123640-41-5Relevant articles and documents
Synthesis and electronic investigation of mono- and di-substituted 4-nitro- and 4-amino-pyrazol-1-yl bis(pyrazol-1-yl)pyridine-type ligands and luminescent Eu(III) derivatives
Strohecker,Lynch,Holliday,Jones
, p. 7733 - 7742 (2017)
Four new disubstituted and monosubstituted nitro- and amino- bis(pyrazol-1-yl)pyridine (bppy) ligands, substituted at the pyrazole 4-position (1, 2, 5, 6) have been synthesized, along with two luminescent Eu(iii) tris-β-diketonate derivatives of the amino
Redox-Induced Single-Molecule Magnetism in Mixed-Valent [2 × 2] Co4 Grid Complexes
Tong, Jin,Demeshko, Serhiy,John, Michael,Dechert, Sebastian,Meyer, Franc
, p. 4362 - 4372 (2016)
Homovalent [2 × 2] Co4 grid complexes [CoII4LH4](BF4)4 (1) and [CoII4LMe4](BF4)4 (2) with two new bis(terdentate) pyrazolate-bridged ligands, HLH = 3,5-bis(6-(1H-pyrazol-1-yl)pyrid-2-yl)pyrazole and HLMe = 4-methyl-3,5-bis(6-(1H-pyrazol-1-yl)pyrid-2-yl)pyrazole, were synthesized and comprehensively characterized. X-ray crystallographic analyses of 1 and 2 showed a square arrangement of cobalt(II) ions, each metal ion in distorted octahedral {N6} coordination created by two terdentate compartments from orthogonal ligand strands. Magnetic measurements revealed the metal ions high-spin (S = 3/2) state and moderate antiferromagnetic interactions to give an overall diamagnetic ST = 0 ground state of 1 and 2. Twofold oxidation, electrochemically or chemically, led to the dimixed-valent [2 × 2] Co4 grids [CoII2CoIII2LH4](BF4)6 (3) and [CoII2CoIII2LMe4](BF4)6 (4). ESI mass spectrometry confirmed the ruggedness of all grids 1-4 and their integrity in solution, and analysis of the UV/vis/NIR spectra suggested moderate electronic coupling. Solution 1H and 13C NMR spectra of paramagnetic 1-4 were recorded and confirmed that the dimixed-valent CoII2CoIII2 grids are charge-localized on the NMR time scale. X-ray crystallography revealed significant structural grid distortion upon oxidation, with the low-spin CoIII at opposite corners and in almost octahedral {N6} environment but the remaining CoII ions coordination sphere approaching a trigonal prism. SQUID studies showed the high-spin CoII to be magnetically isolated in the dimixed-valent CoII2CoIII2 grids, and both 3 and 4 to display frequency-dependent peaks in the out-of-phase (X′) component of the alternating-current (ac) magnetic susceptibility data, characteristic for single molecule magnet (SMM) properties (with energy barriers Ueff/kB = 16 and 26 K, and relaxation times 0 = 6.7·10-6 and 5.0·10-6 s for 3 and 4, respectively). The results are discussed in terms of cooperative effects that originate from elastic coupling within the grids, mediated by the rigid bridging ligands. These effects synergistically lead to the preferred trans configuration of the dimixed-valent CoII2CoIII2 grids and to structural distortions that are beneficial for SMM properties.
Palladium(II) pyrazolyl–pyridyl complexes containing a sterically hindered N-heterocyclic carbene moiety for the Suzuki-Miyaura cross-coupling reaction
Luconi, Lapo,Gafurov, Zufar,Rossin, Andrea,Tuci, Giulia,Sinyashin, Oleg,Yakhvarov, Dmitry,Giambastiani, Giuliano
, p. 100 - 105 (2018)
Cationic palladium complexes stabilized by a tridentate neutral {N,N,C} ligand containing a sterically hindered N-heterocyclic carbene (NHC) moiety have been prepared and characterized. The nature of the anionic counterion in the palladium complex has been varied to get crystals suitable for X-ray diffraction. The square planar structure of one of these complexes along with the axial contribution of the sterically hindered NHC fragment has been confirmed by X-ray analysis. In addition, all the isolated [{κ3-N,N,C}PdIICl]+X? [X? = Cl, PF6, BF4, B(C6H3Cl2)4] ion pairs have been scrutinized as catalysts in the cross-coupling Suzuki-Miyaura reaction between phenylboronic acid and variably substituted halo-aryl acceptors. Selected issues from this series have shown improved catalyst turn-over frequencies (TOFs) with respect to structurally related catalytic systems of the state-of-the-art.
Synergetic effect of CN∧N/C∧N∧N coordination and the arylacetylide ligands on the photophysical properties of cyclometalated platinum complexes
Wu, Wenting,Wu, Xueyan,Zhao, Jianzhang,Wu, Mingbo
supporting information, p. 2291 - 2301 (2015/04/27)
Six coordinated Pt(II) complexes were prepared, in which the CN∧N or the C∧N∧N ligand were used to form the Pt(II) coordination center. For each coordination profile, three different arylacetylide ligands were used, i.e. naphthalenediimide (NDI), pyrenyl (Py) and naphthaleneimide (NI) acetylides. The electrochemical and the photophysical properties of the complexes were studied with steady-state and time-resolved absorption and emission spectroscopy, cyclic voltammetry and DFT calculations. The photostability and the photoluminescent properties of the complexes are finely tuned by the photoredox and photophysical properties of the arylacetylide ligands and the CN∧N/C∧N∧N Pt(II) coordination center. The triplet excited states of the complexes are an intraligand feature and the lifetime is long (90.1 μs). The photophysical properties of the complexes were rationalized with DFT calculations. The complexes were used as triplet photosensitizer for triplet-triplet annihilation upconversion. The upconversion quantum yield was up to 29.7%. The results are useful for future designing of Pt(II) complexes showing strong visible light-absorption, RT phosphorescence and long-lived triplet excited states.