Conjugated Copolymers That Shouldn't Be

Abstract

Multiple studies have explored using cage silsesquioxanes (SQs) as backbone elements in hybrid polymers motivated by their well-defined structures and physical and mechanical properties. As part of this general exploration, we report unexpected photophysical properties of copolymers derived from divinyl double decker (DD) SQs, [vinyl(Me)Si-(O 0.5 ) 2 ][PhSiO 1.5 ] 8 [(O 0.5 ) 2 Si(Me)vinyl] (vinylDDvinyl). These copolymers exhibit strong emission red-shifts relative to model compounds, implying unconventional conjugation, despite vinyl(Me)Si(O-) 2 siloxane bridges. In an effort to identify minimum SQ structures that do/do not offer extended conjugation, we explored Heck catalyzed co-polymerization of vinyl-ladder(LL)-vinyl compounds, vinyl(Me/Ph)Si(O 0.5 ) 2 -[PhSiO 1.5 ] 4 (O 0.5 ) 2 Si(Me/Ph)vinyl, with Br-Ar-Br. Most surprising, the resulting oligomers show 30-60 nm emission redshifts beyond those seen with vinylDDvinyl analogs despite lacking a true cage. Further evidence for unconventional conjugation includes apparent integer charge transfer (ICT) between LL-co-thiophene, bithiophene, and thienothiophene with 10 mol % F 4 TCNQ, suggesting potential as p-type doped organic/inorganic semiconductors.

Distinct insight into the use of difunctional double-decker silsesquioxanes as building blocks for alternating A–B type macromolecular frameworks

“…The degree of polymerization (DP n ) of 6a-(d-g) after 24 h was estimated as 5-7 units which seemed to be the expected result for these kinds of DDSQ-based linear systems. 20,28,31,35,45 The additional reaction time (72 h) lead to a minor increase in molecular weights of the obtained copolymers and their Đ values. Based on the analysis of molecular weight distribution plots the low molecular fractions were converted to higher molecular weight products, e.g.…”

“…They are involved in hydrosilylation (HS), cross-metathesis silylative or Heck coupling, dehydrocoupling condensation, O-silylation (metallation), and Friedel-Crafts reactions. [14][15][16][17][18][19][20][21] These reactions lead to novel functionalized molecular and macromolecular silsesquioxanebased systems. While new catalytic methodologies have been developed, hydrosilylation is still one the most important syn-thetic methods of fundamental importance in organosilicon chemistry and also SQ functionalization, mediated by easily available Pt-based Karstedt or Speier catalysts.…”

Hydroxyalkyl-substituted double-decker silsesquioxanes: effective separation ofcisandtransisomers

“…Double-decker silsesquioxanes have shown excellent potential for various applications, including such intriguing areas as materials engineering, smart and self-healing polymers, coordination chemistry, catalysis, and others. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The structure of a typical double-decker silsesquioxane is different from that of the symmetric cubic T 8 polyhedral oligomeric silsesquioxanes (POSSs). It constitutes an open cage network including two connected, via oxygen bridges, decks of cyclosiloxane rings located on top of one another with eight phenyl groups attached to Si atoms (Fig.…”

Double-Decker Silsesquioxanes Self-Assembled in One-Dimensional Coordination Polymeric Nanofibers with Emission Properties

“…The amount of reports of photophysical properties of DDSQs is still restricted to selected derivatives (e.g., vinyl- or styryl-). 69 − 71 …”