Search

The new Cu(I) complex [Cu(PNPNTPh-Ph)Cl] (1) containing the tridentate PNP pincer ligand N,N '-bis(diphenylphosphino)-2,6-diamino-4-phenyl-1,3,5-triazine was obtained from the reaction of [Cu(SMe2)Cl](n) with the ligand as ether solvate 1(.)0.5Et(2)O. 1 was independently obtained from a reaction mixture containing the ligand and the Cu(II) precursor CuCl(2)(.)2H(2)O in 50 % yield alongside with the Cu(II) coordination polymer [Cu(O2PPh2)(2)](n) (2). From the reaction of Cu(NO3)(2) . 3H(2)O with PNPNTPh-Ph in the presence of pyridine the complexes [Cu(O2PPh2)(2)(Py)(2)(H2O)] (3), [Cu(O2PPh2)(Py)(2)(NO3)](2) (4), and [Cu(Py)(4)(NO3)(2)]Py-. (5), were obtained, 2, 3, and 4 contain diphenyl-phosphinate ligands. The underlying redox reaction of the ligand and Cu(II) yielding the oxidised ligands observed in the by-products and the Cu(I) product complex was further studied using electrochemistry and UV-vis spectroelectrochemistry. Attempts to synthesise the Cu(II) complex [Cu(PNPNTPh-Ph)(NO3)(2)] (6) in a mechanochemical experiment gave evidence for this unprecedented species from ESI-MS(+) and EPR spectroscopy but also revealed its very high sensitivity to air and moisture. The catalytic activity of 1 was investigated in the azide-alkyne cycloaddition yielding various 1-benzyl-4-phenyl-1H-1,2,3-triazoles. The environmentally benign (green) and cheap EtOH/H2O solvent mixture turned out to be very suitable. Melting points, FT-IR, and NMR spectra of the triazole products were analysed.

A series of novel cyclometalated Ru-II complexes were investigated featuring the tridentate dqp ligand platform (dqp is 2,6-di(quinolin-8-yl)pyridine), in order to utilize the octahedral coordination mode around the Ru center to modulate the electrochemical and photophysical properties. The heteroleptic complexes feature C-1 symmetry due to symmetry breaking by the peripheral five- or six-membered carbanionic chelate (phenyl, naphthyl, or anthracenyl units). The chelation mode is controlled by the steric effects and C-H activation selectivity of the ligand, which prompted the development of a general synthesis protocol. The optimized conditions to achieve high overall yields (55-75%) involve NaHCO3 as the base and an simplified purification protocol: i.e., facile chromatographic separation using commercially available amino-functionalized silica applying nonaqueous salt-free conditions to omit the necessity of counterion exchange. The structural, photophysical, and electrochemical properties were studied in depth, and the results were corroborated by density functional theory (DFT) calculations. Steady state and time-resolved spectroscopy revealed red-shifted absorption (up to 750 run) and weak IR emission (800-1000 nm) combined with prolonged emission lifetimes (up to 20 ns) in comparison to classical tpy-based (tpy is 2,2':6',2 ''-terpyridine) complexes. An enhanced stability was observed by blocking the reactive positions of the carbanionic ligand framework, while the reactive positions may be exploited for further functionalization., Title in WoS: Asymmetric Cyclometalated Ru-II Polypyridyl-Type Complexes with pi-Extended Carbanionic Donor Sets

Bis-tridentate Ru-II complexes based on the dqp scaffold (dqp is 2,6-di(quinolin-8-yl)pyridine) with multiple aryl substituents were explored to tailor the absorption and emission properties. A synthetic methodology was developed for the facile synthesis and purification of homo- and heteroleptic bis-tridentate Ru complexes. The effect of the aryl substituents in the para positions of the pyridine and quinoline subunits was detailed by X-ray crystallography, steady state and time-resolved spectroscopy, electrochemistry, and computational methods. The attachment of the aryl groups results in enhanced molar extinction coefficients with the largest effect in the pyridine position, whereas the quinoline substituent leads to red-shifted emission tailing into the NIR region (up to 800 nm). Notably, the excited state lifetimes remain in the microsecond time scale even in the presence of O-2, whereas the emission quantum yields are slightly increased with respect to the parental complex [Ru(dqp)(2)](2+). The peripheral functional groups (Br, Me, OMe) have only a minor impact on the optical properties and are attractive to utilize such complexes as functional building blocks.

Poly(2-ethyl-2-oxazoline)s (PEtOx23 - Mn = 2300 g mol-1, D = 1.07; PEtOx46 - Mn = 4400 g mol-1, D = 1.06) end-functionalized with a maleimide moiety were prepared from azide-terminated PEtOxx-N3via copper-catalyzed azide-alkyne cycloaddition (CuAAC) with an alkyne-bearing maleimide (MI). The latter has been synthesized in a three-step procedure, including protection of the maleimide double bond prior to the modification of PEtOx. PEtOxx-MI was characterized by NMR (1H, 13C), SEC, FT-IR, and MALDI-ToF MS and, after deprotection of the maleimide, used in nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) processes for covalent attachment to silicon surfaces in a grafting-to approach. © The Royal Society of Chemistry 2016.

Optimized syntheses of 2-coumaranone derivatives and, based thereon, several new representatives of this class of substances are described. They show a clearly visible chemiluminescence under the exposure of a strong base and in the presence of oxygen. The wavelength and intensity of the light emitted depends on both the substituents on the benzo annealed, as well as on the type of base used. A mechanism is presented in which a delocalized enolate is postulated as a key intermediate.