Formation of a long-lived charge-separated state of a zinc phthalocyanine-perylenediimide dyad by complexation with magnesium ion

Photoexcitation of a zinc phthalocyanine-perylenediimide (ZnPc-PDI) dyad affords the triplet excited state without the fluorescence emission, whereas addition of Mg2+ to the photoexcited ZnPc-PDI results in formation of a long-lived charge-separated state (ZnPc.+-PDI.-/Mg2+) in which PDI.- forms a complex with Mg2+.     

Photoacoustic detection of nitric oxide by use of a quantum-cascade laser

A photoacoustic trace-gas sensor for the measurement of nitric oxide with a detection limit of 500 parts in 10(9) has been demonstrated. The radiation source was a thermoelectrically cooled distributed-feedback quantum-cascade laser operating in pulsed mode near 5.3 microm with an average laser power of 8 mW. A resonant photoacoustic cell was excited in its first longitudinal mode by the modulated laser light. Preliminary measurements have been performed to test the performance of our photoacoustic sensor; possible improvements to reach lower detection limits are discussed.     

Structure and emission properties of Er3Q9 (Q = 8-quinolinolate)

We report the first combined optical and structural investigation of the water free Er-quinolinolate complex, an organo-lanthanide system of interest for 1.5-microm telecom applications. Structural data demonstrate that the complex has a trinuclear structure (Er3Q9) which provides the Er metals with an octa-coordination by the organic ligand and prevents solvent and water molecules from entering the lanthanide coordination sphere. The results of the structural analysis allow us to infer that the strong Er luminescence quenching exhibited by the Er3Q9 complex is due uniquely to resonant energy transfer to the aromatic C-H vibrations of the ligand, providing the correct tools to design more efficient emitters.     

Microwave-assisted synthesis of rhodamine derivatives

The microwave synthesis of 12 rhodamine-derived imines is described. The present work involves condensation of rhodamine hydrazide with various aromatic aldehydes in ethanol under microwave irradiation. The results obtained indicate that, unlike classical heating, microwave irradiation results in higher yields, shorter reaction time, mild reaction condition and simple work-up procedure. The structures of synthesized compounds were confirmed by ¹H-NMR, ¹³C-NMR, FT-IR and high-resolution mass spectra data.     

Isolation and antiproliferative activity of chemical constituents from Asystasia buettneri Lindau

N-hexane and methanol extracts of Asystasia buettneri Lindau aerial parts exhibited antiproliferative activity on leukaemia blood carcinoma, K-562. Hexadecane (1), 1,3-propan-2-ol (9Z,12′Z,15″Z)-bis(doeicos-9,12,15-trienoate) (2), hydrocarbon, 2,3,3,10,23-pentamethyl tetraeicos-10,13,16-trien-1-ol (3), hexadecanoic acid (4) and taraxerol (5) were isolated from n-hexane extract; stigmasterol (6) and (Z)-9-octadecenoic acid (7) were isolated from ethyl acetate extract; while unsaturated hydrocarbons, octadecene (8), 8-methyl tetradec-6-ene (9) and 19-methyl eicos-1-ene (10), fatty acids, (Z)-5-hexadecenoic acid (11), 11,22-dimethyl ethyltrieicos-11-enoate (12) and taraxasterol (13) were isolated from methanol extract of the plant. Compounds 4, 5, 7, 11, 12 and 13 exhibited antiproliferative activity against K-562, while compounds 5, 6, 7 and 9 revealed antiproliferative activity by inhibiting hepatic liver (WRL68) cell lines.     

The Effect of Dispersion on the Structure of Diphenyl Ether Aggregates

Dispersion interactions can play an important role in understanding unusual binding behaviors. This is illustrated by a systematic study of the structural preferences of diphenyl ether (DPE)–alcohol aggregates, for which OH???O‐bound or OH???π‐bound isomers can be formed. The investigation was performed through a multi‐spectroscopic approach including IR/UV and microwave methods, combined with a detailed theoretical analysis. The resulting solvent‐size‐dependent trend for the structural preference turns out to be counter‐intuitive: the hydrogen‐bonded OH???O structures become more stable for larger alcohols, which are expected to be stronger dispersion energy donors and thus should prefer an OH???π arrangement. Dispersion interactions in combination with the twisting of the ether upon solvent aggregation are key for understanding this preference.     

Automatic sample changer for neutron activation analysis at CDTN,Brazil

Journal of Radioanalytical and Nuclear Chemistry - An automatic sample changer was recently developed and installed in the Neutron Activation Analysis (NAA) Laboratory. The certified reference...     

Synthetic modifications of chitin and chitosan as multipurpose biopolymers: A review

Chitin and chitosan are well-thought-out multipurpose biopolymers. Chitosan which is deacetylated chitin is useful than chitin and is biomaterial of great interest. Regardless of its biodegradability, chemical modifications suggest due to the amino side reactivity, helps to impart it other great qualities. Herein, we discuss the preparative methods of synthetically modified derivatives, some are commercially available. This review shields the literature from last few decades.