Panchromatic Push–Pull Dyes of Elongated Form from Triphenylamine, Diketopyrrolopyrrole, and Tetracyanobutadiene Modules

Abstract

Several symmetrical and unsymmetrical thiophene-functionalized diketopyrrolopyrrole chromophores bearing a bis(p-methoxyphenyl)-p-phenylamine substituent were synthesized through palladium-catalyzed cross-coupling reactions. Mono-substitution and di-substitution occur using either alkyne or borolane groups, allowing the preparation of mixed systems. The alkyne derivatives could be prepared in high yields, and are versatile building blocks for the [2+2] cycloaddition of tetracyanoethylene, leading to 1,1,4,4-tetracyanobuta-1,3-diene derivatives. These interesting push-pull molecules exhibit a rich redox activity, which is understandable in light of the behavior of appropriate reference compounds. These innovative and rationally designed scaffolds are highly colored, exhibiting high absorption coefficients and spanning an absorption range of more than 600 nm of the UV/Vis electromagnetic spectrum.Highly dipolar donor-acceptor substituted systems (also called push-pull chromophores) are a fascinating set of synthetic targets that have a wide range of properties such as nonlinear optical (NLO) responses, significant two-photon absorption cross-sections for doubling the frequency of incident radiation, charge transport and charge separation abilities. 1 Potential applications of such sophisticated dyes for fluorescence enhancement, advanced microscopy techniques, biomedical analysis, 2 and for the construction of both organic photovoltaic materials 3 and field-effect transistors, 4 are foreseen.An impressive number of donor groups are used in the design of push-pull systems and the complete list is too large to detail; however, among them, symmetric or dissymmetric triarylamines hold the lead. 5 Similarly, electronwithdrawing groups are numerous, with the most used being nitro-and cyano-(or polycyano) modules, which are suitable for promoting charge-transfer or electron-transfer along the main molecular axis. 6 Of the common dyes, diketopyrrolopyrroles (DPPs) based on a bis-lactam backbone are interesting in regard to their synthetic availability, ease of modification, outstanding robustness, and attractive spectroscopic properties, making them excellent building blocks for a myriad of applications. 7 These chromophores are well known for their strong absorption bands in the UV/Vis region, high solubility in common organic solvents when adequately substituted on the bis-lactam core, high fluorescence quantum yields, and relatively long excited-state lifetimes (1-5 ns). These properties make DPPs promising candidates for OPV applications, 8,9 and for the engineering of dinuclear boron(III) complexes displaying unusual spectral properties. 10 Moreover, the construction of a push-pull system upon the DPP scaffold should engender some new properties, such as photochromism, enhanced charge transport, and recombination of π-conjugated electronic states. These could provide the basis for new developments in organic photovoltaic devices and fluorescent probes for biomedical applications. 11 Water-soluble conjugated and mul...

Enabling Valence Delocalization in Iron(III) Macrocyclic Complexes through Ring Unsaturation

“…−15 °C and generally used within 24 h). 4-Ethynyl- N , N -bis­(4-methoxyphenyl)­aniline (HC 2 TPA; deprotected before use in assumed quantitative yield) and HC 2 Fc (ethynylferrocene) were prepared according to literature procedures. Dry tetrahydrofuran (THF) was distilled under a nitrogen atmosphere over Na/benzophenone, and dry dichloromethane (CH 2 Cl 2 ) was distilled over calcium hydride.…”

Further Exploration of Aza-Cobalt-Cyclobutenes on CoIII(TIM) Complexes: Reactivity and Spectroelectrochemistry

“…As shown in Figure S4, the two TPA-bearing complexes have identical emission profiles within experimental error, revealing that the mode of coordination of the alkyne (i.e., σ-coordinated or addition across a Co–N bond) does not have any significant influence on the emissive nature of the TPA chromophore. In addition, the similarity in the emission profiles between Co III TIM/TIM′ complexes and TPAC 2 H indicates that the emission originates from the S 0 → S 1 excitation of the TPA moiety. , …”

“…In addition, the similarity in the emission profiles between Co III TIM/TIM′ complexes and TPAC 2 H indicates that the emission originates from the S 0 → S 1 excitation of the TPA moiety. 25,26 Electrochemistry. The voltammetric characteristics of the 1-aza-2-cobalt-cyclobutene-containing complexes, 2a, 3, and 4, were explored for the first time, and their relevant electrode potentials (vs Fc +1/0 ) are listed in Table 5.…”

“…[Co­(TIM)­Cl 2 ]­PF 6 was prepared according to literature procedures . Also prepared according to literature procedures were 1a , 2a / b , and 4-ethynyl- N , N -bis­(4-methoxyphenyl)­aniline (HC 2 TPA). , …”

“…37 Also prepared according to literature procedures were 1a, 2a/b, 15 and 4-ethynyl-N,N-bis(4methoxyphenyl)aniline (HC 2 TPA). 26,38 Physical Measurements. UV−vis spectra were obtained with a JASCO V-780 UV−vis−NIR spectrophotometer.…”