Chemistry on the electrodes: post-functionalization and stability enhancement of anchored dyes on mesoporous metal oxide photoelectrochemical cells with copper-free Huisgen cycloaddition reaction

Abstract

Copper-free Huisgen cycloaddition reaction was applied to post grafted dyes on mesoporous electrodes. It enhances the stability towards desorption and offers the possibility of dye functionalization directly performed on the electrodes.

Click Chemistry on NiO Photocathode to Postfunctionalize a Diketopyrrolopyrrole Sensitizer by Naphthalene Diimide Electron Acceptor

“…As discussed previously, 30 the excited-state dynamic of DPP, grafted NiO with or without crosslinking with CA are essentially the same. Figure 3 shows the evolution-associated difference absorption spectra (EADS) 40,41 obtained from a global analysis of the TA data measured with DPP on NiO after 532 nm excitation assuming a series of successive exponential steps with increasing time constants (see Figure S1 for the data).…”

“…35 Moreover, the carbonyl group of propiolate ester is located around 1708 cm -1 and that of the lactam of DPP at 1676 cm -1 . 30 The ethynyl stretching band at 2118 cm -1 of NDI completely collapsed after heating while that of the azido at 2098 cm -1 has strongly shrunk, evidencing thus that most of these two reacting groups have been consumed during the functionalization process. Interestingly, after click reaction and abundant rinsing of the photocathode, the carbonyl stretching band of diimide groups in NDI and of the propiolate ester around 1710 cm -1 appeared next to that of the lactam groups of DPP at 1670 cm -1 accounting for the covalent attachment of the NDI to the DPP dye (Figure 1).…”

“…Interestingly, after click reaction and abundant rinsing of the photocathode, the carbonyl stretching band of diimide groups in NDI and of the propiolate ester around 1710 cm -1 appeared next to that of the lactam groups of DPP at 1670 cm -1 accounting for the covalent attachment of the NDI to the DPP dye (Figure 1). 30 . e data taken from ref.…”

“…27 In the same vein, more recently Tian and Hammarström have used the amide-coupling reaction to attach catalysts on a silatrane-decorated NiO photocathode. 28,29 Building on an innovative copper-free click chemistry strategy, 30 which proved very efficient to stabilize the dye from the desorption from the electrode, we investigate herein the possibility to implement this strategy to post-functionalize the photoelectrode with an active component to fabricate a photoactive hybrid system in view of obtaining a more elaborate property (Scheme 1).…”

“…14 In the same vein, more recently, Tian and Hammarstrom have used the amidecoupling reaction to attach catalysts on a silatrane-decorated NiO photocathode. 15 Building on an innovative copper-free click chemistry strategy, 16 which proved very efficient to stabilize the dye from the desorption from the electrode, we investigate herein the possibility to implement this strategy to postfunctionalize the photoelectrode with an active component to fabricate a photoactive hybrid system in view of obtaining a more elaborate property (Scheme 1). More specifically, we have explored the opportunity to introduction of a naphthalene diimide (NDI) electron acceptor by click chemistry on the already chemisorbed DPP layer on NiO electrode in order slow down the usually fast geminate charge recombination reaction.…”