA units were in fact packed antiparallel ftf resulting in a [4+4]‐cycloaddition polymerization. Encouraged by these results, we decided to make available a collection of DAA‐based monomers and to investigate in depth their potential in context with the synthesis of 2DP and their congeners, covalent monolayer sheets.…”

“…Synthesis of macrocycles 2 and 3 a–3 c : Synthesis of compound 2 (Scheme ) started from the previously reported building blocks dibromo‐DAA 4 , bridge 5 a , and cyclization precursor 6 11. Mono substitution of 5 a with tri(isopropylsilyl)acetylene (TIPSA) afforded 5 b , and further substitution with tri(methylsilyl)acetylene (TMSA) afforded 5 c .…”