Jian-Yong Liu

Highly Efficient Energy Transfer in Subphthalocyanine−BODIPY Conjugates

Two novel subphthalocyanines substituted axially with a BODIPY or distyryl BODIPY moiety have been synthesized. Both systems exhibit a highly efficient photoinduced energy transfer process, either from the excited BODIPY to the subphthalocyanine core (for the former) or from the excited subphthalocyanine to the distyryl BODIPY unit (for the latter).

Mimicking Photosynthetic Antenna‐Reaction‐Center Complexes with a (Boron Dipyrromethene)3–Porphyrin–C60 Pentad

A highly efficient functional mimic of the photosynthetic antenna-reaction-center complexes has been designed and synthesized. The model contains a zinc(II) porphyrin (ZnP) core, which is connected to three boron dipyrromethene (BDP) units by click chemistry, and to a C(60) moiety using the Prato procedure. The compound has been characterized using various spectroscopic methods. The intramolecular photoinduced processes of this pentad have also been studied in detail with steady-state and time-resolved absorption and emission spectroscopic methods, both in polar benzonitrile and nonpolar toluene. The BDP units serve as the antennae, which upon excitation undergo singlet-singlet energy transfer to the porphyrin core. This is then followed by an efficient electron transfer to the C(60) moiety, resulting in the formation of the singlet charge-separated state (BDP)(3)-ZnP(·+) -C(60)(·-) , which has a lifetime of 476 and 1000 ps in benzonitrile and toluene, respectively. Interestingly, a slow charge-recombination process (k(CR)(t)=2.6×10(6) s(-1)) and a long-lived triplet charge-separated state (τ(CS)(T)=385 ns) were detected in polar benzonitrile by nanosecond transient measurements.

Photoinduced Electron Transfer in a Distyryl BODIPY–Fullerene Dyad

A novel distyryl BODIPY-fullerene dyad is prepared. Upon excitation at the distyryl BODIPY moiety, the dyad undergoes photoinduced electron transfer to give a charge-separated state with lifetimes of 476 ps and 730 ps in polar (benzonitrile) and nonpolar (toluene) solvents, respectively. Transient absorption measurements show the formation of the triplet excited state of distyryl BODIPY in the dyad, which is populated from charge-recombination processes in both solvents.

Effects of the number and position of the substituents on the in vitro photodynamic activities of glucosylated zinc(II) phthalocyanines.

A series of mono-beta-, di-alpha- and di-beta-substituted phthalonitriles which contain one or two tetraethylene-glycol-linked 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose unit(s) were prepared by typical substitution reactions. These precursors underwent self-cyclisation or mixed-cyclisation with an excess of unsubstituted phthalonitrile in the presence of Zn(OAc)(2) x 2 H(2)O and DBU to give the corresponding zinc(II) phthalocyanines with 1, 2 or 4 glucosylated substituent(s). For the di-alpha- and tetra-beta-glucosylated analogues, removal of the isopropylidene groups was also performed by the treatment with trifluoroacetic acid and water to give the corresponding water-soluble deprotected glucosylated derivatives. All of these glucoconjugated phthalocyanines were fully characterised with various spectroscopic methods and studied for their photophysical properties and in vitro photodynamic activities against HT29 human colon adenocarcinoma and HepG2 human hepatocarcinoma cells. The tetra-beta-glucosylated phthalocyanines ZnPc(beta-PGlu)(4) (4) and ZnPc(beta-Glu)(4) (5) were found to be essentially non-cytotoxic. By contrast, the mono- and di-glucosylated analogues ZnPc(beta-PGlu) (7), ZnPc(alpha-PGlu)(2) (11), ZnPc(alpha-Glu)(2) (12) and ZnPc(beta-PGlu)(2) (20) exhibited substantial photocytotoxicity. The isopropylidene-protected di-alpha-substituted derivative 11 was particularly potent, having IC(50) values as low as 0.03 microM. The different photodynamic activities of these compounds can be attributed to their different extent of cellular uptake and aggregation tendency in the biological media, which greatly affect their singlet oxygen generation efficiency.

A Highly Selective Colorimetric and Fluorescent Probe for Cu2+ and Hg2+ Ions Based on a Distyryl BODIPY with Two Bis(1,2,3-triazole)amino Receptors†

A new distyryl boron dipyrromethene (BODIPY) with two bis(1,2,3-triazole)amino substituents has been prepared by typical Knoevenagel condensation followed by click reaction. The compound selectively binds to Cu(2+) and Hg(2+) ions in CH(3)CN/H(2)O (1:1 v/v) to give remarkably blueshifted electronic absorption and fluorescence bands as a result of inhibition of the intramolecular charge-transfer process upon binding to these metal ions. The color changes can be easily seen by the naked eye. The binding stoichiometry between this probe and Cu(2+) ions has been determined to be 1:2 by a Job plot of the fluorescence data with a binding constant of ((6.2±0.6)×10(9)) M(-2). The corresponding value for Hg(2+) ions is about sixfold smaller.

Photoinduced Electron Transfer in a Ferrocene–Distyryl BODIPY Dyad and a Ferrocene–Distyryl BODIPY–C60 Triad

A ferrocene-distyryl BODIPY dyad and a ferrocene-distyryl BODIPY-C(60) triad are synthesized and characterized. Upon photoexcitation at the distyryl BODIPY unit, these arrays undergo photoinduced electron transfer to form the corresponding charge-separated species. Based on their redox potentials, determined by cyclic voltammetry, the direction of the charge separation and the energies of these states are revealed. Femtosecond transient spectroscopic studies reveal that a fast charge separation (k(CS) =1.0×10(10) s(-1)) occurs for both the ferrocene-distyryl BODIPY dyad and the ferrocene-distyryl BODIPY-C(60) triad, but that a relatively slow charge recombination is observed only for the triad. The lifetime of the charge-separated state is 500 ps. Charge recombination of the dyad and triad leads to population of the triplet excited sate of ferrocene and the ground state, respectively.

Phthalocyanine-Containing Supramolecular Arrays

Phthalocyanines represent a versatile class of functional dyes which have found applications in various disciplines ranging from materials science, catalysis, nanotechnology to medicine. The intrinsic properties of the macrocycles as well as their molecular arrangements, both in solution and in the condensed phase, can be altered through rational chemical modification. Conjugation of other functional units to phthalocyanines can also complement the characteristics of the macrocycles. All these approaches can improve the performance of these macrocyclic compounds as advanced functional materials. The purpose of this article is to provide an up-to-date review of the current research status of phthalocyanine-containing supramolecular systems. The formation, structures, and properties of self-assembled phthalocyanines as well as the non-covalent hetero-arrays containing phthalocyanines and other functional units are reviewed herein.

Synthesis, Characterization, and In Vitro Photodynamic Activity of Novel Amphiphilic Zinc(II) Phthalocyanines Bearing Oxyethylene-Rich Substituents

Three novel zinc(II) phthalocyanines substituted with one or two 3,4,5-tris(3,6,9-trioxadecoxy)benzoxy group(s) have been prepared and spectroscopically characterized. These compounds are highly soluble and remain nonaggregated in N,N-dimethylformamide. Upon excitation, they exhibit a relatively weak fluorescence emission and high efficiency to generate singlet oxygen compared with the unsubstituted zinc(II) phthalocyanine. These amphiphilic photosensitizers formulated with Cremophor EL are highly photocytotoxic against HT29 human colon adenocarcinoma and HepG2 human hepatocarcinoma cells. The mono-α-substituted analogue 4 is particularly potent with IC50 values as low as 0.02 μM. The higher photodynamic activity of this compound can be attributed to its lower aggregation tendency in the culture media as shown by absorption spectroscopy and higher cellular uptake as suggested by the stronger intracellular fluorescence, resulting in a higher efficiency to generate reactive oxygen species inside the cells.

One-pot controlled synthesis of single-crystal α-Fe2O3 hollow nanostructure and its gas sensing properties

A series of single-crystal α-Fe2O3 nanostructures with tunable morphologies have been prepared via a simple one-pot solvothermal synthesis. The as-prepared nanoparticles were fully characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), selective area electron diffraction (SAED), N2 adsorption–desorption isotherms, and other techniques. The morphologies of the products can be easily adjusted by controlling the amount of NaAc added; with the amount of NaAc increasing the shell thickness of hollow spheres decreases, till the hollow structures disappeared and changed to nanoflower aggregates. Reaction temperature and the solvent ratio also play important roles in the synthesis of hollow nanospheres. The gas sensing properties of the as-prepared samples were also investigated. The results showed that the samples exhibited good gas sensing properties towards acetone vapor, and the gas sensing behavior was related to the morphologies of the samples.

A phthalocyanine-based fluorescent sensor for Zn2+ ion

This paper describes the preparation and spectral properties of a near-infrared fluorophore in which two bis(2-picolyl)amino moieties are axially linked to a silicon(IV) phthalocyanine core. The effects of various metal ions on its absorption and fluorescence spectra have been examined. The results indicate that this compound shows a high sensitivity and moderate selectivity toward Zn2+ ion.