π-Stacking Modulates the Luminescence of [(dppz)Ni(Mes)Br] (dppz = dipyrido[3,2-a:2′,3′-c]phenazine, Mes = 2,4,6-trimethylphenyl)

Assessing the Character of the C6F5 Ligand from the Electrochemical and Photophysical Properties of [Ni(C6F5)2(N∧N)] Complexes

Organonickel complexes containing α-diimine ligands [Ni(C6F5)2(N∧N)] (N∧N = 2,2'-bipyridine (bpy), 2,9-dimethyl-1,10-phenanthroline (dmphen), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen), dipyrido[3,2-a:2',3'-c]phenazine (dppz), 1,4-bis(isopropyl)-1,4-diazabutadiene (iPr-DAB), and 1,4-bis(2,6-dimethylphenyl)-1,4-diazabutadiene (Xyl-DAB) were prepared and studied structurally, spectroscopically, and electrochemically. Their molecular structures from single-crystal X-ray diffraction show near-perfect square planar Ni(II) coordination except in the case of dmphen. Primary reversible electrochemical reductions in the range from -1 to -2 V vs ferrocene/ferrocenium couple lead to mainly diimine-localized radical anion complexes, while secondary reductions in the range from -2 to -2.5 V lead to dianion complexes, as shown through spectroelectrochemistry. Irreversible metal-centered oxidations at around 0.7 V result in rapid aryl-aryl reductive elimination and formation of decafluorobiphenyl. No photoluminescence was detected for the complexes containing chromophoric α-diimine ligands at room temperature. At 77 K in frozen glassy 2-Me-THF matrices, weak photoluminescence was detected for the dmphen and tmphen derivatives, with broad emission bands peaking around 570 nm. All results are rationalized with the support of (TD-)DFT calculations, highlighting the role of the C6F5 ligand in different systems.

Metal/N-donor-induced versatile structures and properties of seven 0D → 3D complexes based on dpq/dppz and O-bridged tricarboxylate: fluorescence and electrochemical behaviors

Seven 0D → 3D coordination polymers based on dpq/dppz and O-bridged tricarboxylates have been hydrothermally synthesized and structurally directed by metal ions, which show different electrochemical and fluorescence behaviors.

Directional Alignment of Polyfluorene Copolymers at Patterned Solid-Liquid Interfaces

Polyfluorene and its derivatives have been recognized as efficient light-emitting semiconductors. However, directional alignment of polyfluorene copolymers at a large scale has rarely been observed, in particular for the two relatively more amorphous members of poly-9,9-dioctylfluorene-co-bethiadisazole (F8BT) and poly-(9,9-dioctylfluorenyl-2,7-diyl)-co-(N,N0-diphenyl)-N,N′di(p-butyl-oxy-pheyl)-1,4-diamino-benzene) (PFB) molecules. Furthermore, the directional alignment of PFB has not been observed so far due to the triphenylamine units in its molecular structures. We present, in this work, a solution-processible method to achieve large-scale alignment of F8BT and PFB molecules into fibers as long as millimeters in a defined direction. Spin-coating the polymer film on to a glass substrate patterned by one-dimensional dielectric nano-grating structures through interference lithography and subsequent modification using 1,5-pentanediol have been used in all of the preparation procedures. Polymer fibers have been obtained in an arrangement parallel to the grating lines. The microscopic, spectroscopic, and photoconductive performances verified the formation and the quality of these directionally-aligned polymeric fibers.

Electrochemical methods for synthesis of organoelement compounds and functional materials

The new efficient and environmentally safe methods for preparation of various classes of organic and organoelement compounds, including organonickel sigma-complexes and organophosphorus compounds bearing P–C bonds have been created using the electrochemical methods. The synthetic application of the elaborated techniques towards the process of formation of new carbon-carbon, carbon-metal and carbon-phosphorus bonds are discussed. The mechanisms of the proposed processes and the nature of the formed in the overall electrochemical process intermediates are disclosed. The elaborated methods operated in the principals of “green chemistry” can be considered as an efficient alternative to some classical methods for preparation of active catalysts, biologically active molecules and new polynuclear complexes displaying practically useful properties.