Supramolecular organization of calix[4]pyrrole with a methyl-trialkylammonium anion exchanger leads to remarkable reversal of selectivity for sulfate extraction vs. nitrate

meso-Octamethylcalix[4]pyrrole (C4P) enhances sulfate selectivity in solvent extraction by Aliquat? 336N, an effect ascribed to the supramolecular preorganization and thermodynamic stability imparted by insertion of the methyl group of the Aliquat cation into the cup of C4P in its cone conformation.     

Synthetic Ditopic Receptors

A small, but emerging field of topical interest in supramolecularchemistry is ion-pair recognition, in which a host simultaneously binds both cationicand anionic guests. Details of these receptors, which combine, for example, crownethers and calixarenes for cation complexation, with Lewis acid centers, pyrroles, amidesor urea groups for anion recognition, will be discussed. The predicate of this approach,successfully achieved in certain instances, is that the binding of one guest ion caninduce electrostatic and conformational changes in the host, thereby enhancing thecomplexation of the counter ion.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.     

Photoinduced Reduction of PtIV within an Anti‐Proliferative PtIV–Texaphyrin Conjugate

In an effort to increase the stability and control the platinum reactivity of platinum–texaphyrin conjugates, two Pt^IV conjugates were designed, synthesized, and studied for their ability to form DNA adducts. They were also tested for their anti‐proliferative effects using wild‐type and platinum‐resistant human ovarian cancer cell lines (A2780 and 2780CP, respectively). In comparison to an analogous first‐generation Pt^II chimera, one of the new conjugates provided increased stability in aqueous environments. Using a combination of ¹H NMR spectroscopy and FAAS (flameless atomic‐absorption spectrometry), it was found that the Pt^IV center within this conjugate undergoes photoinduced reduction to Pt^II upon exposure to glass‐filtered daylight, resulting in an entity that binds DNA in a controlled manner. Under conditions in which the Pt^IV complex is reduced to the corresponding Pt^II species, these new conjugates demonstrated potent anti‐proliferative activity in both test ovarian cancer cell lines.     

Excitonically Coupled Cyclic BF2 Arrays of Calix[8]‐ and Calix[16]phyrin as Near‐IR‐Chromophores

Two giant calix[n]phyrin derivatives namely calix[8]‐ ( 4 ) and calix[16]phyrin ( 5 ), involving two and four BF₂ units, respectively, were prepared through the condensation of the bis‐naphthobipyrrolylmethene‐BF₂ complex ( 3 ) with pentafluorobenzaldehyde. Calix[n]phyrins 4 and 5 display extremely high extinction coefficients (3.67 and 4.82×10⁵ m ^?1 cm^?1, respectively) in the near‐IR region, which was taken as initial evidence for strong excitonic coupling within these cyclic multi‐chromophoric systems. Detailed insights into the effect of excitonic coupling dynamics on the electronic structure and photophysical properties of the macrocycles came from fluorescence, time‐correlated single‐photon counting (TCSPC) and transient absorption (TA) measurements. Support for these experimental findings came from theoretical studies. Theory and experiment confirmed that the coupling between the excitons depends on the specifics of the calix[n]phyrin structure, not just its size.