Benzofuran-/Benzothiophene-Incorporated NIR-Absorbing Triphyrins(2.1.1)

Novel benzofuran-/benzothiophene-incorporated triphyrins(2.1.1) were synthesized using readily available precursors under mild reaction conditions. The X-ray structure revealed that the benzofuran-incorporated triphyrin(2.1.1) macrocycle was slightly ruffled. The triphyrins(2.1.1) exhibit more absorption in the NIR region compared to previously reported dibenzofuran-/dibenzothiophene-incorporated hybrid macrocycles. The benzofuran-incorporated triphyrin shows significant red shift in absorption bands compared to that of benzothiophene-based triphyrin due to its more coplanar arrangement as supported by X-ray and DFT studies

Synthesis and Properties of Covalently Linked AzaBODIPY–BODIPY Dyads and AzaBODIPY-(BODIPY)₂ Triads

The azaBODIPYs containing one and two formyl functional groups on the 1,7-aryl groups present at the azaBODIPY core were synthesized over sequence of steps and characterized by mass, NMR, absorption, and electrochemical techniques. The monoformylated and diformylated azaBODIPYs are very useful synthons to prepare a wide variety of new fluorescent compounds. The mono- and diformylated azaBODIPYs were treated with pyrrole under mild acidic conditions followed by column chromatographic purification to afford azaBODIPYs appended with one and two dipyrromethanyl groups. The dipyrramethanyl groups of azaBODIPYs were oxidized with DDQ and complexed with BF₃·Et₂O to obtain covalently linked azaBODIPY–BODIPY dyads and azaBODIPY-(BODIPY)₂ triads. The dyads and triads were characterized in detail by HR-MS, 1D and 2D NMR, absorption, fluorescence, and electrochemical techniques and the structure of one of the triads was deduced by X-ray crystallography. The crystal structure of azaBODIPY-(BODIPY)₂ triad revealed that the two BODIPY units were in perpendicular orientation with azaBODIPY unit. The absorption and electrochemical studies indicated a weak interaction among the BODIPY and azaBODIPY moieties and the moieties retain their independent characteristic features in dyads and triads. The preliminary fluorescence studies supported an efficient energy transfer from BODIPY unit(s) to azaBODIPY unit in dyads and triads

Synthesis, Structural, Spectral, and Electrochemical Studies of Selenabenziporphyrin and Its Pd(II) Complex

A new nonaromatic selenabenziporphyrin was synthesized by (3 + 1) condensation of <i>m</i>-benzitripyrrane and 2,5-bis­[(<i>p</i>-tolyl)­hydroxymethyl] selenophene under mild trifluoroacetic acid-catalyzed reaction conditions. The selenabenziporphyrin was characterized by high-resolution mass spectrometry, one- and two-dimensional NMR spectroscopy, and X-ray crystallography. The crystal structure revealed that the macrocycle was planar with moderately tilted <i>m</i>-phenylene ring and that the phenylene ring completely blocks the macrocyclic π-delocalization. The selenabenziporphyrin exhibits one broad absorption band at 645 nm along with one sharp band at 415 nm, and electrochemical studies revealed that the macrocycle was electron-deficient. The selenabenziporphyrin readily forms organometallic Pd­(II) complex when treated with PdCl₂ in CH₃CN/CHCl₃ at reflux followed by recrystallization. The X-ray structure revealed that the Pd­(II) ion was coordinated with two pyrrole “N”s, selenophene “Se”, and <i>m</i>-phenylene ring “C” in square-planar fashion, and the complex retained its nonaromatic nature. The Pd­(II) complex exhibits ill-defined absorption bands, and it was more electron-deficient than free-base selenabenziporphyrin macrocycle. Time-dependent density functional theory studies supported the experimental observations

Congeners of Pyrromethene-567 Dye: Perspectives from Synthesis, Photophysics, Photostability, Laser, and TD-DFT Theory

In an attempt to develop photostable and efficient BODIPY (PM) dyes for use in liquid dye lasers, three new congeners of widely used laser dye, PM567, were synthesized and their photophysical properties in various organic solvents, laser performances, and photostabilities in a selected solvent, 1,4-dioxane, have been investigated using a frequency doubled Q-switched (10 Hz) Nd:YAG laser at 532 nm. The results of photostability study in nonpolar 1,4-dioxane revealed the remarkable enhancement in stability of the novel dyes compared to that of PM567 as well as improved laser performances. Cyclic voltammetry study strongly supports the observed enhancement in photostability of the novel dyes compared to that of PM567. The observed properties of the novel dyes in relation to those of PM567 have been rationalized by extensive use of DFT and TD-DFT using the B3LYP/6-31G­(d) method of theory