Using a Photoacid Generator to Switch the Direction of Electronic Energy Transfer in a Molecular Triad

2H-Pyran-2-one-Functionalized Diketopyrrolopyrrole Dye: Design, Synthesis, and Explosives Sensor

In this work, a 2H-pyran-2-one-functionalized diketopyrrolopyrrole (DPP) (coded as receptor 1) was designed, synthesized, and fully characterized by various spectroscopic methods. The physical properties of molecular architecture 1 were studied employing theoretical calculations. Receptor 1 was elegantly scrutinized for the sensing of explosive nitroaromatic compounds (NACs). Receptor 1 exhibited detection of nitro explosives, i.e., picric acid (PA), 2,4-dinitrophenol (DNP), and nitrophenol (NP), via the fluorescence quenching mechanism. The Stern-Volmer equation was employed to evaluate the effectiveness of the quenching process. It was found that 1 exhibited a detection limit of about 7.58 × 10-5, 8.35 × 10-5, and 9.05 × 10-5 M toward PA, DNP, and NP, respectively. The influence of interfering metal ions and anions on PA detection was investigated thoroughly. Furthermore, receptor 1-based low-cost fluorescent thin-layer chromatography (TLC) plates were developed for the recognition of PA.

Porphyrin–diketopyrrolopyrrole conjugates and related structures: Synthesis, properties and applications

A large diversity of porphyrin–diketopyrrolopyrrole conjugates and related structures formed by diketopyrrolopyrrole units and pyrrole-based moieties such as phthalocyanine, porphycene, calix[4]pyrrole or BODIPY have been reported since 2010. The new compounds, whether small molecules or polymeric materials, exhibit very interesting photophysical properties and have been tested in a range of technical or biological applications. This review summarizes the advances in the synthesis of such compounds. Their photophysical properties and potential applications are also briefly discussed.

End-to-end communication in a linear supermolecule with a BOPHY centre and N,N-dimethylanilino-based terminals

Long-range electrostatic interactions are sufficient to cause sequential ionization of the terminal groups in a BOPHY-based supermolecule.

Enhanced Photophosphorylation of a Chloroplast-Entrapping Long-Lived Photoacid

Enhancing solar energy conversion efficiency is very important for developing renewable energy, protecting the environment, and producing agricultural products. Efficient enhancement of photophosphorylation is demonstrated by coupling artificial photoacid generators (PAGs) with chloroplasts. The encapsulation of small molecular long-lived PAGs in the thylakoid lumen is improved greatly by ultrasonication. Under visible-light irradiation, a fast intramolecular photoreaction of the PAG occurs and produces many protons, remarkably enhancing the proton gradient in situ. Consequently, compared to pure chloroplasts, the assembled natural-artificial hybrid demonstrates approximately 3.9 times greater adenosine triphosphate (ATP) production. This work will provide new opportunities for constructing enhanced solar energy conversion systems.

BODIPY-Appended 2-(2-Pyridyl)benzimidazole Platinum(II) Catecholates for Mitochondria-Targeted Photocytotoxicity

Platinum(II) complexes of the type [Pt(L)(cat)] (1 and 2), in which H2 cat is catechol and L represents two 2-(2-pyridyl)benzimidazole ligands with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) pendants, were synthesized to achieve mitochondria-targeted photocytotoxicity. The complexes showed strong absorptions in the range λ=510-540 nm. Complex 1 exhibited intense emission at λ=525 nm in 1 % DMSO/water solution (fluorescence quantum yield of 0.06). Nanosecond transient absorption spectral features indicated an enhanced population of the triplet excited state in di-iodinated complex 2. The generation of singlet oxygen by complex 2 upon exposure to visible light, as evidenced from experiments with 1,3-diphenylisobenzofuran, is suitable for photodynamic therapy because of the remarkable photosensitizing ability. The complexes resulted in excellent photocytotoxicity in HaCaT cells (half maximal inhibitory concentration IC50 ≈3 μm, λ=400-700 nm, light dose=10 J cm(-2) ), but they remained non-toxic in the dark (IC50 >100 μm). Confocal microscopy images of 1 and Pt estimation from isolated mitochondria showed colocalization of the complexes in the mitochondria. Complex 2 displayed generation of reactive oxygen species induced by visible light, disruption of the mitochondrial membrane potential, and apoptosis.

Artificial light-harvesting arrays for solar energy conversion

Following natures' blueprint, the concept of artificial light-harvesting antennae is discussed in terms of sophisticated molecular arrays displaying a tailored cascade of electronic energy transfer steps.

Synthesis and use of “clickable” bay-region tetrasubstituted perylene tetracarboxylic tetraesters and a perylene monoimide diester as energy acceptors

Novel perylene derivatives are ready to be used as functional energy acceptors in light-harvesting systems.

Switching of the photophysical properties of Bodipy-derived trans bis(tributylphosphine) Pt(ii) bisacetylide complexes with rhodamine as the acid-activatable unit

A rhodamine moiety was used in two Bodipy-derived trans bis(tributylphosphine) Pt(ii) bisacetylide complexes for switching the photophysical properties of the complexes.

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

Two novel triads based on a diketopyrrolopyrrole (DPP) central core and two 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) units attached by thiophene rings have been synthesised having high molar extinction coefficients. These triads were characterised and used as donor materials in small molecule, solution processable organic solar cells. Both triads were blended with PC71BM as an acceptor in different ratios by wt % and their photovoltaic properties were studied. For both the triads a modest photovoltaic performance was observed, having an efficiency of 0.65%. Moreover, in order to understand the ground and excited state properties and vertical absorption profile of DPP and BODIPY units within the triads, theoretical DFT and TDDFT calculations were performed.

Providing power for miniaturized medical implants: triplet sensitization of semiconductor surfaces

Here, we recognize the growing significance of miniaturized devices as medical diagnostic tools and highlight the need to provide a convenient means of powering such instruments when implanted into the body. One of the most promising approaches to this end involves using a light-collection facility to absorb incident white light and transfer the photonic energy to a tiny semiconductor embedded on the device. Although fluorescent organic molecules offer strong potential as modules for such solar collectors, we emphasize the promise offered by transition metal complexes. Thus, an extended series of binuclear Ru(II)/Os(II) poly(pyridine) complexes has been shown to be highly promising sensitizers for amorphous silicon solar cells. These materials absorb a high fraction of visible light while the Ru(II)-based units possess triplet energies that are comparable to those of the naphthalene-based bridge. The metal complex injects a triplet exciton into the bridge and this, in turn, is trapped by the Os(II)-based terminal. The result is extremely efficacious triplet-energy transfer; at room temperature the rate of energy transfer is independent of distance over some 6 nm and only weakly dependent on temperature.