β-Substituted ferrocenyl porphyrins: synthesis, structure, and properties

Third-order nonlinear optical properties of highly electron deficient, nonplanar push-pull porphyrins: β-nitro-hexa-substituted porphyrins bearing bromo, phenyl, and phenylethynyl groups

β-Heptasubstituted porphyrins [MTPP(NO2)X6; M = 2H, NiII, CuII, and ZnII; X = Br, Ph, and PE] were synthesized and their third-order nonlinear optical (NLO) properties explored using the single-beam Z-scan technique with femtosecond, MHz pulses in the visible range. The three-photon absorption (γ), third-order nonlinear optical susceptibility (χ3), three-photon absorption cross-section (σ3), and nonlinear refractive index (n2) have been determined from theoretical fits with experimental results. The sign and magnitude of the nonlinear refractive index (n2) have been obtained from the closed-aperture experiment while the three-photon absorption coefficient and three-photon absorption cross-section were determined from the open-aperture experiment. The magnitudes of the 3PA and σ3 extended in the range of (2.7-3.4) × 10-23 cm3 W-2 and (5.5-7.0) × 10-78 cm6 s2, respectively. The higher magnitude of the NLO coefficients ensures their utility in optical and photonic applications.

Similar, Yet Different: Long-Range Metal-Metal Coupling and Electron-Transfer Processes in Metal-Free 5,10,15,20-Tetra(ruthenocenyl)porphyrin

The electronic structure, redox properties, and long-range metal-metal coupling in metal-free 5,10,15,20-tetra(ruthenocenyl)porphyrin (H₂TRcP) were probed by spectroscopic (NMR, UV-vis, magnetic circular dichroism (MCD), and atmospheric pressure chemical ionization (APCI)), electrochemical (cyclic voltammetry, CV, and differential pulse voltammetry, DPV), spectroelectrochemical, and chemical oxidation methods, as well as theoretical (density functional theory, DFT, and time-dependent DFT, TDDFT) approaches. It was demonstrated that the spectroscopic properties of H₂TRcP are significantly different from those in H₂TFcP (metal-free 5,10,15,20-tetra(ferrocenyl)porphyrin). Ruthenocenyl fragments in H₂TRcP have higher oxidation potentials than the ferrocene groups in the H₂TFcP complex. Similar to H₂TFcP, we were able to access and spectroscopically characterize the one- and two-electron oxidized mixed-valence states in the H₂TRcP system. DFT predicts that the porphyrin π-system stabilizes the [H₂TRcP]⁺ mixed-valence cation and prevents its dimerization, which is characteristic for ruthenocenyl systems. However, formation of the mixed-valence [H₂TRcP]²⁺ is significantly less reproducible than the formation of [H₂TRcP]⁺. DFT and TDDFT calculations suggest the ruthenocenyl fragment dominance in the highest occupied molecular orbital (HOMO) energy region and the presence of the low-energy MLCT (Rc → porphyrin (π*)) transitions in the visible region with energies higher than the predominantly porphyrin-centered Q-bands.

New Materials Based on Cationic Porphyrins Conjugated to Chitosan or Titanium Dioxide: Synthesis, Characterization and Antimicrobial Efficacy

The post-functionalization of 5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin tri-iodide, known as a highly efficient photosensitizer (PS) for antimicrobial photodynamic therapy (aPDT), in the presence of 3- or 4-mercaptobenzoic acid, afforded two new tricationic porphyrins with adequate carboxylic pending groups to be immobilized on chitosan or titanium oxide. The structural characterization of the newly obtained materials confirmed the success of the porphyrin immobilization on the solid supports. The photophysical properties and the antimicrobial photodynamic efficacy of the non-immobilized porphyrins and of the new conjugates were evaluated. The results showed that the position of the carboxyl group in the mercapto units or the absence of these substituents in the porphyrin core could modulate the action of the photosensitizer towards the bioluminescent Gram-negative Escherichia coli bacterium. The antimicrobial activity was also influenced by the interaction between the photosensitizer and the type of support (chitosan or titanium dioxide). The new cationic porphyrins and some of the materials were shown to be very stable in PBS and effective in the photoinactivation of E. coli bacterium. The physicochemical properties of TiO2 allowed the interaction of the PS with its surface, increasing the absorption profile of TiO2, which enables the use of visible light, inactivating the bacteria more efficiently than the corresponding PS immobilized on chitosan.

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.

C3-Symmetric star shaped donor–acceptor truxenes: synthesis and photophysical, electrochemical and computational studies

This manuscript reports the design and synthesis of C₃-symmetric star shaped donor and acceptor substituted truxenes 6, 7, 10 and 11 using Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition–retroelectrocyclization reactions.

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.

An insight into the communication between β-olefin/phenyl olefin-mediated acceptors and porphyrin π-system: a way to establish porphyrin based chemodosimeters and chemosensors

Porphyrins bearing electron acceptors attached to β-carbon through olefin or phenyl–olefin bridges act as chemodosimeters for CN⁻ as well as chemosensors for F⁻, CN⁻ and OAc⁻ ions depends on acceptor strength and position.

β-Substituted ferrocenyl porphyrins: The role of the spacer and of the number of substituents on their structural and spectroscopic characteristics

Mono and bis ethynyl and ethynylphenyl [Formula: see text]-substituted porphyrins have been synthesized and characterized. Their conformational properties have been analyzed through a combination of NMR experiments and molecular mechanic calculations, while UV-Vis absorption and fluorescence measurements together with electrochemical studies allows us to probe the existence of intramolecular electronic processes. The role of the beta-substituents and of the spacer is underlined.

NIR absorbing diferrocene-containing meso-cyano-BODIPY with a UV-Vis-NIR spectrum remarkably close to that of magnesium tetracyanotetraferrocenyltetraazaporphyrin

Diferrocene-containing meso-cyano-BODIPY (4) was prepared and characterized by spectroscopy, X-ray crystallography, and DFT calculations.

Heteroatom-connected ferrocenyl substituted naphthalimides

A family of heteroatom (oxygen, sulphur and nitrogen) connected ferrocenyl naphthalimides 3a–3f were designed and synthesized by the nucleophilic aromatic substitution and Buchwald coupling reactions.

β-Substituted triarylborane appended porphyrins: photophysical properties and anion sensing

β-Substituted triarylborane porphyrins were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling reaction.

Star shaped ferrocenyl substituted triphenylamines

This manuscript reports design and synthesis of star shaped ferrocenyl substituted triphenylamine conjugates (Fc-TPA) 3a–3c by the Pd-catalyzed Sonogshira cross-coupling reaction.

Synthesis, characterization, redox, and Hg2+ optical ion sensing properties of ferrocenyl-containing maleo- and fumaronitrile derivatives

Mono-((Z)-2-amino-3-((E)-ferrocenylideneamino)butenedinitrile) (1) and bis-((E)-2,3-bis-((E)-ferrocenylideneamino)butenedinitrile) (2) substituted Schiff bases obtained by the reaction between ferrocenecarbaldehyde and diaminomaleonitrile were prepared and characterized by 1H and 13C NMR, IR, and UV-vis-NIR spectroscopy methods, elemental analysis, and X-ray crystallography. Density functional theory and time-dependent density functional theory were used to elucidate the electronic structure and the origin of observed excited states in both compounds. Electrochemical techniques were employed to investigate the possibility for the formation of a mixed-valence state of the iron centers in 2+, which are connected by a conjugated π-system. Two reversible oxidation potentials were observed in cyclic voltammetry, and spectroelectrochemical experiments revealed the presence of a low-energy intervalence charge transfer band in 2+, corresponding to class II of the mixed-valence systems. Both complexes were tested for cation-recognition properties using a variety of main group and transition-metal cations. It was shown that complex 1 can be used as a selective optical sensor in recognition of Hg2+ ions. It was also shown by NMR spectroscopy and X-ray crystallography that one of the final reaction products between Hg2+ ions and complex 1 is 2-ferrocenyl-4,5-dicyanoimidazole (3).

The corrole and ferrocene marriage: 5,10,15-triferrocenylcorrolato Cu

Two synthetic routes have been defined for the preparation of a 5,10,15-triferrocenylcorrole Cu derivative and preliminary electronic properties were investigated.