N-Nitrosomelatonin, an efficient nitric oxide donor and transporter in Arabidopsis seedlings.

Nitric oxide (NO) produced in plant cells has the unique ability to interact with various other biomolecules, thereby facilitating its own as well as their signaling and associated actions at their sites of biosynthesis and at other sites via transcellular long distance transport of the molecular complexes. Melatonin (Mel) is one such biomolecule produced in plant cells which has fascinated plant biologists with regard to its molecular crosstalk with other molecules to serve its roles as a growth regulator. Present work reports the synthesis of N-nitrosomelatonin (NOMela) and its preferential uptake by Arabidopsis seedlings roots and long distance transport to the leaves through vascular strands. Equimolar (250 µM) concentrations of NOMela and S-nitrosoglutathione (GSNO) in aqueous solutions bring about 52.8% more release of NO from NOMela than from GSNO. Following confocal laser scanning microscopic (CLSM) imaging, Pearson's correlation coefficient analysis of the Scatter gram of endogenously taken up NOMela demonstrates significant NO signal in roots emanating from mitochondria. NOMela (250 µM) taken up by Arabidopsis seedling roots also proved more efficient as a NO transporter from primary root to leaves than 250 µM of GSNO. These novel observations on NOMela thus hold promise to decipher its crucial role as a NO carrier and reservoir in plant cells, and also as a facilitator of melatonin action in plant development.

A highly selective pH switchable colorimetric fluorescent rhodamine functionalized azo-phenol derivative for thorium recognition up to nano molar level in semi-aqueous media: Implication towards multiple logic gates.

A new rhodamine functionalized Schiff base (3',6'-bis(diethylamino)-2-((Z)-(5-((E)-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl)-2,4-dihydroxybenzylidene) amino)spiro[isoindoline-1,9'-xanthen]-3-one (1) has been synthesized and was characterized spectroscopically. The optical properties of the schiff base have been studied using UV-vis and fluorescence spectra. Schiff base 1 displayed a selective behaviour towards Th4+ ions, as evidenced by UV-vis and fluorescence spectra. It shows visible colour change from orangish-yellow to red upon addition of Th4+ ions. A strong new emission band at 586 nm and about 24-fold enhancement in fluorescence intensity was observed upon binding with Th4+ which could be quenched by subsequent addition of oxalate and chromate ions. Probe 1 also acts as a reversible pH sensor in the highly acidic region (pH < 4, pKa = 2.01) via the photophysical response to pH as well as visible detectable colour change from orangish-yellow to red to pink. The absorbance and emission intensities of 1 diminished in the pH region from 4 to 11.5 and could be recovered by adding acid to adjust the pH < 4. Probe 1 exhibited high binding constant (8.595 × 106 M-1) and low limit of detection (1.122 × 10-9) compared to most previously reported sensors for Th4+ ions. Furthermore, two multiple logic gates i.e. 3 and 5 input, have been constructed.

Synthesis, photophysical studies, solvatochromic analysis and TDDFT calculations of diazaspiro compounds.

Diazaspiro[5.5]undecane-1,3,5,9-tetraones and 3-thioxo-diazaspiro[5.5]undecane-1,5,9-trione have been synthesized via double Michael addition of 1,5-diphenyl-1,4-pentadien-3-one with active methylene heterocycles N,N-dimethyl barbituric acid, barbituric acid and thiobarbituric acid in water:ethanol (1:1) using TBAB as catalyst. The solvent effect on photophysical behavior of these compounds showed that stokes shift increases with increase in polarity of solvents. The solvent effect on the spectral properties has been investigated by using the Lippert-Mataga and Reichardt methods. The solvatochromism is analyzed by linear solvation energy relationship using the new four-parameter Catalán polarity scales. The relative fluorescence quantum yield of these diazaspiro compounds varies in solvents of different polarity. The HOMO and LUMO energies have been calculated by TDDFT (B3LYP/6-311G (d, p)) approach. TDDFT calculations were also used to compare the experimental and theoretical absorption spectra.

Ultrasound promoted one pot synthesis of novel fluorescent triazolyl spirocyclic oxindoles using DBU based task specific ionic liquids and their antimicrobial activity.

Spirocyclic oxindoles and triazolyl derivatives posses remarkable biological activities. In present work, we have described an efficient one pot four-component domino reaction of 1-(prop-2-ynyl)indoline-2,3-dione, cyclic 1,3-diketones, malononitrile and various aryl azides in DBU based ionic liquids [DBU-H]OAc and [DBU-Bu]OH under ultrasonic irradiation for the construction of heterocycles, comprising spiro-oxindole, 2-amino-4H-pyran, and 1,2,3-triazoles substructures. The antimicrobial activity of all compounds has been investigated against six microbial strains. All compounds showed good antimicrobial activity. All newly synthesized compounds exhibit fluorescence in methanol with large stoke shift.

Synthesis of novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones and evaluation of their biocidal effects.

Novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones have been synthesized in high yields by treatment of the corresponding oxo analogs with Lawesson's reagent. The structure has been confirmed by X-ray analysis. The compounds were tested for in vitro antifungal activity against Rhizoctonia bataticola, Sclerotium rolfsii, Fusarium oxysporum and Alternaria porii. The compounds exhibited moderate to good activity against all pathogens. Insecticidal activity of these compounds against Spodoptera litura was observed to be comparable to commercial pyrethroid insecticide, cypermethrin. The urease inhibitory activity has also been studied.

Unexpected formation of hydroxybiphenylmethane derivatives and some new observations on Labat test.

An unexpected synthesis of symmetrical hydroxybiphenylmethanes involving the reaction of 2-hydroxyphenyl benzyl ketones with ethoxymethyl chloride has been observed. Some new interesting observations of Labat test on colorimetric detection of bichalconyloxy, bichalconyl and biflavonylmethanes having oxygenated ortho positions are presented.

Facile reductive coupling of benzylic halides with ferrous oxalate dihydrate.

Facile reductive coupling of benzylic halides is reported with ferrous oxalate dihydrate in DMF or HMPA under nitrogen atmosphere at 155-160 degrees C. The coupling is proposed to proceed by two successive oxidative additions of benzylic halides to ferrous oxalate to give an intermediate organoiron complex which undergoes concerted dimerization to give the corresponding reductively coupled dimers in high yields.