Polytopic cation receptor functional phthalocyanines: Synthesis, characterization, electrochemistry and metal ion binding

Synthesizing and evaluating the photodynamic efficacy of asymmetric heteroleptic A7B type novel lanthanide bis-phthalocyanine complexes

In this study heteroleptic A₇B type novel Lu(iii) and Eu(iii) lanthanide phthalocyanines (LnPc(Pox)[Pc′(AB₃SH)]) with high extinction coefficients have been synthesized as candidate photosensitizers with reaction yields higher than 33%. The singlet oxygen quantum yields of LuPc(Pox)[Pc′(AB₃SH)] and EuPc(Pox)[Pc′(AB₃SH)], respectively, were measured 17% and 1.4% by the direct method in THF. The singlet oxygen quantum yield of LuPc(Pox)[Pc′(AB₃SH)] in THF is the highest among lutetium(iii) bis-phthalocyanine complexes to date. The photodynamic efficacy of the heteroleptic lanthanide phthalocyanines was evaluated by measuring cell viabilities of A549 and BEAS-2B lung cells, selected to representing in vitro models for testing cancer and normal cells against potential drugs. The cell viabilities demonstrated concentration dependent behavior and were varied by the type of phthalocyanines complexes. Irradiation of the cells for 30 minutes with LED array at 660 nm producing flux of 0.036 J cm⁻² s⁻¹ increased cell death for LuPcPox-OAc, LuPc(Pox)[Pc′(AB₃SH)] and ZnPc. The IC₅₀ concentrations of LuPc(Pox)[Pc′(AB₃SH)] and ZnPc were determined to be below 10 nM for both cell lines, agreeing very well with the singlet oxygen quantum yield measurements. These findings suggest that LuPc(Pox)[Pc′(AB₃SH)] and particularly LuPcPox-OAc are promising drug candidates enabling lowered dose and shorter irradiation time for photodynamic therapy.

Novel bis-lanthanide Lu(iii) and Eu(iii) phthalocyanine complexes have been designed/synthesized and tested their photodynamic efficacy for A549 and BEAS-2B cells in vitro conditions as candidate photosensitizers in PDT.

Targeted photoimmunotherapy based on photosensitizer-antibody conjugates for multiple myeloma treatment

Despite the high in vitro efficacy of photodynamic therapeutics, lack of tumor targeting significantly reduces their in vivo efficacy and thus limits their clinical use. Photoimmunotherapy (PIT) is a new synthetic strategy to target and treat cancer by photodynamic therapy (PDT). In this study, we describe design and synthesis of a third-generation photosensitizer comprising a PEGylated-phthalocyanine star-polymer photosensitizer that covalently bound to a myeloma tumor-selective antibody (MAb) via the carbodiimide chemistry. The free photosensitizer demonstrated a minimum dark toxicity when tested in mammalian myeloma cell line (SP2/OR); and a moderate phototoxicity after irradiation with non thermal laser red light as a result of light-induced production of cytotoxic singlet oxygen species. Covalent attachment of the photosensitizer (Pc) to the MAb resulted in a significantly enhanced phototoxicity. This is mainly ascribed to the fact that internalization enhances phototoxicity of Pc-MAb bioconjugates. The radioactivated photoimmuno-conjugates ¹³¹I(PcMAb) demonstrated the highest phototoxicity to myeloma cells. The suggested bioconjugates are promising candidates as multiple therapeutic models for in vivo treatment of myeloma.

A novel ratiometric AIEE/ESIPT probe for palladium species detection with ultra-sensitivity

Existing fluorescent probes for palladium (Pd) species detection have revealed their vulnerabilities, such as low sensitivity, poor anti-interference ability and long reaction time. In order to develop a faster and more accurate detection method for palladium species at extremely low concentrations, in this study, we designed a novel ratiometric AIEE/ESIPT probe (HPNI-1) based on the Tsuji–Trost reaction for Pd. According to the data obtained, the probe was able to detect Pd species with an ultra-high anti-interference ability (Pd : other metals = 1 : 1000), rapid detection time (within 2 minute) and ratiometric fluorescent signal changes with a 1.34 nM detection limit. This study not only proves that existing methods can be improved but also provides future prospects for HPNI-1 as one of the greatest probes for Pd species detection.

Existing fluorescent probes for palladium (Pd) species detection have revealed their vulnerabilities, such as low sensitivity, poor anti-interference ability and long reaction time.

Fluorescent H-aggregates of an asymmetrically substituted mono-amino Zn(ii) phthalocyanine

The photophysical properties of a newly synthesized unsymmetrically substituted zinc phthalocyanine derivative (1) bearing in its peripheral positions six n-hexylsulfanyl substituents and one amino-terminated n-hexylsulfanyl substituent were investigated. This mono-amino phthalocyanine exhibited a high tendency to form H-type aggregates in all of the investigated solvents: dichloromethane (DCM), tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO). Several species of H-aggregates were present together in relatively broad concentration ranges in THF and DCM, whereas in DMSO they were observed separately depending on the concentration used. Despite the widely accepted non-emissive character of H-type dimers, the H-type aggregates of phthalocyanine 1 were highly emissive in all solvents: the fluorescence quantum yield in DMSO for the n-aggregate is equal to 0.05, whereas for the (n + 1)-aggregate it is 0.11. Upon (n + 1)-aggregation, the fluorescence lifetime of the n-aggregate increased from ca. 2.5 ns to 3.3 ns. Based on these results, the radiative lifetimes of both species were computed: 48 ns for the n-aggregate and 29 ns for the (n + 1)-aggregate. The determined oscillator strengths for the n-aggregate and the (n + 1)-aggregate in DMSO were 0.04 and 0.12, respectively. The observed emission of the H-type (n + 1)-aggregate was assigned to the radiative transition from the upper exciton state to the ground state, which could be rationalized by a constant thermal repopulation of the upper exciton state. The experimental findings were supported by theoretical calculations.

Optical, electrochemical, third-order nonlinear optical, and excited state dynamics studies of thio-zinc phthalocyanine

Zinc phthalocyanine with S-aryl groups at α-positions have been synthesized and its optical, emission, electrochemical and third-order nonlinear optical properties were investigated. Both the Soret and Q-bands were red-shifted and obeyed Beer–Lambert's law. 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 while time-resolved fluorescence data revealed lifetimes of typically few ns. Excited state dynamics in this novel thio-zinc phthalocyanine molecule has been investigated using femtosecond (fs) degenerate pump-probe spectroscopy. Nonlinear optical properties of this molecule have been examined using the Z-scan technique with picosecond (ps) and fs pulses. Both open and closed aperture Z-scan curves were recorded with ~2 ps/~150 fs laser pulses at a wavelength of 800 nm and nonlinear optical coefficients were extracted from both the studies. Degenerate pump-probe data performed at 600 nm suggested a single long lifetime of ~300 ps, possibly originating from the non-radiative decay of S1 state.

Colourimetric and fluorescent probes for the optical detection of palladium ions

In recent years, the development of optical probes to analyse trace palladium ions (Pd(2+)) has attracted great attention because of the residual palladium released by catalytic converters or from various Pd-catalysed reactions. These residual palladium ions may cause potential health hazards. This review provides a brief introduction to the new methods used to determine trace amounts of Pd(2+), which then mainly focuses on the different reporting systems and unique mechanisms of the colourimetric and fluorescent probes used to detect Pd(2+), including Pd(2+) complex formation or Pd-catalysed reactions.

Synthesis and investigation on photophysical and photochemical properties of 7-oxy-3-methyl-4-phenylcoumarin bearing zinc phthalocyanines

The synthesis of peripherally and non-peripherally tetrakis-(7-oxy-3-methyl-4-phenylcoumarin) and peripherally octakis-[tetrachlorotetra-(7-oxy-3-methyl-4-phenyl coumarin)] substituted zinc(II) phthalocyanines are performed and characterized for the first time in this study. The new compounds show excellent solubility in organic solvents, which makes them candidates for use in different applications. Photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties of these novel coumarino phthalocyanines are investigated in dimethylformamide (DMF). The effects of the positions (peripheral or nonperipheral) of the substituents on the photophysical and photochemical parameters of the coumarino zinc(II) phthalocyanines are reported. The fluorescence quenching behavior of the studied zinc(II) phthalocyanines by addition of 1,4-benzoquinone (BQ) are also described.

Electrochemical hydrogen peroxide sensor based on cobalt phthalocyanine captured in polyaniline film on a glassy carbon electrode

This work demonstrated preparation, characterization, and application of a cobalt phthalocyanine based enzymeless/mediatorless hydrogen peroxide sensor. The cobalt phthalocyanine (CoPc) was retained in polyaniline (PANI) film on a glassy carbon electrode during electrochemical polymerization of aniline and consequently a novel composite electrode (GCE/PANI/ CoPc ) for the electrochemical sensor application was constructed. The CoPc functionalized composite electrode, GCE/PANI/ CoPc , was evaluated by voltammetry, electrochemical impedance spectroscopy, and UV-vis spectroscopy. The results displayed retaining of the CoPc molecules in the PANI film on the GCE electrode. Presence of CoPc in PANI increased conductivity of the composite on the electrode. Sensing performance of the GCE/PANI/ CoPc composite electrode to H2O2 were evaluated in detail with respect to the selectivity, reproducibility, repeatability, stability, linear concentration range, and sensitivity with voltammetric and double potential step chronoamperometric techniques. The GCE/PANI/ CoPc composite electrode gives a linear range for H2O2 between 2 and 18 μM H2O2 with sensitivities of 1.55 A.M-1 during the cathodic SWV scan and with sensitivities of 4.01 A.M-1 during the anodic SWV scan. A direct application of the sensor was performed in a real working condition, for the detection of hydrogen peroxide produced from the reaction between the glucose and glucose oxidase enzyme.

Both alcohol and halogenated solvents soluble soft-metal sensor functional phthalocyanines: synthesis, electrochemistry, spectroelectrochemistry

In this study, we report a novel both alcohol and haloganated solvent soluble selective ionophore functional ligand and its β-substituted 2(3),9(10),16(17),23(24)-tetrakis(1-hydroxyhexan-3-ylthio)-phthalocyanines, M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}, (Pc: Phthalocyanine) ( M = Zn , Cu , Co ), where -OH indicates peripheral functionality. Pcs exhibiting both hydrophobic and hydrophilic character were characterized spectroscopically (FT-IR, 1 H and 13 C NMR, MS (MALDI-TOF) and UV-vis), electrochemically and spectroelectrochemically. The complexes were soluble in both polar solvents, such as MeOH and EtOH, and non-polar solvents such as CHCl 3, CH 2 Cl 2, benzene, toluene, and even hexane. Absorption spectral changes of the functional MPcs during addition of AgI and PdII soft-metal ions are evaluated by monomer-oligomer and even polymer formations technique and monitored for in situ monitoring technique in the UV-vis spectroscopy. The binding process results in considerable blue-shift in the absorption spectra of MPcs . According to continuous variation method, the ligand:metal ratio was found ca. 1:1 and 1.5:1 for total concentration of 1.0 × 10-5 M and 7.5 × 10-5 M , respectively. Their electrochemical and spectroelectrochemical studies show that the complexes exhibited stable monoanionic M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}1-, dianionic M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}2- and monocationic M { Pc [ S-CH ( CH 2 CH 2 CH 3)( CH 2 CH 2 OH )]4}1+ species during reduction and oxidation processes.

Voltammetric and spectroelectrochemical characterization and electrocatalytic application of metallophthalocyanines carrying pendant bulky units

In this work, voltammetric, spectroelectrochemical, and electrocatalytic properties of the metallophthalocyanines bearing four chloro and four biphenyl-malonic ester bulky groups were investigated. Voltammetric and spectroelectrochemical measurements of the metallophthalocyanines show that while cobalt phthalocyanine presents both metal-based and ring-based redox processes, all other complexes give only ring-based reduction and oxidation processes. The redox processes have generally diffusion-controlled, reversible and one-electron transferred mechanisms. Cobalt phthalocyanine electrocoated easily on the glassy carbon working electrode during the repeating cycles, a very useful feature for application in fabrication of thin films. Electrocatalytic activity of cobalt phthalocyanine to hydrogen evolution reaction was studied in solution titrated with perchloric acid and on glassy carbon electrode modified with cobalt phthalocyanine in aqueous solution. Electrocatalytic measurements show that cobalt phthalocyanine has significant catalytic activities towards hydrogen evolution reaction. Moreover, the catalytic activity of the complex enhanced significantly when the complex was incorporated into the cation exchange Nafion polymeric matrix.

Potential aluminium(III)- and gallium(III)-selective optical sensors based on porphyrazines

Porphyrazines possessing non-coordinating alkyl (propyl) and aralkyl (4-tert-butylphenyl) groups in the periphery were studied as optical sensors for a set of mono-, di- and trivalent cations. Investigated porphyrazines in the UV-Vis monitored titrations revealed significant responses towards aluminium and gallium cations, unlike other metal ions studied. Additionally, porphyrazine possessing 4-tert-butylphenyl peripheral substituents showed sensor property towards ruthenium cation and was chosen for further investigation. The presence of isosbestic points in absorption spectra for its titration with aluminium, gallium and ruthenium cations, accompanied by a linear Benesi-Hildebrand plot, proved complex formation. The continuous variation method was used to determine binding stoichiometry in 1:1 porphyrazine-metal ratio. X-Ray studies and density functional theory calculations were employed to investigate octa(4-tert-butylphenyl)porphyrazine structure. The results helped to explain the observed selectivity towards certain ions. Interaction between ion and porphyrazine meso nitrogen in a Lewis acid-Lewis base manner is proposed.

Synthesis and Spectroscopic Properties of a Series of Metal-Free and Metallo-Phthalocyanines Substituted with 8-Quinolinoxy Moieties

Peripherally tetraquinolinoxy-substituted, metal-free phthalocyanines and metallo-phthalocyanines 1c–f, 2c–f have been synthesised by reaction of an inorganic salt with phthalonitriles substituted with 5-(phenylamino)methyl-8-quinolinoxy and 5-[(4-chlorophenylamino)methyl]-8-quinolinoxy groups, respectively. The effects of metal ions [Zn(II), Cu(II), Co(II); N,i(II)], substituent, solvent and concentration on the UV-Vis spectra of these new complexes and their fluorescent properties are also described. The diamagnetic Zn(II) and Ni(II) complexes display intense fluorescence.

Spectroscopic behavior of cationic metallophthalocyanines in the presence of anionic quantum dots

The interactions and spectroscopic properties between cationic zinc phthalocyanine derivatives (peripherally and non-peripherally tetrasubstituted and peripherally octa substituted with 2-diethylmethylaminoethylsulfanyl (betaTZnPc, alphaTZnPc and betaOZnPc)) and CdTe core quantum dots (QDs) capped with mercaptopropionic acid or thioglycolic acid (represented as CdTe@MPA and CdTe@TGA, respectively) have been studied in methanol:water mixture. Strong coupling of MPcs was deduced from the interaction since the UV-vis spectroscopic studies of the ground state complex formed on mixing both components showed loss of the phthalocyanine monomeric band with the formation of a dimeric band (spectrum of aggregated species). The dimerization constants were of the order of 10(4)M(-1).