Synthesis of optically active vicinal fluorohydrins by lipase-catalyzed deracemization

Three microbial lipases have been used to deracemize trans-2-fluorocycloalkanols 2 both by hydrolysis of the corresponding acetates 3 or chloroacetates 4 and by esterification of the fluorohydrins 2 using vinyl acetate and vinyl chloroacetate, respectively. Pseudomonas cepacia lipase was the most selective for the six- and the seven-membered-ring compounds, while the lipase from Candida rugosa was most useful for the eight-membered-ring compounds. Both lipases transform the (R)-enantiomers preferentially. In contrast the lipase from Candida antarctica hydrolyzed the esters of trans-2-fluorocyclohexanol 2a and esterified the fluorohydrin itself with very low enantiopreference for the (R)-isomers. The seven- and the eight-membered ring esters and the corresponding fluorohydrins were also transformed with low, but reverse, enantioselectivity.     

Production of slow singly charged fragments in 200 GeV/c hadron nucleus interactions

Measurements of slow, singly charged fragments in the target rapidity region have been performed for proton and pion induced reactions with various nuclei at 200 GeV/c. Multiplicity, angular and energy distributions are examined and used to study the effects of rescattering in the nuclear medium. Data are compared to a geometric cascade model and to simulations with the VENUS 3.11 and the FRITIOF 1.7 Monte Carlo codes.     

High-resolution spectroscopy of bacteriochlorin in n-alkane host crystals at 4.2 K

Site-selection spectroscopy of free-base bacteriochlorin (7,8,17,18-tetrahydroporphin) in n-hexane, n-octane and n-decane at 4.2 K are reported. The vibrational frequencies of the ground state, and first and second excited singlet states were determined from the fluorescence and excitation spectra. Low-frequency modes were observed, from which the angle of reorientation of the Molecule upon excitation is estimated (< 1.5°).     

Pitfalls in the determination of optical homogeneous linewidths in amorphous systems by hole-burning. Influence of the structure of the host

An analysis is given of the conditions requires for the determination of the optical homogeneous linewidth (Γ_hom) in an organic glass from hole-burning experiments, in particular as regards laser power and detection method. The influence of the structure of polymer hosis on Γ_hom of free-base porphin as guest is studied with respect to solvents and size of polymer sidegroups.     

Investigation of therapeutic efficiency of phenytoin (PHT) labeled with radioactive 131I in the cancer cell lines

The aim of this study is to determine the incorporations of PHT radiolabeled with ¹³¹I (¹³¹I-PHT) on U-87 MG, Daoy and A549 cancerous cell lines. For this, cold and radio-labeling studies were carried out. The radio-labeling yield of ¹³¹I-PHT was obtained about 95 %. Subsequently, cell culture studies were carried out and radio-labeling yields of ¹³¹I, ¹³¹I-PHT on U-87 MG, Daoy and A549 cancerous cells were investigated. Cell culture studies demonstrated that the incorporation values of ¹³¹I-PHT on the three cell lines decreased with increasing radioactivity. Consequently, ¹³¹I-PHT may be a good radiopharmaceutical for targeting radionuclide therapy of Central Nervous System Tumors.     

Dendritic-Like Molecules Built on a Pillar[5]arene Core as Hole Transporting Materials for Perovskite Solar Cells

Multi-branched molecules have recently demonstrated interesting behaviour as charge-transporting materials within the fields of perovskite solar cells (PSCs). For this reason, extended triarylamine dendrons have been grafted onto a pillar[5]arene core to generate dendrimer-like compounds, which have been used as hole-transporting materials (HTMs) for PSCs. The performances of the solar cells containing these novel compounds have been extensively investigated. Interestingly, a positive dendritic effect has been evidenced as the hole transporting properties are improved when going from the first to the second-generation compound. The stability of the devices based on the best performing pillar[5]arene material has been also evaluated in a high-throughput ageing setup for 500 h at high temperature. When compared to reference devices prepared from spiro-OMeTAD, the behaviour is similar. An analysis of the economic advantages arising from the use of the pillar[5]arene-based material revealed however that our pillar[5]arene-based material is cheaper than the reference.