Tetracyanobutadiene functionalized ferrocenyl BODIPY dyes

Perspectives on push-pull chromophores derived from click-type [2 + 2] cycloaddition-retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

Various push-pull chromophores can be synthesized in a single and atom-economical step through [2 + 2] cycloaddition-retroelectrocyclization (CA-RE) reactions involving diverse electron-rich alkynes and electron-deficient alkenes. In this review, a comprehensive investigation of the recent and noteworthy advancements in the research on push-pull chromophores prepared via the [2 + 2] CA-RE reaction is conducted. In particular, an overview of the physicochemical properties of the family of these compounds that have been investigated is provided to clarify their potential for future applications.

Tetracyanobutadiene Bridged Push-Pull Chromophores: Development of New Generation Optoelectronic Materials

This review describes the design strategies used for the synthesis of various tetracyanobutadiene bridged donor-acceptor molecular architectures by a click type [2+2] cycloaddition-retroelectrocyclization (CA-RE) reaction sequence. The photophysical and electrochemical properties of the tetracyanobutadiene bridged molecular architectures based on various moieties including diketopyrrolopyrrole, isoindigo, benzothiadiazole, pyrene, pyrazabole, truxene, boron dipyrromethene (BODIPY), phenothiazine, triphenylamine, thiazole and bisthiazole are summarized. Further, we discuss some important applications of the tetracyanobutadiene bridged derivatives in dye sensitized solar cells, bulk heterojunction solar cells and photothermal cancer therapy.

Synthesis and DSSC application of BODIPY decorated triazole bridged and benzene nucleus cored conjugated dendrimers

Conjugated dendrimers decorated with 5,5-difluoro-10-(4-(prop-2-ynyloxy)phenyl)-5H-dipyrrolo[1,2-c:1',2'-f][1,3,2]diazaborinin-4-ium-5-uide, usually known as boron dipyrromethene (BODIPY), have been synthesized and their application as photosensitizer in dye sensitized solar cells (DSSCs) has been evaluated. Third generation triazole bridged BODIPY dendrimers show higher light energy harvesting efficiency of 2.5% better than the first and second generation dendrimers, when used as a dye material in solar cells. The current intensity increases with an increase in the generation of the dendrimer as revealed by cyclic voltammetry. Fluorescence decay analysis shows that the relaxation times τ ₁ and τ ₂ increase as the dendrimer generation increases, however τ ₂ for the third generation dendrimer decreases because of fluorescence quenching due to molecular crowding.

Tetracyanobutadiene (TCBD) functionalized benzothiadiazole derivatives: effect of donor strength on the [2+2] cycloaddition–retroelectrocyclization reaction

A series of unsymmetrical and symmetrical mono/di 1,1,4,4-tetracyanobutadiene (TCBD) substituted benzothiadiazoles (BTDs) 2a–2g was synthesized by [2+2] cycloaddition–retroelectrocyclization reaction.

Recent advances in the synthesis of [a]-benzo-fused BODIPY fluorophores

This feature article summarizes the different strategies for the synthesis of [a]-benzo-fused BODIPYs that have been reported in the literature until 2018. These π-extended BODIPYs are promising fluorophores for bio-imaging and organic photovoltaic applications due to both their attractive photophysical properties in the near-infrared area and their higher (photo)chemical stability compared to conventional bis-styryl derivatives. The four main strategies described in this review can be used to access either directly the expected [a]-benzo-fused BODIPYs or through the di-/tetra-hydroisoindole.

Self-quenched ferrocenyl diketopyrrolopyrrole organic nanoparticles with amplifying photothermal effect for cancer therapy

Organic nanoparticles (NPs) with near-infrared absorbance possess high photothermal conversion (PTC) efficiency and an excellent photoacoustic signal, presenting a great prospect for photoacoustic imaging (PAI)-guided photothermal therapy (PTT). Herein, a novel diketopyrrolopyrrole derivative (DPPCN-Fc) is synthesized for use as a PTT agent with PAI performance. Due to photo-induced electron transfer (PET), the two flanked ferrocene moieties significantly quench the radiative decay and intersystem crossing process, resulting in an enhanced nonradiative transition, and an amplifying photothermal effect is observed. Exposing the DPPCN-Fc NP aqueous dispersion (100 μg mL-1) to 730 nm (1.0 W cm-2) laser radiation results in a temperature elevation of 33.4 °C within 10 min and the PTC efficiency reaches up to 59.1%, which is higher than most reported photothermal therapeutic agents. Furthermore, under irradiation from 730 nm lasers, cancer cells could be completely killed in vivo due to the amplifying photothermal effects. Therefore, the as-prepared DPPCN-Fc NPs are a promising cancer theranostic agent for photoacoustic imaging-guided cancer photothermal therapy.

NIR-Absorbing Donor-Acceptor Based 1,1,4,4-Tetracyanobuta-1,3-Diene (TCBD)- and Cyclohexa-2,5-Diene-1,4-Ylidene-Expanded TCBD-Substituted Ferrocenyl Phenothiazines

A series of unsymmetrical (D-A-D₁ , D₁ -π-D-A-D₁ , and D₁ -A₁ -D-A₂ -D₁ ; A=acceptor, D=donor) and symmetrical (D₁ -A-D-A-D₁ ) phenothiazines (4 b, 4 c, 4 c', 5 b, 5 c, 5 d, 5 d', 5 e, 5 e', 5 f, and 5 f') were designed and synthesized by a [2+2] cycloaddition-electrocyclic ring-opening reaction of ferrocenyl-substituted phenothiazines with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The photophysical, electrochemical, and computational studies show a strong charge-transfer (CT) interaction in the phenothiazine derivatives that can be tuned by varying the number of TCNE/TCNQ acceptors. Phenothiazines 4 b, 4 c, 4 c', 5 b, 5 c, 5 d, 5 d', 5 e, 5 e', 5 f and 5 f' show redshifted absorption in the λ=400 to 900 nm region, as a result of a low HOMO-LUMO gap, which is supported by TD-DFT calculations. The electrochemical study exhibits reduction waves at low potential due to strong 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) and cyclohexa-2,5-diene-1,4-ylidene-expanded TCBD acceptors. The incorporation of cyclohexa-2,5-diene-1,4-ylidene-expanded TCBD stabilized the LUMO energy level to a greater extent than TCBD.

Ferrocene–BODIPYmerocyanine dyads: new NIR absorbing platforms with optical properties susceptible to protonation

Ferrocene–BODIPYmerocyanine dyads 5 and 6 were synthesized and characterized by spectroscopy, electrochemistry, and DFT calculations.

Synthesis, structure and photophysical properties of near-infrared 3,5-diarylbenzoBODIPY fluorophores

An efficient synthetic method for 3,5-diarylbenzoBODIPYs was reported, which showed tunable absorption/emission via the variation of the 3,5-aryl substituents.