Zirconium arene-phosphonates: chemical and structural characterization of 2-naphthyl- and 2-anthracenylphosphonate systems

Several new zirconium phosphonates incorporating naphthalene and anthracene ring systems and having the general formula Zr(O3PR)1(O3PR')1 [R and R' = -C10H7, -C14H9, -OC4H9, and -OC2H5] have been synthesized. These compounds were chemically characterized using thermal gravimetric analysis (percentage of organic content), infrared spectroscopy (presence of the desired organic functional groups), and solid-state 31P NMR (phosphorus environments), while the structural parameters were determined using X-ray powder diffraction (interlayer d spacings). The d spacings of the zirconium bis(phosphonates) correlate well with a simple predictive model based on the effective length of the organic functional group. The zirconium mixed phosphonates examined are single-phase structures with random mixtures of the organic moieties within the interlayer and possess d spacings that are between those of the two parent zirconium bis(phosphonates).     

Displacement reactions of 2-chloro- and 2,9-dichloro-1,10-phenanthroline: synthesis of a sulfur-bridged bis-1,10-phenanthroline macrocycle and a 2,2′-amino-substituted-bis-1,10-phenanthroline

The synthesis and structural assignments of 9-chloro-1,1-phenanthroline-2(1H)-thione and 1,10-dihydro-1,10-phenanthroline-2,9-dithione have been accomplished. The sulfur-bridged bis-1,10-phenanthroline macrocycle was readily prepared by heating the thione or equimolar amounts of the dithione and 2,9-dichloro-1,10-phenanthroline in diphenyl ether. Displacements of 2-chloro- or 2,9-dichloro-1,10-phenanthroline with N,N-dimethylethylenediamine afforded the corresponding amine and diamino analogues. An amino-substituted-2,2′-bis-1,10-phenanthroline has been prepared.     

Excimer formation in the interlayer region of arene-derivatized zirconium phosphonates

Photophysical investigations are reported for two arene-derivatized zirconium phosphonates (layered solids). The chromophore groups that are attached within the interlayer region of these materials are seen to form excimer pairs. Whereas the naphthalene-containing system exhibits both monomer and excimer fluorescence, the potentially greater overlap of chromophores for the system containing anthracene-pendant groups causes that compound to only show excimer fluorescence.     

OPTICAL-MICROWAVE DOUBLE RESONANCE SPECTROSCOPY OF IN VIVO CHLOROPHYLL

At low temperatures, chloroplast and subchloroplast preparations exhibit complex fluorescence spectra. Emission bands can be attributed to photosystem (PS) particles and various antenna-chl proteins as well as solubilized chls. Initial results from a systematic study of the components of these fluorescence spectra via optical-microwave double resonance spectroscopy are presently reported. Conclusions regarding possible structural features are discussed. Experiments on triplet sublevel decay rates yielded data consistent with an interpretation of triplet energy transfer within antenna fragments.     

A comparative study of dimerization of chlorophylls and pheophytins by fluorescence and odmir

Optical and ODMR data for dimers of pheophytin a and b and chlorophyll a and b are presented. It is proposed that pheophytin a forms a parallel dimer arising from π-π interaction, binding being essentially different from that in the corresponding chlorophyll dimer. The dimer of phcophytin a is less stable (K ≈ 10⁴ ol/mol) than that of chlorophyll a(K ≈ 10⁶ ol/mol).     

Raman spectroscopy can discriminate distinct glioma subtypes as defined by RNA expression profiling

Raman spectroscopy is a molecular spectroscopic technique that can measure the molecular composition of tissue samples within seconds without any extraction processes or dyes. In microbiology, Raman spectroscopy is used to identify bacteriae. In glioblastoma tissue, it was reported that necrosis, normal brain and tumor can be discriminated using Raman spectroscopy. Therefore, we hypothesized that Raman spectroscopy could discriminate glioblastoma tissue from different glioma subtypes defined by RNA expression profiling. We analyzed 20 glioma samples from two distinct molecular subtypes. Both subtypes consisted of glioblastoma samples showing a variety in glioma grading and typing. The Raman spectroscopic results could be grouped in two distinct clusters in an unsupervised cluster analysis. Further analysis of these clusters showed that they were fully congruent with the two clusters as defined by RNA expression profiling. Conclusion: our results demonstrate that Raman spectroscopy can discriminate between different molecular subtypes of glioma and, therefore, may prove to be a valuable tool in in vitro cancer research. Copyright © 2013 John Wiley & Sons, Ltd.