Refined Synthesis of 5-Substituted Dipyrromethanes

Synthesis and specific fluoride binding properties of expanded dithiacalixphyrins

We report the synthesis of expanded dithiacalixphyrins which showed specific sensitivity towards F⁻ ions.

Synthesis and structural characterization of silver(i), copper(i) coordination polymers and a helicate palladium(ii) complex of dipyrrolylmethane-based dipyrazole ligands: the effect of meso substituents on structural formation

A striking difference in the structures of silver complexes was observed because of the different substituents at the meso carbon atom of the dipyrrolylmethane-based ligand.

Rigid yet flexible heteroleptic Co(iii) dipyrrin complexes for the construction of heterometallic 1- and 2-D coordination polymers

Acetylacetonate Co(iii)–dipyrrin complexes form flexible metallatectons displaying diverse shapes when combined with CdX₂salts.

Synthesis and photochemical properties of BODIPY-functionalized silica nanoparticles for imaging Cu2+ in living cells

A highly selective copper(ii) sensor based on BODIPY-functionalized silica nanoparticles, BODIPY–DPA@SN, is designed and synthesized.

Synthesis and catalytic properties of trans-A2B2-type metalloporphyrins in cyclohexane oxidation

A new efficient and mild protocol for synthesizing a series of trans-A2B2-porphyrins through a TFA-catalyzed condensation reaction between various aldehydes and dipyrromethanes has been developed. Several trans-A2B2-metalloporphyrins (cobalt, nickel) were synthesized and used to catalyze cyclohexane oxidation C–H bonds with dioxygen in the absence of additives and solvents. The results show that the catalytic activities were relative to the nature of the substituted groups and the central metal ions of trans-A2B2-metalloporphyrin. Cobalt metalloporphyrin presents better catalytic performance in the conversion of cyclohexane than the nickel metalloporphyrin under the same reaction conditions.

Ethynyl thiophene-appended unsymmetrical zinc porphyrin sensitizers for dye-sensitized solar cells

Zn porphyrin sensitizers with ethynyl thiophene linker, pyrene/fluorene donors and cyanoacrylic or malonic acid anchoring group were synthesized for DSSC applications. Conversion efficiency up to 3.14% was exhibited.

Synthesis, photophysical properties and solvatochromism of meso-substituted tetramethyl BODIPY dyes

The 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene fluorescent dyes (BODIPYs) were first synthesized almost 50 years ago; however, the exploration of their technological application has only begun in the last 20 years. These dyes possess interesting photophysical properties, increasing interest in their application as fluorescent markers and/or dyes. Herein, we report the synthesis of tetramethyl BODIPY and four meso-substituted dyes (2-thienyl, 4-pyridinyl, 4-fluorophenyl and 4-nitrophenyl derivatives). Their photophysical characterization (absorption spectra, emission spectra, fluorescence quantum yields and time-resolved fluorescence) and solvatochromic behavior were studied. Absorption and emission were barely affected by substituents, with a slightly higher stokes shift observed in the substituted dyes. Substitutions could be associated with a shorter fluorescence lifetime and lower quantum yields. Good correlations were observed between the Catalán solvent descriptors and the photophysical parameters. Also, better correlation was observed between the solvent polarizability descriptor (SP) and photophysical parameters. Overall, only slight solvatochromism was observed. The 4-pyridinyl derivative was the subject of a relatively significant solvatochromism regarding the wavelengths of the emission spectra, with the observation of a bathochromically shifted emission in methanol. The fluorescence quantum yield of the 4-nitrophenyl substituted BODIPY was approximately 30 times higher in hexane, which may be of interest for practical applications.

Synthesis and antiprotozoal activity of original porphyrin precursors and derivatives

Importance of heme in African trypanosomes, Leishmania sp. and Plasmodium sp. metabolisms justifies considering the potential of porphyrins and their precursors and derivatives as potential antiparasitic agents by interfering with heme metabolism. Consequently, twenty-four porphyrin precursors and derivatives were evaluated against Leishmania donovani, Trypanosoma brucei and Plasmodium sp. The best active compound against Trypanosoma brucei brucei was a new porphyrin derivative; compound 4i, with a MEC value of 6.25 μM justifying further in vivo evaluation. Whereas these compounds were not active against intramacrophage amastigotes of L. donovani, another new porphyrin derivative, compound 4f was active in vitro against Plasmodium falciparum at 20 nM and a slight delay of mice survival was observed on the Plasmodium berghei/Swiss mice model at 50 μmol/kg/day × 4. Pharmacomodulations should be further developed relying on a better knowledge on the porphyrin behaviour into the parasites comparatively to host cells.

Synthesis and evaluation of gold(III) complexes as efficient DNA binders and cytotoxic agents

In recent years, great interest has been focused on gold(III) complexes as cytotoxic and antitumor drugs. Recent studies demonstrated that simple bidentate or polydentate ligands containing nitrogen donor atoms may offer sufficient redox stabilization to produce viable Au(III) anticancer drug targets under physiologic conditions. So, we have synthesized square planer Au(III) complexes of type [Au(A(n))Clx]·Cly and characterized them using UV-Vis absorption, C, H, N elemental analysis, FT-IR, LC-MS, (1)H and (13)C NMR spectroscopy. These compounds manifested significant cytotoxic properties in vitro for brine shrimp lethality bioassay. The metal complexes were screened for series of DNA binding activity using UV-Vis absorption titration, hydrodynamic measurement and thermal DNA denaturation study. The nucleolytic activity was performed on plasmid pUC19 DNA. The Michaelis-Menten kinetic studies were performed to evaluate rate of enhancement in metal complexes mediated DNA cleavage over the non-catalyzed DNA cleavage.

α-Monoacylated and α,α'- and α,β'-diacylated dipyrrins as highly sensitive fluorescence "turn-on" Zn2+ probes

With the purpose of developing readily synthesized CHEF (chelation-enhanced fluorescence) type Zn(2+) probes with relatively simple molecular structures and excellent sensing behavior, p-anisoyl chloride was used for the acylation of 5-(pentafluorophenyl)dipyrromethane. Interestingly, the α,β'-diacylated product PS2 with a unique substitution mode was obtained in high yield in addition to the normal α-substituted mono- and diacylated products PS1 and PS3. Further oxidation of PS1-PS3 afforded dipyrrins S1-S3. Crystal structure and (1)H NMR measurements of S2 demonstrate the existence of a pure tautomer, which is consistent with DFT calculations. S1-S3 show highly Zn(2+) selective "turn-on" fluorescence based on a CHEF mechanism by the formation of 2:1 (probe:metal) Zn(2+) complexes. The emission colors can be easily tuned from green to red by changing the dipyrrin substitution modes. Furthermore, these probes demonstrate fast responses and wide applicable pH ranges. Among them, S2 shows the highest Zn(2+) sensitivity, with a detection limit of 4.4 × 10(-8) M.

Synthesis, electrochemistry, and photophysics of a family of phlorin macrocycles that display cooperative fluoride binding

A homologous set of 5,5-dimethylphlorin macrocycles in which the identity of one aryl ring is systematically varied has been prepared. These derivatives contain ancillary pentafluorophenyl (3H(Phl(F))), mesityl (3H(Phl(Mes))), 2,6-bismethoxyphenyl (3H(Phl(OMe))), 4-nitrophenyl (3H(Phl(NO2))), or 4-tert-butylcarboxyphenyl (3H(Phl(CO2tBu))) groups at the 15-meso-position. These porphyrinoids were prepared in good yields (35-50%) and display unusual multielectron redox and photochemical properties. Each phlorin can be oxidized up to three times at modest potentials and can be reduced twice. The electron-donating and electron-releasing properties of the ancillary aryl substituent attenuate the potentials of these redox events; phlorins containing electron-donating aryl groups are easier to oxidize and harder to reduce, while the opposite trend is observed for phlorins containing electron-withdrawing functionalities. Phlorin substitution also has a pronounced effect on the observed photophysics, as introduction of electron-releasing aryl groups on the periphery of the macrocycle is manifest in larger emission quantum yields and longer fluorescence lifetimes. Each phlorin displays an intriguing supramolecular chemistry and can bind 2 equiv of fluoride. This binding is allosteric in nature, and the strength of halide binding correlates with the ability of the phlorin to stabilize the buildup of charge. Moreover, fluoride binding to generate complexes of the form 3H(Phl(R))·2F(-) modulates the redox potentials of the parent phlorin. As such, titration of phlorin with a source of fluoride represents a facile method to tune the ability of this class of porphyrinoid to absorb light and engage in redox chemistry.

Fluorinated Boron-Dipyrromethene (BODIPY) Dyes: Bright and Versatile Probes for Surface Analysis

A family of bright boron-dipyrromethene-type fluorophores with a high number of fluorine atoms (F-BODIPYs) has been developed and characterized by X-ray crystallography and optical spectroscopy. The introduction of 3,5-bis(trifluoromethyl)phenyl and pentafluorophenyl moieties significantly enhances the photostability of such dyes, yielding for instance photostable near-infrared (NIR) fluorophores that show emission maxima>750 nm, when the BODIPY's π system is extended with two (dimethylamino)styryl and (dimethylamino)naphthastyryl moieties, or green-emitting BODIPYs with fluorescence quantum yields of unity. When equipped with a suitable group that selectively reacts for instance with amines, F-BODIPYs can be used as potent dual labels for the quantification of primary amino groups on surfaces by X-ray photoelectron spectroscopy (XPS) and fluorescence, two powerful yet complementary tools for the analysis of organic surface functional groups. The advantage of reactive F-BODIPYs is that they allow a fast and non-destructive mapping of the labelled supports with conventional fluorescence scanners and a subsequent quantification of selected areas of the same sample by the potentially traceable XPS technique. The performance is exemplarily shown here for the assessment of the amino group density on SiO2 supports, one of the most common reactive silica supports, in particular, for standard microarray applications.

In vitro demonstration of apoptosis mediated photodynamic activity and NIR nucleus imaging through a novel porphyrin

We synthesized a novel water-soluble porphyrin THPP and its metalated derivative Zn-THPP having excellent triplet excited state quantum yields and singlet oxygen generation efficiency. When compared to U.S. Food and Drug Administration approved and clinically used sensitizer Photofrin, THPP showed ca. 2-3-fold higher in vitro photodynamic activity in different cell lines under identical conditions. The mechanism of the biological activity of these porphyrin systems has been evaluated through a variety of techniques: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, comet assay, poly(ADP-ribose)polymerase (PARP) cleavage, CM-H(2)DCFDA assay, DNA fragmentation, flow cytometric analysis, fluorescence, and confocal microscopy, which confirm the apoptotic cell death through predominantly reactive oxygen species (ROS). Moreover, THPP showed rapid cellular uptake and are localized in the nucleus of the cells as compared to Hoechst dye and Photofrin, thereby demonstrating its use as an efficient sensitizer in photodynamic therapy and live cell NIR nucleus imaging applications.