Rapid and selective detection of biothiols by novel ruthenium(II) complex-based phosphorescence probes.

Considering the excellent photochemical properties of ruthenium(II) complexes, two new ruthenium(II) complexes, RuL1-DNBS and RuL2-DNBS, have been developed as phosphorescence probes for detection of biothiols in 100:1 (v/v) Hepes buffer (20 mM, pH = 7.2)/CH3CN solution. The response rate was highly improved of these two probes toward biothiols because the steric interactions between 1H-imidazo [4, 5-f] [1,10] phenanthroline group and ortho-2, 4-dinitrobenzensulfonate resulted in a relatively rapid thiol-induced SNAr substitution reaction. RuL1-DNBS and RuL2-DNBS were weakly phosphorescent owing to the effectual photoinduced electron transfer from ruthenium(II) luminophore to the sensing group, 2,4-dinitrobenzenesulfonyl. After reacting with biothiols, the 2,4-dinitrobenzenesulfonyl group of RuL1-DNBS and RuL2-DNBS were cleavaged and the RuL1 and RuL2 were obtained. Meanwhile, the phosphorescence were "turn-on". Both of these two probes can detect biothiols sensitively and selectively under physiological conditions with submicromolar detection limits. Furthermore, application of RuL2-DNBS for detecting of intracellular biothiols has been successfully performed in living Glioma cells.

The synthesis, characterization and optical properties of novel 2-acyl 6-arylindolizines.

A series of novel 2-acyl-6-aryl substituted indolizine derivatives was synthesized by a novel tandem reaction between 4-acyl-pyrrole-2-carbaldehyde derivatives and ethyl 4-bromo-3-arylbut-2-enoate under mild conditions. The compounds were characterized using IR, (1)H NMR (13)C NMR and HRMS. The crystal structure of 7a was determined using single crystal X-ray crystallography. The absorption results showed that compounds 7a-e presented their absorption maxima at ca. 270 nm, while compounds 7f and 7g with a larger conjugation system exhibited red-shifted absorption character (ca. 280 nm). Fluorescence spectra revealed that these compounds exhibited blue fluorescence (434-456 nm) in dilute solutions and showed quantum yields of fluorescence between 0.02 and 0.39 in dichloromethane.

The synthesis, characterization and optical properties of novel 5-(3-aryl-1H-pyrazol-5-yl)-2-(3-butyl-1-chloroimidazo[1,5-a]pyridin-7-yl)-1,3,4-oxadiazole.

A series of novel 5-(3-aryl-1H-pyrazol-5-yl)-2-(3-butyl-1-chloroimidazo[1,5-a]- pyridin-7-yl)-1,3,4-oxadiazole derivatives has been synthesized from 3-butyl-1-chloroimidazo[1,5-a]pyridine-7-carboxylic acid and ethyl 3-aryl-1H-pyrazole-5-carboxylate. The compounds were characterized using IR, (1)H NMR, HRMS and UV-vis absorption. The fluorescence spectral characteristics of the compounds in dichloromethane were investigated. The results showed that absorption λmax and emission λmax was less correlated with substituent groups on N-1 position of pyrazole moiety and para position of benzene moiety. The calculated molecular orbital correlates well with their absorption.

Synthesis, crystal structure, optical properties and antibacterial evaluation of novel imidazo[1, 5-a]pyridine derivatives bearing a hydrazone moiety.

A series of novel imidazo[1,5-a]pyridine-hydrazone derivatives were synthesized and characterized by infrared spectroscopy (IR), 1H NMR, 13C NMR and high resolution mass spectrometer (HRMS). Typically, the spatial structure of compound 3j was determined using X-ray diffraction analysis. The UV-vis absorption and fluorescence spectral characteristics of the compounds in dichloromethane and acetonitrile were investigated. Absorption peaks could be observed in the wavelength range 290-450 nm. It can also be seen that they display very similar maximum emission. The group attached to hydrazone hardly influenced the maximum emission. Furthermore, all the compounds were evaluated for antibacterial activity and were found to be more effective against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella compared with chloramphenicol.

4-Acetyl-1H-pyrrole-2-carbaldehyde.

The title compound, C(7)H(7)NO(2), was synthesized via a one-pot Vilsmeier-Haack and subsequent Friedel-Crafts reaction. The pyrazole ring makes dihedral angles of 4.50 (9) and 2.06 (8)°, respectively, with the aldehyde and acetyl groups. In the crystal, classical N-H⋯O hydrogen bonds and weak C-H⋯O inter-actions assemble the mol-ecules into a chain along the b axis.

Ethyl 2,4-dimethyl-pyrido[1,2-a]benz-imidazole-3-carboxyl-ate.

The title compound, C(16)H(16)N(2)O(2), was synthesized using a novel tandem annulation reaction between 1-(1H-benzo[d]imidazol-2-yl)ethanone and ethyl (E)-4-bromo-but-2-enoate under mild conditions. The dihedral angles formed by the mean plane of the five-membered imidazole ring with the dihydro-pyridin and benzene rings are 1.54 (9) and 1.85 (9)°, respectively.

The optical properties, synthesis and characterization of novel 5-aryl-3-benzimidazolyl-1-phenyl-pyrazoline derivatives.

A series of novel 5-aryl-3-benzimidazolyl-1-phenyl-pyrazoline derivatives were synthesized by the reaction of benzimidazolyl chalcone and phenylhydrazine in 41-72% yields. The compounds were characterized using IR, (1)H NMR and HRMS. Absorption and fluorescence spectra were measured in different organic solvent. An intense absorption maxima was noted at ca. 370 nm and emission maxima was noted at ca. 460 nm. The absorption spectra of the pyrazoline derivatives reveal that 5-aryl group attached to the pyrazoline ring hardly influenced the maximum absorption. The fluorescence spectra of these compounds indicated the emission wavelength was red shifted and the fluorescence intensity was decreased with the increase in solvent polarity.

3-(4-Bromo-phen-yl)-1-(4-chloro-benz-yl)-1H-pyrazole-5-carbaldehyde.

The title compound, C(17)H(12)BrClN(2)O, was synthesized by oxidation of [3-(4-bromo-phen-yl)-1-(4-chloro-benz-yl)-1H-pyrazol-5-yl]methanol under mild conditions. The pyrazole ring makes dihedral angles of 3.29 (9) and 74.91 (4)°, respectively, with the bromo-phenyl and chloro-phenyl rings.

Synthesis, characterization, optical properties and theoretical studies of novel substituted imidazo[1,5-a]pyridinyl 1,3,4-oxadiazole derivatives.

Novel imidazo[1,5-a]pyridinyl 1,3,4-Oxadiazole derivatives were synthesized and characterised by IR, (1)H NMR and HRMS.UV-vis absorption and fluorescence properties of these compounds in different solutions showed that the maximal emission wavelength was not significantly changed in different solvents; however, maximum absorption wavelength was blue-shifted with the increase of solvent polarity. Absorption λ(max) and emission λ(max) was less correlated with substituent groups on benzene rings. The calculated molecular orbital correlates well with their absorption.

1-(1-Benzyl-1H-benzimidazol-2-yl)ethanone.

In the title compound, C16H14N2O, the benzimidazole ring system is essentially planar. The planes of the benzene rings make a dihedral angle of 85.92 (8)°. In the crystal, neighbouring molecule are connected into paris along the c axis by weak C-H⋯O interactions and the connected pairs are expanded through C-H⋯N hydrogen bonds and C-H⋯π interactions along the b axis.

Ethyl 1-benzyl-3-(4-bromo-phen-yl)-1H-pyrazole-5-carboxyl-ate.

In the title compound, C(19)H(17)BrN(2)O(2), the pyrazole ring makes dihedral angles of 88.00 (16) and 5.78 (13)° with the phenyl and bromo-phenyl rings, respectively. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds.

Ethyl 1-(4-chloro-benz-yl)-3-(4-fluoro-phen-yl)-1H-pyrazole-5-carboxyl-ate.

In the title compound, C(19)H(16)ClFN(2)O(2), the pyrazole ring makes dihedral angles of 5.15 (6) and 77.72 (6)°, with the fluoro-phenyl and chloro-phenyl rings, respectively.

Ethyl 2-methyl-4-phenyl-pyrido[1,2-a]benzimidazole-3-carboxyl-ate.

The title compound, C(21)H(18)N(2)O(2), was synthesized using a novel tandem annulation reaction between (1H-benzimidazol-2-yl)(phen-yl)methanone and (E)-ethyl 4-bromo-but-2-enoate under mild conditions. The dihedral angles between the mean planes of the five-membered imidazole ring and the pyridine, benzene and phenyl rings are 0.45 (6), 1.69 (1) and 70.96 (8)°, respectively. In the crystal, mol-ecules are linked through inter-molecular C-H⋯N hydrogen bonds.

Ethyl 6-methyl-2-p-tolyl-pyrazolo[1,5-a]pyridine-5-carboxyl-ate.

In the title mol-ecule, C(18)H(18)N(2)O(2), the bicyclic ring system and the benzene ring form a dihedral angle of 13.45 (3)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules into chains propagated along [201].

1-(2-Hydr-oxy-5-methoxy-phen-yl)ethan-1-one N-[(E)-1-(2-hydr-oxy-5-methoxy-phen-yl)ethyl-idene]hydrazone.

In the title mol-ecule, C(18)H(20)N(2)O(4), which resides on a crystallographic centre of inversion (at the centre of the N-N bond), all non-H atoms apart from the meth-oxy substituent are approximately coplanar. The structure displays intra-molecular O-H⋯N hydrogen bonding.

Ethyl 5-(ethoxy-carbon-yl)-3-(4-methoxy-phen-yl)-1H-pyrazole-1-acetate.

In the title compound, C(17)H(20)N(2)O(5), all bond lengths and angles show normal values. The dihedral angle between the pyrazole ring and the benzene ring is 6.98 (11)°. The mol-ecules are linked by inter-molecular C-H⋯π inter-actions.