1449-68-9Relevant articles and documents
The Origin of Chalcogen-Bonding Interactions
Pascoe, Dominic J.,Ling, Kenneth B.,Cockroft, Scott L.
, p. 15160 - 15167 (2017)
Favorable molecular interactions between group 16 elements have been implicated in catalysis, biological processes, and materials and medicinal chemistry. Such interactions have since become known as chalcogen bonds by analogy to hydrogen and halogen bonds. Although the prevalence and applications of chalcogen-bonding interactions continues to develop, debate still surrounds the energetic significance and physicochemical origins of this class of σ-hole interaction. Here, synthetic molecular balances were used to perform a quantitative experimental investigation of chalcogen-bonding interactions. Over 160 experimental conformational free energies were measured in 13 different solvents to examine the energetics of O···S, O···Se, S···S, O···HC, and S···HC contacts and the associated substituent and solvent effects. The strongest chalcogen-bonding interactions were found to be at least as strong as conventional H-bonds, but unlike H-bonds, surprisingly independent of the solvent. The independence of the conformational free energies on solvent polarity, polarizability, and H-bonding characteristics showed that electrostatic, solvophobic, and van der Waals dispersion forces did not account for the observed experimental trends. Instead, a quantitative relationship between the experimental conformational free energies and computed molecular orbital energies was consistent with the chalcogen-bonding interactions being dominated by n → σ? orbital delocalization between a lone pair (n) of a (thio)amide donor and the antibonding σ? orbital of an acceptor thiophene or selenophene. Interestingly, stabilization was manifested through the same acceptor molecular orbital irrespective of whether a direct chalcogen···chalcogen or chalcogen···H-C contact was made. Our results underline the importance of often-overlooked orbital delocalization effects in conformational control and molecular recognition phenomena.
Asymmetric Heteroleptic Ir(III) Phosphorescent Complexes with Aromatic Selenide and Selenophene Groups: Synthesis and Photophysical, Electrochemical, and Electrophosphorescent Behaviors
Feng, Zhao,Wang, Dezhi,Yang, Xiaolong,Jin, Deyuan,Zhong, Daokun,Liu, Boao,Zhou, Guijiang,Ma, Miaofeng,Wu, Zhaoxin
, p. 11027 - 11043 (2018/09/14)
With the aim of evaluating the potential of selenium-containing groups in developing electroluminescent (EL) materials, a series of asymmetric heteroleptic Ir(III) phosphorescent complexes (Ir-Se0F, Ir-Se1F, Ir-Se2F, and Ir-Se3F) have been synthesized by using 2-selenophenylpyridine and one ppy-type (ppy = 2-phenylpyridine) ligand with a fluorinated selenide group. To the best of our knowledge, these complexes represent unprecedented examples of asymmetric heteroleptic Ir(III) phosphorescent emitters bearing selenium-containing groups. Natural transition orbital (NTO) analysis based on optimized geometries of the first triplet state (T1) have shown that the phosphorescent emissions of these Ir(III) complexes dominantly show 3π- π? features of the 2-selenophenylpyridine ligand with slight metal to ligand charge transfer (MLCT) contribution. In comparison with their symmetric parent complex Ir-Se with two 2-selenophenylpyridine ligands, these asymmetric heteroleptic Ir(III) phosphorescent complexes can show much higher phosphorescent quantum yields (φP) of ca. 0.90. Both the hole- and electron-trapping ability of these Ir(III) phosphorescent complexes can be enhanced by selenophene and fluorinated selenide groups to improve their EL efficiencies. The EL abilities of these asymmetric heteroleptic Ir(III) phosphorescent emitters fall in the order Ir-Se3F > Ir-Se2F > Ir-Se1F > Ir-Se0F. The highest EL efficiencies have been achieved by Ir-Se3F in the solution-processed OLEDs with external quantum efficiency (next), current efficiency (n L), and power efficiency (n P) of 19.9%, 65.6 cd A-1, and 57.3 lm W-1, respectively. These encouraging EL results clearly indicate the great potential of selenium-containing groups in developing high-performance Ir(III) phosphorescent emitters.
Base-catalyzed halogen dance reaction and oxidative coupling sequence as a convenient method for the preparation of dihalo-bisheteroarenes
Getmanenko, Yulia A.,Tongwa, Paul,Timofeeva, Tatiana V.,Marder, Seth R.
supporting information; experimental part, p. 2136 - 2139 (2010/08/05)
Figure presented A one-pot preparation of the 2,2′-dibromo-1, 1′-bisheteroarenes 3a-d from bromo-heteroarenes utilizing the sequence of the base-catalyzed halogen dance (BCHD) reaction and CuCl2-promoted oxidative coupling of the in situ formed α-lithio-β-halo-heteroarenes 2a-d provides a convenient access to precursors for the preparation of tricyclic heteroaromatic cores. The structures of 3a,b,d, 6, and 9 were confirmed by single-crystal X-ray analysis, and dibromides 3a and 3b were used for the preparation of dithieno-[2,3-b:3′,2′-d]-pyrrole 10a and its selenophene analogue 10b, respectively.
