82799-91-5Relevant articles and documents
Copper(II) complexes of two TEMPO-functionalized polypyridyl ligands: structure and catalytic activity in alcohol oxidation
Lu, Xiaoshuang,Wu, Nini,Zhang, Bingguang,Deng, Kejian
, p. 475 - 486 (2017)
The reaction of copper(II) salts with Bpy-TEMPO and Tpy-TEMPO (Bpy-TEMPO?=?[2,2′]Bipyridinyl-5,5′-dicarboxylic acid bis-[(2,2,6,6-tetramethyl-1-oxy-piperidin-4-yl)-amide]; Tpy-TEMPO?=?2,2,6,6-tetramethyl-4-(2,2′:6′,2″-terpyridin-4′-yloxy)piperidin-1-oxyl) gave dinuclear Bpy-TEMPO-Cu2 (1) and mononuclear Tpy-TEMPO-Cu (2), respectively. The Cu(II) complexes were characterized by single crystal X-ray analysis. In 1, Cu(II) has a distorted square pyramidal coordination geometry, with a bridging chloride as the axial ligand. The Cu(II) core in 2 also exhibited a distorted square pyramidal coordination geometry, with one chloride as an axial ligand. Weak interactions such as π-interactions and hydrogen bonds are observed in both complexes. When applied as catalysts for the oxidation of benzyl alcohol to benzaldehyde in air, 1 exhibited higher activity than 2 for reactions in o-xylene at 60°C with DBU as a base. High yield (67%) of benzaldehyde was observed when using 1 as a catalyst in a solution of o-xylene with DBU at 60°C.
Induction of diastereoselectivity in fe(II) Tris(amino acid-bipyridine) complexes
Ahn,Tae Woo Kim,Hong
, p. 5008 - 5011 (2001)
A group of iron(II) tris-bipyridine complexes bearing L-amino acids (L-Lys, L-Phe, L-Ser, L-Val) was prepared to investigate the predetermination of chirality of metal complexes by the chiral amino acid subunits. Noncovalent interactions and solvent polarity seemed to be important factors in inducing diastereoselectivity of the metal complexes. These phenomena were explained by 1H NMR and CD spectroscopic studies and molecular mechanics calculations.
Pigment-acceptor-catalyst triads for photochemical hydrogen evolution
Kitamoto, Kyoji,Sakai, Ken
, p. 4618 - 4622 (2014)
In order to solve the problems of global warming and shortage of fossil fuels, researchers have been endeavoring to achieve artificial photosynthesis: splitting water into H2 and O2 under solar light illumination. Our group has recently invented a unique system that drives photoinduced water reduction through "Z-scheme" photosynthetic pathways. Nevertheless, that system still suffered from a low turnover number (TON) of the photocatalytic cycle (TON=4.1). We have now found and describe herein a new methodology to make significant improvements in the TON, up to around TON=14-27. For the new model systems reported herein, the quantum efficiency of the second photoinduced step in the Z-scheme photosynthesis is dramatically improved by introducing multiviologen tethers to temporarily collect the high-energy electron generated in the first photoinduced step. These are unique examples of "pigment-acceptor-catalyst triads", which demonstrate a new effective type of artificial photosynthesis. Electron harvesting: Photo-hydrogen-evolving molecular devices showing substantially improved turnover numbers have been developed by introducing multiviologen tethers into a [PtCl2(2,2′-bipyridine)]-based moiety serving as a light-harvesting and H2-evolving center (see scheme). The improved photocatalytic performance is attributed to the rapidly regenerating character of the pigment due to intramolecular electron transfer from the pigment to the electron reservoirs.
Spectroscopic and 1O2 Sensitization Characteristics of a Series of Isomeric Re(bpy)(CO)3Cl Complexes Bearing Pendant BODIPY Chromophores
Potocny, Andrea M.,Teesdale, Justin J.,Marangoz, Alize,Yap, Glenn P. A.,Rosenthal, Joel
supporting information, p. 5042 - 5050 (2019/04/25)
Two new Re(I)bipyridyltricarbonyl chloride complexes, Re(BB3)(CO)3Cl and Re(BB4)(CO)3Cl, featuring BODIPY groups appended to the 5,5′- or 6,6′-positions of the bipyridine ligand, respectively, were synthesized as structurally isomeric compliments to a previously reported 4,4′-substituted homologue, Re(BB2)(CO)3Cl. X-ray crystal structures of the compounds show that the 4,4′-, 5,5′-, and 6,6′-substitution patterns place the BODIPY groups at progressively shorter distances of 9.43, 8.39, and 5.56 ?, respectively, from the complexes' Re centers. The photophysical properties of the isomeric complexes were investigated to ascertain the manner in which the heavy rhenium atom might induce intersystem crossing of the pendant BODIPY moieties positioned at progressively shorter through-space distances. Electronic absorption spectroscopy revealed that the three metal complexes retain the strong visible absorption features characteristic of the bpyBODIPY (BB2-BB4) ligands; however, the fluorescence of the parent borondipyrromethane appended ligands is attenuated by more than an order of magnitude in Re(BB2)(CO)3Cl and Re(BB3)(CO)3Cl and by more than two orders of magnitude in Re(BB4)(CO)3Cl. Furthermore, phosphorescence from Re(BB4)(CO)3Cl is observed under a nitrogen atmosphere, consistent with highly efficient ISC to the triplet-excited state. Singlet oxygen sensitization studies confirm that all three complexes produce singlet oxygen with quantum yields that increase as the distance of the BODIPY groups to the heavy rhenium center is decreased. The trends observed across the series of rhenium complexes with respect to emission and 1O2 sensitization properties can be rationalized in terms of the varied distal separation between the metal center and BODIPY groups in each system.
Platinum(II)-glutamic acid dendrimer conjugates: Synthesis, characterization, DFT calculation, conformational analysis and catalytic properties
Lataifeh, Anas,Kraatz, Heinz-Bernhard,Awwadi, Firas F.,Zaitoun, Mohammed A.,Sakai, Ken
, p. 245 - 254 (2018/02/09)
A series of platinum(II)-L-glutamic acid dendrimer conjugates having the formula PtCl2(5,5′-Gn(OR)-2,2′-bipyridine); Gn (n = 0, 1, 2), have been synthesized by various amide bond formation methods. The dendrimer complexes were terminated as car
