Influence of Polar Solvents on Third-Order Nonlinear Optical Features of Methyl Red Dye

This study emphasis the solvent effect on third-order nonlinear optical (NLO) features of methyl red (MR) dye dissolved in polar solvents including ethanol, methanol, acetone, 1-propanol, DMF and DMSO using low power diode laser. Z-scan technique operating at 405 nm wavelength, is used to estimate the third-order NLO features of MR dye in various solvents. The dye discloses self-defocusing nonlinear index of refraction (n2), which is determined to be the order of 10-7 cm2/W. The nonlinear coefficient of absorption (β) of MR dye displays both negative and positive value owing to saturable absorption (SA) and reverse saturable absorption (RSA), respectively. The real and imaginary components of the third-order NLO susceptibility of MR dye in polar solvents are measured to be the order of 10-6 esu and 10-7 esu, respectively. The dye exhibits a large NLO susceptibility in DMSO, which is estimated to be 1.21 × 10-6 esu. The effect of solvent spectral features on MR dye is determined by applying a multi-parameter scale called Kamlet-Abboud-Taft. The experiment results indicate that MR dye is a promising NLO material that may find applications in photonics and optoelectronics.

Phosphorescence of hexachlorosubstituted subphthalocyanine and its pyrazine analogue

Spectral luminescence, kinetic and energetic properties of hexachlorosubphthalocyaninatoboron(III) chloride and its azaanalogue containing fused pyrazine fragments instead of benzene rings were studied at 298 and 77 K. Weak phosphorescence of complexes was detected and characterized in near-infrared region of spectrum, its parameters depend substantially on the presence of methyl iodide due to its external effect of heavy atom in solutions. Quantum yields of photosensitized formation of singlet oxygen were determined by the relative luminescence method.

Heterometallic Al6Zn12 nano-plate with π-conjugated ligand: synthesis and nonlinear absorption properties

Presented herein is the synthesis, structure, and optical properties of the aluminum(III)-zinc(II) heterometallic compound AlOC-57. This compound was found to form a large unit cell (approximately sixteen thousand atoms) and a three-shell nano-plate structure. Based on the Z-scan patterns, the third-order nonlinear optical response of the heterometallic nano-plate was mainly attributed to its nonlinear absorption (reverse saturable absorption).

Two-Dimensional Metal-Polyphthalocyanine Conjugated Porous Frameworks as Promising Optical Limiting Materials

Two-dimensional transition-metal-containing polyphthalocyanine conjugated porous frameworks are synthesized, and transition-metal (TM) ions ranging from Fe, Co, Ni, Cu to In are chosen to combine in phthalocyanine centers to tune their delocalized electronic structure. The fully closed planar delocalized π-conjugated frameworks exhibit efficient nonlinear optical absorption and excellent optical limiting performance under ns pulsed laser. The metal ion (Co, Ni) with ferromagnetism in phthalocyanine center manifests its contribution in enhanced nonlinear optical response through resonance enhancement of the nonlinear excited-state absorption.

Electrodeposited Benzothiazole Phthalocyanines for Corrosion Inhibition of Aluminium in Acidic Medium

Tetrakis[(benzo[d]thiazol-2-yl-thio) phthalocyaninato] gallium(III)chloride (1) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. The aim of this study was to compare the corrosion resistance of electrodeposited metallated phthalocyanines. Scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy (EIS), and polarization confirmed the aluminium corrosion inhibition potentials of complexes 1 and 2. EIS and polarization techniques showed that complex 2 performed better than complex 1, with values from EIS measurements of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution. The importance of electrodeposition in industries and a dearth of research on the use of electrodeposited metallated phthalocyanines necessitated this study, and results show that coatings formed by electrodeposition of 1 and 2 onto aluminium reduced its susceptibility to corrosion attack.

Phthalocyanine-sensitized evolution of hydrogen and degradation of organic pollutants using polyoxometalate photocatalysts

In this study, 2 (3), 9 (10), 16 (17), 23 (24)-tetrakis-(8-quinoline-oxy) phthalocyanine zinc(II) (ZnQPc) was prepared and then quaternized to obtain water soluble zinc phthalocyanine (ZnQPc⁴⁺). Then, ZnQPc⁴⁺ was used as a photosensitizer for a series of POM catalysts, including Dawson type K₆[α-P₂W₁₈O₆₂]·14H₂O (P₂W₁₈) and K₁₀[α-P₂W₁₇O₆₁]·20H₂O (P₂W₁₇) and Keggine type H₃PW₁₂O₄₀·xH₂O (PW₁₂). The Keggin type PW₁₂ showed higher efficiency with 18.2 μmol of H₂ evolution (turnover number (TON) = 14,550) for 6 h upon ZnQPc⁴⁺ sensitization in relation to two Dawson P₂W₁₇ and P₂W₁₈ in a visible light-driven water-soluble system with isopropanol and H₂PtCl₆·6H₂O. In addition, the complexes of ZnQPc⁴⁺ with a series of POM catalysts (P₂W₁₇, P₂W₁₈, and PW₁₂) were also used as photocatalysts for the degradation of methylene blue (MB) in water, and it was found that the complexes of ZnQPc⁴⁺ with P₂W₁₇ and PW₁₂ showed improved photocatalytic activity, and the degradation rates of MB reached 100% at a small dosage under natural pH and visible light. The high efficacy of POM catalysts for H₂ evolution and the degradation of MB were attributed to the sensitization of POMs by ZnQPc⁴⁺, which was enabled by the transfer of photogenerated electrons of ZnQPc⁴⁺ to the lowest unoccupied molecular orbital (LUMO) of POM.

Dual phototransformation of the pollutants methyl orange and Cr (VI) using phthalocyanine-cobalt ferrite based magnetic nanocomposites

Bifunctional nanocomposites based on zinc phthalocyanines and glutathione capped CoFe2O4 magnetic nanoparticles (GSH-CoFe2O4 MNPs) are applied in a binary system wherein simultaneous photooxidation of methyl orange (MO) and photoreduction of Cr (VI) are conducted. The photoactivity of two zinc Pcs with different functional moieties are compared based on their interactions with GSH-CoFe2O4 MNPs. Conjugation of the Pcs to the GSH-CoFe2O4 MNPs not only enhanced their singlet oxygen production but also their photocatalytic activity in both photooxidation and photoreduction experiments. Using electron paramagnetic resonance (EPR) spectroscopy, the Pc-MNP conjugates reported herein were found to exhibit superparamagnetic behaviour, giving the advantage of easy separation using an external magnetic field post application, an attractive attribute for heterogeneous catalysis. The catalysts reported herein are therefore good candidates as catalysts for real life water purification analyses as they facilitate the treatment of both organic and inorganic water pollutants.

Unusual cis-diprotonated forms and fluorescent aggregates of non-peripherally alkoxy-substituted metallophthalocyanines

Protonation and aggregation of two metallophthalocyanines (zinc and magnesium) non-peripherally substituted with 1,4,7-trioxanonyl moieties were studied by steady-state and time-resolved optical spectroscopy. Both compounds are easily protonated in organic solvents, but the central metal ion strongly affects the character of this process. In particular, the magnesium derivative forms the cis-diprotonated isomer observed for the first time in phthalocyanines, in contrast to its zinc counterpart which forms the typical trans-diprotonated isomer. In addition, studies performed on phthalocyanines substituted with n-butoxy groups at their non-peripheral positions indicated that the formation of the cis-diprotonated forms is a more common feature of alkoxy-substituted magnesium metallophthalocyanines, in contrast to derivatives with other metal ions. The cis-diprotonated forms of the magnesium derivatives are formed at much lower proton concentrations than the trans-diprotonated forms of their zinc counterparts. The cis-isomers were also found to have more advantageous photophysical properties for photoactive applications than the trans-isomers. Aggregation studies of the trioxanonyl phthalocyanines revealed that the magnesium derivative aggregates much more easily in non-coordinating solvents than its zinc counterpart. Both the derivatives form fluorescent aggregates, which is typically attributed to the presence of oxygen-to-metal intermolecular coordination preventing the formation of non-fluorescent face-to-face stacks. The results indicate that the oxygen-to-metal coordination plays a significant role in the studied systems and the stronger oxygen-coordination ability of magnesium ions compared to zinc ions may underlie the observed differences between the phthalocyanines metallated with these two ions.

Third-order NLO properties of ultrathin films containing cationic phthalocyanine and Keggin polyoxometalates fabricated using layer-by-layer deposition from aqueous solution

Third-order optical nonlinearities of ultrathin films derived from cationic phthalocyanine and Keggin polyoxometalates can be well tuned and enhanced.

Optical, electrochemical and third-order nonlinear optical studies of triphenylamine substituted zinc phthalocyanine

Zinc phthalocyanine possessing triphenylamine at its peripheral position has been synthesized and its optical, emission, electrochemical and third-order nonlinear optical (NLO) properties were investigated. Soret band was broadened due to the presence of triphenylamine moiety. Electrochemical properties indicated that both oxidation and reduction processes were ring centered. Emission spectra were recorded in different solvents and the fluorescence yields obtained were in the range of 0.02–0.17 while the time-resolved fluorescence data revealed radiative lifetimes of typically few ns. Third-order NLO properties of this molecule have been examined using the Z-scan technique with picosecond (ps) and femtoseocnd (fs) pulses. Closed and open aperture Z-scan data were recorded with 2 ps/1 50 fs laser pulses at a wavelength of 800 nm and NLO coefficients were extracted from both the data. Our data clearly suggests the potential of this molecule for photonics applications.

Fabrication and notable optical nonlinearities of ultrathin composite films derived from water-soluble Keggin-type polyoxometalates and water-insoluble phthalocyanine

Composite films with the general formula (POM/CuTAPc)_n derived from water-soluble Keggin-type polyoxometalates (POMs = H₅PMo₁₀V₂O₄₀, H₄SiW₁₂O₄₀, H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀) and water-insoluble 4,9,16,23-copper tetraaminophthalocyanine (denoted CuTAPc) are successfully fabricated by a layer-by-layer self-assembly technique and systematically characterized. The structure of the polyoxometalate anions in the multilayers is kept intact; the deposition amounts of POM and CuTAPc remain constant in every adsorption cycle of the composite film assembly process. The nonlinear optical properties of the composite films were studied by a Z-scan technique at a wavelength of 532 nm and a pulse width of 7 ns. The results not only show that the composite films exhibit notable optical nonlinear self-defocusing behavior and a saturated absorption effect with the nonlinear optical absorption co-efficient β, refractive index n₂, and third-order NLO susceptibility χ⁽³⁾ of the films increasing with the increase in number of layers of the films, but also reveal importantly that the discrepancy of LUMO levels between CuTAPc and POMs is proportional to their third-order NLO response.