The first examples of terminally thiol-functionalized alkoxycyanobiphenyls

In this communication, we report the synthesis of the first examples of terminally thiol-functionalized alkoxycyanobiphenyls. The thermal behaviour of these mesogens and their intermediates was investigated by polarizing optical microscopy, differential scanning calorimetry and X-ray diffractometry.     

Metal nanoparticle-doped coloured films on glass and polycarbonate substrates

In a program on the development of metal (e.g. Au, Ag, Cu and their alloy) nanoparticles in sol-gel derived films, attempts were made to synthesize different coloured coatings on glasses and plastics. The absorption position of surface plasmon resonance (SPR) band arising from the embedded metal nanoparticles was tailored by controlling the refractive index of the matrix for the development of different colours. Thus different coloured (pink to blue) coatings on ordinary sheet glasses were prepared by generating Au nanoparticles in mixed SiO₂-TiO₂ matrices having refractive index values ranging from about 1.41 to 1.93. In another development,in situ generation of Ag nanoparticles in the inorganic-organic hybrid host leads to the formation of different abrasion resistant coloured coatings (yellow to pink) on polycarbonate substrates after curing. As expected, the SPR peak of Ag or Au is gradually red-shifted due to the increase of refractive index of the coating matrices causing a systematic change of colour     

Studies on the Evolution of Silver Nanoparticles in Micelle by UV-Photoactivation

Ultraviolet (UV) photoirradiation of Ag(I) compounds in the presence of an aqueous Triton X-100 solution has been exploited for the first time to prepare reproducible yellow silver hydrosol. The evolution of nanosized silver particles has been examined critically under the influence of different anions/ligands. Hence, time dependent evolution of silver hydrosol from different silver compounds in micelle via photochemical reduction is observed. Anions/ligands of precursor salts have been found to show profound influence (due to electron scavenging property, solubility, stability etc.) on the evolution route and efficiency of photochemical reduction of Ag(I) to Ag(O) in micelle and thereby classification of silver compounds becomes possible. Kinetic results reveal that the formation of silver particles proceeds via autocatalytic growth mechanism. The observed variation in rate constant values for the evolution of nanoparticles from different silver compounds have been explained in terms of available thermodynamic and kinetic parameters. Nucleophile induced dissolution and reversible photogeneration of zerovalent silver particles have been investigated under ambient condition.     

Shortest Path Problem on a Network with Imprecise Edge Weight

A network with its arc lengths as imprecise number, instead of a real number, namely, interval number and triangular fuzzy number is considered here. Existing ideas on addition and comparison between two imprecise numbers of same type are introduced. To obtain a fuzzy shortest path from a source vertex to all other vertices, a common algorithm is developed which works well on both types of imprecise numbers under consideration. In the proposed algorithm, a decision-maker is to negotiate with the obtained fuzzy shortest paths according to his/her view only when the means are same but the widths are different of the obtained paths. Otherwise, a fuzzy optimal path is obtained to which the decision-maker always satisfies with different grades of satisfaction. All pairs fuzzy shortest paths can be found by repeated use of the proposed algorithm.     

Phase transitions in novel disulphide-bridged alkoxycyanobiphenyl dimers

The synthesis, characterization and mesomorphic properties of the first examples of novel disulphide-bridged alkoxycyanobiphenyl dimers are reported. The thermal behaviour of these mesogens was investigated by polarizing optical microscopy, differential scanning calorimetry and X-ray diffractometry. The dimers with a shorter spacer exhibit only the nematic phase while dimers with a longer spacer display nematic as well as smectic phases. X-ray diffraction experiments reveal the intercalated structure of the SmA phase of these dimers and the presence of short range SmA-like order in the N phase (cybotactic nematic) of all the compounds, except the one with the shortest spacer.     

General method of synthesis for metal nanoparticles

Sugar-assisted stable monometallic nanoparticles were synthesized by wet chemical method following a general scheme. Judicious manipulation of the reducing capabilities of different sugars has shown to have a bearing on the particle size that corroborates the shift of the absorbance peak positions and TEM analysis. Evaporation of the precursor solutions on the solid surface (strong metal--support interaction), led to the formation of smaller particles. Under the experimental condition, spherical nanoparticles of approximately 1, 3, 10 and 20 nm sizes were prepared reproducibly for gold, platinum, silver and palladium, respectively. Fructose has been found to be the best suited sugar for the synthesis of smaller particles and remained stable for months together.     

Quantitative structure-toxicity relationship: An “in silico study” using electrophilicity and hydrophobicity as descriptors

To investigate the importance and suitability of quantitative structure-toxicity relationship approach in the field of aquatic toxicology, we have performed an extensive study introducing multiple linear regression (MLR) and multilayer perceptron neural network (MLP-NN) techniques. In this study, toxicity (pIGC₅₀) prediction of 169 aliphatic compounds toward Tetrahymena pyriformis (a freshwater protozoa) has been made by using all possible combinations of electrophilicity index (ω), square of electrophilicity index (ω²), cube of electrophilicity index (ω³), hydrophobicity (logP), and its square term {(logP)²} as predictors in the developed models. The MLR and MLP employed to construct the linear prediction models for the complete sets lead to a good correlation coefficient (R²) ranging from 0.703 to 0.779 in case of electronic factors (ω, ω², ω³) and 0.790 to 0.983 in case of lipophilic factors {logP, (logP)²}, respectively, except for amino alcohols. Furthermore, to cross-check the variable selection, a three-set cross-validation approach has been carried out. To demonstrate our overall result, the sum of ranking differences with ties has been evaluated considering the whole data set.     

Synthesis,biological evaluation,and docking study of a series of 1,4-disubstituted 1,2,3-triazole derivatives with an indole-triazole-peptide conjugate

A series of new compounds containing an indole-triazole - peptide conjugate were designed as potential agents possessing the dual anti-bacterial and anticancer activities. Accordingly, 20 compounds were prepared via a multi-step synthesis involving the copper-catalyzed azide-alkyne cycloaddition (CuAAC) as a key step in moderate to high yield. All the synthesized compounds were purified by chromatographic techniques and characterized by IR, ¹H and ¹³C NMR and mass spectral data. The synthesized derivatives were screened for their antimicrobial activities against one gram-positive (Staphylococcus aureus) and three gram-negative (Escherichia coli, Klebsiella pneumonia, and Proteus vulgaris) bacteria using an agar-well diffusion method. Most of the compounds showed moderate to reasonable antibacterial activities especially the compound 9e that showed good activities against all the strains. The potential of DNA gyrase inhibitory activity of this compound was assessed by using molecular docking studies in silico carried out using Autodock Vina software. The low ΔG_bind value (−9.4 Kcal/mol) of compound 9e suggested its good interactions with the target protein in silico. The cytotoxic activities of some of the compounds synthesized were evaluated via a MTT assay using the human lung cancer cell line A549. Several compounds showed promising activities among which compound 9b , 9k, and 9e showed low IC₅₀ values.