Ultrasensitive reversible chromophore reaction of BODIPY functions as high ratio double turn on probe.

Chromophore reactions with changes to conjugation degree, especially those between the conjugated and unconjugated state, will bring a large spectral variation. To realize such a process, a meso-naked BODIPY (MNBOD) with two electron-withdrawing groups around the core is designed and synthesized. The resulting system is extremely sensitive to bases. The red, highly fluorescent solution readily becomes colorless and non-fluorescent after base addition; however, the color and fluorescence can be totally and instantly restored by addition of acid or formaldehyde. Analyses show that two identical MNBODs are connected by a C-C single bond (sp3) at the meso-position through a radical reaction that results in an unconjugated, colorless dimer complexed with bases. When the bases are consumed, the dimer immediately dissociates into the red, highly fluorescent, conjugated MNBOD monomer. With 260 nm spectral change and over 120,000 turn-on ratio, this chromophore-reaction can be utilized as a sensitive reaction-based dual-signal probe.

Theoretical studies on structures and spectroscopic properties of self-assembled bis(2,4,8,10-tetramethyl-9-methoxycarbonylethyldipyrrin-3-yl)methane with Co(II).

We report a combined experimental and computational study of the large self-assembly complex (CoL)(2) [L= bis(2,4,8,10-tetramethyl-9-methoxycarbonylethyldipyrrin-3-yl)methane] containing 172 atoms. An extensive density functional theory (DFT) and time-dependent DFT study of this complex in gas phase and in CH(2)Cl(2) solution was performed, investigating the effect of substitutions of methyl and methyl propionate on the electronic structure and optical properties of this complex. The calculated IR and Raman spectra are in excellent agreement with the experiment, thus allowing a detailed assignment of the vibrational absorption bands. Comparing the vibrational spectrum of (CoL)(2) with that of (ZnL')(2) [L' = bis(2,4-dimethyldipyrrin-3-yl)methane], the substitution of methyl on the C(beta) atom results in sizable shifts on the same modes; particularly in the case of mode upsilon(C(beta)-C(beta)), the shift is more than 20 cm(-1). The lowest 70 singlet-singlet spin-allowed excited states were taken into account for the calculation by TDDFT in gas phase and PCM-TDDFT in CH(2)Cl(2) solution. Theoretical calculations provide a good description on positions of the two band maximums in observed spectrum but predict a contrary relatively intensity for these two bands. In the UV-vis absorption spectrum of (CoL)(2) complex, the band maximum at 525.5 nm is mainly attributed to the pi-->pi* transition. The band maximum at 488.1 nm is originated from metal-ligand charge-transfer (MLCT) transition mixed with interligand pi-->pi* transition.

Distinct nanostructures from isomeric molecules of bis(iminopyrrole) benzenes: effects of molecular structures on nanostructural morphologies.

The effects of molecular structures on nanostructural morphologies have been studied through the preparation of nanospheres, square nanowires, and nanocubes from three isomeric molecules of bis(iminopyrrole)benzene.

Spectroscopic and computational studies on the coordination-driven self-assembly complexes (ZnL)2 and (NiL)2 [L= bis(2,4-dimethyldipyrrin-3-yl)methane].

FT-IR, FT-Raman and electronic absorption spectroscopies were utilized in conjunction with density functional theory (DFT) calculations to investigate the ground and excited states of self-assembled dinuclear dimeric helicates (ZnL)2 and (NiL)2 [L = bis(2,4-dimethyldipyrrin-3-yl)methane]. These studies afford a detailed description of the ground-state geometric and electronic structures of (ZnL)2 and (NiL)2 and provide a comparison with similar geometrical metal-porphyrins. The results demonstrate that enlarging the basis set used in the DFT calculations results in an obvious alteration of the calculated bond lengths but negligible alteration of the calculated bond angles. The predicted spectra are in good agreement with the experimental ones with the deviations generally less than 30 cm(-1). In comparison with vibrational spectra of metal-porphyrins, the breathing vibration of the pyrrole ring is shifted by over 100 cm(-1) toward higher wavenumber due to local conjugation of molecular geometry. Time-dependent density functional theory (TD-DFT) provides a good description of the excitation energy. Because of the break in symmetry, the absorption band (corresponding to the Q-band of porphyrin) of (ZnL)2 and (NiL)2 is no longer weak. Local conjugation makes the absorption wavelength of (NiL)2 and (ZnL)2 shift to the blue compared with those of NiP and ZnP.

[Effect of bilirubin derivative on HIV-1 in vitro].

BACKGROUND: To study the effect of DTB against HIV-1, for developing anti-HIV drugs. METHODS: Different concentration of DTB was added to cell culture system after viral inoculation, MTT staining method for viable cells (MTT assay) and p24 (ELISA) were used as markers to monitor the viral replication. RESULTS: The inhibition rates of DTB at concentrations 160, 80, and 40mg/ml were 93.0%, 56.2% and 18.1%, respectively. CONCLUSIONS: DTB could effectively inhibit HIV-1 in vitro.