Supramolecular macrocycles reversibly assembled by Te ⋯ O chalcogen bonding

Organic molecules with heavy main-group elements frequently form supramolecular links to electron-rich centres. One particular case of such interactions is halogen bonding. Most studies of this phenomenon have been concerned with either dimers or infinitely extended structures (polymers and lattices) but well-defined cyclic structures remain elusive. Here we present oligomeric aggregates of heterocycles that are linked by chalcogen-centered interactions and behave as genuine macrocyclic species. The molecules of 3-methyl-5-phenyl-1,2-tellurazole 2-oxide assemble a variety of supramolecular aggregates that includes cyclic tetramers and hexamers, as well as a helical polymer. In all these aggregates, the building blocks are connected by Te(…)O-N bridges. Nuclear magnetic resonance spectroscopic experiments demonstrate that the two types of annular aggregates are persistent in solution. These self-assembled structures form coordination complexes with transition-metal ions, act as fullerene receptors and host small molecules in a crystal

Experimental and theoretical studies of the products from the reactions of silylated amidines with organosulfur chlorides

Bibliography: p. 153-166

Supramolecular Chromotropism of the Crystalline Phases of 4,5,6,7-Tetrafluorobenzo-2,1,3-telluradiazole

The remarkable effect that secondary bonding interactions can have on the macroscopic properties of a material is illustrated by two polymorphs of the title compound. The phase which is most stable under ambient pressure and temperature consists of puckered supramolecular ribbon polymers assembled by Te--N secondary bonding interactions and displays a characteristic red-orange color. A second yellow phase consists of ribbons with alternating short and long intermolecular Te--N secondary bonding distances and is metastable; at 127 \ub0C the material undergoes an exothermic irreversible transition to the red polymorph. A third phase consists of pyridine-solvated supramolecular dimers; it is also yellow and transforms into the red phase after the crystals effloresce. Computational DFT studies indicate that the observed changes in optical properties are related to intermolecular mixing of \u3c0 orbitals enabled by the supramolecular interactions and the symmetry of the supramolecular synthon.Peer reviewed: YesNRC publication: Ye

Experimental and Theoretical Investigations of Tellurium(IV) Methanediides and Their Insertion Products with Sulfur and Iodine

The reactions of Li₂[C­(Ph₂PS)₂] with tellurium tetrahalides in a 1:1 molar ratio in toluene afford the complexes {TeX₂[C­(Ph₂PS)₂]}₂ (<b>7a</b>, X = Cl; <b>7b</b>, X = Br; <b>7c</b>, X = I). These complexes dimerize through halide bridges in the solid state, and the tridentate ligand is <i>S,C,S-</i>coordinated to the tellurium center with a Te–C bond length of 2.024(3), 2.030(6), and 2.045(8) Å, respectively. In the case of TeBr₄, small amounts of the complex TeX₂[SC­(Ph₂PS)₂] (<b>8b</b>, X = Br) were isolated and shown by X-ray analysis to be the result of formal sulfur insertion into the Te–C bond of <b>7b</b>. Complex <b>8b</b> and the corresponding dichloride and diiodide, <b>8a</b> (X = Cl) and <b>8c</b> (X = I), may be prepared in good yields by the metathetical reactions of Li₂[SC­(Ph₂PS)₂] with TeX₄ in toluene. The complex TeI₂[(I₂)­C­(Ph₂PS)₂] (<b>9</b>) was isolated as a minor product from the reaction of Li₂[C­(Ph₂PS)₂] and TeI₄ and identified by X-ray crystallography. Complex <b>9</b> is constructed from the insertion of an iodine atom of an I₂ molecule into the Te–C bond of <b>7c</b>, resulting in a T-shaped geometry at that iodine atom and an almost linear Te–I–I unit with an elongated I–I bond; the C–I bond length is typical for a C­(sp³)–I bond. DFT calculations supplemented with Hirshfeld charge analysis, Boys–Foster localization of molecular orbitals, and evaluation of the electron localization functions indicate that in these species the ligand engages predominantly in σ bonding through the lone pairs on the carbon and sulfur atoms. The latter atoms participate in three-center interactions with tellurium. The bonds between the heavy elements and carbon are strongly polarized, and the character of the latter atom ranges from sp² to sp³

Planar P6E6 (E = Se, S) macrocycles incorporating P2N2 scaffolds

Oxidation of alkali metal derivatives of the dianions [E((BuN)-Bu-t)P(mu-(NBu)-Bu-t)(2)P((NBu)-Bu-t)E](2-) (E = S, Se) with I-2 produces 15-membered macrocycles in which a planar P6E6 motif is stabilised by perpendicular P2N2 scaffolds.PostprintPeer reviewe

Photophysical Tuning of the Aggregation-Induced Emission of a Series of Para-Substituted Aryl Bis (Imino)Acenaphthene Zinc Complexes

Bis(imino)acenaphthene (BIAN) zinc complexes with para-substituted aryl groups have been synthesized and investigated from the standpoint of their photophysical properties. Each complex was found to be nonemissive in solution. However, complexes 1-6 turned out to be emissive in the solid state, while complexes 7 and 8 remained nonemissive. The emissions for complexes 1-8 displayed color tunability ranging from red-yellow. A detailed crystallographic study of the "as-synthesized" structures revealed a distinct difference in the crystal packing environments of the emissive and nonemissive complexes. Furthermore, a solvatomorphic study provided further emission tunability via changes in the crystal packing environments of each solvatomorph. Lastly, TD-DFT calculations were performed in order to investigate the effect of different para-substituents on the flanking aryl rings of the BIAN ligand.Robert A. Welch foundation F-0003Canada Natural Sciences and Engineering Research CouncilChemistr