The effects of central metals and peripheral substituents on the photophysical properties and optical limiting performance of phthalocyanines with axial chloride ligand

Third-order nonlinear optical properties of axially modified indium phthalocyanines with alkyl chains

Novel axially substituted indium phthalocyanine with strong NLO properties: effects of the length of the alkyl chain.

Octa-substituted metallophthalocyanines bearing (2,3-dihydrobenzo-1,4-benzodioxin-2-yl)methoxy and chloro groups: Synthesis, characterization and photophysicochemical studies

In this study, the synthesis and characterization of novel 4-chloro-5-((2,3-dihydrobenzo-1,4-benzodioxin-2-yl)methoxy)phthalonitrile (1) and its peripherally octa-substituted Zn(II) (Pc-Zn), In(III) (PcInCI) and Mg(II) (Pc-Mg) phthalocyanine (Pc) derivatives are reported for the first time. FT-IR, elemental analysis, UV-vis, NMR and MS techniques were used for characterization studies of the compounds. Aggregation properties of the compounds were evaluated in DMF, DMSO and THF solvents in different concentrations, and the compounds did not tend to aggregate in these solvents. In addition, photophysicochemical properties such as fluorescence, photodegradation and singlet oxygen quantum yield of the compounds were examined in DMSO, DMF and THF solvents to show the potential use of these novel compounds as photosensitizers for photodynamic therapy (PDT). The effects of zinc, indium and magnesium metals, octa substitutions in peripheral positions and different types of solvents on photophysicochemical properties were investigated. The singlet oxygen quantum yield values of compounds ranged from 0.27 to 0.77 in different solvents. As a result of the photophysicochemical properties, these compounds can be considered as potential candidates for PDT, applications.

Synthesis, photodynamic activities, and cytotoxicity of new water-soluble cationic gallium(III) and zinc(II) phthalocyanines

The cationic Ga(III) and Zn(II) phthalocyanines carrying N-methyl-pyridinium groups at eight peripheral β-positionshave been synthesized. These complexes are highly soluble in dimethyl sulfoxide (DMSO) and moderately soluble in water and phosphate buffered saline (PBS); both Ga(III)Cl and Zn(II) complexes have shown no aggregation in water up to 1.2 × 10^-4 and 1.5 × 10^-5 M, respectively. A higher water-solubility of Ga(III)Cl complex as compared to Zn(II) complex is ascribed to the presence of an axially coordinated chloride. The spectroscopic properties, photogeneration of singlet oxygen (¹O₂), and cytotoxicity of these complexes have been investigated. The absolute quantum yields (ΦΔ_absolute) for the photogeneration of singlet oxygen using Ga(III)Cl and Zn(II) complexes have been determined to be 4.4 and 5.3%, respectively, in DMSO solution. The cytotoxicity and intracellular sites of localization of Ga(III)Cl and Zn(II) complexes have been evaluated in human HEp2 cells. Both complexes, localized intracellularly in multiple organelles, have shown no cytotoxicity in the dark. Upon exposure to a low light dose (1.5 J/cm²), however, Zn(II) complex has exhibited a high photocytotoxicity. The result suggests that Zn(II) complex can be considered as a potential photosensitizer for Photodynamic therapy (PDT).

Optical limiting of germanium(IV) and tin(IV) phthalocyanines in solution and polymer matrices and comparison to an indium(III) phthalocyanine

A series of peripheral and axial substituted germanium(IV) and tin(IV) phthalocyanines substituted by fluoro, chloro, nitro or phenoxy groups were prepared and characterized by their absorption spectra in solution and in polymer matrices. Multi-layer films of PMMA and PVC containing monomolecular Ge(IV) or Sn(IV) phthalocyanines were obtained by spin-coating from solution on glass plates. Optical limiting properties of these phthalocyanines in solution and in polymer films were investigated using the Z-scan technique at 532 nm. A known indium(III) phthalocyanine was also investigated to compare its optical limiting behavior with the Ge(IV) and Sn(IV) containing compounds. Ge(IV) and Sn(IV) phthalocyanines exhibit a better optical limiting performance in polymer matrices than in solution, which is interesting for practical applications.

Novel nano-dyad of homoleptic sandwich-type phthalocyanines with nitrogen doped graphene quantum dots for nonlinear optics

The synthesis and nonlinear optical (NLO) behaviour of three novel double decker sandwich-type phthalocyanine complexes and their conjugates with nitrogen doped graphene dots (NGQDs) were reported herein. The conjugates afforded the most efficient NLO behaviour.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation

The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.

Axially substituted phthalocyanine/naphthalocyanine doped in glass matrix: an approach to the practical use for optical limiting material

A novel glass matrix doped with phthalocyanine or naphthalocyanine is prepared by a modified sol-gel technique. The photophysical and optical limiting properties of the phthalocyanine compounds both in glass matrix and in THF solution were investigated. The obtained glass matrix is homogeneous and transparent, as well as mechanically and thermodynamically stable enough to withstand very high laser fluence; the optical limiting performances of these compound samples are better than that of benchmark materials like C₆₀ in toluene, carbon black in water, and graphene oxide in water or ethanol under nanosecond pulsed laser at 532 nm. Two prototypes of optical limiters doped in the glass matrix have very good optical limiting performances, which may provide potential practical use for optical limiting materials in a near future.

Intramolecular aggregation and optical limiting properties of triazine-linked mono-, bis- and tris-phthalocyanines

A series of triazine-linked mono-, bis- and tris-phthalocyanines are synthesized, intramolecular aggregation is found in bis- and tris-phthalocyanines via π-π stacking interaction. Theoretical and experimental studies reveal the formation of the intramolecular aggregation. The spectrographic, photophysical and nonlinear optical properties of these compounds are adjusted for the formation of the intramolecular aggregation. The bis-phthalocyanine dimer presents smaller fluorescence quantum yield, lower triplet formation yield and the triplet-minus-ground state extinction coefficient, which causes poorer optical limiting performance. It is interesting that the tris-phthalocyanine is composed of a mono-phthalocyanine part and a bis-phthalocyanine part, the optical limiting property of the tris-phthalocyanine is similar to that of mono-phthalocyanine.

The effects of central metals on the photophysical and nonlinear optical properties of reduced graphene oxide-metal(II) phthalocyanine hybrids

Reduced graphene oxide-metal(II) phthalocyanine (RGO-MPc, M = Cu, Zn and Pb) hybrid materials have been prepared by the covalent functionalization method. The resultant RGO-MPc hybrids are characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, ultraviolet-visible absorption and fluorescence spectroscopy. The RGO-MPc hybrids exhibit strong fluorescence quenching by means of the photo-induced electron transfer or the energy transfer (PET/ET) process between the RGO and MPc moieties. The PET/ET process particularly depends on the fluorescence quantum yield of MPc molecules with different central metals. The nonlinear optical (NLO) properties of the RGO-MPc hybrids are investigated by using the Z-scan technique at 532 nm with 4 ns laser pulses. The results show that the NLO properties of MPc molecules increase in the order of Zn < Pb < Cu, but the RGO-MPc hybrids exhibit NLO performance in the inverse sequence of Zn > Pb > Cu, implying that the NLO response arising from the efficient PET/ET process between RGO and MPc may play a more important role in the NLO properties of RGO-MPc hybrids than that originating from the MPc moiety.

The effect of peripheral substituents attached to phthalocyanines on the third order nonlinear optical properties of graphene oxide–zinc(ii)phthalocyanine hybrids

Both kinds of GO–ZnPc hybrid materials exhibit transformation of the NLO response from SA to RSA, and the β value of GO–ZnPc(DG)₄ is larger than that of GO–ZnPc(TD)₄ because of the stronger electron-donating peripheral substituents.

Heavy metal effects on physicochemical properties of non-aggregated azaphthalocyanine derivatives

Two series of peripherally substituted azaphthalocyanines (AzaPcs) containing different transition metals ( Al(III), Zn(II), Ga(III), In(III) and Fe(II) ) were synthesized and studied for their photophysical properties. As confirmed by UV-vis and1H NMR analyses, the non-aggregation behavior was effectively induced by the applied bulky peripheral substituents which had no effect on the photophysical properties. Tuning the Q-band position was clearly achievable by using different central heavy metals which have considerable effects on the fluorescence quantum yield and singlet oxygen generation efficiency. This comparative study showed an interesting linear relationship between the former and atomic number of the central metal. The indium containing complexes exhibited the best result due to the heavy metal effect and therefore could be promoted as a potential photosensitizer in photodynamic therapy (PDT) application.