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Porphyrin-centered star-shaped polymers were synthesized through living cationic ring-opening polymerization of 2-methyl-2-oxazoline employing tetra(p-chloromethylphenyl)porphyrin (CMPP) and its zinc complex as initiators. The polymers were characterized by GPC, ¹H NMR and UV-vis and their properties were examined by fluorescence quenching.

A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction. The molecular structure and optical properties were highly investigated through ¹H-NMR, UV and PL spectroscopy. The quenching behavior was also investigated, and the results demonstrate that incomplete quenching exists, which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents, probably correlated with the conformation of conjugated backbone and intermolecular aggregation.

The optical-limiting properties of several water-soluble phthalocyanine derivatives in aqueous solution were measured at 532 nm with 10 ns pulses. The excited state absorption cross-section σ_ex of the derivatives were determined with the Z-scan technique. The results showed that the phthalocyanine derivatives are materials for reverse saturable absorption. It was noted that the optical limiting performance of the phthalocyanine derivatives in aqueous solutions can be controlled through the addition of alkalis. These phthalocyanine derivatives possess good solubility in water and optical limiting controllability, which give rise to their use for practical applications.

This article reviews recent developments that have taken place in research related to new porphyrin architectures and their host-guest chemistry, as described in a microsymposium bearing the same name held during the 3^rd International Conference on Porphyrins and Phthalocyanines (ICPP-3). The usefulness of representative arrays, aggregates, donor-acceptor systems, and receptor motifs based on porphyrin architectures is highlighted as it applies to the fabrication of molecular devices, understanding the biomimetic electron transfer processes, and recognition of bioorganic substrates.

Aggregation behaviors of phthalocyanine derivatives which have a dendritic structure were examined in an aqueous solution. We prepared the first- and second-generation dendrimers (WG1-PC and WG2-PC), having water-soluble substituents as a peripheral group, to be resolved in water. From spectroscopic measurement, WG2-PC acted in a monomeric manner, even in an aqueous solution, in contrast to WG1-PC, which exhibited spectra attributed to aggregation. This implies that a higher generation of water-soluble dendrimers can prevent a phthalocyanine core from forming an aggregation. The introduction of the second-generation dendrons to an aggregatable core may be effective to avoid self-aggregation and an undesirable deactivation process.

We synthesized an uncharged water-soluble porphyrin, meso-tetrakis-(3,4,5-tri-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-phenyl)-porphyrin, to solubilize single-walled carbon nanotubes (SWNTs) in aqueous solutions through supramolecular interactions. The porphyrin-SWNTs composites in aqueous solution are stable for several weeks. The porphyrin-SWNTs composites in aqueous solution have been characterized by UV-vis absorption and fluorescence spectroscopy and with atomic force microscope (AFM). The fluorescence emitted from the porphyrin ring in the aqueous solution of the porphyrin-SWNTs composite is highly quenched, evidently implying the presence of strong electronic interactions between the SWNTs and the porphyrin molecules in aqueous solution. The AFM investigation furthermore supports that the porphyrin molecules are complexed on the SWNTs side wall through π-π interaction.

A novel catalytic route for the synthesis of a water-soluble and electrically conducting polypyrrole (PPy) in the presence of sulfonated polystyrene (SPS) is presented. Anionic water-soluble transition-metal tetrasulfonated porphyrins (TSPP) were used to catalyze the polymerization. The reactions were carried out with different monomer, catalyst, template and initiator concentrations and the optimum conditions are reported. Also various pH values ranging from 1 to 4 were investigated. The absorbance of the polaron bands at different pH values demonstrates that pH 2 is the best condition for polymerization. Precipitation or "salting out" phenomenon was highly dependent on the mentioned factors. The formation of PPy was confirmed by UV-vis and FT-IR spectroscopy. Cyclic voltammetry (CV) showed that the synthesized polymer has convenient electroactivity. Furthermore, the presence of SPS that serves as a charge-compensating dopant in this complex provides a unique combination of properties such as processability and water solubility.

Phthalocyanines having hydrophilic or lipophilic dendrons were synthesized to investigate the efficiencies of singlet molecular oxygen (¹Δ_g) formation. The introduction of higher generation of dendrons to the central metal (Si) of phthalocyanine in vertical direction to their ring plane has resulted in the successful improvement in avoiding aggregate formation that resulted in efficient generation of ¹Δ_g even in water.

Dissociation of imino proton(s) in the cavity of the macrocycle of a highly water-soluble, metal-free phthalocyanine (H₂(H₄tsppc); where H₄tsppc denotes tetrakis{(2′,6′-dimethyl-4′-sulfonic acid)phenoxy}phthalocyaninate) in ethanolic and aqueous solutions has spectrophotometrically been investigated. The spectral changes associated with reaction with NaOH have been found to involve one-proton transfer process in aqueous media while two-protons process in ethanolic media. The acid-dissociation constant of the first imino proton in water (in the presence of Triton X-100) has been determined to be 12.5 ± 0.2 (as pKa) at 25 °C. The doubly deprotonated species in EtOH has been easily converted to its corresponding cobalt(II) derivative by thermal reaction with anhydrous CoCl₂.

Porphyrins bearing a single bioconjugatable group and a single water-solubilization motif in a trans-AB-architecture (with no other substituents) provide a compact design of value for studies in diverse disciplines. Established synthetic methods have been employed to prepare four new free base porphyrins and one Mn(III) chelate. The hydrophilic motif includes 4-N-methylpyridinium, 2,4,6-tris(carboxymethoxy)phenyl, 2,6-bis(phosphonomethoxy)phenyl, and carboxy; the bioconjugatable unit includes carboxy, maleimido, and N-hydroxysuccinimido (NHS) ester. Bioconjugation experiments with a protected porphyrin-diphosphate or unprotected porphyrin-diphosphonate were examined in organic solution or water, respectively. Both approaches were employed to conjugate to the ε-amino group of Lys¹¹ in AcKPV-NH₂, a tripeptide fragment [Ac-α-MSH(11-13)-NH₂] of melanocyte stimulating hormone, yielding porphyrin-peptide conjugates.

The synthesis, acid-base properties, and kinetics of Cu${}^{2+}$ incorporation into water-soluble highly substituted porphyrins were studied. The basicity increased and the stepwise acid-base equilibrium was clarified by increasing the number of phenyl groups at the $\beta$ position, and the basicity of a dodeca-substituted porphyrin increased with the ionic strength. The metalation reaction of the dodeca-substituted porphyrin with Cu${}^{2+}$ in aqueous solution revealed a biphasic absorbance change at 453 nm. Plots of $k_{\mathrm{\text{pre}}}$ or$k_{\mathrm{\text{post}}}$vs. the Cu${}^{2+}$ concentration and of log ($k_{\mathrm{\text{pre}}}$ or$k_{\mathrm{\text{post}}}$/$k_I=$ 0) vs. the ionic strength show that $k_{\mathrm{\text{pre}}}$ is dependent on the Cu${}^{2+}$ concentration and ionic strength, while $k_{\mathrm{\text{post}}}$ is independent of these parameters. These results confirm the stepwise metalation mechanism and the existence of an intermediate in aqueous solution, which is indicated by the biphasic absorbance change at 453 nm.

Molecular aggregation phenomena of a highly water-soluble, metal-free phthalocyanine, H${}_{\mathrm{\text{2}}}$Pc, and its copper complex, Cu(Pc); where Pc denotes tetrakis{(2$\prime$,6$\prime$-dimethyl-4$\prime$-sulfonic acid)phenoxy}phthalocyaninate) in water, ethanol, and their mixed solvent systems have been investigated by spectroscopic approach In both aqueous and ethanolic solutions, H${}_{\mathrm{\text{2}}}$Pc molecules aggregate in a slipped-cofacial manner, although very weakly in ethanol. On the other hand, Cu(Pc) molecules aggregate in a cofacial manner in water while aligning in a slipped-cofacial manner in ethanol. Magnetic circular dichroism spectroscopy was undertaken to investigate aggregation behaviors of Cu(Pc) in water and ethanol. Presence of 4-phenylpyridine in ethanol effectively inhibited aggregation of Cu(Pc) molecules, although little affected the spectra of the monomers. In a mixed solvent system, where water/ethanol $=$ 10/90 (v/v), Cu(Pc) is free from aggregation up to almost 10${}^{\mathrm{\text{-4}}}$ M. Driving forces of this molecular aggregation are discussed on the basis of $\pi$–$\pi$ interaction and coordination chemistry involving copper ions.

In this study, we have analyzed the effect a newly synthesized water-soluble alpha tetra-substituted zinc phthalocyanine (Pc) compound on superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) activities and biomass accumulation in the Arthrospira platensis-M2 strain to test whether this compound could be used as an algaecide or not. We found that lower concentrations (3 μg mL${}^{\mathrm{\text{-1}}}$ and 6 μg mL${}^{\mathrm{\text{-1}}})$ of Pc compound were not toxic to algae cells, as indicated by enduring biomass accumulation during the study (7 days). Higher Pc concentrations, however, were toxic and inhibited biomass accumulation. This inhibition appeared on the fourth day and persisted during the study. At higher Pc concentrations, SOD activity decreased significantly, but APX and GR activity were not affected. These results may show that Pc applications did not cause the accumulation of reactive oxygen species in Arthrospira platensis-M2 cells. Our result suggests that higher Pc concentrations did not cause oxidative stress but biomass accumulation inhibited, possibly due to some different toxicity mechanism(s), which should be carried out in the future studies. As a result, we may offer use of this compound as a means to keep under control algal populations in natural environments.

In this paper, we report the first examples of amphiphilic metal(II) complexes of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (M-TADAPs) containing triethylene glycol (TriEG) or tetraethylene glycol (TetEG) auxiliaries. A common dipyrrin precursor substituted with TriEG or TetEG groups underwent metal-templated cyclization with zinc(II), nickel(II), or copper(II) acetate to afford the corresponding TriEG- or TetEG-appended M-TADAPs (M = Zn, Ni, Cu) as air-stable 19$\pi$-electron radical cations. These 19$\pi$-electron M-TADAPs were reversibly interconvertible with 20$\pi$-electron antiaromatic M-TADAPs and 18$\pi$-electron aromatic M-TADAP dications by redox reactions. The newly prepared M-TADAPs were basically amphiphilic, but their water solubilities varied considerably depending on the charge of the diazaporphyrin (DAP) ring and the number of ethylene glycol units. The neutral 20$\pi$-electron M-TADAPs were poorly soluble in water, whereas the 18$\pi$-electron M-TADAP dications were soluble in water. Cyclic voltammetry of all M-TADAP derivatives revealed 20$\pi$/19$\pi$-electron and 19$\pi$/18$\pi$-electron redox couples in both CH₂Cl₂ and H₂O with appropriate electrolytes. The addition of M$\prime$X (M$\prime$ = Li, Na; X = Cl, OH) or HCl to aqueous solutions of the M-TADAPs highlighted their reactivities with anions and changes in pH. When treated with M$\prime$X in H₂O, the 19$\pi$-electron M-TADAP radical cations underwent anion exchange but the 18$\pi$-electron Zn-TADAP dications were reduced to the corresponding 19$\pi$-electron species. Upon treatment with HCl in H₂O, the 19$\pi$-electron M-TADAP radical cations underwent one-electron oxidation of the DAP ring, and the resulting 18$\pi$/19$\pi$-electron abundance ratio increased with decreasing solution pH.

Since cancer is one of the leading causes of death worldwide, the development of new anticancer drugs has become important. Phthalocyanines (Pcs) as anticancer agents have attracted particular attention in recent years. Especially water-soluble sulfonated phthalocyanines have been used consistently for both the diagnosis and treatment of many different types of cancer, such as small lung tumors. Motivated by these facts, since the anti-cancer activity of sulfonated water-soluble cobalt phthalocyanine in prostate and breast cancer without photoactivation is not known before, we aimed to investigate the in vitro anti-cancer effectiveness (cyto- and genotoxic effect) of alpha-substituted water-soluble cobalt phthalocyanine (WS-CoPc) complex on prostate and breast cancer cells for the first time. For this purpose ROS production, cell death, and DNA damage levels, changes in nuclear and cell morphology, and the expression of apoptosis and ROS-related genes were determined. WS-CoPc exhibited anti-cancer effects with cytotoxic and genotoxic features in both prostate and breast cancer cells also the anti-cancer efficacy is more prominent in prostate cancer cells. Therefore our results demonstrated that this Pc has high cytotoxic and genotoxic effects, especially in prostate cancer cells in vitro and further studies are needed to reveal the current anticancer potential of this Pc without photoactivation.

We report the synthesis of luminescent-doped core/shell quantum dots (QDs) of water-soluble manganese-doped zinc sulfide (ZnS:Mn²⁺/ZnS). QDs of ZnS:Mn²⁺/ZnS were prepared by nucleation doping strategy, with thioglycolic acid (TGA) as stabilizer in aqueous solution. Structure and optical properties of the ZnS:Mn²⁺/ZnS core/shell quantum dots were characterized by X-ray diffraction and photoluminescence emission spectroscopy. The influence of the synthesis conditions on the luminescent properties of ZnS:Mn²⁺/ZnS QDs is discussed. Different Mn²⁺ concentrations, ratios of the TGA/(Zn+Mn) and thickness of the ZnS shell were used. Results showed that the ZnS:Mn²⁺/ZnS QDs are water-soluble and have improved fluorescence properties. Therefore, Mn²⁺-doped ZnS quantum dots could be potential candidates as fluorescent labeling agents in biology.

Water-soluble and stable dispersions of silver nanoparticles (Ag NPs) were obtained using a straightforward one-step synthesis method. Polyacrylamide (PAM), a kind of water-soluble polymer with polar amide group, is used as stabilizing agent to prevent the aggregation of Ag NPs in aqueous medium. The successful formation of PAM-stabilized Ag NPs was demonstrated by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). In addition, the SERS-active substrate made of Ag NPs was fabricated to enhance the Raman signal of R6G and graphene. The significant SERS effective makes the as-synthesized substrate to be widely used in practical applications for routine SERS analysis and water environment biological monitoring.

Water-soluble, ultrasmall, and superparamagnetic Fe₃O₄ nanoparticles were in-situ prepared using one-step coprecipitation method by using poly (amidoamine) (PAMAM) dendrimer templates. Photographs show that Fe₃O₄ nanoparticles prepared at the Fe³⁺/Fe²⁺/PAMAM molar ratio no higher than 40/30/1 disperse stably in water, forming clear colloidal solutions. TEM images show Fe₃O₄ nanoparticles have uniform size and good dispersity. The average diameter of particles is less than 8 nm. The HRTEM image indicates these Fe₃O₄ nanoparticles are of high crystallinity, and their crystal structure belongs to cubic system. XRD patterns show these nanoparticles as prepared are Fe₃O₄ of reverse spinel phase. The hysteresis loops confirm the superparamagnetism of Fe₃O₄ nanoparticles, and the saturation magnetization reaches 48.6 emu/g. FTIR spectra show the strong interactions between Fe₃O₄ nanoparticle surfaces and PAMAM dendrimers. Fe₃O₄ nanoparticles colloidal solutions prepared at the Fe³⁺/Fe²⁺/PAMAM molar ratio no higher than 20/15/1 keep on clarify and transparent after 6 months.