Wen-Long Pan's research while affiliated with Institute for Scientific Analysis and other places

Photodynamic therapy (PDT) is a modern cancer therapy. But it is still difficult to obtain ideal photosensitizers. We synthesized six new peri-xanthenoxanthene derivatives rapidly and efficiently using solid-phase carbon-bath microwave irradiation technology, and investigated their in vitro photodynamic antitumor activity with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Our results showed that all compounds exhibited extremely low dark cytotoxicity and good phototoxicity against four human cancer cell lines. In particular, compound 3c showed the best in vitro PDT activity against Hela cells and Bel-7402 cells with IC50 values of 91 and 74 nmol/L, respectively. Its value of 1-octanol/water partition coefficient (log Kow) was 0.5309, suggesting that it is a promising photosensitizer for PDT due to its low dark cytotoxicity, high phototoxicity, and potential water solubility. Graphical Abstract Fullsize Image

Three novel quinoline– and fluorene–coumarin hybrids were prepared and characterised by Fourier Transform–infrared spectroscopy, proton and carbon nuclear magnetic resonance spectroscopy, mass spectrometry, elemental analysis and ultraviolet–visible spectrophotometry. Their photoluminescence properties were investigated. All of these hybrid molecules exhibited a broadband emission from ca. 450 to 800 nm when excited by a 325 nm helium–cadmium laser at room temperature. Importantly, the fluorene–coumarin hybrid shows a very bright red emission at ca. 650 nm and displays up to a 10-fold increase in fluorescence emission intensity, as compared with the other samples. The experimental results confirm that remarkable enhancements in the fluorescence emission intensity can be obtained by introducing a fluorene group into the azo-bridged coumarin-based π-conjugated framework. The geometry structures and frontier orbitals are calculated by the ab initio Hartree–Fock method.

A series of 1,3,4-oxadiazole derivatives containing an imidazole unit were synthesized and characterized using 1H NMR, 13C NMR, mass spectrometry (or high-resolution mass spectrometry) and elemental analysis. The crystal structure of 2,5-bis(4-(1-n-butyl-4,5-diphenylimidazol-2-yl)phenyl)-1,3,4-oxadiazole was determined as monoclinic, space group C2/c type, using single crystal X-ray crystallography. For nine samples, UV–visible absorption coefficient (ɛ), maximum wavelength (λmax), fluorescence excitation wavelength (λex), fluorescence emission wavelength (λem), fluorescence quantum yield (ΦF), fluorescence lifetime (T) were measured in dichloromethane and in the solid state. For these selected compounds, thermogravimetric analysis was also employed and structure:optical behaviour characteristics were discussed.

Eight 2-(9-phenanthrenyl)-, 2-(9-anthryl)- and 2-(1-pyrenyl)-1-alkyl-benzimidazole compounds, three 2-(9-anthryl)-1-alkylphenanthroimidazole compounds and five 4,5-diphenyl-1-alkyl-2-(9-anthryl)imidazole compounds were synthesized by alkylation reactions of the corresponding benzimidazole, phenanthroimidazole or imidazole compounds. 2-(10-Bromo-9-anthryl)-1-alkyl-benzimidazole compounds were prepared by bromination reaction of 2-(9-anthryl)-1-alkylbenzimidazole compounds. All the synthesized compounds were characterized by elemental analysis, (1)H NMR, (13)C NMR, MS or HRMS; their absorption coefficients (epsilon), maximum absorption lambda(amax), fluorescence emission maximum lambda(em), Stokes shifts and fluorescence quantum yields (Phi(F)) in ethyl acetate were determined; their fluorescent lifetimes (T(1) and T(2)) were measured in ethyl acetate and in solid state, respectively. The crystal structure of 2-(9-anthryl)-1-n-butyl-4,5-diphenylimidazole (12a) was determined to be triclinic, space group P-1 types, using single crystal X-ray crystallography technique. The results showed that these compounds exhibited moderate fluorescence-emission abilities and higher solubility in most organic solvents than their corresponding starting materials. The relationships between the optical behaviors and structures for these compounds were discussed.

A series of 1-alkyl-2,4,5-triphenylimidazole derivatives were synthesized by the alkylation of corresponding 2,4,5-triphenylimidazole derivatives with alkyl bromide using tetra-n-butylammonium bromide as phase-transfer catalyst in the presence of 50% NaOH in butanone in a good yield and five 1-alkyl-2,4,5-triphenylimidazole derivatives containing benzimidazole or benzothiazole fragments in the 4′-position of 2-phenyl ring were prepared by condensation of 1-alkyl-4,5-diphenyl-2-(4-carboxyphenyl)imidazoles with o-benzenediamine or 2-aminothiophenol in PPA under microwave irradiation. These products were identified by 1H NMR, 13C NMR, MS, IR and elemental analysis. At the same time, their UV–visible absorption coefficient (ɛ), maximum absorption wavelengths (λa), fluorescence emission wavelengths (λe), quantum yields (Φ), fluorescence lifetime in solution and solid state were measured. Single crystal of 1-n-butyl-4,5-diphenyl-2-(4-carboxyphenyl)imidazoles was obtained and the structure was determined by X-ray diffraction technique, based on which the relationships between spectral behaviors and molecular structure were discussed. The alkylation method of 2,4,5-triphenylimidazole derivatives and synthetic pathway for 1-alkyl-2,4,5-triphenylimidazole derivatives containing benzimidazole or benzothiazole fragments could provide an attractive and alternative, even a convenient and efficient approach to the preparation of some useful dyes and pigments.

The title compound, 2,5-bis(1-butyl-benzimidazol-2-yl)thiophene (C26H32N4O2S, Mr = 464.62), was synthesized and its crystal structure determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/n with a = 8.7215(8), b = 18.9156(18), c = 14.7475(14)Å, β = 96.696(2)°, V = 2416.3(4)Å3, Z = 4; the final R = 0.0426 and wR = 0.1064. The molecules are linked by intermolecular hydrogen bonds (O-H···O, and O-H···N) to form a parallel dimer structure, which stabilizes the crystal structure. 2007

Thirteen conjugated-chain compounds which contain benzene and furan units were prepared, their optical behaviors, including UV-vis absorption coefficient (epsilon), absorption wavelengths (lambdaa), fluorescence emission wavelengths (lambdae), and quantum yields (Phi) were measured. Meanwhile, their LUMO and HOMO energy were determined by cyclic voltammetry and their second-order polarizations (betaxxx) values were determined by solvatochromic method, respectively. The results showed that this kind of compounds possess a shorter lambdaa (320-365 nm) and performance a higher Phi values, especially for 2aa, 2ab, 2ac and 2bb, their Phi values are all more than 90%. These compounds, except 2db, showed a higher betaxxx values in DMSO, especially for 2dc (75.77x10(-30) m5 C-1) and 2dd (83.32x10(-30) m5 C-1), than that 10-methyl-acridone (6.578x10(-30) m5 C-1) or 10-benzylacridone (6.845x10(-30) m5 C-1) in DMSO did, and second harmonic generation value of 10-methylacridone and 10-benzylacridone in powder are, respectively, 1.381 and 1.861 times of that value of urea. The betaxxx values and Phi values determined for these compounds in this work were lower than these values which were desired in the original work, this phenomena was explained from their molecular structures. This work confirmed that as these compounds performance shorter lambdaa and higher Phi values, they could be good blue-color optical materials for some fields, such as OLED materials, two-photo absorption materials, fluorescent dyes.