Photochemical formation and decomposition of 8-[β-arylethenyl]-2,2,6-trimethyl-7,9,10-trioxa-tricyclo[6.2.2.0]dodec-11-ene to novel 6-hydroxy-1,7,7-trimethyl-2-oxa-bicyclo[4.4.0]dec-4-en-3-one in the presence of oxygen

Irradiation of (E,E)-arylidene-β-ionones in the presence of oxygen leads to the formation of 8-[β-arylethenyl]-2,2,6-trimethyl-7,9,10-trioxa-tricyclo[6.2.2.0^1,6]dodec-11-enes (3). However, prolonged irradiation in the presence of oxygen leads to their conversion to 6-hydroxy-1,7,7-trimethyl-2-oxa-bicyclo[4.4.0]dec-4-en-3-one (4), apparently proceeding through addition of oxygen to the side chain π-bond in 3.     

Synthesis of tetra-substituted pyrroles, a potential phosphodiesterase 4B inhibitor, through nickel(II) chloride hexahydrate catalyzed one-pot four-component reaction

A wide variety of tetra-substituted pyrrole derivatives were synthesized through one-pot four-component condensation reaction of aromatic aldehydes, benzylamines, β-ketoesters, and nitroalkanes in the presence of 10 mol % NiCl₂·6H₂O in good yields. Some of them exhibit properties as potential inhibitors of phosphodiesterase 4B (PDE4B) through docking studies.     

Studies on a novel class of triaryl pyridine N-glycosylamine amphiphiles as super gelators

A novel class of six different triaryl pyridine N-glycosylamine amphiphiles was synthesised and characterized based on different spectral techniques, such as NMR and mass analysis. Gelation properties in different aromatic and aliphatic solvents were studied and gelation was observed predominantly in aliphatic solvents with CGC of 0.5% (w/v) and is attributed to the presence of long alkyl chain. All the gels thus obtained were studied using FE-SEM and powder XRD techniques which reveal fibrous entanglement of the molecules in the gel state with intermolecular spaces of 3.62 nm and 0.43 nm.     

Dielectric relaxation spectroscopy of phlogopite mica

An in-depth investigation of the dielectric characteristics of annealed phlogopite mica has been conducted in the frequency range 0.1 Hz–10 MHz and over the temperature range 653–873 K through the framework of dielectric permittivity, electric modulus and conductivity formalisms. These formalisms show qualitative similarities in relaxation processes. The frequency dependence of the M″ and dc conductivity is found to obey an Arrhenius law and the activation energy of the phlogopite mica calculated both from dc conductivity and the modulus spectrum is similar, indicating that same type of charge carriers are involved in the relaxation phenomena. The electric modulus and conductivity data have been fitted with the Havriliak–Negami function. Scaling of M′, M″, ac conductivity has also been performed in order to obtain insight into the relaxation mechanisms. The scaling behaviour indicates that the relaxation describes the same mechanism at different temperatures. The relaxation mechanism was also examined using the Cole–Cole approach. The study elaborates that the investigation regarding the temperature and frequency dependence of dielectric relaxation in the phlogopite mica will be helpful for various cutting edge applications of this material in electrical engineering.     

A facile photo-induced synthesis of COOH functionalized meso-macroporous carbon films and their excellent sensing capability for aromatic amines

A simple photo-induced approach is developed for the preparation of COOH functionalized meso-macroporous carbon films with tunable pores without using any inorganic mesoporous silica templates, which show excellent sensing selectivity for aniline and the selectivity can be enhanced upon increasing COOH functional groups.     

Strain-induced reversal of charge transfer in contact electrification

We have contact! Material strain can have a dominating effect on contact electrification. When a deflated (relaxed) balloon is rubbed against teflon, the teflon surface charges positively, but when the same balloon is inflated (strained), the teflon surface charges negatively. This result illustrates that material strain can control contact electrification and alter the driving force of some (yet unknown) charge-transfer species.     

Infinite families of non‐embeddable quasi‐residual Menon designs

A Menon design of order h² is a symmetric (4h²,2h²‐h,h²‐h)‐design. Quasi‐residual and quasi‐derived designs of a Menon design have parameters 2‐(2h² + h,h²,h²‐h) and 2‐(2h²‐h,h²‐h,h²‐h‐1), respectively. In this article, regular Hadamard matrices are used to construct non‐embeddable quasi‐residual and quasi‐derived Menon designs. As applications, we construct the first two new infinite families of non‐embeddable quasi‐residual and quasi‐derived Menon designs. © 2008 Wiley Periodicals, Inc. J Combin Designs 17: 53–62, 2009     

Impact of computational structure-based predictive toxicology in drug discovery

Computational tools for predicting toxicity have been envisioned to have the potential to broadly impact up on the attrition rate of compounds in pre-clinical drug discovery and development. An integrated approach of computer-assisted, predictive, and physico-chemical properties of a compound, along with its in vitro and in vivo analysis, needs to be routinely exercised in the lead identification and lead optimization processes. Starting with a good lead can save a lot of money and it can significantly reduce the entire drug discovery process. The journey towards triple R's- reduce, replace and refine, further proves to be successful in predicting adverse drug reactions in patients (or animals) enrolled in clinical trials. However, the impact of predictive toxicity analysis was modest and relatively narrow in scope, due to the limited domain knowledge in this field. It is important to note that advances within medical science and newer approaches in drug development will require predictive toxicology applications to be viable. The field of computational toxicology has been heading in a direction more relevant to human diseases by reducing the adverse drug reactions. Therefore, efforts must be directed to integrating these tools relevant to the goal of preventing undesired toxicity in pre-clinical trials followed by different phases of clinical trials.     

Polarization modulation spectroscopy of single fluorescent nanodiamonds with multiple nitrogen vacancy centers

A technique based on polarization modulation spectroscopy (PMS) has been developed to determine quantitatively the number of fluorophores in nanoparticles at the single-molecule level. The technique involves rotation of the polarization of the excitation laser on a millisecond time scale, leading to fluorescence intensity modulation. By taking account of the heterogeneous orientation among the dipoles of the fluorophores and simulating the modulation depth distribution with Monte Carlo calculations, we show that it is possible to deduce the ensemble average and number distribution of the fluorophores. We apply the technique to fluorescent nanodiamonds (FNDs) containing multiple nitrogen vacancy (NV) centers. Comparing the experimental and simulated modulation depth distributions of 11 nm FNDs, we deduce an average number of = 3, which is in good agreement with independent photon correlation measurements. The method is general, rapid, and applicable to other nanoparticles, polymers, and molecular complexes containing multiple and randomly orientated fluorophores as well.     

Excited-state proton transfer via hydrogen-bonded acetic acid (AcOH) wire for 6-hydroxyquinoline

Spectroscopic studies on excited-state proton transfer (ESPT) of hydroxyquinoline (6HQ) have been performed in a previous paper. And a hydrogen-bonded network formed between 6HQ and acetic acid (AcOH) in nonpolar solvents has been characterized. In this work, a time-dependent density functional theory (TDDFT) method at the def-TZVP/B3LYP level was employed to investigate the excited-state proton transfer via hydrogen-bonded AcOH wire for 6HQ. A hydrogen-bonded wire containing three AcOH molecules at least for connecting the phenolic and quinolinic -N- group in 6HQ has been confirmed. The excited-state proton transfer via a hydrogen-bonded wire could result in a keto tautomer of 6HQ and lead to a large Stokes shift in the emission spectra. According to the results of calculated potential energy (PE) curves along different coordinates, a stepwise excited-state proton transfer has been proposed with two steps: first, an anionic hydrogen-bonded wire is generated by the protonation of -N- group in 6HQ upon excitation to the S(1) state, which increases the proton-capture ability of the AcOH wire; then, the proton of the phenolic group transfers via the anionic hydrogen-bonded wire, by an overall "concerted" process. Additionally, the formation of the anionic hydrogen-bonded wire as a preliminary step has been confirmed by the hydrogen-bonded parameters analysis of the ESPT process of 6HQ in several protic solvents. Therefore, the formation of anionic hydrogen-bonded wire due to the protonation of the -N- group is essential to strengthen the hydrogen bonding acceptance ability and capture the phenolic proton in the 6HQ chromophore.