The Malleable Excited States of Benzothiadiazole Dyes and Investigation of their Potential for Photochemical Control

<p>A strategy to control the efficiency of a photocleavage reaction based on changing the nature of the excited state is presented. A novel class of photoactive compounds has been synthesized by combining the classical o-nitrobenzyl scaffold with an environmentally sensitive dye, 4-amino-nitrobenzothiazole. Irradiation in a polar solvent lead to an excited state that is inoperative for photochemistry whereas excitation in a nonpolar solvent lead to an excited state that is photochemically active. A photochemical degradation appears to be the preferred process in contrast to the intended photocleavage process.</p>

The Malleable Excited States of Benzothiadiazole Dyes and Investigation of their Potential for Photochemical Control

<p>A strategy to control the efficiency of a photocleavage reaction based on changing the nature of the excited state is presented. A novel class of photoactive compounds has been synthesized by combining the classical o-nitrobenzyl scaffold with an environmentally sensitive dye, 4-amino-nitrobenzothiazole. Irradiation in a polar solvent lead to an excited state that is inoperative for photochemistry whereas excitation in a nonpolar solvent lead to an excited state that is photochemically active. A photochemical degradation appears to be the preferred process in contrast to the intended photocleavage process.</p>

EKSTRAKSI MINYAK ATSIRI BUNGA MELATI DENGAN MENGGUNAKAN PELARUT ISOPROPIL ETER : PENGARUH WAKTU, TEMPERATUR, DAN RASIO MASSA BUNGA MELATI DENGAN VOLUME PELARUT

Jasmine flower is one of the high value commodities. One of the applications of jasmine flower is jasmine essential oil. Jasmine essential oil is often used to produce high quality parfume. Extraction is one of the methods for extracting jasmine essential oil, usually by the help of solvent. In this study, the effect of extraction time, extraction temperature, and solvent to jasmine flower ratio on jasmine oil extraction was studied. The extraction was carried out at 30oC, 35oC, and 40oC for 2 hours, 3 hours, 4 hours, and 5 hours by using isopropyl ether. The ratio of jasmine flower to isopropyl ether were 1:3; 1:4; and 1:5 (m/v). The resulting jasmine oil was analyzed by GC-MS and its quality was assessed according to SNI 06-2385-2006 which include colour test, refractive index analysis, acid number analysis, and ester number analysis. This experiment showed that increasing of extraction time, extraction temperature, and volume of solvent lead to increase of absolute yield of jasmine essential oil. The highest jasmine oil yield was obtained at 10.63 %. The jasmine oil contained 45.34% benzyl acetate and had yellow color. Its refractive index, acid number, and ester number were 1.485, 26.228 mg KOH/gram jasmine essential oil, and 159.885 mg KOH/gram jasmine essential oil.

EKSTRAKSI MINYAK ATSIRI BUNGA MELATI: PENGARUH RASIO MASSA BUNGA MELATI DENGAN VOLUME PELARUT N-HEKSANA, WAKTU EKSTRAKSI, DAN TEMPERATUR EKSTRAKSI

Jasmine flower (Jasminum sambac) contains essential oil compounds. Jasmine flower essential oil is a high-quality essential oil. Essential oils are volatile oils that have aroma similar to the original plant. Jasmine flower essential oil is sought due to its calming and anti-depression nature. In this study, the effect of extraction temperature, extraction time and solvent to jasmine flower ratio on jasmine oil was studied. The extraction was carried out at 30oC, 35oC, and 40oC for 2 hours, 3 hours, 4 hours, and 5 hours by using n-hexane. The ratio of jasmine flower to n-hexanes were 1:3; 1:4; and 1:5 (w/v). Resulting jasmine oil was analyzed by GC-MS, and its quality was assessed according to SNI 06-2385-2006 which include colour test, refractive index analysis, acid number analysis, and ester number analysis. This experiment showed that increasing of extraction time, extraction temperature, and volume of solvent lead to increase of absolute yield of jasmine essential oil. The highest jasmine oil yield obtained at 11.69 %. The jasmine oil contained was 47.14 % benzyl acetate and had yellow color. Its refractive index, acid number, and ester number were 1.478, 20.92 mg KOH/gram jasmine essential oil, and 150.27 mg KOH/gram jasmine essential oil respectively.

Effect of Nematic Order Coupling on the Phase Diagrams of Side-Chain Polymer Gels with Liquid Crystal Solvent

We have explored the influence of nematic order coupling on the swelling and phase diagram of polymer networks in nematogenic low molar weight LC solvent, in view of the increasing importance of such systems in advanced optical devices. Firstly, one isotropic polyacrylate network and one nematic sidechain polyacrylate network is prepared. Immersing these two networks in nematic LC solvent lead to the formation of well-defined polymer gels with LC solvents and allow us to establish the phase diagram of these relatively new materials in the concentration-temperature frame. Results were critically analysed as a function of temperature and network nature (isotropic or nematic). We demonstrate that in the case of gel made from an isotropic polymer network, the LC solvents fails to form a nematic phase inside the gel due to the lack of anisotropic coupling. Moreover, in that case the gel shrinks below TNI Solvent because of a strong “entropic” incompatibility between the isotropic flexible coils and the LC nematogens. However, the situation is drastically different in the case of LC side-chain network due to a strong coupling of the nematic order between the mesogens of the solvents and those of the polymer backbone. In that case, tremendous distortions appear in the phase-diagram, in which we especially emphasize the apparition of a stable nematic gel phase and a miscibility gap between TNI Solvent and TNI Gel. Finally, results are critically examined and compared to the few studies found in the literature.

The Swelling of Unfilled and Highly Filled Polymers

The swelling of elastomers in solvents is a useful method for determining the effective crosslinking of the polymeric structure. However, it is now shown that this method may be applied satisfactorily to highly filled polymers. A unique method has been devised for the accurate measurement of the swelling ratio of the gel phase of the filled polymers. The method is based on the observation that the binder-filler bond, for most filler particles, releases on swelling. The binder around the particle swells, leaving a hollow pocket which becomes filled with solvent. Corrections for this “waste” solvent lead to the equations from which the swelling of the polymer can be calculated. Experimental verification is given for several filled systems.