623-51-8Relevant articles and documents
Tris(5-aryl-1,3,4-oxadiazolyl)benzotrithiophenes – Discotic Liquid Crystals with Enormous Mesophase Ranges
Tober, Natalie,Winter, Johannes,Jochem, Matthias,Lehmann, Matthias,Detert, Heiner
supporting information, p. 798 - 809 (2021/02/01)
C3-symmetrical, alkoxyphenyl substituted 2,5,8-(tris-1,3,4-oxadiazol-2-yl)benzo [1,2-b; 3,4-b′; 5,6-b′′]trithiophenes (OXD-BTT) are synthesized via threefold Huisgen-reaction. A broad variation of alkoxy substitution pattern and chain lengths is reported. The thermal behavior was investigated via differential scanning calorimetry (DSC), polarized optical microscopy (POM) and thermogravimetry (TGA). Optical properties were studied via UV-Vis and fluorescence spectroscopy. Structural information of the LC phases was gained from X-ray diffraction on oriented fibers. OXD-BTT provide enormous phase widths (ΔT≥289 K) with clearing points close to thermal decomposition. Most of the derivatives exhibit two different mesophases, the lower phase with a rectangular 3D-structure and a hexagonal 2D-lattice at higher temperature. The variation of the chain length allows a tuning of melting and clearing points. OXD-BTT emit blue light with fluorescence quantum yields up to 30 % in good solvents. The emission is very sensitive to aggregation, thus, in poor solvents the emission intensity decreases, and red shift of maxima occurs.
Biofunctional silicon nanoparticles by means of thiol-ene click chemistry
Ruizendaal, Loes,Pujari, Sidharam P.,Gevaerts, Veronique,Paulusse, Jos M. J.,Zuilhof, Han
supporting information; experimental part, p. 2776 - 2786 (2012/06/01)
The preparation and characterization of butylene-terminated silicon nanoparticles (SiNPs) and their functionalization using thiol-ene chemistry is described, as well as the coupling of DNA strands. Bromide-terminated SiNPs were prepared by means of the oxidation of magnesium silicide and functionalized with butylene chains through treatment with the corresponding Grignard reagent. The successful coupling was confirmed by NMR and FTIR spectroscopy. TEM measurements revealed a silicon-core diameter of (2.4±0.5)nm. The fluorescence emission maximum is at λmax=525nm when excited at λexc=430nm. The conjugation of these alkene-terminated SiNPs by means of thiol-ene chemistry is described for a variety of functional thiols. Efficient coupling was evidenced by NMR and FTIR spectroscopy. Moreover, the characteristic fluorescence properties of the SiNPs remained unaltered, thus demonstrating the value of this approach towards functional oxide-free SiNPs. Activation of the attached carboxylic acid moieties allowed for conjugation of NH2-terminated oligo-ssDNA (ss=single strand) to the SiNPs. Successful coupling was confirmed by a characteristic new UV absorption band at 260nm, and by the still-present distinctive fluorescence of the SiNPs at 525nm. Gel electrophoresis confirmed coupling of 2 to 3 DNA strands onto the SiNPs, whereas no uncoupled DNA was observed.
Synthesis and effect of two new penetration enhancers on the transdermal delivery of 5-fluorouracil through excised rat skin
Hanif, Raja Muhammad,Qineng, Ping,Fenzhu, Muo
, p. 1428 - 1431 (2007/10/03)
The tetrahydrogeraniol (THG) derivative, ethyl-(3,7-dimethyl octyl thio) acetate (EDOTA) was prepared by reacting tetrahydrogeranyl bromide (obtained by reaction of 40% hydrobromic acid and concentrated sulfuric acid) with ethyl 2-mercaptoacetate, while 3,7-dimethyl octyl propionate (DOP) was synthesized by a common esterification reaction by reacting THG with propionic acid in the presence of cyclohexane and concentrated sulfuric acid. The penetration-enhancing effect of the new enhancers were compared with THG and Azone in vitro using excised rat skin in modified Franz-type diffusion cells. 5-Fluorouracil (5-FU), a hydrophilic drug with poor skin permeability was used as a model permeant. Skin samples were pretreated with pure liquid enhancers for 12 h. 5-FU flux through the control and enhancer-treated skin increased linearly with its concentration in the receptor compartment. EDOTA and DOP interacted with the skin rapidly (2 h), and the duration of action is at least 24 h. Significant differences were found in the flux values of 5- FU; EDOTA and DOP enhanced the permeability of the drug about 6-fold and 11- fold respectively. Increased partition coefficient and diffusion coefficient values were obtained by these enhancers. The results suggested that the amount of EDOTA and DOP in the skin, especially in the stratum corneum, may be related to their penetration-enhancing effect.
