Review on Synthesis of 2-(2-Hydroxyaryl) Benzothiazoles (HBT) for Excited-State Intra-molecular Proton Transfer (ESIPT)-Based Detection of Ions and Biomolecules.

In this review, we present a systematic and comprehensive summary of the recent developments in the synthetic strategies of 2-(2-hydroxyarylsubstituted)-benzothiazole (HBT) framework along with incorporation of various substituents on phenolic and benzothiazole rings which affect the emission process. The literature, spanning the years 2015-2024, on excited-state intramolecular proton transfer (ESIPT)-based studies of HBT derivatives comprising the effects of solvent polarity, substituents, and extended conjugation on fluorophores has been searched. ESIPT, intramolecular charge transfer, and aggregation-induced emissions enable these fluorescent probes to specifically interact with analytes, thereby altering their luminescence characteristics to achieve analyte detection. These fluorescent probes exhibit large Stokes shifts, high quantum yields, and excellent color transitions. Finally, the applications of HBTs as ESIPT-based fluorescent probes for the detection of cations, anions, and biomolecules have been summarized. We anticipate that this review will provide a comprehensive overview of the current state of research in this field and encourage researchers to develop novel ESIPT-based fluorophores with new applications.

Synthesis, prototropic tautomerism studies of indenocarbothioamides and their conversion to biologically active indenothiazole derivatives.

Indenocarbothioamides 2, obtained from reaction of indane-1,3-dione with aryl isothiocyanates, on condensation with 3-chloropentane-2,4-dione and chloroacetyl chloride furnished 1,3-indanedione coupled thiazole and thiazolidin-5-one derivatives, respectively. The structure of the obtained products was assigned on the basis of spectral data (IR, NMR and Mass). Prototropic tautomerism studies of carbothioamides 2 were carried out in solution (1H NMR, 13C NMR and UV-vis), gas phase (Mass) and solid state (IR and X-ray). X-ray diffraction studies of carbothioamide 2a have revealed the existence of enolic form in the solid state. DFT studies of various possible tautomeric forms in gas phase as well as in solution state corroborated by the experimental results. Antibacterial studies of indenothiazole and indenothiazolidin-5-one derivatives have been reported.

New method for synthesis of Pt nanoparticles embedded in a carbon matrix.

Platinum (Pt) nanoparticles embedded in a carbon matrix were synthesized for the first time in benzene by an electric plasma discharge generated in the cavitation field of benzene due to an ultrasonic horn. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the particle size, structure and morphology of the synthesized nanoparticles. The Pt nanoparticles have FCC bulk Pt crystal structure. On the average Pt nanoparticle diameter ranged from 8 nm to 40 nm when synthesized at 4.1 kV and from 5 nm to 25 nm when synthesized at 3.4 kV. X-ray photoelectron Spectroscopy (XPS) and Energy dispersive X-ray Spectroscopy (EDX) were used to study the chemical composition of the synthesized nanoparticles. A cost effective new method for carbon supported Pt nanoparticles will be of potential interest in fuel cell and catalysis applications.

Antiviral activity of some plants used in Nepalese traditional medicine.

Methanolic extracts of 41 plant species belonging to 27 families used in the traditional medicine in Nepal have been investigated for in vitro antiviral activity against Herpes simplex virus type 1 (HSV-1) and influenza virus A by dye uptake assay in the systems HSV-1/Vero cells and influenza virus A/MDCK cells. The extracts of Astilbe rivularis, Bergenia ciliata, Cassiope fastigiata and Thymus linearis showed potent anti-herpes viral activity. The extracts of Allium oreoprasum, Androsace strigilosa, Asparagus filicinus, Astilbe rivularis, Bergenia ciliata and Verbascum thapsus exhibited strong anti-influenza viral activity. Only the extracts of A. rivularis and B. ciliata demonstrated remarkable activity against both viruses.

Scleritis and Takayasu's disease - rare combined presentation.

INTRODUCTION: Takayasu's disease (TD) (pulseless disease, aortic arch syndrome) is a rare but potentially life-threatening chronic giant cell vasculitis. The major complications attributed to the disease include Takayasu's retinopathy, secondary hypertension, aortic regurgitation, and arterial aneurysm. The aim of this study is to describe a patient with Takayasu's disease and scleritis and to show its association. CASE REPORT: We describe a 44-year-old female patient with Takayasu's disease who presented with bilateral anterior scleritis in the form of painful red eye. Patient did not have any associated autoimmune diseases. Patient was diagnosed to have TD and was treated with immunosuppressant. CONCLUSION: Scleritis though rare can be a vasculitic feature of TD. This is a first report of Takayasu's disease with scleritis, which has been documented in Nepal.

Synthesis, X-ray, DFT and photophysical properties of some new ferrocenyl hydrazono thiazolidin-4-ones and their derivatives.

Cyclocondensation of thiosemicarbazone of 2-acetylferrocene with α-haloacids and α-haloketones afford new ferrocenyl hydrazono thiazolidin-4-ones and ferrocenyl hydrazono thiazoles respectively. Ferrocenyl hydrazono thiazolidin-4-one is easily converted into enamino ketone with N,N-dimethylformamide dimethyl acetal (DMF-DMA). The compounds were characterized by spectroscopic means and the structure of the new ferrocenyl hydrazono thiazolidin-4-one (3a) was determined by means of X-ray crystallography. The photophysical properties of these compounds were studied by means of UV/visible absorption spectroscopy and fluorescence spectroscopy. Density functional theory (DFT) calculations have been carried out with Gaussian 09W using B3LYP density functional method and 6-31G (d) basis set. (1)H and (13)C Nuclear Magnetic Resonance (NMR) have been calculated and correlated with experimental results. Antimicrobial activity studies of some new compounds have been reported.

Synthesis, structure and antimicrobial evaluation of new 3,3a,4,5-tetrahydro-2H-benzo[g]indazol-2-yl-thiazol-4(5H)-ones.

The reaction of semicarbazide or thiosemicarbazide with 2-arylidene-1-tetralones under alkaline condition affords 3,3a,4,5-tetrahydro-2H-benzo[g]indazole-2-carbo(thio)amides as a mixture of cis and trans diastereoisomers of 3-H and 3a-H. The synthesis of new indazolyl-thiazol-4(5H)-ones from the condensation of cis isomer and α-halo acids is reported. A DFT study along with X-ray single crystal data of a representative compound is presented. All the eight newly synthesised indazolyl-thiazol-4(5H)-ones were screened for their antibacterial and antifungal activities and some compounds have shown promising activities.