Postfunctionalization of aromatic polyamine by [2+2] cycloaddition of 7,7,8,8-tetracyanoquinodimethane with side chain alkynes

Abstract

Electron-rich, side chain alkynes of an aromatic polyamine were functionalized by a [2?2] cycloaddition, followed by retro-cyclization with the electronaccepting 7,7,8,8-tetracyanoquinodimethane (TCNQ). 1 H NMR studies were used to optimize the reaction conditions. Mild heating to [50°C afforded the postfunctionalized aromatic polyamines with the desired acceptor amounts. The quantitative TCNQ addition was demonstrated by the MALDI-TOF mass spectrum and elemental analysis. Introduction of the cyano-based acceptor moieties into the polymer side chains resulted in unusually strong intermolecular interactions. In addition to the p-p interactions of the extended acceptor moieties, these intermolecular forces were supposed to improve the thermal stability of the aromatic polymers. Furthermore, the donor-acceptor chromophores formed by this postfunctionalization displayed low energy charge-transfer bands and redox activities in both the anodic and cathodic directions. The straightforward postfunctionalization technique using the alkyne-TCNQ addition is useful for the preparation of narrow band gap polymers in one step.

Construction of Donor–Acceptor Chromophores in Platinum Polyyne Polymer by [2 + 2] Cycloaddition of Organic Acceptors

“…The lowest energy CT band of the TCNQ‐adducted P3 more bathochromically shifted to 598 nm with the solution color being green. The red color for the TCNE‐adduct and green color for the TCNQ‐adduct are consistent with the previous reports on the postfunctionalization of various polymers 5, 12–14. The optical band gaps of P2 and P3 estimated from the end absorption ( λ end ) were 676 and 1020 nm (1.83 and 1.22 eV), respectively, which are quite narrow compared with that of P1 (2.78 eV) (Table 1).…”

“…The slower retention times of P2 and P3 than that of P1 were due to the strong adhesive feature of the multi‐cyanated polymers to the polystyrene gels used for GPC columns. A similar behavior was previously observed for the TCNQ‐adducted aromatic polyamines 14. Another strong support for quantitative yields was elemental analyses, which showed fairly good agreement with the calculated values.…”

Colorimetric sensing of cations and anions by clicked polystyrenes bearing side chain donor–acceptor chromophores

“…In contrast to this result, TCNQ addition required heating. 20 For example, the reaction was completed within 4 hours at 160 C. The stepwise addition of TCNQ to P1 in odichlorobenzene followed by heating to 100 C provided a clear spectral change with a low energy CT band at 727 nm ( Fig. 1b).…”

Die [2+2]‐Cycloadditions‐Retroelektrocyclisierungs(CA‐RE)‐Klick‐Reaktion: ein einfacher Zugang zu molekularen und polymeren Push‐pull‐Chromophoren

“…Das gleiche Polymer konnte auch über die CA‐RE‐Reaktion mit TCNQ unter Bildung von P16 postfunktionalisiert werden (Abbildung ) . Zur Vervollständigung der Reaktion war eine milde Erwärmung auf >50 °C erforderlich, und die gebildeten Push‐pull‐Chromophore wurden als regioisomere Gemische erhalten, je nach der Orientierung von TCNQ in der CA‐RE‐Reaktion.…”