Laser dye spectroscopy of some pyrromethene-BF(2) complexes

Photoinduced and Classical Sol-Gel Synthesis: Spectral and Photophysical Behavior of Silica Matrix Doped by Novel Fluorescent Dye Based on Boron Difluoride Complex

The boron difluoride complex is known as an extraordinary class of fluorescent dyes, which has attracted research interest because of its excellent properties. This article reports the optical properties such as absorption, fluorescence, molar absorptivity, and photo-physical parameters like dipole moment, and oscillator strength of new fluorescent organic dye based on boron difluoride complex 2-(1-(difluoroboraneyl)-1,2-dihydroquinolin-2-yl)-2-(1-methylquinoxalin-2-ylidene) acetonitrile (DBDMA). The spectral characterization of the dye was measured in sol-gel glass, photosol-gel, and organic-inorganic matrices. The absorption and fluorescence properties of DBDMA in sol-gel glass matrices were compared with each other. Compared with the classical sol-gel, it was noticed that the photosol-gel matrix is the best one with immobilized DBDMA. In the latter, a large stokes shift was obtained (97 nm) and a high fluorescence quantum yield of 0.5. Special attention was paid to the addition of gold NPs into the hybrid material. The fluorescence emission intensity of the DBDMA with and without gold nanoparticles in different solid media is described, and that displayed organic-inorganic matrix behavior is the best host.

Solid-state host–guest influences on a BODIPY dye hosted within a crystalline sponge

Hosting a BODIPY dye in a crystalline sponge bathochromically shifts luminescent emission.

NLOphoric benzyl substituted BODIPY and BOPHY: A comprehensive linear and nonlinear optical study by spectroscopic, DFT and Z-scan measurement

BOPHY (BPY) and BODIPY (BDY) dye bearing benzyl group (Bn) at 4,4' and 2,6 position respectively were synthesized and characterized. The fluorescence decay measurements were performed which reveal that benzyl BOPHY (Bn-BPY) has shorter fluorescence lifetime compared to benzyl BODIPY (Bn-BDY). The difference in transition dipole moment is found to be 6.93 and 11.3 D for Bn-BDY and Bn-BPY respectively in toluene. The molecular electrostatic potential (MEP) plot shows Bn-BDY is more polarised compared to Bn-BPY. The nonlinear optical (NLO) property was evaluated using Z-scan measurement. The molecular electronic arrangement of Bn-BPY significantly affects the nonlinear absorption properties resulting into reverse saturable absorption (nonlinear absorption coefficient β = 0.256 × 10^-11 m/W). In contrast, the Bn-BDY displays saturable absorption character. The calculated third-order nonlinear susceptibility χ⁽³⁾ value is 12.23 × 10^-13 esu and 2.49 × 10^-13 esu for Bn-BDY and Bn-BPY respectively. The power limiting behaviour of Bn-BPY displays limiting threshold energy around 70 Jcm^-2 with clamped output at ~35 Jcm^-2.

Enhanced fluorescence of aqueous BODIPY by interaction with cavitand cucurbit[7]uril

Host–guest interactions of the host cucurbit[7]uril (CB[7]) with a water soluble cationic BODIPY dye 2 are scarcely reported.

Novel pyrromethene dyes with N-ethyl carbazole at the meso position: a comprehensive photophysical, lasing, photostability and TD-DFT study

Two novel BODIPY (pyrromethene, PM) dyes containing N-ethyl carbazole at the meso position are synthesized and their photophysical properties in different solvents and the photochemical stabilities and laser performances in n-heptane are investigated. The n-heptane solution of the dyes was used as a gain medium in a constructed narrow band dye laser, pumped by a Q-switched (10 Hz) frequency-doubled (532 nm) Nd:YAG laser and the results gave enhanced photo stabilities and similar peak efficiencies of the synthesized dyes as compared to parent dye PM567. When substituted at the meso position with N-alkyl carbazole, photostability is found to be increased in comparison to PM567, and also when substituted at 2- and 6-positions with a benzyl group instead of an ethyl group along with N-ethyl carbazole at the meso position, the photo stability is further increased in n-heptane. A comprehensive study on structural, photophysical and electronic properties of dyes by means of DFT and TD-DFT in the solvents of various polarities has revealed remarkable characteristics of the BODIPY chromophore.

High laser efficiency and photostability of pyrromethene dyes mediated by nonpolar solvent

Many pyrromethene (PM) dyes have been shown to outperform established rhodamine dyes in terms of laser efficiency in the green-yellow spectral region, but their rapid photochemical degradation in commonly used ethanol or methanol solvents continues to limit its use in high average power liquid dye lasers. A comparative study on narrowband laser efficiency and photostability of commercially available PM567 and PM597 dyes, using nonpolar n-heptane and 1,4-dioxane and polar ethanol solvents, was carried out by a constructed pulsed dye laser, pumped by the second harmonic (532 nm) radiation of a Q-switched Nd:YAG laser. Interestingly, both nonpolar solvents showed a significantly higher laser photostability (∼100 times) as well as peak efficiency (∼5%) of these PM dyes in comparison to ethanol. The different photostability of the PM dyes was rationalized by determining their triplet-state spectra and capability to generate reactive singlet oxygen (O₂1) by energy transfer to dissolved oxygen in these solvents using pulse radiolysis. Heptane is identified as a promising solvent for these PM dyes for use in high average power dye lasers, pumped by copper vapor lasers or diode-pumped solid-state green lasers.

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.

Fluorescence spectral studies of some imidazole derivatives

The photophysical properties of imidazole derivatives namely 2-(2,4-difluorophenyl)-4,5-dimethyl-1-p-tolyl-1H-imidazole and N,N-dimethyl-4-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl)benzenamine, synthesized from an unusual four components assembling, were studied in several solvents. Polarization also plays major role in the increase of excited-state dipole moment (μ(e)). From the spectral results, it was found that there is equilibrium between neutral species and monocationic (MC) species in polar aprotic and polar protic solvents. The basicity of the solvent, C(β) or C(SB) has a negative value, suggesting that the absorption and fluorescence bands shift to lower energies with increasing electron-donating ability of the solvent. Therefore, resonance structures 1b and 2b has the positive charge located at the nitrogen atom stabilized in basic solvents.

Photophysical properties of novel picrate derivatives--solvent effect

H and (13)C NMR spectra were recorded for some novel picrate derivatives derived from 3,3-dimethyl-2,6-diarylpiperidin-4-ones and 3-benzyl-2,6-diarylpiperidin-4-one. The photophysical properties of the picrate derivatives were studied in several solvents, which include a wide range of apolar, polar and protic media. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed due to the presence of increased electrostatic interaction between N-protonated piperidone ring and picryl anion ring so that the picryl anion ring lies perpendicular to the plane of the N-protonated piperidone ring i.e., non co-planarity. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption and reemission effects in the detected emission in highly concentrated solutions. The higher fluorescence quantum yield of the picrate derivatives are observed in polar media.

Improved Sol-Gel Materials for Efficient Solid State Dye Lasers

Photoresistant laser dyes were trapped in silica based xerogel host matrices to obtain solid state tunable lasers. For this purpose very dense xerogel samples with improved chemical and physical properties were prepared at room temperature by the sol-gel technology. The as-prepared materials were polished to obtain optical quality surfaces and were used as new lasing media.

Lasing action of such different dyes as rhodamine, perylene and pyrromethene doping dense sol-gel matrices was demonstrated. Efficiencies of 30 % or lifetimes of more than 100,000 shots were achieved with different new ≤dye dopant/host matrix≥ couples. Their different performances are reviewed and discussed.

Synthesis, Photophysical Properties, and Laser Behavior of 3-Amino and 3-Acetamido BODIPY Dyes

The asymmetrically substituted BODIPY dyes 9a and 9b have been synthesized through a key redox step involving the alpha-nitroso derivative of the starting pyrrol. Both dyes emit fluorescence with quantum yields of ca. 0.7, but only 8b behaves as a good laser dye, with an efficiency of 48% in ethanol solution.

Photophysical and lasing properties of new analogs of the boron-dipyrromethene laser dye pyrromethene 567 incorporated into or covalently bounded to solid matrices of poly(methyl methacrylate)

The photophysical, lasing and thermostability properties of newly synthesized analogs of the commercial dye pyrromethene 567 (PM567) have been measured in polymeric matrices of poly(methyl methacrylate) both when used as a dopant and when covalently bounded to the polymeric chain. These analogs have an acetoxy or a polymerizable methacryloyloxy group at the end of a polymethylene chain at Position 8 of the PM567 chromophore core. Clear correlations between photophysical and lasing characteristics are observed. Linking chain lengths with three or more methylene units give the highest fluorescence quantum yields (as high as 0.89) and lasing efficiencies (as high as 41%). The covalent linkage of the chromophore to the polymeric chain via the methacryloyloxy group improves the photostability of the PM567 chromophore.

Methacrylate-tethered analogs of the laser dye PM567--synthesis, copolymerization with methyl methacrylate and photostability of the copolymers

The synthesis and characterization of new analogs of the laser dye PM567 (4,4-difluoro-1,3,5,7,8-pentamethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene) with the 8-position substituted by a linear chain with n methylenes (n = 1, 3, 5, 10 or 15) tethered with an acetoxy or methacryloyloxy group (PnAc and PnMA, respectively) is described. The monomeric dyes PnMA have been successfully copolymerized with methyl methacrylate (MMA), yielding linear copolymers of high optical quality where the covalently bonded chromophore is separated from the polymeric main chain by a spacer of variable length. The photostability of the solid polymeric materials under UV (310 nm) irradiation (method ASTM G 53-77) has been compared with those of the model dyes PnAc and PM567 as solid solutions in poly-MMA (PnAc-PMMA and PM567-PMMA, respectively). In all the cases, the chromophore bound to the polymer is more photostable than that simply dissolved in the same polymer, with photodegradation quantum yields in the range 2.3 x 10(-5) to 4.8 x 10(-5), which was interpreted as due to additional modes for the dissipation of the absorbed energy along the polymeric chain. In both polymer solutions and copolymers, the length of the polymethylene chain has low or null influence on the photostability. In ethanol solution, PnAc model dyes with polymethylene chains with three or more methylene groups show about the same photostability; this is of an order of magnitude higher than that of the parent dyes P1Ac and PM567 in the same solvent.

Perylene- and pyrromethene-doped xerogel for a pulsed laser

Hydrophobic photostable dye molecules such as perylenes or pyrromethenes were trapped in xerogel matrices. Using these new materials as solid-state dye lasers, we have demonstrated efficient laser operation. Slope efficiencies of up to 30% were obtained in the millijoule output-energy range. Tunabilities of up to 60 nm were observed, and more than 150,000 pulses were emitted by the same spot of a given sample when the laser was pumped at millijoule energy levels.