Alternating donor–acceptor indigo-cyclopentadithiophene copolymers: competition between excited state conformational relaxation, energy transfer and excited state proton transfer

Abstract

In a copolymer with indigo and CPDT, fast ESPT and/or intrachain energy transfer are observed whereas conformational relaxation is absent.

Macroscale Biomolecular Electronics and Ionics

“…The vat dying redox chemistry foreshadows the reversible redox chemistry that indigoids can support, an important feature when considering application as an organic electronic component. A significant feature of indigoids is the presence of ultrafast photoinduced proton transfer in the exited state, resulting in rapid (<10 ps) deactivation of the excited state . Because of this, indigos have very low fluorescence and phosphorescence quantum yields on the order of 1 × 10 −3 .…”

Polymeric near infrared emitters with bay-annulated indigo moieties

“…The shortest decay time component (t 1 ) which, at shorter emission wavelengths is associated to a negative preexponential for the PBAIC-1 copolymer (Table 3), should be considered to be associated to solvent dynamics (in THF with characteristic times ranging from 0.43 ps to 0.94 ps), 45 or attributed to vibrational relaxation due to the depopulation of a hot vibrational state generated through the 770 nm excitation (since excitation was not performed in the lowest energy 0-0 electronic transition). 38 Yet, this is not the case with PBAIC-2 and PBAIBD-1, where a longer component is observed with 2.4 ps and 8.9 ps (Table 3), respectively, in addition to a longer t 3 component in the order of hundreds of ps. These t 1 and t 2 decay components are associated to excitation energy migration within different segments of the polymer chain (higher to lower energy conjugated segments) ending up in the t 3 decay component which mirrors the decay of the more relaxed segment to the ground state.…”

“…The Stille-type cross-coupling reaction of the two different BAI monomers (BAI2 and BAI4) with distannylated CPDT (4,4bis(2-octyldodecyl)-2,6-bis(trimethylstannyl)-4H-cyclopenta[1, 2-b:5,4-b 0 ]dithiophene-2,6-diyl, C9) was carried out as previously described for the synthesis of corresponding indigo-containing copolymers. 38 Hereby, tetrakis(triphenylphosphane)palladium(0), Pd(PPh 3 ) 4 , was used as a catalyst in a microwave-assisted coupling reaction. After irradiation at 125 1C for 25 minutes, the reaction mixture was stirred at 90 1C for a further 72 h (Scheme 3).…”

“…From the donor-acceptor (D-A) character of the copolymers, one can determine the energy transfer (k ET ) rate constant from: 38,[46][47][48]…”

Synthesis and Characterization of New Organic Dyes Containing the Indigo Core

“…Procedures for the modification of preformed indigo are more recent and take advantage mainly of cross-coupling reactions of the 6-6′ dibromo derivative Tyrian Purple (C.I. Natural Violet) with electrophiles ( Figure 2 ) [ 38 , 39 , 40 , 41 ]. Spectroscopic characterization of such derivatives pointed out that it is possible to affect the energy levels of indigoids by chemical design and that the effect of substituents can be qualitatively predicted by DFT calculations.…”