Werner Complexes Can Still Surprise: The Chelated OBOH Ligand.

The synthesis and characterization of the Co(III) complex [Co(pmap)(OBOH)]ClO·4HO (pmap = bis(2-(2-pyridyl)ethyl)-(2-pyridylmethyl)amine) are reported. This is an unprecedented example of a mononuclear transition metal complex containing an oxoanion ligand derived from the deprotonation of boric acid. The complex was synthesized by air oxidation of a solution containing [Co(OH)](ClO), pmap, and borax (NaBO·10HO), with purification effected by cation exchange chromatography.

1,3-Dipolar cyclisation reactions of nitriles with sterically encumbered cyclic triphosphanes: synthesis and electronic structure of phosphorus-rich heterocycles with tunable colour.

We describe the synthesis, solid state and electronic structures of a series of tunable five-membered cationic and charge-neutral inorganic heterocycles featuring a PCN core. 1-Aza-2,3,4-triphospholenium cations [(PR)N(H)CR'], [1] (R' = Me, Ph, 4-MeOCH, 4-CFCH) were formed as triflate salts by the formal [3 + 2]-cyclisation reactions of strained cyclic triphosphanes (PR) (R = Bu, 2,4,6-MeCH (Mes), 2,6- PrCH (Dipp), 2,4,6- PrCH (Tipp)) with nitriles R'CN in the presence of triflic acid. The corresponding neutral free bases (PR)NCR' (2) were readily obtained by subsequent deprotonation with NEt.

Robust S ⋅⋅⋅O Supramolecular Synthons: Structures of Radical-Radical Cocrystals [p-XC F CNSSN] [TEMPO] (X=F, Cl, Br, I, CN).

Cocrystallization of the dithiadiazolyl (DTDA) radicals p-XC F CNSSN (X=F, Cl, Br, I, CN) with TEMPO afforded the 2 : 1 cocrystals [p-XC F CNSSN] [TEMPO] (1-5) whose structures all reflect a common S ⋅⋅⋅O supramolecular motif. The nature of this interaction was probed by DFT calculations (M06/aug-cc-pVDZ) on 1 which revealed that the enthalpy of formation of the [C F CNSSN] [TEMPO] supramolecular motif from [C F CNSSN] and TEMPO is substantial (-54.0 kJ mol ).

Structural, Magnetic, and Optical Studies of the Polymorphic 9'-Anthracenyl Dithiadiazolyl Radical.

The fluorescent 9'-anthracenyl-functionalized dithiadiazolyl radical (3) exhibits four structurally determined crystalline phases, all of which are monomeric in the solid state. Polymorph 3α (monoclinic P2/ c, Z' = 2) is isolated when the radical is condensed onto a cold substrate (enthalpically favored polymorph), whereas 3β (orthorhombic P2 2 2, Z' = 3) is collected on a warm substrate (entropically favored polymorph). The α and β polymorphs exhibit chemically distinct structures with 3α exhibiting face-to-face π-π interactions between anthracenyl groups, while 3β exhibits edge-to-face π-π interactions.

On the Design of Radical-Radical Cocrystals.

Formation of radical-radical cocrystals is an important step towards the design of organic ferrimagnets. We describe a simple approach to generate radical-radical cocrystals through the identification and implementation of well-defined supramolecular synthons which favor cocrystallization over phase separation. In the current paper we implement the structure-directing interactions of the E-E bond (E=S, Se) of dithiadiazolyl (DTDA) and diselenadiazolyl (DSDA) radicals to form close contacts to electronegative groups.

Multifunctional Dithiadiazolyl Radicals: Fluorescence, Electroluminescence, and Photoconducting Behavior in Pyren-1'-yl-dithiadiazolyl.

The pyren-1'-yl-functionalized dithiadiazolyl (DTDA) radical, CHCNSSN (1), is monomeric in solution and exhibits fluorescence in the deep-blue region of the visible spectrum (440 nm) upon excitation at 241 nm. The salt [1][GaCl] exhibits similar emission, reflecting the largely spectator nature of the radical in the fluorescence process, although the presence of the radical leads to a modest quenching of emission (Φ = 98% for 1 and 50% for 1) through enhancement of non-radiative decay processes. Time-dependent density functional theory studies on 1 coupled with the similar emission profiles of both 1 and 1 are consistent with the initial excitation being of predominantly pyrene π-π* character.

Synthesis and characterization of Ciprofloxacin-containing divinyl oligomers and assessment of their biodegradation in simulated salivary esterase.

Objective: Two leading causes contributing to dental restoration replacement are the marginal breakdown at the composite/dentin interface and secondary caries mediated by bacteria. The objective of the present study was to synthesize oligomers which incorporated enhanced bio-stability but would also be able to generate antimicrobial function if they underwent degradation.

Methods: Stability was incorporated into the oligomers by generating structural features that would physically hinder the availability of hydrolytically sensitive groups in the oligomers.