1,720,961 research outputs found
Photophysics and nonlinear optical properties of tetra- and octabrominated silicon naphthalocyanines
No full textThe effect of the number of bromide substituents on the photophysical and nonlinear optical properties of the tetrabrominated naphthalocyanine Br 4(tBu 2PhO) 4NcSi[OSi(Hex) 3] 2 (1) and the octabrominated naphthalocyanine Br 8NcSi[OSi(Hex) 3] 2 (2) has been investigated through various spectroscopic techniques. Absorption and emission of 1 and 2 have been studied at room temperature and 77 K to determine the spectral properties of the ground and the excited states and the lifetimes and quantum yields of formation of the excited states. There is a moderate increase of the quantum yield of the triplet excited-state formation (Φ T = 0.10 vs 0.13) and a decrease of the triplet excited-state lifetime (τ T ≈ 70 vs 50 μs) from 1 to 2. These can be attributed to the stronger heavy atom effect produced by the larger number of peripheral bromide substituents in 2 considering that an excited state with a triplet manifold is involved in the excitation dynamics of both complexes 1 and 2. The quantum yields of the singlet oxygen formation (Φ Δ) upon irradiation of 1 and 2 at 355 nm were also evaluated, and a value of Φ Δ(1) = Φ Δ(2) = 0.16 was obtained. In addition to that, octabrominated complex 2 displays a larger decrease of nonlinear optical transmission for nanosecond pulses at 532 nm with respect to the tetrabrominated complex 1. The nanosecond Z-scan experiments reveal that 1 and 2 exhibit both a reverse saturable absorption and a nonlinear refraction at 532 nm. However, both the sign and the magnitude of the nonlinear refraction change from 1 to 2. For picosecond Z-scan in the visible spectral region, these two complexes exhibit only reverse saturable absorption, and the excited-state absorption cross-section increases at longer wavelengths. © 2008 American Chemical Society
Large two-photon absorption cross sections of hemiporphyrazines in the excited state: The multiphoton absorption process of hemiporphyrazines with different central metals
No full textA series of five hemiporphyrazines (Hps) with different coordinating central atoms (H2, GeCl2, InCl, Pt, Pb), and the acyclic derivative 1,3-bis-(6′-amino-4′-butoxy-2′-pyridylimino)-1,3- dihydroisoindoline have been synthesized and their multiphoton absorption properties examined at the second harmonic frequency of the Nd:YAG laser in the nanosecond time regime. Metal-free and platinum Hps display saturation of optical transmittance within incident fluence values of 6 J cm-2. Comparison with other similar molecular structures like phthalocyanines and related molecules shows that Hps are strong nonlinear absorbers. The experimental curves of nonlinear transmission at 532 nm have been fitted by means of a three-level model with the occurrence of simultaneous two-photon absorption from an excited state. In the sole case of the InCl complex we found that a five-level model is needed because of the participation of triplet states. Contrary to phthalocyanines, naphthalocyanines, and porphyrins, a heavy central atom does not improve the nonlinear absorption properties since a different excited states dynamic is involved. The large nonlinear absorption of Hps combined with the very small absorption in the visible spectral range makes these molecules a very interesting class of molecules for nonlinear optical applications. © 2008 American Chemical Society
Indium Phthalocyanines with Different Axial Ligands: A Study of the Influence of the Structure on the Photophysics and Optical Limiting Properties
No full textThe photophysical properties of four axially substituted indium phthalocyanines, namely, 2,(3)-tetra-tert-butyl-phthalocyaninato indium chloride (1), 2,(3)-tetra-[(3,5-di-tert-butyl)-phenyloxy]-phthalocyaninato indium bromide (2), 2,(3)-tetra-[(3,5-di-tert-butyl)-phenyloxy]-phthalocyaninato indium iodide (3), and 2,3-octa-[(2-hexyl)-ethyloxy]-phthalocyaninato indium trifluoroacetate (4), have been investigated, and their optical limiting properties with nanosecond light pulses were evaluated. All complexes behave as reverse saturable absorbers in the range of 400-625 nm due to a triplet-triplet excited-state transition. Excited-state absorption cross sections and triplet state lifetimes are not significantly affected by the nature of the axial ligand. On the other hand, remarkable differences in the variation of nonlinear transmittance are observed for 1-4 due to significantly different intersystem crossing rates. Heavier axial ligands in phthalocyanines 2 and 3 produce the largest variations of nonlinear transmission (heavy-atom effect). Complex 1 in polystyrene matrix shows reversible nonlinear absorption when incident fluence does not exceed 0.025 J cm-2. © 2008 American Chemical Society
Demonstration of the optical limiting effect for an hemiporphyrazine
No full textThe hemiporphyrazine complex 9,22-bis(dibutoxy)hemiporphyrazinato chloroindium(iii) (1) is one of the few examples for this class of compounds, which displays the nonlinear optical effect of reverse saturable absorption for nanosecond laser pulses in the visible spectrum. The high linear transmission combined with the fast switching into a strongly absorbing excited state in the same spectral range (400-650 nm), renders the studied hemiporphyrazine an ideal material for the passive shuttering of pulsed radiations. © The Royal Society of Chemistry 2006
Axial halogen ligand effect on photophysics and optical power limiting of some indium naphthalocyanines
No full textThree axially substituted complexes, 2,3-octa(3,5-di-terf-butylphenoxy)-2, 3-naphthalocyaninato indium chloride (1a), 2,3-octa(3,5-di-tert-butylphenoxy)-2, 3-naphthalocyaninato indium bromide (1b), and 2,3-octa(3,5-ditert-butylphenoxy)- 2,3-naphthalocyaninato indium iodide (1c) have been synthesized and their photophysical properties have been investigated. Optical power limiting of nanosecond (ns) and picosecond (ps) laser pulses at 532 nm using these complexes has been demonstrated. All complexes display strong Q(0,0) absorption and measurable emission in the near-infrared region and exhibit strong excited-state absorption in the range of 470-700 nm upon ns laser excitation. The different axial ligands show negligible effect on the linear absorption, emission, and transient difference absorption spectra. However, the excited-state lifetime, triplet excited-state quantum yield, and efficiency to generate singlet oxygen are affected significantly by the heavier axial ligand. Brominated and iodinated complexes 1b and 1c show higher triplet excited-state quantum yield, while chlorinated complex 1a has longer excited-state lifetime and is more efficient in generating singlet oxygen. The iodinated complex le displayed the best optical limiting due to the higher ratio of excited-state absorption cross section to ground state absorption cross section (σeff/ σ0). © 2007 American Chemical Society
Nonlinear transmission of a tetrabrominated naphthalocyaninato indium chloride
No full textThe axially substituted complex chloro indium(III) 2-tetrabromo-3-tetra-(3,5-di-tert-butylphenyloxy)naphthalocyanine [Br-4(tBu(2)PhO)(4)NcInCl (1); MW = 1996] has been synthesized for the first time, and its nonlinear transmission properties have been evaluated with the Z-scan technique in both open and closed aperture configurations at 532 nm for nanosecond pulsed radiation. The tetrabrominated complex 1 displayed a larger positive nonlinear absorption coefficient when compared to an analogous nonbrominated naphthalocyanine [(tBu(2)PhO)(8)NcInCl (2); MW = 2498]. The effect of the four Br atoms on the nonlinear optical behavior of 1 is evaluated, discussed, and compared with the nonlinear optical behavior of 2. It is shown that the bromination of the naphthalocyanine ring considerably improves the limiting properties of such a system when high-intensity radiations are produced by nanosecond laser pulses at 532 nm
Synthesis, DFT calculations, linear and nonlinear optical properties of binuclear phthalocyanine gallium chloride
No full text10.1007/s00894-005-0043-5Journal of Molecular Modeling125543-550JMMO
Synthesis and high ranked NLT properties of new sulfonamide-substituted indium phthalocyanines
No full textThe synthesis and characterization of three new indium phthalocyanines bearing eight N-alkyl- or N-arylsulfonamide groups is described. The new compounds are {2,3,9,10,16,17,23,24-octakis[4-(4-methoxyphenylaminosulfonyl] phenoxy]phthalocyaninato}indium(III) chloride (7), {2,3,9,10,16,17,23,24- octakis[4-diethylaminosulfonyl)phenoxy]phthalocyaninato}indium(III) chloride (8) and {2,3,9,10,16,17,23,24-octakis[4-didodecylaminosulfonyl)phenoxy] phthalocyaninato}indium(III) chloride (9), and were obtained in 23-49% yields. The precursors of phthalocyanines 7-9 are sulfonamide-substituted phthalonitriles that can be prepared by reacting 4,5-bis(4- chlorosulfonylphenoxy)phthalonitrile (3) with amines. The nonlinear transmission (NLT) of complexes 7-9 was determined at 532 nm using ns pulses. All three phthalocyanines behave as reverse saturable absorbers with increasing efficiency of optical limiting in the order 7 < 8 < 9. A comparative analysis of the NLT results is attempted in terms of the structural differences in 7-9. © 2010 Elsevier B.V. All rights reserved
Synthesis of a bisphthalocyanine and its nonlinear optical properties
No full textThe synthesis and the nonlinear optical properties of an axially substituted binuclear InCl/InCl phthalocyanine 1 with an unsymmetrical substitution pattern are described. The preparation of this new type of binuclear phthalocyanine has been carried out through a multi-step synthetic strategy, which was specially developed for binuclear phthalocyanines. The study has been carried out with the aim of analyzing which variations of the electronic properties accompany the unsymmetrical extension of the pi-electron system of a binuclear Pc when compared to a mononuclear Pc (the complex tBu(4)PcInCl is here taken for comparison). The nonlinear optical properties of InCl/InCl plithalocyanine 1 in toluene were studied with the Z-scan technique in both open- and closed-aperture configurations at 532 nm with nanosecond laser pulses, The binuclear complex displayed a positive nonlinear absorption coefficient. It is found that the linear optical properties were little changed but the optical limiting effectiveness of the binuclear fused phthalocyanine 1 is lower relative to tBu(4)PcInCl. Explanations for such differences are given. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005
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